drawing.m

//
//  drawing.m
//  PDColoredProgressViewDemo
//
//  Created by Pascal Widdershoven on 03-01-09.
//  Copyright 2009 P-development. All rights reserved.
//

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 @source http://developer.apple.com/mac/library/samplecode/QuartzShapes/listing10.html
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 */ 
 
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth,
								 float ovalHeight)
{
	float fw, fh;
	// If the width or height of the corner oval is zero, then it reduces to a right angle,
	// so instead of a rounded rectangle we have an ordinary one.
	if (ovalWidth == 0 || ovalHeight == 0) {
		CGContextAddRect(context, rect);
		return;
	}
	
	//  Save the context's state so that the translate and scale can be undone with a call
	//  to CGContextRestoreGState.
	CGContextSaveGState(context);
	
	//  Translate the origin of the contex to the lower left corner of the rectangle.
	CGContextTranslateCTM(context, CGRectGetMinX(rect), CGRectGetMinY(rect));
	
	//Normalize the scale of the context so that the width and height of the arcs are 1.0
	CGContextScaleCTM(context, ovalWidth, ovalHeight);
	
	// Calculate the width and height of the rectangle in the new coordinate system.
	fw = CGRectGetWidth(rect) / ovalWidth;
	fh = CGRectGetHeight(rect) / ovalHeight;
	
	// CGContextAddArcToPoint adds an arc of a circle to the context's path (creating the rounded
	// corners).  It also adds a line from the path's last point to the begining of the arc, making
	// the sides of the rectangle.
	CGContextMoveToPoint(context, fw, fh/2);  // Start at lower right corner
	CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);  // Top right corner
	CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1); // Top left corner
	CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1); // Lower left corner
	CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); // Back to lower right
	
	// Close the path
	CGContextClosePath(context);
	
	// Restore the context's state. This removes the translation and scaling
	// but leaves the path, since the path is not part of the graphics state.
	CGContextRestoreGState(context);
}

static void fillRectWithLinearGradient(CGContextRef context, CGRect rect, CGFloat colors[], int numberOfColors, CGFloat locations[]) {
	CGContextSaveGState(context);
	
	if(!CGContextIsPathEmpty(context))
		CGContextClip(context);
	
	CGContextTranslateCTM(context, CGRectGetMinX(rect), CGRectGetMinY(rect));
	CGPoint start = CGPointMake(0, 0);
	CGPoint end = CGPointMake(0, rect.size.height);
	
	CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
    CGGradientRef gradient = CGGradientCreateWithColorComponents(space, colors, locations, numberOfColors);
	CGContextDrawLinearGradient(context, gradient, end, start, 0);
	CGContextRestoreGState(context);
	
	CGColorSpaceRelease(space);
	CGGradientRelease(gradient);
}