Image Table issues (transparency & background)

[mischnic]

On macOS (not Windows): On the right is the (png) image as it should be displayed, but in the table there are these green bits.

The code below has this output: Firstly, the green as described above, but secondly the alternating row background doesn't seem to work correctly.

Code: https://github.com/mischnic/libui-tests/tree/master/png

[msink]

Pixel format is 32bit ARGB
https://github.com/msink/png2kt

[mischnic]

The decoder returns 32bit RGBA, with the libui output above (the colors do look correct, just something about the transparency).
Reordering the components using this code (which is basically what your tool does?) yields

for(unsigned int i = 0; i < width*height*4; i+=4){
	const unsigned char alpha = image[i+3];
	image[i+3] = image[i+2];
	image[i+2] = image[i+1];
	image[i+1] = image[i];
	image[i] = alpha;
}

Setting the alpha component to 255 and passing RGBA to libui:

[msink]

Strange, it worked for me 3 months ago.
Will check tomorrow, now far from computer, sorry.

[mischnic]

Passing RGBA to libui works fine on Windows (no green artifacts)
@msink It is RGBA:

libui/ui.h

Lines 1165 to 1166 in 30d4129

	// stored in [R G B A] order (so ((uint8_t *) pixels)[0] is the R of the
	// first pixel and [3] is the A of the first pixel). pixelWidth and

So the green is a macOS bug indeed.

[msink]

So something was broken in macOS version between alpha4 and alpha4.1.

[msink]

Does it work in https://github.com/msink/kotlin-libui/releases/download/alpha-4.1-1/libui-samples-kotlin-macos.tgz ?
I do not have mac, so cannot check.

On Windows:

[mischnic]

No, same problem:

[mischnic]

Another example (not tested on Windows):

Icon: (outline is not part of the icon)

Displayed in the table on macOS (black smoke around):

There are no artifacts after replacing all transparency with white.

[mischnic]

Huh, with this change:

diff --git a/darwin/image.m b/darwin/image.m
index 0b10cb09..75ed6347 100644
--- a/darwin/image.m
+++ b/darwin/image.m
@@ -37,7 +37,7 @@ void uiImageAppend(uiImage *i, void *pixels, int pixelWidth, int pixelHeight, in
                hasAlpha:YES
                isPlanar:NO
                colorSpaceName:NSCalibratedRGBColorSpace
-               bitmapFormat:0
+               bitmapFormat:NSAlphaNonpremultipliedBitmapFormat
                bytesPerRow:0
                bitsPerPixel:32];

The image is displayed correctly. But I thought libui used premultiplied image data now? This tells Cocoa, that the values aren't premuliplied. 🤔

@andlabs On this page, there are also some options regarding endianness, have you seen these? https://developer.apple.com/documentation/appkit/nsbitmapformat?language=objc