Are there APIs for image convolutions in Compose on `ImageBi

Question

Are there APIs for image convolutions in Compose on `ImageBitmap` In general there doesn t seem to be a way maybe by design to get access to the underlying pixel information for direct manipulation `AndroidImageAsset` and `DesktopImageAsset` go through a somewhat of a contortion to expose the underlying pixel information to the `ImageBitmap` but I don t see any way to get those pixels afterwards

cb · Answer

There s the new `toPixelMap ` which gives you read access to the pixels You say manipulation as in to mutate the pixel array values

Kirill Grouchnikov · Answer

Yes This is common for libraries that provide dynamically generated image effects where you don t necessarily have an asset to begin with One use case is to dynamically generate a texture noise weave fabric anything really then apply a set of filters convolutions directly to the int array and then create an `ImageBitmap` out of the final buffer

Kirill Grouchnikov · Answer

And image convolution is a common thing as well On Android it can be done with RenderScript see <https blog stylingandroid com image convolution implementation > but that wouldn t translate directly to Compose In general it s about dropping down to the underlying buffer of pixels for reading transforming and creating a new buffer and then creating a new image out of it Or alternatively rewriting the pixels in the destination so that you don t create a new image object every time

Nader Jawad · Answer

Right now there is no support for image convolutions in compose Nowadays if folks want to manipulate textures they usually leverage opengl But as < cb> mentioned if you want to query pixel formation you can use the `toPixelMap` api on ImageBitmap or provide your own array to store pixel information using `readPixels`

Kirill Grouchnikov · Answer

Is it only on `ImageAsset` or also on `ImageBitmap`

Nader Jawad · Answer

`ImageAsset` is renamed to `ImageBitmap`

Nader Jawad · Answer

And there is a type alias for `ImageAsset` that points to `ImageBitmap`

Nader Jawad · Answer

`toPixelMap` is an extension method on `ImageBitmap` which would need an explicit import

Kirill Grouchnikov · Answer

Ah great I missed the alias part So I can use `readPixels` for two things Get pixels from an existing image and also do that same remapping trick as in `AndroidImageAsset` and `DesktopImageAsset` to map a dynamically created buffer of pixels to a compose image object that can be drawn on a canvas

Kirill Grouchnikov · Answer

Well that didn t work see my latest post in this channel I can create a custom implementation of `ImageAsset` and then it s going to throw an `UnsupportedOperationException` while drawing it on a canvas