Quartz2D简单绘制之直线&虚线

1、画直线和虚线

// 画线 
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    // 线边冒的三种类型
    // CGLineCap. kCGLineCapButt, kCGLineCapRound, kCGLineCapSquare
    CGLineCap lineCap = kCGLineCapButt;
    // 线段拐角出设置的三种类型
    // CGLineJoin. kCGLineJoinMiter(直角), kCGLineJoinRound(圆角), kCGLineJoinBevel(平角)
    CGLineJoin lineJoin = kCGLineJoinMiter;
    
    CGContextSetRGBStrokeColor(contextRef, 1.0f, 1.0f, 1.0f, 1);
    CGContextSetLineWidth(contextRef, 2.0f);
    CGContextSetLineJoin(contextRef, lineJoin);
    CGContextSetLineCap(contextRef, lineCap);
    CGContextMoveToPoint(contextRef, 50.0f, 200.0f);
    CGContextAddLineToPoint(contextRef, 200.0f, 300.0f);
    CGContextAddLineToPoint(contextRef, 200.0f, 500.0f);
    
    // 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
    
    // 以下两行是设置虚线
     CGFloat lengths[] = {10, 10};
     CGContextSetLineDash(contextRef, 5.0f, lengths, sizeof(lengths)/sizeof(lengths[0]));
    
    CGContextStrokePath(contextRef);
    
    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(contextRef, addLines, sizeof(addLines)/sizeof(addLines[0]));
    CGContextStrokePath(contextRef);
    
    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(contextRef, strokeSegments, sizeof(strokeSegments)/sizeof(strokeSegments[0]));