用平行线填充UIBezierPath

Question

我正在尝试使用UIBezierPath绘制自定义形状：

UIBezierPath *aPath = [UIBezierPath bezierPath];

    [aPath moveToPoint:CGPointMake(100.0, 0.0)];

    // Draw the lines.
    [aPath addLineToPoint:CGPointMake(200.0, 40.0)];
    [aPath addLineToPoint:CGPointMake(160, 140)];
    [aPath addLineToPoint:CGPointMake(40.0, 140)];
    [aPath addLineToPoint:CGPointMake(0.0, 40.0)];
    [aPath closePath];

我想用平行线填充它以使其剥离。我也想更改这些线条的颜色。假设我要使它们垂直。我必须定期计算此路径上的点数，我该怎么做？

我找到了这个UIColor colorWithPatternImage，但是后来我无法更改形状中线条的颜色和“密度”。

Answer 1

就像Nikolai Ruhe所说，最好的选择是使用形状作为剪切路径，然后在形状的边界框内绘制一些图案。这是代码的示例

- (void)drawRect:(CGRect)rect
{
    // create a UIBezierPath for the outline shape
    UIBezierPath *aPath = [UIBezierPath bezierPath];
    [aPath moveToPoint:CGPointMake(100.0, 0.0)];
    [aPath addLineToPoint:CGPointMake(200.0, 40.0)];
    [aPath addLineToPoint:CGPointMake(160, 140)];
    [aPath addLineToPoint:CGPointMake(40.0, 140)];
    [aPath addLineToPoint:CGPointMake(0.0, 40.0)];
    [aPath closePath];
    [aPath setLineWidth:10];

    // get the bounding rectangle for the outline shape
    CGRect bounds = aPath.bounds;

    // create a UIBezierPath for the fill pattern
    UIBezierPath *stripes = [UIBezierPath bezierPath];
    for ( int x = 0; x < bounds.size.width; x += 20 )
    {
        [stripes moveToPoint:CGPointMake( bounds.origin.x + x, bounds.origin.y )];
        [stripes addLineToPoint:CGPointMake( bounds.origin.x + x, bounds.origin.y + bounds.size.height )];
    }
    [stripes setLineWidth:10];

    CGContextRef context = UIGraphicsGetCurrentContext();

    // draw the fill pattern first, using the outline to clip
    CGContextSaveGState( context );         // save the graphics state
    [aPath addClip];                        // use the outline as the clipping path
    [[UIColor blueColor] set];              // blue color for vertical stripes
    [stripes stroke];                       // draw the stripes
    CGContextRestoreGState( context );      // restore the graphics state, removes the clipping path

    // draw the outline of the shape
    [[UIColor greenColor] set];             // green color for the outline
    [aPath stroke];                         // draw the outline
}

使用Swift

override func draw(_ rect: CGRect){

        // create a UIBezierPath for the outline shape
        let aPath = UIBezierPath()
        aPath.move(to: CGPoint(x: 100.0, y: 0.0))
        aPath.addLine(to: CGPoint(x: 200.0, y: 40.0))
        aPath.addLine(to: CGPoint(x: 160, y: 140))
        aPath.addLine(to: CGPoint(x: 40.0, y: 140))
        aPath.addLine(to: CGPoint(x: 0.0, y: 40.0))
        aPath.close()
        aPath.lineWidth = 10

        // get the bounding rectangle for the outline shape
        let bounds = aPath.bounds

        // create a UIBezierPath for the fill pattern
        let stripes = UIBezierPath()
        for x in stride(from: 0, to: bounds.size.width, by: 20){
            stripes.move(to: CGPoint(x: bounds.origin.x + x, y: bounds.origin.y ))
            stripes.addLine(to: CGPoint(x: bounds.origin.x + x, y: bounds.origin.y + bounds.size.height ))
        }
        stripes.lineWidth = 10

        let context = UIGraphicsGetCurrentContext()

        // draw the fill pattern first, using the outline to clip
        context!.saveGState()         // save the graphics state
        aPath.addClip()                        // use the outline as the clipping path
        UIColor.blue.set()                    // blue color for vertical stripes
        stripes.stroke()                       // draw the stripes
        context!.restoreGState()      // restore the graphics state, removes the clipping path

        // draw the outline of the shape
        UIColor.green.set()             // green color for the outline
        aPath.stroke()                         // draw the outline
    }

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