I think one ugly thing is that Compose for Desktop `Image.makeFromEncoded()` as well as Android `co...

# compose-desktop

[Stefan Oltmann]

I think one ugly thing is that Compose for Desktop Image.makeFromEncoded() as well as Android contentResolver.loadThumbnail() give you a Bitmap , but Compose Image needs an ImageBitmap and as far as I can see the implementation of the extension asImageBitmap() is on both worlds a really expensive conversation. 😞

Why isn't there a way to directly load an ImageBitmap if that's the needed format? 🤔

[romainguy]

What’s expensive about it? The Android implementation just wraps the Bitmap inside an ImageBitmap

[romainguy]

I don’t know how the desktop implementation works but I assume it’s something similar

[Stefan Oltmann]

Dunno.. looks expensive.

targetBitmap.getPixels(
    buffer,
    bufferOffset,
    stride,
    startX,
    startY,
    width,
    height
)

[Stefan Oltmann]

for Android

[Stefan Oltmann]

for Desktop Compose:

val bytes = bitmap.readPixels(imageInfo, stride * bytesPerPixel.toLong(), startX, startY)!!

ByteBuffer.wrap(bytes)
    .order(ByteOrder.LITTLE_ENDIAN) // to return ARGB
    .asIntBuffer()
    .get(buffer, bufferOffset, bytes.size / bytesPerPixel)

[Stefan Oltmann]

So there is this "read all pixels into a new int/byte array" step which doubles the amount of data. Doesn't it?

[Stefan Oltmann]

And this is executed everytime a call to readPixels() , the main method of that BitmapImage interface, happens

[Stefan Oltmann]

I assume that means some extra GC on every image draw operation. Doesn't it?

[Stefan Oltmann]

I wonder if there is a Painter (the third possible argument beside ImageBitmap and ImageVector for a Compose Image) implementation that can draw a Bitmap directly without making that call to readPixels() that will create an extra array on every call.

[Stefan Oltmann]

looking at accompanist for Coil and Glide they have rememberGlidePainter() which I guess is a way around that.

Only that there is no such thing as Glide or Coil available for Compose for Desktop... or is it?

[Stefan Oltmann]

Coil won't come... https://github.com/google/accompanist/issues/136#issuecomment-722693781

[romainguy]

For Android getPixel() is only invoked from readPixels(), which is not used for rendering

[romainguy]

I assume the same is true on desktop

[Albert Chang]

Yes, on both Android and desktop Bitmap.asImageBitmap() just wraps the bitmap with a new class without doing anything else.