From 89c33fae6841dd9c35e62cd6e32e9dfeffe0d67e Mon Sep 17 00:00:00 2001
From: mbartlett21 <29034492+mbartlett21@users.noreply.github.com>
Date: Fri, 30 May 2025 20:32:40 +1000
Subject: [PATCH] [peek, explorer] Update QOI reader for 3-channel images
 (#39304)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

Make sure we account for Bitmap row length being a multiple of 4 when
reading Qoi files.

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## PR Checklist

- [x] **Closes:** #31948
- [ ] **Communication:** Not discussed, but a bug fix
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end user facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments



<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

Built and run and restarted file explorer.
Sample files from my comment on the issue (after rewriting each one to
force the thumbnail to regenrate):

![image](https://github.com/user-attachments/assets/5874f958-0f03-4683-abe3-d54c979ad2a1)
---
 src/common/FilePreviewCommon/QoiImage.cs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/common/FilePreviewCommon/QoiImage.cs b/src/common/FilePreviewCommon/QoiImage.cs
index ac315eb832..fd72cb0e29 100644
--- a/src/common/FilePreviewCommon/QoiImage.cs
+++ b/src/common/FilePreviewCommon/QoiImage.cs
@@ -92,6 +92,9 @@ namespace Microsoft.PowerToys.FilePreviewCommon
                 var run = 0;
                 var chunksLen = fileSize - QOI_PADDING_LENGTH;
 
+                var x = 0;
+                var rowAdd = bitmapData.Stride - (channels * bitmapData.Width);
+
                 for (var dataIndex = 0; dataIndex < dataLength; dataIndex += channels)
                 {
                     if (run > 0)
@@ -153,6 +156,14 @@ namespace Microsoft.PowerToys.FilePreviewCommon
                             bitmapPixel[3] = pixel.A;
                         }
                     }
+
+                    x++;
+                    if (x == bitmapData.Width)
+                    {
+                        // We align dataIndex with the stride
+                        dataIndex += rowAdd;
+                        x = 0;
+                    }
                 }
 
                 bitmap.UnlockBits(bitmapData);