[Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling

[SyedAbdulAzeemSF4852]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Issue Details

• When downsizing an image to a specific width and height, the aspect ratio is not maintained on Android and Windows. Instead, the image is resized to the exact dimensions provided.
• In contrast, iOS and macOS preserve the aspect ratio during downsizing.

Root Cause

Android & Windows :

• The original implementation did not maintain the image's aspect ratio when both maxWidth and maxHeight were provided. It directly scaled the image to those dimensions.

Description of Change

Android & Windows :

• The updated implementation unifies the resizing logic by having the single-parameter overload delegate to the two-parameter version, reducing code duplication.
• It calculates a proportional scaling factor based on both width and height constraints, ensuring the aspect ratio is preserved. Resizing is now only performed if the original image exceeds the provided size limits, improving efficiency and correctness.

iOS & MacOS :

• The original implementation used a two-step scaling process—first scaling based on width, then correcting based on height if needed. The new implementation improves this by first checking whether resizing is necessary, then calculating scaling factors for both width and height, and applying the smaller factor to maintain the image's aspect ratio while fitting it within the specified maximum dimensions. If the image is already within bounds, it returns the original image without modification.

Issues Fixed

Fixes #30803

Validated the behaviour in the following platforms

• Windows
• Android
• iOS
• Mac

Output

Platform	Before	After
Android	Android_Before.mov	Android_After.mov
Windows	Windows_Before.mp4	Windows_After.mp4

[dotnet-policy-service]

Hey there @@SyedAbdulAzeemSF4852! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[Copilot]

Pull Request Overview

This pull request fixes a bug where the Downsize method in image processing was not maintaining aspect ratio when both maxWidth and maxHeight parameters were specified on Android and Windows platforms. The fix unifies the behavior across all platforms (Android, Windows, iOS, macOS) to properly preserve aspect ratios during image downsizing.

Key changes:

• Updated downsizing algorithms to calculate proportional scaling factors using Math.Min(factorX, factorY) to maintain aspect ratio
• Refactored single-parameter overloads to delegate to two-parameter versions, reducing code duplication
• Added early return optimization when images are already within size bounds

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Graphics/src/Graphics/Platforms/iOS/UIImageExtensions.cs	Simplified scaling logic to use minimum factor approach and early return
src/Graphics/src/Graphics/Platforms/Windows/PlatformImage.cs	Fixed aspect ratio preservation and unified overload implementations
src/Graphics/src/Graphics/Platforms/Android/GraphicsExtensions.cs	Updated downsizing to maintain aspect ratio using minimum scaling factor
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30803.cs	Added automated UI test to verify aspect ratio preservation
src/Controls/tests/TestCases.HostApp/Issues/Issue30803.cs	Created test UI page with downsize functionality validation

[jsuarezruiz]

/azp run

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Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://github.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 30808

Or

• Run remotely in PowerShell:

iex "& { $(irm https://github.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 30808"

[rmarinho]

🤖 AI Summary

📊 Expand Full Review

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🔍 Pre-Flight — Context & Validation

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📝 Review Session — Refactor LoadImage to synchronous and clean up formatting · 10d03bc

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Issue: #30803 - [Android & Windows] In GraphicsView, the aspect ratio is not maintained when Downsize is called with both maxWidth and maxHeight
PR: #30808 - [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling
Platforms Affected: Android, Windows (iOS also refactored for consistency)
Files Changed: 3 implementation files, 2 test files, 2 snapshot files

Issue Summary

When calling Downsize(maxWidth, maxHeight) on Android and Windows, the image was being stretched to exact dimensions rather than maintaining its aspect ratio. iOS/macOS already preserved aspect ratio correctly.

Steps to reproduce: run sample on Android/Windows, tap "Downsize (10x10)", observe image stretched to exact 10x10 instead of preserving ratio (which should be 10x8 for an image with ~5:4 aspect ratio).

Reviewer Discussion

File:Line	Reviewer Says	Author Says	Status
GraphicsExtensions.cs:445	Handle edge cases: zero/negative dimensions	Added guard when maxWidth or maxHeight <= 0	✅ Resolved
Issue30803.cs:70	Magic number hardcoded dimensions (10x8) should use constants	Not addressed	⚠️ Open (Copilot suggestion)
Issue30803.cs:56	Magic downsize dimensions (10, 10) should be constants	Not addressed	⚠️ Open (Copilot suggestion)

Edge Cases Noted

• Zero/negative dimensions - handled (guard added per jsuarezruiz review)
• Image already within maxWidth/maxHeight bounds - returns original (not explicitly tested)

File Classification

• Fix files:
  • src/Graphics/src/Graphics/Platforms/Android/GraphicsExtensions.cs (+17/-25)
  • src/Graphics/src/Graphics/Platforms/Windows/PlatformImage.cs (+17/-7)
  • src/Graphics/src/Graphics/Platforms/iOS/UIImageExtensions.cs (+14/-11)
• Test files:
  • src/Controls/tests/TestCases.HostApp/Issues/Issue30803.cs (+77)
  • src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30803.cs (+25)
• Snapshot files:
  • src/Controls/tests/TestCases.Android.Tests/snapshots/android/ImagePaintWithDownsize.png
  • src/Controls/tests/TestCases.WinUI.Tests/snapshots/windows/ImagePaintWithDownsize.png
• Test type: UI Tests

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #30808	Use Math.Min(factorX, factorY) to find minimum scaling factor; single-param overload delegates to two-param; iOS refactored to same unified approach; added guard for zero/negative values	⏳ PENDING (Gate)	GraphicsExtensions.cs (+17/-25), PlatformImage.cs (+17/-7), UIImageExtensions.cs (+14/-11)	Original PR

Prior Agent Review

A prior agent review was found (by rmarinho). Pre-Flight was completed, but Gate was marked ⏳ PENDING. Re-running full workflow.

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🚦 Gate — Test Verification

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📝 Review Session — Refactor LoadImage to synchronous and clean up formatting · 10d03bc

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Result: ✅ PASSED
Platform: android
Mode: Full Verification

Check	Expected	Actual	Result
Tests WITHOUT fix	FAIL	FAIL	✅
Tests WITH fix	PASS	PASS	✅

• Tests FAIL without fix ✅ (bug is present - image is 10x10 instead of 10x8)
• Tests PASS with fix ✅ (aspect ratio correctly preserved - image is 10x8)

Test: VerifyDownsizeMaintainsRatioWithMaxWidthHeight in Issue30803
Device: emulator-5554

Fix Candidates (Updated)

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #30808	Use Math.Min(factorX, factorY) scaling factor; single-param overload delegates to two-param	✅ PASS (Gate)	GraphicsExtensions.cs (+17/-25), PlatformImage.cs (+17/-7), UIImageExtensions.cs (+14/-11)	Original PR

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🔧 Fix — Analysis & Comparison

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📝 Review Session — Refactor LoadImage to synchronous and clean up formatting · 10d03bc

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Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix (claude-sonnet-4.6)	Aspect ratio comparison: compute imageAspect = W/H, boundsAspect = maxW/maxH; pick constraining dimension directly	✅ PASS	GraphicsExtensions.cs (+16/-23)	Mathematically equivalent to PR, different algorithmic path
2	try-fix (claude-opus-4.6)	Try-width-first: compute proportional height assuming width constraint; fall back to height constraint if it overflows	✅ PASS	GraphicsExtensions.cs (+30/-24)	More branches, same correctness
3	try-fix (gpt-5.2)	Android Matrix.SetRectToRect with ScaleToFit.Center delegates bounding-box fit to Android's matrix API	✅ PASS	GraphicsExtensions.cs (+15/-1)	Uses Android API but adds complexity; ScaleToFit.Center centers, may leave empty space
4	try-fix (gpt-5.3-codex)	Delegate Downsize(maxWidth, maxHeight) to Downsize(Math.Min(maxWidth, maxHeight)) — reuse single-dimension overload	✅ PASS	GraphicsExtensions.cs	Only correct when bounds are square; incorrect if maxWidth ≠ maxHeight in extreme cases
5	try-fix (gemini)	Matrix.PostScale(factor, factor) + Bitmap.CreateBitmap(..., matrix, true) where factor = Math.Min(factorX, factorY)	✅ PASS	GraphicsExtensions.cs (+15/-10)	Correct but adds matrix object overhead vs direct CreateScaledBitmap
6	try-fix (gpt-5.2 R2)	Explicit targetW/targetH via float cross-multiplication + CreateScaledBitmap(targetW, targetH)	✅ PASS	GraphicsExtensions.cs	Very similar to PR; clean
7	try-fix (gpt-5.3-codex R2)	Two-pass integer-floor: (srcH * maxW) / srcW, fall back if > maxH	❌ FAIL	GraphicsExtensions.cs	Floor gives 7 instead of 8 for 512×384 image; rounding matters
8	try-fix (gpt-5.2 R3)	Rounding cross-multiplication with MidpointRounding.AwayFromZero; try-width-first, fall back to height	✅ PASS	GraphicsExtensions.cs	Correct but more verbose than PR
PR	PR #30808	Math.Min(factorX, factorY) uniform scale factor; single-param delegates to two-param; guard for zero/negative bounds; early return if image within bounds	✅ PASS (Gate)	GraphicsExtensions.cs (+17/-25), PlatformImage.cs (+17/-7), UIImageExtensions.cs (+14/-11)	Original PR — cleanest, most readable, cross-platform unified

Cross-Pollination Summary

Round	claude-sonnet-4.6	claude-opus-4.6	gpt-5.2	gpt-5.3-codex	gemini
R2	NO NEW IDEAS	NO NEW IDEAS	NEW (→ Attempt 6)	NEW (→ Attempt 7)	NO NEW IDEAS
R3	NO NEW IDEAS	NO NEW IDEAS	NEW (→ Attempt 8)	NO NEW IDEAS	NEW (inSampleSize — skipped, power-of-2 only)
R4	NO NEW IDEAS	NO NEW IDEAS	NEW (area-maximization variant)	NO NEW IDEAS	NEW (Canvas.DrawBitmap variant)

Exhausted: Yes (past 3-round max; remaining ideas are incremental variations of already-explored approaches)

Selected Fix: PR's fix — the Math.Min(factorX, factorY) approach is the simplest, most readable, and most consistent across platforms. It unifies Android, Windows, and iOS with the same algorithm. 7 independent alternatives all confirmed this is the correct approach; none were simpler or more robust.

Root Cause

The original Downsize(maxWidth, maxHeight) on Android called Bitmap.CreateScaledBitmap(target, maxWidth, maxHeight, true) — directly stretching to exact dimensions with no aspect ratio preservation. On Windows, the same pattern existed. The fix computes a uniform scale factor Math.Min(factorX, factorY) that fits the image within both bounds while preserving aspect ratio.

Why Attempt 4 Has a Caveat

Delegating to Downsize(Math.Min(maxWidth, maxHeight)) only works correctly when the image is roughly square or the bounds are square. For example, Downsize(100, 50) on a 200×200 image would use maxSize=50, producing 50×50, but the correct result is 50×50 — coincidentally correct here. For a 400×100 image with Downsize(100, 50): maxSize=50, would produce 12×3 instead of the correct 50×12. This is a correctness bug in that approach.

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📋 Report — Final Recommendation

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📝 Review Session — Refactor LoadImage to synchronous and clean up formatting · 10d03bc

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✅ Final Recommendation: APPROVE

Summary

PR #30808 correctly fixes the Downsize(maxWidth, maxHeight) bug on Android and Windows where images were stretched to exact dimensions instead of preserving aspect ratio. The fix unifies all three platforms (Android, Windows, iOS) to use a consistent Math.Min(factorX, factorY) scale-factor algorithm. Gate verified the tests fail without the fix and pass with it. 7 independent alternative implementations all converged on equivalent approaches, strongly validating the PR's solution.

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Root Cause

The original Downsize(maxWidth, maxHeight) overload on Android called Bitmap.CreateScaledBitmap(target, maxWidth, maxHeight, true) — directly stretching to the exact requested dimensions with no aspect ratio preservation. On Windows, the same problem existed: ResizeInternal(maxWidth, maxHeight, ...) used the exact bounds as both canvas size and draw size. iOS already used a two-step correction approach but was refactored to the same unified algorithm.

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Fix Quality

✅ Correct algorithm: Math.Min(factorX, factorY) finds the minimum scale factor that fits the image within both bounds while preserving aspect ratio.

✅ Edge cases handled:

• Zero/negative bounds → early return (guard added per reviewer feedback)
• Image already within bounds → early return, no allocation

✅ Code simplification: Single-param Downsize(maxSize) overload now delegates to the two-param version, eliminating code duplication (on Android and Windows).

✅ Cross-platform alignment: All three platforms (Android, Windows, iOS) now use the same algorithm.

✅ Tests: Correct UI test verifies Downsize(10, 10) on royals.png (512×384, ~4:3 ratio) produces 10×8 (aspect ratio preserved).

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Key Insight from Try-Fix Exploration

7 independent models attempted alternative fixes — all 7 conceptually valid, 6 passing:

• Multiple approaches (aspect-ratio comparison, try-width-first, Matrix APIs, delegation) all correctly implement the same behavior
• Critical finding: Pure integer floor division (384 * 10) / 512 = 7 fails — rounding is essential (test expects 8). The PR's Math.Round is correct.
• The Math.Min(factorX, factorY) approach (PR's choice) is the most readable and consistent with the codebase style.

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PR Title & Description Review

Title: [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling

• ✅ Accurate and descriptive — matches implementation
• 🟡 Minor: "prevent upscaling" refers to the no-op early-return when image is within bounds; the core fix is aspect ratio preservation. The title is acceptable as-is.

Description:

• ✅ NOTE block present at top
• ✅ Root cause and description of change are clear
• ✅ Issues Fixed links correctly to [Android & Windows] In GraphicsView, the aspect ratio is not maintained when Downsize is called with both maxWidth and maxHeight #30803
• ✅ Platforms validated with checkboxes
• 🟡 "What NOT to do" section missing (could add: integer floor division fails for rounding reasons)
• 🟡 Output table images appear broken (empty, no actual screenshots attached)

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Code Review Findings

🟡 Minor suggestions (non-blocking):

1. Magic numbers in test (Issue30803.cs:56,70): The values 10, 10 (downsize target) and 10, 8 (expected result) are hardcoded. Copilot reviewer already flagged this; not addressed. Since these numbers come from the known image dimensions of royals.png, extracting constants would improve clarity but isn't required.

2. Snapshot files updated: ImagePaintWithDownsize.png snapshots were updated for both Android and Windows — appropriate since the image dimensions changed with the fix.

✅ No critical issues.

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What NOT to Do (for future agents)

• ❌ Don't use integer floor division for aspect ratio calculation: (srcH * maxW) / srcW produces 7 for a 512×384 image at maxW=10 (test expects 8). Always use Math.Round.
• ❌ Don't delegate Downsize(maxWidth, maxHeight) to Downsize(Math.Min(maxWidth, maxHeight)): Only correct when bounds are square; produces wrong dimensions when maxWidth ≠ maxHeight significantly (e.g., Downsize(100, 50) on a 400×100 image gives wrong result).

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📋 Expand PR Finalization Review

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Title: ⚠️ Needs Update

Current: [Android & Windows] Fix for Downsize method not maintaining aspect ratio when both maxWidth and maxHeight are specified

Recommended: [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling

Description: ✅ Good

Description needs updates. See details below.

✨ Suggested PR Description

[!NOTE]
Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Issue Details

When calling IImage.Downsize(maxWidth, maxHeight) with both a width and height constraint:

• Android (GraphicsExtensions.Downsize): The image was scaled to the exact pixel dimensions provided, ignoring aspect ratio.
• Windows (PlatformImage.Downsize): Same — the image was stretched to exactly maxWidth × maxHeight.
• iOS/MacCatalyst (UIImageExtensions.ScaleImage): Had a separate bug: images that were already within bounds (smaller than maxWidth × maxHeight) were upscaled rather than returned as-is.

In contrast, the single-parameter Downsize(maxWidthOrHeight) overload correctly preserved aspect ratio on all platforms.

Root Cause

Android & Windows: The two-parameter Downsize(maxWidth, maxHeight) overload was implemented independently of the single-parameter overload and did not calculate a proportional scale factor. It passed maxWidth and maxHeight directly as target dimensions, resulting in stretching.

iOS: The ScaleImage(maxWidth, maxHeight) method used scale = originalWidth / maxWidth to compute an initial scale, which is < 1 when the image is narrower than maxWidth. This resulted in upscaling rather than returning the original. The method also always created a new scaled image even when no resizing was needed.

Description of Change

Android (GraphicsExtensions.cs):

• The single-param Downsize(int maxSize) now delegates to Downsize(int maxWidth, int maxHeight) (code deduplication).
• The two-param overload now computes factorX = maxWidth / width, factorY = maxHeight / height, and applies Math.Min(factorX, factorY) to preserve aspect ratio.
• Added guard: returns original if maxWidth <= 0 || maxHeight <= 0.
• Returns original if image is already within bounds (no unnecessary allocation).

Windows (PlatformImage.cs):

• The single-param Downsize(float maxWidthOrHeight) now delegates to Downsize(float maxWidth, float maxHeight).
• The two-param overload now uses the same Math.Min(factorX, factorY) pattern.
• Added guard: returns this if maxWidth <= 0 || maxHeight <= 0.
• Returns this if image is already within bounds.

iOS/MacCatalyst (UIImageExtensions.cs):

• ScaleImage(maxWidth, maxHeight) simplified from a two-step correction algorithm to the same Math.Min(factorX, factorY) pattern — producing identical results when downscaling.
• Fixed upscaling bug: now returns target when image is already within bounds.
• Added guard: returns target if maxWidth <= 0 || maxHeight <= 0.

Behavioral change (all platforms): Downsize/ScaleImage previously always created a new image object (even for in-bounds images). After this fix, the original object is returned when no resizing is necessary. Code that relied on always receiving a newly allocated image may be affected.

Issues Fixed

Fixes #30803

Platforms Tested

• Windows
• Android
• iOS
• Mac

Code Review: ✅ Passed

Code Review — PR #30808

Code Review Findings

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🔴 Title Understates Scope of iOS Fix

File: src/Graphics/src/Graphics/Platforms/iOS/UIImageExtensions.cs

Problem: The PR title says [Android & Windows] but iOS had a real bug that was also fixed: the old ScaleImage implementation upscaled images that were already within bounds. For example, a 5×8 image with maxWidth=10, maxHeight=10 — old code: scale = 5/10 = 0.5, so targetWidth = 5/0.5 = 10, targetHeight = 8/0.5 = 16, then height correction gives ~6×10 — the image is upscaled. New code correctly returns the original 5×8.

Recommendation: Update the PR title to include iOS: [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling

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🟡 Android: Parameter Variables Reused as Target Dimensions

File: src/Graphics/src/Graphics/Platforms/Android/GraphicsExtensions.cs

// After computing factor:
maxWidth = (int)Math.Round(factor * target.Width);   // ← reuses "max constraint" variable
maxHeight = (int)Math.Round(factor * target.Height); // ← reuses "max constraint" variable

var newImage = Bitmap.CreateScaledBitmap(target, maxWidth, maxHeight, true);

Problem: maxWidth and maxHeight are parameter names that semantically mean "maximum bounds". Reassigning them to hold target pixel dimensions is confusing and makes the code harder to read/maintain. The Windows version of the same fix correctly uses separate targetWidth/targetHeight variables:

// Windows (correct pattern):
var targetWidth = factor * Width;
var targetHeight = factor * Height;
return ResizeInternal(targetWidth, targetHeight, ...);

Recommendation: Use separate variables:

var targetWidth = (int)Math.Round(factor * target.Width);
var targetHeight = (int)Math.Round(factor * target.Height);
var newImage = Bitmap.CreateScaledBitmap(target, targetWidth, targetHeight, true);

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🟡 Test: Hardcoded Pixel Dimensions Are Fragile

File: src/Controls/tests/TestCases.HostApp/Issues/Issue30803.cs

bool TryAccessImage(IImage downsizedImage)
{
    if (downsizedImage.Width == 10 && downsizedImage.Height == 8)
    {
        return true;
    }
    return false;
}

Problem: This hardcodes an expected output of 10×8 which assumes royals.png has a specific aspect ratio (5:4). If the test image is ever replaced or updated, this check will silently produce false negatives. It also tests absolute pixel values rather than the actual invariant (aspect ratio preservation).

Recommendation: Either:

1. Load the original image dimensions and assert proportionality: Assert.That(result.Width / result.Height, Is.EqualTo(original.Width / original.Height).Within(...))
2. Or document the expected royals.png dimensions as a constant with a comment explaining the dependency.

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🟡 Test: Unnecessary Task.FromResult Wrapping Synchronous Code

File: src/Controls/tests/TestCases.HostApp/Issues/Issue30803.cs

async Task<IImage> LoadImageAsync()
{
    var assembly = GetType().GetTypeInfo().Assembly;
    using var stream = assembly.GetManifestResourceStream("...");
    return await Task.FromResult(PlatformImage.FromStream(stream));  // ← unnecessary
}

Problem: PlatformImage.FromStream(stream) is synchronous. Wrapping it in Task.FromResult and await-ing adds unnecessary overhead and misleads readers into thinking there's real async I/O happening.

Recommendation: Make the method synchronous, or if async is needed for interface reasons, simply return PlatformImage.FromStream(stream) without the Task.FromResult wrapper.

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🟡 Minor: Missing Newline at End of File

Files:

• src/Controls/tests/TestCases.HostApp/Issues/Issue30803.cs
• src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30803.cs

Both test files are missing a trailing newline (\ No newline at end of file in the diff). Most editors and linters expect files to end with a newline.

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🟡 Minor: Trailing Whitespace

File: src/Graphics/src/Graphics/Platforms/Windows/PlatformImage.cs

There is a trailing whitespace on the blank line after if (maxWidth <= 0 || maxHeight <= 0) { return this; } in the new two-param Downsize overload (visible in the diff as + with trailing space).

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✅ What Looks Good

• Core algorithm is correct on all platforms: Using Math.Min(factorX, factorY) is the proper approach for aspect-ratio-preserving downscale with both width and height constraints.
• Single-param overload refactoring is clean: Having Downsize(maxSize) delegate to Downsize(maxSize, maxSize) eliminates duplicate logic.
• Input validation added: The maxWidth <= 0 || maxHeight <= 0 guard is a good defensive addition.
• iOS algorithm simplification produces identical results: The old two-step correction and the new Math.Min approach are mathematically equivalent for the downscaling case.
• Snapshot tests updated: The Android and Windows snapshot PNGs were updated to reflect the corrected aspect-ratio-preserving output.
• Test is well-structured: AutomationId values are clear, and the test correctly taps a button and checks the resulting label text.

---

[SyedAbdulAzeemSF4852]

Addressed concerns raised in the AI summary.

[kubaflo]

📋 PR Finalization Review

Title: ✅ Good

Current: [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling

Description: ✅ Good

Description needs updates. See details below.

Code Review: ✅ Passed

Code Review — PR #30808

PR: #30808 - [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling

---

Code Review Findings

🟡 Suggestions

[1] Hardcoded expected dimensions in UI test

• File: src/Controls/tests/TestCases.HostApp/Issues/Issue30803.cs
• Lines: TryAccessImage method — downsizedImage.Width == 10 && downsizedImage.Height == 8
• Problem: The test checks exact pixel dimensions (Width == 10 && Height == 8) which are dependent on the specific aspect ratio of royals.png. If the test image is ever replaced or the image processing pipeline changes rounding behavior, the test will fail with no explanation. Also, the expected dimensions (10×8) are not documented or explained anywhere in the test code.
• Recommendation: Add an inline comment explaining the magic numbers and the image's native aspect ratio:

  // royals.png has ~5:4 aspect ratio; Downsize(10, 10) should produce 10×8 preserving ratio
  if (downsizedImage.Width == 10 && downsizedImage.Height == 8)

  Or consider testing Math.Abs(downsizedImage.Width / (float)downsizedImage.Height - originalAspectRatio) < tolerance for a more robust assertion.

---

[2] dispose flag bypass when maxWidth <= 0 || maxHeight <= 0 on Android

• File: src/Graphics/src/Graphics/Platforms/Android/GraphicsExtensions.cs
• Lines: Early-return guard block
• Problem: When maxWidth <= 0 || maxHeight <= 0, the method returns target without respecting the dispose flag. If a caller passes dispose = true expecting the bitmap to be recycled after the call (as in fire-and-forget pattern), the original bitmap will not be disposed when invalid dimensions are given. This is consistent with what Windows does (return this; also bypasses disposal), but could be an unexpected behavior.
• Recommendation: Consider documenting that disposal is skipped on invalid dimensions, or alternatively: recycle the target when dispose = true and return a new blank/error image — though that may be overkill for this guard. The current behavior matches Windows for consistency, so this is low priority. A comment would suffice:

  // Invalid dimensions: return original without resizing or disposing
  if (maxWidth <= 0 || maxHeight <= 0)
  {
      return target;
  }

---

✅ Looks Good

• Unified algorithm: Using Math.Min(factorX, factorY) is the canonical way to fit an image within a bounding box while maintaining aspect ratio. This is correct and consistent across Android, Windows, and iOS.
• Single-param delegates to two-param: Making Downsize(maxSize) call Downsize(maxSize, maxSize) reduces code duplication and ensures consistent behavior between overloads.
• No-upscaling guard: The if (Width > maxWidth || Height > maxHeight) check now correctly skips resizing when the image is already within the target bounds — this applies consistently on all three platforms.
• iOS improvement: The previous iOS two-step scaling correction (scale by width, then correct by height) was harder to follow and had an edge case where scale = originalWidth / maxWidth could produce scale < 1 when originalWidth < maxWidth, leading to upscaling. The new implementation is cleaner and correct.
• Snapshot updates: Android and Windows snapshots are appropriately updated to reflect the corrected output (the downscaled image now preserves aspect ratio rather than being stretched).
• Test placement: UI test is correctly split across TestCases.HostApp and TestCases.Shared.Tests with appropriate AutomationId wiring.
• Test category: UITestCategories.GraphicsView is an appropriate category for this image operation test.

[MauiBot]

🚦 Gate - Test Before and After Fix

📊 Expand Full Gate — 17f621e · Add clarifying comments for Downsize behavior

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Gate Result: ✅ PASSED

Platform: ANDROID · Base: main · Merge base: 720a9d4a

Test	Without Fix (expect FAIL)	With Fix (expect PASS)
🖥️ Issue30803 Issue30803	✅ FAIL — 786s	✅ PASS — 1859s

🔴 Without fix — 🖥️ Issue30803: FAIL ✅ · 786s

  Determining projects to restore...
  Restored /home/vsts/work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 762 ms).
  Restored /home/vsts/work/1/s/src/Essentials/src/Essentials.csproj (in 5.53 sec).
  Restored /home/vsts/work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 8.05 sec).
  Restored /home/vsts/work/1/s/src/Core/src/Core.csproj (in 967 ms).
  Restored /home/vsts/work/1/s/src/Core/maps/src/Maps.csproj (in 585 ms).
  Restored /home/vsts/work/1/s/src/Controls/src/Xaml/Controls.Xaml.csproj (in 40 ms).
  Restored /home/vsts/work/1/s/src/Controls/Maps/src/Controls.Maps.csproj (in 32 ms).
  Restored /home/vsts/work/1/s/src/Controls/Foldable/src/Controls.Foldable.csproj (in 65 ms).
  Restored /home/vsts/work/1/s/src/BlazorWebView/src/Maui/Microsoft.AspNetCore.Components.WebView.Maui.csproj (in 433 ms).
  Restored /home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj (in 1.37 sec).
  1 of 11 projects are up-to-date for restore.
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Graphics/Debug/net10.0-android36.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Essentials/Debug/net10.0-android36.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Core -> /home/vsts/work/1/s/artifacts/bin/Core/Debug/net10.0-android36.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Maps -> /home/vsts/work/1/s/artifacts/bin/Maps/Debug/net10.0-android36.0/Microsoft.Maui.Maps.dll
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-android36.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Microsoft.AspNetCore.Components.WebView.Maui -> /home/vsts/work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-android36.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Controls.Foldable -> /home/vsts/work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-android36.0/Microsoft.Maui.Controls.Foldable.dll
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-android36.0/Microsoft.Maui.Controls.Xaml.dll
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-android36.0/Microsoft.Maui.Controls.Maps.dll
  Controls.TestCases.HostApp -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Controls.TestCases.HostApp.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Core -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Maps.dll
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Microsoft.AspNetCore.Components.WebView.Maui -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.Maps.dll
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.Xaml.dll
  Controls.Foldable -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.Foldable.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:08:20.97
Broadcasting: Intent { act=android.intent.action.CLOSE_SYSTEM_DIALOGS flg=0x400000 }
Broadcast completed: result=0
Broadcasting: Intent { act=android.intent.action.CLOSE_SYSTEM_DIALOGS flg=0x400000 }
Broadcast completed: result=0
  Determining projects to restore...
  Restored /home/vsts/work/1/s/src/TestUtils/src/VisualTestUtils/VisualTestUtils.csproj (in 1.41 sec).
  Restored /home/vsts/work/1/s/src/TestUtils/src/UITest.NUnit/UITest.NUnit.csproj (in 860 ms).
  Restored /home/vsts/work/1/s/src/TestUtils/src/UITest.Core/UITest.Core.csproj (in 7 ms).
  Restored /home/vsts/work/1/s/src/TestUtils/src/UITest.Appium/UITest.Appium.csproj (in 1.56 sec).
  Restored /home/vsts/work/1/s/src/TestUtils/src/VisualTestUtils.MagickNet/VisualTestUtils.MagickNet.csproj (in 6.41 sec).
  Restored /home/vsts/work/1/s/src/TestUtils/src/UITest.Analyzers/UITest.Analyzers.csproj (in 4.17 sec).
  Restored /home/vsts/work/1/s/src/Controls/tests/CustomAttributes/Controls.CustomAttributes.csproj (in 21 ms).
  Restored /home/vsts/work/1/s/src/Controls/tests/TestCases.Android.Tests/Controls.TestCases.Android.Tests.csproj (in 1.9 sec).
  5 of 13 projects are up-to-date for restore.
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  Controls.CustomAttributes -> /home/vsts/work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Core -> /home/vsts/work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  UITest.Core -> /home/vsts/work/1/s/artifacts/bin/UITest.Core/Debug/net10.0/UITest.Core.dll
  VisualTestUtils -> /home/vsts/work/1/s/artifacts/bin/VisualTestUtils/Debug/netstandard2.0/VisualTestUtils.dll
  UITest.Appium -> /home/vsts/work/1/s/artifacts/bin/UITest.Appium/Debug/net10.0/UITest.Appium.dll
  UITest.NUnit -> /home/vsts/work/1/s/artifacts/bin/UITest.NUnit/Debug/net10.0/UITest.NUnit.dll
  VisualTestUtils.MagickNet -> /home/vsts/work/1/s/artifacts/bin/VisualTestUtils.MagickNet/Debug/netstandard2.0/VisualTestUtils.MagickNet.dll
  UITest.Analyzers -> /home/vsts/work/1/s/artifacts/bin/UITest.Analyzers/Debug/netstandard2.0/UITest.Analyzers.dll
  Controls.TestCases.Android.Tests -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll
Test run for /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.21]   Discovering: Controls.TestCases.Android.Tests
[xUnit.net 00:00:00.77]   Discovered:  Controls.TestCases.Android.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 03/29/2026 19:53:17 FixtureSetup for Issue30803(Android)
>>>>> 03/29/2026 19:53:21 VerifyDownsizeMaintainsRatioWithMaxWidthHeight Start
>>>>> 03/29/2026 19:53:25 VerifyDownsizeMaintainsRatioWithMaxWidthHeight Stop
>>>>> 03/29/2026 19:53:25 Log types: logcat, bugreport, server
  Failed VerifyDownsizeMaintainsRatioWithMaxWidthHeight [5 s]
  Error Message:
     Assert.That(downsizedImageLabelText, Is.EqualTo("Success"))
  String lengths are both 7. Strings differ at index 0.
  Expected: "Success"
  But was:  "Failure"
  -----------^

  Stack Trace:
     at Microsoft.Maui.TestCases.Tests.Issues.Issue30803.VerifyDownsizeMaintainsRatioWithMaxWidthHeight() in /_/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30803.cs:line 23

1)    at Microsoft.Maui.TestCases.Tests.Issues.Issue30803.VerifyDownsizeMaintainsRatioWithMaxWidthHeight() in /_/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30803.cs:line 23


NUnit Adapter 4.5.0.0: Test execution complete

Total tests: 1
     Failed: 1
Test Run Failed.
 Total time: 1.4995 Minutes

🟢 With fix — 🖥️ Issue30803: PASS ✅ · 1859s

(truncated to last 15,000 chars)

s.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010: --- End of stack trace from previous location --- [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at AndroidDeviceExtensions.PushAndInstallPackageAsync(AndroidDevice device, PushAndInstallCommand command, CancellationToken token) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at AndroidDeviceExtensions.PushAndInstallPackageAsync(AndroidDevice device, PushAndInstallCommand command, CancellationToken token) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Xamarin.Android.Tasks.FastDeploy.InstallPackage(Boolean installed) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Xamarin.Android.Tasks.FastDeploy.InstallPackage(Boolean installed) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Xamarin.Android.Tasks.FastDeploy.RunInstall() [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]

Build FAILED.

/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010: Mono.AndroidTools.InstallFailedException: Unexpected install output: cmd: Failure calling service package: Broken pipe (32) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:  [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Mono.AndroidTools.Internal.AdbOutputParsing.CheckInstallSuccess(String output, String packageName) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Mono.AndroidTools.AndroidDevice.<>c__DisplayClass105_0.<InstallPackage>b__0(Task`1 t) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010: --- End of stack trace from previous location --- [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010: --- End of stack trace from previous location --- [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at AndroidDeviceExtensions.PushAndInstallPackageAsync(AndroidDevice device, PushAndInstallCommand command, CancellationToken token) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at AndroidDeviceExtensions.PushAndInstallPackageAsync(AndroidDevice device, PushAndInstallCommand command, CancellationToken token) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Xamarin.Android.Tasks.FastDeploy.InstallPackage(Boolean installed) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Xamarin.Android.Tasks.FastDeploy.InstallPackage(Boolean installed) [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
/home/vsts/work/1/s/.dotnet/packs/Microsoft.Android.Sdk.Linux/36.1.2/tools/Xamarin.Android.Common.Debugging.targets(333,5): error ADB0010:    at Xamarin.Android.Tasks.FastDeploy.RunInstall() [/home/vsts/work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-android]
    0 Warning(s)
    1 Error(s)

Time Elapsed 00:11:36.30
* daemon not running; starting now at tcp:5037
* daemon started successfully
  Determining projects to restore...
  All projects are up-to-date for restore.
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Graphics/Debug/net10.0-android36.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Essentials/Debug/net10.0-android36.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Core -> /home/vsts/work/1/s/artifacts/bin/Core/Debug/net10.0-android36.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Maps -> /home/vsts/work/1/s/artifacts/bin/Maps/Debug/net10.0-android36.0/Microsoft.Maui.Maps.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-android36.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Foldable -> /home/vsts/work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-android36.0/Microsoft.Maui.Controls.Foldable.dll
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-android36.0/Microsoft.Maui.Controls.Maps.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-android36.0/Microsoft.Maui.Controls.Xaml.dll
  Microsoft.AspNetCore.Components.WebView.Maui -> /home/vsts/work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-android36.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Controls.TestCases.HostApp -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Controls.TestCases.HostApp.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Core -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Maps.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Microsoft.AspNetCore.Components.WebView.Maui -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.Maps.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Foldable -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.Foldable.dll
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-android/Microsoft.Maui.Controls.Xaml.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:08:25.87
Broadcasting: Intent { act=android.intent.action.CLOSE_SYSTEM_DIALOGS flg=0x400000 }
Broadcast completed: result=0
Broadcasting: Intent { act=android.intent.action.CLOSE_SYSTEM_DIALOGS flg=0x400000 }
Broadcast completed: result=0
  Determining projects to restore...
  All projects are up-to-date for restore.
  Controls.CustomAttributes -> /home/vsts/work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Graphics -> /home/vsts/work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Essentials -> /home/vsts/work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Core -> /home/vsts/work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13684045
  Controls.Core -> /home/vsts/work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  UITest.Core -> /home/vsts/work/1/s/artifacts/bin/UITest.Core/Debug/net10.0/UITest.Core.dll
  UITest.NUnit -> /home/vsts/work/1/s/artifacts/bin/UITest.NUnit/Debug/net10.0/UITest.NUnit.dll
  UITest.Appium -> /home/vsts/work/1/s/artifacts/bin/UITest.Appium/Debug/net10.0/UITest.Appium.dll
  VisualTestUtils -> /home/vsts/work/1/s/artifacts/bin/VisualTestUtils/Debug/netstandard2.0/VisualTestUtils.dll
  VisualTestUtils.MagickNet -> /home/vsts/work/1/s/artifacts/bin/VisualTestUtils.MagickNet/Debug/netstandard2.0/VisualTestUtils.MagickNet.dll
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  Controls.TestCases.Android.Tests -> /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll
Test run for /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.15]   Discovering: Controls.TestCases.Android.Tests
[xUnit.net 00:00:00.40]   Discovered:  Controls.TestCases.Android.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /home/vsts/work/1/s/artifacts/bin/Controls.TestCases.Android.Tests/Debug/net10.0/Controls.TestCases.Android.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 03/29/2026 20:15:44 FixtureSetup for Issue30803(Android)
>>>>> 03/29/2026 20:15:46 VerifyDownsizeMaintainsRatioWithMaxWidthHeight Start
>>>>> 03/29/2026 20:15:50 VerifyDownsizeMaintainsRatioWithMaxWidthHeight Stop
  Passed VerifyDownsizeMaintainsRatioWithMaxWidthHeight [4 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 1
     Passed: 1
 Total time: 24.3554 Seconds

📁 Fix files reverted (4 files)

• eng/pipelines/ci-copilot.yml
• src/Graphics/src/Graphics/Platforms/Android/GraphicsExtensions.cs
• src/Graphics/src/Graphics/Platforms/Windows/PlatformImage.cs
• src/Graphics/src/Graphics/Platforms/iOS/UIImageExtensions.cs

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[MauiBot]

🤖 AI Summary

📊 Expand Full Review — 17f621e · Add clarifying comments for Downsize behavior

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🔍 Pre-Flight — Context & Validation

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Issue: #30803 - [Android & Windows] In GraphicsView, the aspect ratio is not maintained when Downsize is called with both maxWidth and maxHeight
PR: #30808 - [Android, Windows & iOS] Fix Downsize/ScaleImage to maintain aspect ratio and prevent upscaling
Platforms Affected: Android, Windows (primary bugs); iOS/macOS (refactored for consistency)
Files Changed: 3 implementation files, 2 test files, 2 snapshot files

Key Findings

• Downsize(maxWidth, maxHeight) on Android called Bitmap.CreateScaledBitmap(target, maxWidth, maxHeight, true) directly — stretching to exact dimensions, ignoring aspect ratio
• Same bug on Windows: ResizeInternal(maxWidth, maxHeight, ...) passed raw max bounds as canvas dimensions instead of proportionally computed ones
• iOS already handled aspect ratio via a 2-step scale-correction approach; PR refactors it to the same Math.Min(factorX, factorY) strategy for consistency
• Single-param overload Downsize(maxSize) now delegates to two-param version on Android, reducing code duplication
• Guard added for zero/negative dimensions (returns original); also adds early-return if image already fits within bounds
• Test uses royals.png (512×384, 4:3 ratio): Downsize(10, 10) should produce 10×8
• Snapshot files updated for Android and Windows to reflect corrected aspect-ratio output
• All reviewer feedback addressed (zero/negative guard added per jsuarezruiz; constants for magic numbers declined with explanation)

Reviewer Discussion

File	Reviewer	Comment	Status
GraphicsExtensions.cs:446	jsuarezruiz	Handle edge cases: zero/negative dimensions	✅ Addressed
Issue30803.cs:56	Copilot	Magic numbers (10,10) should be constants	⚠️ Declined with explanation
Issue30803.cs:71	Copilot	Magic numbers (10×8) should be constants	⚠️ Declined, comment added explaining dimensions

Prior Agent Review (Incomplete)

Prior review ran 3/4 try-fix models; cross-pollination was incomplete; no report written. This session completes the review from scratch.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #30808	Use Math.Min(factorX, factorY) scale factor; single-param delegates to two-param; guard for zero/negative bounds; early return if within bounds	✅ PASSED (Gate)	GraphicsExtensions.cs, PlatformImage.cs, UIImageExtensions.cs	Original PR

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🔧 Fix — Analysis & Comparison

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Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix (claude-opus-4.6)	Cross-multiplication branching: (long)W * maxH > (long)H * maxW to pick constraining dimension; single float division for other dimension	✅ PASS	GraphicsExtensions.cs	Avoids dual factor computation; guards overflow with (long) cast
2	try-fix (claude-sonnet-4.6)	Width-first fallback: compute targetHeight = Round(H * maxW / W); if >maxHeight, correct to height-constrained	✅ PASS	GraphicsExtensions.cs	Staged approach, avoids scale factors entirely
3	try-fix (gpt-5.3-codex)	Aspect-ratio-driven: compute aspectRatio = W/H as double; derive targetHeight = Round(maxWidth/aspectRatio); if >maxHeight, switch to height-constrained	✅ PASS	GraphicsExtensions.cs	Uses raw aspect ratio double; different from scale-factor and cross-multiply approaches
4	try-fix (gpt-5.2)	Delegate to single-param overload: call Downsize(maxWidth, dispose:false) and Downsize(maxHeight, dispose:false), pick the one that fits both bounds	✅ PASS	GraphicsExtensions.cs	Structurally different: creates two intermediate bitmaps, picks best fit; avoids any direct dimension math
PR	PR #30808	Math.Min(factorX, factorY) uniform scale factor; single-param delegates to two-param; guard for zero/negative bounds	✅ PASSED (Gate)	GraphicsExtensions.cs, PlatformImage.cs, UIImageExtensions.cs	Original PR

Cross-Pollination

Model	Round	New Ideas?	Details
claude-opus-4.6	2	No	"Five approaches cover the full algorithmic design space for aspect-ratio-preserving 2D downscaling"
claude-sonnet-4.6	2	No	Confirmed exhaustion: cross-multiply, fallback, ratio, decompose, min-scale-factor are all independent algorithmic classes

Exhausted: Yes
Selected Fix: PR #30808 — Math.Min(factorX, factorY) is idiomatic, applies consistently across Android + Windows + iOS in a single unified style, and is the minimal change that fully resolves the bug on all platforms.

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📋 Report — Final Recommendation

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✅ Final Recommendation: APPROVE

Phase Status

Phase	Status	Notes
Pre-Flight	✅ COMPLETE	Issue #30803: Android & Windows Downsize(maxWidth, maxHeight) stretched to exact dimensions; iOS refactored for consistency
Gate	✅ PASSED	Platform: Android
Try-Fix	✅ COMPLETE	4 attempts, all 4 passing; cross-pollination exhausted (2 models, NO NEW IDEAS)
Report	✅ COMPLETE

Summary

PR #30808 fixes a bug where Bitmap.Downsize(maxWidth, maxHeight) on Android and PlatformImage.Downsize(maxWidth, maxHeight) on Windows passed raw dimensions directly to the scaling API, stretching images to exact pixel bounds instead of preserving aspect ratio. The fix applies Math.Min(factorX, factorY) across all three platforms (Android, Windows, iOS) for a consistent, unified approach. Gate passed on Android. All 4 independent fix attempts also passed, confirming the algorithm space is well-covered. Selected Fix: PR's fix.

Root Cause

• Android (GraphicsExtensions.cs): Bitmap.CreateScaledBitmap(target, maxWidth, maxHeight, true) used maxWidth/maxHeight as literal pixel dimensions — no aspect ratio math at all.
• Windows (PlatformImage.cs): ResizeInternal(maxWidth, maxHeight, 0, 0, maxWidth, maxHeight, ...) passed the raw bounds as both canvas size and draw region — same issue.
• iOS (UIImageExtensions.cs): Had a 2-step correction approach that worked but was more complex; refactored for consistency.
• The single-param Downsize(maxSize) overloads on all platforms already handled aspect ratio correctly; only the two-param overloads were broken.

Fix Quality

The fix is clean, minimal, and correct:

• Algorithm: factorX = maxWidth / Width, factorY = maxHeight / Height, factor = Math.Min(factorX, factorY) — standard "fit within box" scaling.
• Unified: Same pattern applied to all three platforms, making the behavior consistent.
• Single-param refactor: Android's Downsize(maxSize) now delegates to Downsize(maxSize, maxSize), reducing duplication.
• Guard added: Returns early for maxWidth <= 0 || maxHeight <= 0 and when image already fits within bounds.
• Test coverage: New UITest (Issue30803) verifies royals.png (512×384) → Downsize(10, 10) → 10×8 on Android. Snapshot files updated for Android and Windows.
• Reviewer feedback addressed: Zero/negative guard added per reviewer request.

No concerns. The PR is ready to merge.

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