Why skia looks so poorly on Android?

[jyswjjgdwtdtj]

This is how my program shows on Desktop:

And this is how it shows on Android real phone

I create my SkiaControl, following the example
Text in TextBox still performs a high quality, and i want my skcanvas can render a clear graphics.
Maybe i should reset the Dpi? I can find where to change its value.....

[stevemonaco]

This doesn't seem to be anything performance-related? What is the actual issue? It looks like you have bugs due to not properly clipping or layering.

[jyswjjgdwtdtj]

this is my project, and the Apk file
Could you have a look at my apk? Thank you!
I guess that pixel in android is not a block with 1x1 width and height, but the skia can only render the pixel.

[stevemonaco]

Sorry, I can't run arbitrary APKs from the internet.

I think there's a translation issue here. Are you talking about the text rendering being poor? I see you're on SkiaSharp 3.119 but you're creating your font like:
TextFont = new SKFont(SKTypeface.FromFamilyName("Microsoft Yahei UI"));

The default is Antialiasing, but that's not cleartype. Try:
TextFont.Edging = SKFontEdging.SubpixelAntialias;

[jyswjjgdwtdtj]

Thank you! i will try after finish my homework😁
So controls in avalonia use the subpixel antialias? But it seems that texts in textbox on Android have a very clear edge, not just improving quality by antialias? the line is also rendered unclearly.

I'm trying to run my project in browser on Android platform and use DrawingImage (avalonia docs said that i can perform the high quality graphics in any platforms by DrawingImage), thus i can find out the reason of such a low quality perhaps.
Thank you again!(˵¯͒〰¯͒˵)

[stevemonaco]

I think Avalonia uses a fallback strategy for antialiasing text depending on RenderOptions.EdgeMode.

As for blurry lines, I'm not sure. SkiaSharp 3 deprecated SKFilterOptions.Antialias in SKPaint and the related draw methods don't seem to have anything for that.

Maybe it's something with layer blending. Try setting:

<Window
    RenderOptions.BitmapInterpolationMode="HighQuality"
    RenderOptions.EdgeMode="Antialias"

Though it doesn't seem like EdgeMode does anything for drawn shapes (ie. not text) except set the SKPaint.IsAntialias:

Avalonia/src/Skia/Avalonia.Skia/DrawingContextImpl.cs

Lines 1359 to 1363 in 969eabf

	internal PaintWrapper CreatePaint(SKPaint paint, IBrush brush, Rect targetRect)
	{
	var paintWrapper = new PaintWrapper(paint);
	paint.IsAntialias = RenderOptions.EdgeMode != EdgeMode.Aliased;

[jyswjjgdwtdtj]

No...... RenderOptions.EdgeMode just improve the antialias. Actually it is of no help in improving drawing accuracy.
I still think the problem occurs in the skia, because the width and height on Android are: (the screenshot)

Not integers like 1200, 800 on Windows. Which means the smallest drawing unit is not pixel (width=1 height=1), but something smaller than pixel. Maybe i should reset dpi?
I just want to know how avalonia do this, as the doc says.

Resolution-independent and device-independent graphics. The basic unit of measurement in the Avalonia graphics system is the device-independent pixel, which is 1/96th of an inch, regardless of actual screen resolution, and provides the foundation for resolution-independent and device-independent rendering. Each device-independent pixel automatically scales to match the dots-per-inch (dpi) setting of the system it renders on.
However i find nothing about Dpi, except the dpi property of WritableBitmap