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IDProjectCategoryView StatusLast Update
0002153NoesisGUIC# SDKpublic2021-10-20 13:01
ReporterDavidYawCSpeed Assigned Tosfernandez  
PrioritynormalSeverityminorReproducibilityalways
Status resolvedResolutionfixed 
Product Version3.1.1 
Target Version3.1.2Fixed in Version3.1.2 
Summary0002153: PNG Alpha Transparency not applied properly depending on PNG format
DescriptionWe've got a PNG image which is not 32-bit RGBA. When displayed in some contexts, the alpha is not blended with the background properly.

I have seen this issue on both Windows x64 and Linux ARM64.

Workaround: Convert the image to full RGBA.

Attached:
- Both the PNG that causes the issue, and the result of converting it to RGBA, which fixes the issue.
- Screenshot of the issue occurring on Windows x64. It ends up drawing black.
- Picture of the issue occurring on Linux ARM64, on our real device. It ends up drawing transparent, so the video overlay shows through.
Steps To ReproduceI can reproduce the issue very reliably in our real application, but in the real application, the Image object is 20 levels deep in the Visual Tree. But in a standalone application, with just the Image over top of a colored background, it works fine. Unfortunately, I'm not sure exactly what UI Controls need to be set up in order to trigger this bad alpha blending.

However, I do know what is needed in a PNG image.

Examining the images under Linux:
$ file *.png
icon_batt_plug_in_broken.png: PNG image data, 128 x 128, 8-bit gray+alpha, non-interlaced
icon_batt_plug_in_works.png:  PNG image data, 128 x 128, 8-bit/color RGBA, non-interlaced


Using https://www.nayuki.io/page/png-file-chunk-inspector:
- Broken
  - Bit depth: 8 bits per channel
  - Color type: Grayscale+Alpha (4)
- Works
  - Bit depth: 8 bits per channel
  - Color type: RGBA (6)
TagsNo tags attached.
PlatformAny

Activities

DavidYawCSpeed

DavidYawCSpeed

2021-10-20 02:20

reporter  

icon_batt_plug_in_broken.png (1,459 bytes)   
icon_batt_plug_in_broken.png (1,459 bytes)   
icon_batt_plug_in_works.png (8,989 bytes)   
icon_batt_plug_in_works.png (8,989 bytes)   
Windows-ScreenshotTestApp.png (4,503 bytes)   
Windows-ScreenshotTestApp.png (4,503 bytes)   
Linux-PictureOfRealApp.jpg (37,030 bytes)   
Linux-PictureOfRealApp.jpg (37,030 bytes)   

Issue History

Date Modified Username Field Change
2021-10-20 02:20 DavidYawCSpeed New Issue
2021-10-20 02:20 DavidYawCSpeed File Added: icon_batt_plug_in_broken.png
2021-10-20 02:20 DavidYawCSpeed File Added: icon_batt_plug_in_works.png
2021-10-20 02:20 DavidYawCSpeed File Added: Windows-ScreenshotTestApp.png
2021-10-20 02:20 DavidYawCSpeed File Added: Linux-PictureOfRealApp.jpg
2021-10-20 02:25 DavidYawCSpeed Description Updated
2021-10-20 02:41 DavidYawCSpeed Steps to Reproduce Updated
2021-10-20 10:28 sfernandez Assigned To => sfernandez
2021-10-20 10:28 sfernandez Status new => assigned
2021-10-20 10:28 sfernandez Target Version => 3.1.2
2021-10-20 13:01 sfernandez Status assigned => resolved
2021-10-20 13:01 sfernandez Resolution open => fixed
2021-10-20 13:01 sfernandez Fixed in Version => 3.1.2