Hello Sop,
welcome to our forum!
Assuming you have already a bitmap prepared, the simplest approach would be to display the bitmap in an Image view. Then you can adjust the width of the image at the runtime so more or less of the bitmap will be visible. If the Image view is smaller than the bitmap, the bitmap content is clipped automatically. To adjust the width of the Image view you modify its property Bounds, for example:
var int32 desiredWidth = ...
Image.Bounds.w = desiredWidth;
Please note that the Image view is per default configured to center the bitmap within its own area. For your application case you will thus need to align the bitmap at the left edge of the Image view. This is configured by Image view's property Alignment.
Does it help you further?
Best regards
Paul Banach