Hi! Is there a way to get pixel color on `Canvas` ...

# compose

[Evgeniy Shmoilov]

Hi! Is there a way to get pixel color on Canvas by coordinates?

[Adam Powell]

What is your use case? Generally it is quite slow to read pixels back from GPU memory. If you are working from source data like an image or other data derived from app state, it's better to get what you need from there instead of from final pixels.

[romainguy]

Getting a pixel color would mean interrupting command recording, flushing the command buffer to the render thread then GPU, then wait for frame completion for readback, all the while blocking the main thread

[romainguy]

That or you'd get the previous frame's color (which may not exist)

[romainguy]

A cheaper way is to draw what you want to draw in a Bitmap (it can even be 1x1) and read back from that

[Evgeniy Shmoilov]

I am implementing a recursive flood fill algorithm as part of a lab

[romainguy]

You should do this on a Canvas that wraps a Bitmap then

[romainguy]

Or better yet, directly in an array of integers that you then convert to a Bitmap

[Kyant]

Is there a way to convert Composables to Bitmap?

[romainguy]

You can use a ComposeView to host your composables and draw that view into a Bitmap

[Kyant]

Oh, I crashed with "width and height must be > 0"

[romainguy]

Well how big is your Bitmap? 🙂

[Kyant]

The problem has been resolved. 😀

[Kyant]

I see there is a Modifier.blur() proposal in the issue tracker, when it will be implemented?

[romainguy]

Any updates will be posted on the bug