Don't shift the large image around. Don't even have a large image. Have an arrray of tiles and only draw those which would be displayed in the canvas. When you move the slider simply take the input to adjust a 'start from' value and draw the tiles from there.
I really must be missing something though.
Why, exactly, do you need a large image?
I really must be missing something though.
Why, exactly, do you need a large image?