Offline image processing¶

ImageProcessor applies an effect to encoded image bytes and returns a ShaderResult<ByteArray>. The processor shares a factory's compilation cache. It is synchronous, so large images or batches can block the calling thread.

Check platform support first¶

The Skia implementation supports individual runtime effects and native blur. It rejects CompositeEffect. Android's implementation returns ProcessingError: software bitmap export cannot draw a hardware RenderNode. In 0.1.4, it rejects the operation before decoding input, inspecting the effect, compiling shaders, or allocating destination bitmaps. Invalid image bytes therefore receive the same platform-limitation error. Use the Compose modifier for on-screen Android effects.

Process an image with explicit cleanup¶

This example uses public APIs available in 0.1.3 and 0.1.4. Run it on a supported Skia target, and handle the result at the call site:

import com.debanshu.shaderlab.shaderx.effect.impl.SepiaEffect
import com.debanshu.shaderlab.shaderx.factory.ImageProcessor
import com.debanshu.shaderlab.shaderx.factory.ShaderFactory
import com.debanshu.shaderlab.shaderx.factory.create
import com.debanshu.shaderlab.shaderx.result.ShaderResult

fun sepiaImage(imageBytes: ByteArray): ShaderResult<ByteArray> {
    val factory = ShaderFactory.create(maxCacheSize = 8)
    return try {
        val processor = ImageProcessor.create(factory)
        processor.process(imageBytes, SepiaEffect(intensity = 0.8f))
    } finally {
        factory.close()
    }
}

Use onSuccess to save the returned bytes and onFailure to display or log the error. Do not save the original input as though it were a successful processed result.

For a batch, keep one factory and processor for the batch, process images sequentially, and close the factory afterward. For background processing, create a dedicated factory inside the worker and close it there; do not pass a Compose UI factory to a background export. A Skia factory is not thread-safe. Shared access requires external serialization of every factory, processor, and session operation, including cache eviction and disposal.

In 0.1.4, the Skia processor closes each call's decoded image, shader builder, image filter, surface, paint, snapshot, and encoded-data wrappers on both success and failure. Compiled effects remain in the factory's bounded cache for reuse. This reduces delayed native-memory cleanup during batches; encoding and rasterization still run synchronously on the calling thread.

Dimensions and output¶

The optional width and height arguments override dimensions supplied to shader uniforms. They do not resize the output bitmap. The current processors encode successful results as PNG. Invalid input bytes, unsupported effects, shader compilation, or encoding can produce failures.

See platform support and troubleshooting for the known limitations.