/* |
File: QuartzLines.m |
Abstract: Demonstrates Quartz line drawing facilities (QuartzLineView), including dash patterns (QuartzDashView), stroke width, line cap and line join (QuartzCapJoinWidthView). |
Version: 3.0 |
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*/ |
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#import "QuartzLines.h" |
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@implementation QuartzLineView |
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-(void)drawInContext:(CGContextRef)context |
{ |
// Drawing lines with a white stroke color |
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); |
// Draw them with a 2.0 stroke width so they are a bit more visible. |
CGContextSetLineWidth(context, 2.0); |
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// Draw a single line from left to right |
CGContextMoveToPoint(context, 10.0, 30.0); |
CGContextAddLineToPoint(context, 310.0, 30.0); |
CGContextStrokePath(context); |
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// Draw a connected sequence of line segments |
CGPoint addLines[] = |
{ |
CGPointMake(10.0, 90.0), |
CGPointMake(70.0, 60.0), |
CGPointMake(130.0, 90.0), |
CGPointMake(190.0, 60.0), |
CGPointMake(250.0, 90.0), |
CGPointMake(310.0, 60.0), |
}; |
// Bulk call to add lines to the current path. |
// Equivalent to MoveToPoint(points[0]); for(i=1; i<count; ++i) AddLineToPoint(points[i]); |
CGContextAddLines(context, addLines, sizeof(addLines)/sizeof(addLines[0])); |
CGContextStrokePath(context); |
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// Draw a series of line segments. Each pair of points is a segment |
CGPoint strokeSegments[] = |
{ |
CGPointMake(10.0, 150.0), |
CGPointMake(70.0, 120.0), |
CGPointMake(130.0, 150.0), |
CGPointMake(190.0, 120.0), |
CGPointMake(250.0, 150.0), |
CGPointMake(310.0, 120.0), |
}; |
// Bulk call to stroke a sequence of line segments. |
// Equivalent to for(i=0; i<count; i+=2) { MoveToPoint(point[i]); AddLineToPoint(point[i+1]); StrokePath(); } |
CGContextStrokeLineSegments(context, strokeSegments, sizeof(strokeSegments)/sizeof(strokeSegments[0])); |
} |
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@end |
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#pragma mark - |
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@implementation QuartzCapJoinWidthView |
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-(void)drawInContext:(CGContextRef)context |
{ |
// Drawing lines with a white stroke color |
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); |
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// Preserve the current drawing state |
CGContextSaveGState(context); |
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// Setup the horizontal line to demostrate caps |
CGContextMoveToPoint(context, 40.0, 30.0); |
CGContextAddLineToPoint(context, 280.0, 30.0); |
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// Set the line width & cap for the cap demo |
CGContextSetLineWidth(context, self.width); |
CGContextSetLineCap(context, self.cap); |
CGContextStrokePath(context); |
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// Restore the previous drawing state, and save it again. |
CGContextRestoreGState(context); |
CGContextSaveGState(context); |
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// Setup the angled line to demonstrate joins |
CGContextMoveToPoint(context, 40.0, 190.0); |
CGContextAddLineToPoint(context, 160.0, 70.0); |
CGContextAddLineToPoint(context, 280.0, 190.0); |
|
// Set the line width & join for the join demo |
CGContextSetLineWidth(context, self.width); |
CGContextSetLineJoin(context, self.join); |
CGContextStrokePath(context); |
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// Restore the previous drawing state. |
CGContextRestoreGState(context); |
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// If the stroke width is large enough, display the path that generated these lines |
if (self.width >= 4.0) // arbitrarily only show when the line is at least twice as wide as our target stroke |
{ |
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0); |
CGContextMoveToPoint(context, 40.0, 30.0); |
CGContextAddLineToPoint(context, 280.0, 30.0); |
CGContextMoveToPoint(context, 40.0, 190.0); |
CGContextAddLineToPoint(context, 160.0, 70.0); |
CGContextAddLineToPoint(context, 280.0, 190.0); |
CGContextSetLineWidth(context, 2.0); |
CGContextStrokePath(context); |
} |
} |
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-(void)setCap:(CGLineCap)c |
{ |
if(c != _cap) |
{ |
_cap = c; |
[self setNeedsDisplay]; |
} |
} |
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-(void)setJoin:(CGLineJoin)j |
{ |
if(j != _join) |
{ |
_join = j; |
[self setNeedsDisplay]; |
} |
} |
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-(void)setWidth:(CGFloat)w |
{ |
if(w != _width) |
{ |
_width = w; |
[self setNeedsDisplay]; |
} |
} |
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@end |
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#pragma mark - |
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@implementation QuartzDashView |
{ |
CGFloat dashPattern[10]; |
size_t dashCount; |
} |
|
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-(void)setDashPhase:(CGFloat)phase |
{ |
if (phase != _dashPhase) |
{ |
_dashPhase = phase; |
[self setNeedsDisplay]; |
} |
} |
|
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-(void)setDashPattern:(CGFloat *)pattern count:(size_t)count |
{ |
if ((count != dashCount) || (memcmp(dashPattern, pattern, sizeof(CGFloat) * count) != 0)) |
{ |
memcpy(dashPattern, pattern, sizeof(CGFloat) * count); |
dashCount = count; |
[self setNeedsDisplay]; |
} |
} |
|
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-(void)drawInContext:(CGContextRef)context |
{ |
// Drawing lines with a white stroke color |
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); |
|
// Each dash entry is a run-length in the current coordinate system |
// The concept is first you determine how many points in the current system you need to fill. |
// Then you start consuming that many pixels in the dash pattern for each element of the pattern. |
// So for example, if you have a dash pattern of {10, 10}, then you will draw 10 points, then skip 10 points, and repeat. |
// As another example if your dash pattern is {10, 20, 30}, then you draw 10 points, skip 20 points, draw 30 points, |
// skip 10 points, draw 20 points, skip 30 points, and repeat. |
// The dash phase factors into this by stating how many points into the dash pattern to skip. |
// So given a dash pattern of {10, 10} with a phase of 5, you would draw 5 points (since phase plus 5 yields 10 points), |
// then skip 10, draw 10, skip 10, draw 10, etc. |
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CGContextSetLineDash(context, self.dashPhase, dashPattern, dashCount); |
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// Draw a horizontal line, vertical line, rectangle and circle for comparison |
CGContextMoveToPoint(context, 10.0, 20.0); |
CGContextAddLineToPoint(context, 310.0, 20.0); |
CGContextMoveToPoint(context, 160.0, 30.0); |
CGContextAddLineToPoint(context, 160.0, 130.0); |
CGContextAddRect(context, CGRectMake(10.0, 30.0, 100.0, 100.0)); |
CGContextAddEllipseInRect(context, CGRectMake(210.0, 30.0, 100.0, 100.0)); |
// And width 2.0 so they are a bit more visible |
CGContextSetLineWidth(context, 2.0); |
CGContextStrokePath(context); |
} |
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@end |
