I have read some posts on this website about using drawInRect instead of the CGContext draw methods. It still draws it upside down? I thought using drawInRect would print it right side up with the coordinate system originating at the top left?
-(voi开发者_开发百科d) drawImage:(UIImage*) image atX:(float) x andY:(float) y withWidth:(float) width andHeight:(float) height onContext:(CGContextRef) context{
UIGraphicsPushContext(context);
[image drawInRect:CGRectMake(x, size.height-y-height, width, height)];
UIGraphicsPopContext();
}
Notice I'm doing size.height-y-height
and if I don't do that it doesn't go where I expect (assuming drawInRect
using a topleft coordinate system). It renders in the correct spot with the above code but still upside down. HELP!!!!!!
UPDATE
Thanks to the answer below this is the working method
-(void) drawImage:(UIImage*) image atX:(float) x andY:(float) y withWidth:(float) width andHeight:(float) height onContext:(CGContextRef) context{
UIGraphicsPushContext(context);
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0, size.height);
CGContextScaleCTM(context, 1.0, -1.0);
[image drawInRect:CGRectMake(x, y, width, height)];
CGContextRestoreGState(context);
UIGraphicsPopContext();
}
UIGraphicsBeginImageContext(imageViewSize);
CGContextRef imageContext = UIGraphicsGetCurrentContext();
// Draw the image in the upper left corner (0,0) with its actual size
CGContextDrawImage(imageContext, imageViewRect, oldImage.CGImage);
// As it draws the image from lower right corner,
// following code will flip it up side down vertically.
CGContextTranslateCTM(imageContext, 0.0, 0.0);
CGContextScaleCTM(imageContext, 1.0, -1.0);
CGContextDrawImage(imageContext, imageViewRect, oldImage.CGImage);
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