CanvasIO.load

Prepare an image for drawing. For hardware accelerated backends, this may involve uploading the texture to the GPU.

An image may be passed to this function even if it was already loaded. The field image.data.ptr can be used to uniquely identify an image, so the canvas can use it to reuse previously prepared images. Additionally, the image.revisionNumber field will increase if the image was updated, so the change should be reflected in the canvas.

There is no corresponding unload call. The canvas can instead unload images based on whether they were loaded during a resize. This may look similar to this:

int resizeNumber;
void load(Image image) {
    // ... load the resource ...
    resource.lastResize = resizeNumber;
}
void resizeImpl(Vector2 space) {
    auto frame = this.implementIO();
    resizeNumber++;
    super.resizeImpl();
    foreach_reverse (ref resource; resources) {
        if (resource.lastResize < resizeNumber) {
            unload(resource);
            resource.isInvalid = true;
        }
    }
    return size;
}

Important: To make partial resizing possible, load can also be called outside of resizeImpl.

Unloading resources may change resource indices, but load calls must then set the new indices.