Question

In this code

CGRect contextRect = self.bounds;

will refer which bound? rectangle, imageRect, or whole iOS view.

I am trying to manipulate image using quartz2D, i created this code by looking different examples, and code written between // is from Apple Quartz2D guide draw text.

Thanks in advance,
Regards.

    - (void)drawRect:(CGRect)rect
    {
        CGSize cgs = CGSizeMake(250.0, 400.0);
        UIGraphicsBeginImageContext(cgs);

        CGRect rectangle = CGRectMake(0,0,cgs.width,cgs.height);
        CGRect imageRect = CGRectInset(rectangle, 5.4, 5.4);
        imageRect.size.height -= 100;

        UIImage *myImage = [UIImage imageNamed:@"pumpkin.jpg"]; 
        [myImage drawInRect:imageRect];    

        CGContextRef context = UIGraphicsGetCurrentContext();
        CGContextSetLineWidth(context, 10.0);
        CGContextSetRGBStrokeColor(context, 0.0, 0.0, 1.0, 1.0);
        CGContextStrokeRect(context, rectangle);

        //    

        CGRect contextRect = self.bounds;

        CGContextTranslateCTM(context, 0, contextRect.size.height);
        CGContextScaleCTM(context, 1, -1);

        float w, h;
        w = contextRect.size.width;
        h = contextRect.size.height;

        CGAffineTransform myTextTransform;
        CGContextSelectFont (context, "Helvetica-Bold", h/10, kCGEncodingMacRoman);
        CGContextSetCharacterSpacing (context, 10);
        CGContextSetTextDrawingMode (context, kCGTextFillStroke);

        CGContextSetRGBFillColor(context, 0, 1, 0, .5);
        CGContextSetRGBStrokeColor(context, 0, 0, 1, 1);
        myTextTransform =  CGAffineTransformMakeRotation(0);
        CGContextSetTextMatrix(context, myTextTransform);
        CGContextShowTextAtPoint(context, 0, 50, "Quartz 2D", 9);

        //    

        UIImage *testImg =  UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        [testImg drawAtPoint:CGPointMake(35, 10)];
}

Answer 1

self.frame indicates the coords and size of the view in its parent view coordinate system.

self.bounds indicates the coords and size of the view in its own coordinate system. So it always has the same width and height as self.frame, but it has x and y equal to 0.

self.bounds is equal to CGRectMake(0, 0, self.frame.size.width, self.frame.size.height).

So your code:

CGRect contextRect = self.bounds;

is the same as:

CGRect contextRect = rect;