The image data is read from the JPEG files in order as a series of 8x8 pixel blocks (in left-to-right then top-to-bottom order). Each instruction is basically "draw the next {{length}} blocks from the JPEG files to location {{location}} on the canvas".
Surprisingly, there is no mechanism to explicitly state which blocks to get from the JPEG. Instead, it always just uses the next unused blocks. (This means that blocks from the JPEG cannot be reused.)
Surprisingly, there is no mechanism to explicitly state which blocks to get from the JPEG. Instead, it always just uses the next unused blocks. (This means that blocks from the JPEG cannot be reused.)