jrandel / ios-image.stamper Goto Github PK

iOS-image.stamper

Created by Jason Randel 6.15.2012

A class that superimposes two UIImages, where the top image is positioned using an arbitrary affine transform.

JRImageStamper.h
JRImageStamper.m

HEADS UP: THIS CLASS IS NOT WELL-DOCUMENTED OR TESTED YET.

The general usage is as follows:
In a UIImageView, place a high-resolution photo (the "image").  This UIImageView has frame "imageFrame",
and--if its content mode is set such that it does not occupy the entire frame--is offset from the corner
of the imageFrame by imageFrameOffset.
Create another UIImageView (containing the "stampImage") in a frame "initialStampFrame".  The JRImageStamper
class is useful when the stampImage is in a UIImageView subclass that allows the user to drag, pinch,
and rotate the stampImage relative to the image.
Once the user has positioned the stampImage, create an instance of JRImageStamper, and pass it the
image, stampImage, imageFrame, the transform property of the stampImage's UIImageView, the stampImage itself,
and the initialStampFrame.  Next, if there is a non-zero imageFrameOffset, set it.
Finally, call the stampedImage method to return a UIImage at the same resolution as the original image that
has the stampImage superimposed as the same position as it appeared on the screen.

More documentation to come at some point.

Properties:
image               the "bottom" image (usually an opaque photo) (UIImage*)
imageFrame          the frame in which the image is placed
stampImage          the "top" image (usually a partially-transparent image from PNG data) (UIImage*)
initialStampFrame   the stamp image's original frame relative to the 
transform           the CGAffineTransform that describes the desired stampImage position, in the initialStampFrame
imageFrameOffset    if the image does not occupy the entire imageFrame, it's upper left corner 
                      relative to the imageFrame should be given by this CGPoint.

Methods:
+ imageStamperWithImage:imageFrame:transform:stamp:initialStampFrame:
- stampedImage (returns the image with the stampImage superimposed on top of it, with position set by transform)
- appendTransform:  (allows for additional transformations on the stampImage)