GradientView.m

/*
 
File: GradientView.m
 
Abstract: Implements a view that uses a CGGradientRef and the given
    parameters to render a gradient within it's bounds.
 
Version: 1.0
 
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*/
 
#import "GradientView.h"
 
@implementation GradientView
 
- (id)initWithFrame:(NSRect)frameRect
{
    self = [super initWithFrame:frameRect];
    if(self != nil)
    {
        // Default to a square clipping area,
        // linear gradient, show the clip & end points,
        // and don't extend past start or end point.
        shape = 0;
        type = 0;
        gradient = NULL;
        showClip = showEndpoints = true;
        extendStart = extendEnd = false;
    }
    return self;
}
 
-(void)dealloc
{
    CGGradientRelease(gradient);
    [super dealloc];
}
 
-(void)drawRect:(NSRect)rect
{
    // Obtain the current context
    CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
    
    // Move 0,0 to the center of the view
    CGContextTranslateCTM(context, rect.size.width / 2.0, rect.size.height / 2.0);
    
    CGContextSaveGState(context);
 
    // Scale the coordinate system to -1,1 on both axies.
    CGContextScaleCTM(context, rect.size.width / 2.0, rect.size.height / 2.0);
    
    // Clip to the correct shape.
    switch(shape)
    {
        case 0: // Square
            CGContextAddPath(context, GetSquarePath());
            CGContextClip(context);
            break;
        
        case 1: // Triangle
            CGContextAddPath(context, GetCirclePath());
            CGContextClip(context);
            break;
        
        case 2: // Filled Star
            CGContextAddPath(context, GetStarPath());
            CGContextClip(context);
            break;
        
        case 3: // Hollow Star
            CGContextAddPath(context, GetStarPath());
            CGContextEOClip(context);
            break;
    }
    
    // If we need to show the clipping region, then add a black fill with 25% opacity.
    if(showClip)
    {
        CGContextSetGrayFillColor(context, 0.0, 0.25);
        CGContextFillRect(context, CGRectMake(-1, -1, 2, 2));
    }
    
    // Draw the correct gradient
    switch(type)
    {
        case 0: // Linear (perpendicular to the line from startPoint to endPoint)
            CGContextDrawLinearGradient(context, gradient, startPoint, endPoint,
                (extendStart ? kCGGradientDrawsBeforeStartLocation : 0) | (extendEnd ? kCGGradientDrawsAfterEndLocation : 0));
            break;
            
        case 1: // Radial (concentric circles, interpolating radius from startRadius to endRadius,
                //and center from startPoint to endPoint)
            CGContextDrawRadialGradient(context, gradient, startPoint, startRadius, endPoint, endRadius,
                (extendStart ? kCGGradientDrawsBeforeStartLocation : 0) | (extendEnd ? kCGGradientDrawsAfterEndLocation : 0));
            break;
    }
    
    CGContextRestoreGState(context);
 
    // If we need to show the endpoints, then draw them.
    if(showEndpoints)
    {
        DrawEmbellishments(context, NSSizeToCGSize(rect.size), startPoint, startRadius, endPoint, endRadius, type == 1);
    }
}
 
-(void)setShapeSquare
{
    shape = 0;
    [self setNeedsDisplay:YES];
}
 
-(void)setShapeCircle
{
    shape = 1;
    [self setNeedsDisplay:YES];
}
 
-(void)setShapeFilledStar
{
    shape = 2;
    [self setNeedsDisplay:YES];
}
 
-(void)setShapeHollowStar
{
    shape = 3;
    [self setNeedsDisplay:YES];
}
 
-(void)setTypeAxial
{
    type = 0;
    [self setNeedsDisplay:YES];
}
 
-(void)setTypeRadial
{
    type = 1;
    [self setNeedsDisplay:YES];
}
 
-(void)setExtendStart:(BOOL)extend
{
    if(extend != extendStart)
    {
        extendStart = extend;
        [self setNeedsDisplay:YES];
    }
}
 
-(void)setExtendEnd:(BOOL)extend
{
    if(extend != extendEnd)
    {
        extendEnd = extend;
        [self setNeedsDisplay:YES];
    }
}
 
-(void)setStartPoint:(CGPoint)p
{
    startPoint = p;
    [self setNeedsDisplay:YES];
}
 
-(void)setEndPoint:(CGPoint)p
{
    endPoint = p;
    [self setNeedsDisplay:YES];
}
 
-(void)setStartRadius:(CGFloat)r
{
    startRadius = r;
    [self setNeedsDisplay:YES];
}
 
-(void)setEndRadius:(CGFloat)r
{
    endRadius = r;
    [self setNeedsDisplay:YES];
}
 
-(void)setShowClip:(BOOL)yn
{
    showClip = yn;
    [self setNeedsDisplay:YES];
}
 
-(void)setShowEndpoints:(BOOL)yn
{
    showEndpoints = yn;
    [self setNeedsDisplay:YES];
}
 
-(void)setGradient:(CGGradientRef)g
{
    if(gradient != g)
    {
        CGGradientRelease(gradient);
        CGGradientRetain(g);
        gradient = g;
        [self setNeedsDisplay:YES];
    }
}
 
@end