find actual size of makeImageSnapshot

[raminious]

I need to export a selected box (x, y, w, h) from the canvas while building a simple cropper.

When using makeImageSnapshot I discovered that the height and width of the resulting snapshot is different with the actual canvas size.
Therefore, as a workaround, I call skia.ref.current?.makeImageSnapshot() once to determine the image's real dimensions and makeImageSnapshot() again to crop it. I don't think it's a good idea that I have to call makeImageSnapshot() twice.

• Is there a critical performance issue with calling this function two times?
• Is it possible to avoid doing that? (It seems that since I'm also using some blur effects, I can't use offscreen. I'm not certain if I can use filters with offscreen.)

const snapshot = skia.ref.current?.makeImageSnapshot()

if (!snapshot) {
  return
}

const scale = {
  x: snapshot.width() / canvas.width,
  y: snapshot.height() / canvas.height,
}

const imageSnapshot = skia.ref.current?.makeImageSnapshot({
  x: box.left * scale.x,
  y: box.top * scale.y,
  width: box.width * scale.x - box.left * scale.x * 2,
  height: box.height * scale.y - box.top * scale.y * 2,
})

const image = imageSnapshot?.encodeToBytes(ImageFormat.JPEG, 100)

[wcandillon]

makeImageSnapshot is very fast, doing twice is ok, offscreen you can do the blur so it might be the best solution then you can really control what you are doing.