I experimenting with creating a simple finger-painting application on the ipad. I am able to draw a path to the screen correctly, but I want to have an option that completely clears the screen of all drawn paths. The code I currently have clears the context, but when I call the drawing code block all the paths reappear on screen.
- (void)drawRect:(CGRect)rect
{
//Drawing code
CGContextRef context = UIGraphicsGetCurrentContext();
if(clearContext == 0){
CGContextSetLineWidth(context, 6);
CGContextSetRGBStrokeColor(context, 1, 0, 0, 1);
CGContextAddPath(context, drawingPath);
CGContextStrokePath(context);
}
if(clearContext == 1){
//This is the code I currently have to clear the context, it is clearly wrong
//Just used as experimentation.
CGContextSetBlendMode(context, kCGBlendModeClear);
CGContextAddPath(context, drawingPath);
CGContextStrokePath(context);
clearContext = 0;
}
}
im assuming drawingPath is a CGPath ... are you clearing that CGPath? that might be the cause of your problem
in the action to clear your path, do:
CGPathRelease(drawingPath);
drawingPath = CGPathCreateMutable();
[self setNeedsDisplay];
and do the normal drawing you usually do. if the path is empty, nothing will be drawn