In JavaScript I can directly manipulate the pixels of a canvas and refresh them with a single copy:
ctx = canvas.getContext('2d')
imageData = ctx.getImageData(0, 0, canvas.width, canvas.height)
pixelTypedArray = imageData.data
modifyPixels(pixelTypedArray)
// refresh canvas with single copy
ctx.putImageData(imageData, 0, 0)
But in wasm we must allocate our own TypedArray using the wasm memory, and we can then use imageData.data.set(myTypedArray) but that seems to just copy the entire contents of the new typed array into the canvas's typed array, which must still be followed by putImageData, copying the entire contents a second time.
Is there any way to reassign the canvas's ImageData to our new ImageData so that we can update the canvas with only a single copy using ctx.putImageData()?
If not, it seems much of the benefit of using wasm to manipulate the image would be wasted by the inefficient double copy and dual in-memory representation, especially when working with large images and/or continuously updating canvas.