void scrollHorizontally(ScrollBar scrollBar) {
		if (image == null) return;
		Rectangle canvasBounds = imageCanvas.getClientArea();
		int width = Math.round(imageData.width * xscale);
		int height = Math.round(imageData.height * yscale);
		if (width > canvasBounds.width) {
			// Only scroll if the image is bigger than the canvas.
			int x = -scrollBar.getSelection();
			if (x + width < canvasBounds.width) {
				// Don't scroll past the end of the image.
				x = canvasBounds.width - width;
			}
			imageCanvas.scroll(x, iy, ix, iy, width, height, false);
			ix = x;
		}
	}