/* |
File: QuartzCurves.m |
Abstract: Demonstrates using Quartz to draw ellipses & arcs (QuartzEllipseArcView) and bezier & quadratic curves (QuartzBezierView). |
Version: 3.0 |
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*/ |
#import "QuartzCurves.h" |
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@implementation QuartzEllipseArcView |
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-(void)drawInContext:(CGContextRef)context |
{ |
// Drawing with a white stroke color |
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); |
// And draw with a blue fill color |
CGContextSetRGBFillColor(context, 0.0, 0.0, 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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// Add an ellipse circumscribed in the given rect to the current path, then stroke it |
CGContextAddEllipseInRect(context, CGRectMake(30.0, 30.0, 60.0, 60.0)); |
CGContextStrokePath(context); |
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// Stroke ellipse convenience that is equivalent to AddEllipseInRect(); StrokePath(); |
CGContextStrokeEllipseInRect(context, CGRectMake(30.0, 120.0, 60.0, 60.0)); |
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// Fill rect convenience equivalent to AddEllipseInRect(); FillPath(); |
CGContextFillEllipseInRect(context, CGRectMake(30.0, 210.0, 60.0, 60.0)); |
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// Stroke 2 seperate arcs |
CGContextAddArc(context, 150.0, 60.0, 30.0, 0.0, M_PI/2.0, false); |
CGContextStrokePath(context); |
CGContextAddArc(context, 150.0, 60.0, 30.0, 3.0*M_PI/2.0, M_PI, true); |
CGContextStrokePath(context); |
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// Stroke 2 arcs together going opposite directions. |
CGContextAddArc(context, 150.0, 150.0, 30.0, 0.0, M_PI/2.0, false); |
CGContextAddArc(context, 150.0, 150.0, 30.0, 3.0*M_PI/2.0, M_PI, true); |
CGContextStrokePath(context); |
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// Stroke 2 arcs together going the same direction.. |
CGContextAddArc(context, 150.0, 240.0, 30.0, 0.0, M_PI/2.0, false); |
CGContextAddArc(context, 150.0, 240.0, 30.0, M_PI, 3.0*M_PI/2.0, false); |
CGContextStrokePath(context); |
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// Stroke an arc using AddArcToPoint |
CGPoint p[3] = |
{ |
CGPointMake(210.0, 30.0), |
CGPointMake(210.0, 60.0), |
CGPointMake(240.0, 60.0), |
}; |
CGContextMoveToPoint(context, p[0].x, p[0].y); |
CGContextAddArcToPoint(context, p[1].x, p[1].y, p[2].x, p[2].y, 30.0); |
CGContextStrokePath(context); |
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// Show the two segments that are used to determine the tangent lines to draw the arc. |
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0); |
CGContextAddLines(context, p, sizeof(p)/sizeof(p[0])); |
CGContextStrokePath(context); |
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// As a bonus, we'll combine arcs to create a round rectangle! |
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// Drawing with a white stroke color |
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); |
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// If you were making this as a routine, you would probably accept a rectangle |
// that defines its bounds, and a radius reflecting the "rounded-ness" of the rectangle. |
CGRect rrect = CGRectMake(210.0, 90.0, 60.0, 60.0); |
CGFloat radius = 10.0; |
// NOTE: At this point you may want to verify that your radius is no more than half |
// the width and height of your rectangle, as this technique degenerates for those cases. |
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// In order to draw a rounded rectangle, we will take advantage of the fact that |
// CGContextAddArcToPoint will draw straight lines past the start and end of the arc |
// in order to create the path from the current position and the destination position. |
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// In order to create the 4 arcs correctly, we need to know the min, mid and max positions |
// on the x and y lengths of the given rectangle. |
CGFloat minx = CGRectGetMinX(rrect), midx = CGRectGetMidX(rrect), maxx = CGRectGetMaxX(rrect); |
CGFloat miny = CGRectGetMinY(rrect), midy = CGRectGetMidY(rrect), maxy = CGRectGetMaxY(rrect); |
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// Next, we will go around the rectangle in the order given by the figure below. |
// minx midx maxx |
// miny 2 3 4 |
// midy 1 9 5 |
// maxy 8 7 6 |
// Which gives us a coincident start and end point, which is incidental to this technique, but still doesn't |
// form a closed path, so we still need to close the path to connect the ends correctly. |
// Thus we start by moving to point 1, then adding arcs through each pair of points that follows. |
// You could use a similar tecgnique to create any shape with rounded corners. |
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// Start at 1 |
CGContextMoveToPoint(context, minx, midy); |
// Add an arc through 2 to 3 |
CGContextAddArcToPoint(context, minx, miny, midx, miny, radius); |
// Add an arc through 4 to 5 |
CGContextAddArcToPoint(context, maxx, miny, maxx, midy, radius); |
// Add an arc through 6 to 7 |
CGContextAddArcToPoint(context, maxx, maxy, midx, maxy, radius); |
// Add an arc through 8 to 9 |
CGContextAddArcToPoint(context, minx, maxy, minx, midy, radius); |
// Close the path |
CGContextClosePath(context); |
// Fill & stroke the path |
CGContextDrawPath(context, kCGPathFillStroke); |
} |
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@end |
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#pragma mark - QuartzBezierView |
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@implementation QuartzBezierView |
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-(void)drawInContext:(CGContextRef)context |
{ |
// Drawing 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); |
|
// Draw a bezier curve with end points s,e and control points cp1,cp2 |
CGPoint s = CGPointMake(30.0, 120.0); |
CGPoint e = CGPointMake(300.0, 120.0); |
CGPoint cp1 = CGPointMake(120.0, 30.0); |
CGPoint cp2 = CGPointMake(210.0, 210.0); |
CGContextMoveToPoint(context, s.x, s.y); |
CGContextAddCurveToPoint(context, cp1.x, cp1.y, cp2.x, cp2.y, e.x, e.y); |
CGContextStrokePath(context); |
|
// Show the control points. |
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0); |
CGContextMoveToPoint(context, s.x, s.y); |
CGContextAddLineToPoint(context, cp1.x, cp1.y); |
CGContextMoveToPoint(context, e.x, e.y); |
CGContextAddLineToPoint(context, cp2.x, cp2.y); |
CGContextStrokePath(context); |
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// Draw a quad curve with end points s,e and control point cp1 |
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); |
s = CGPointMake(30.0, 300.0); |
e = CGPointMake(270.0, 300.0); |
cp1 = CGPointMake(150.0, 180.0); |
CGContextMoveToPoint(context, s.x, s.y); |
CGContextAddQuadCurveToPoint(context, cp1.x, cp1.y, e.x, e.y); |
CGContextStrokePath(context); |
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// Show the control point. |
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0); |
CGContextMoveToPoint(context, s.x, s.y); |
CGContextAddLineToPoint(context, cp1.x, cp1.y); |
CGContextStrokePath(context); |
} |
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@end |
