ios 如何以编程方式绘制三角形
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时间：2020-08-30 20:45:57 来源:igfitidea点击:
How to draw a triangle programmatically
提问by user804306
I have a triangle solver, I want a way to use the values I get from the answer to draw a triangle to the screen that matches it.
我有一个三角形求解器，我想要一种方法来使用我从答案中获得的值在与其匹配的屏幕上绘制一个三角形。
回答by progrmr
If you subclass a UIView you can implement something like this in drawRect to draw a triangle:
如果你继承 UIView 你可以在 drawRect 中实现类似的东西来绘制一个三角形：
-(void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextBeginPath(ctx);
CGContextMoveToPoint (ctx, CGRectGetMinX(rect), CGRectGetMinY(rect)); // top left
CGContextAddLineToPoint(ctx, CGRectGetMaxX(rect), CGRectGetMidY(rect)); // mid right
CGContextAddLineToPoint(ctx, CGRectGetMinX(rect), CGRectGetMaxY(rect)); // bottom left
CGContextClosePath(ctx);
CGContextSetRGBFillColor(ctx, 1, 1, 0, 1);
CGContextFillPath(ctx);
}
回答by Santosh
Swift 3equivalent for progrmr's answer:
Swift 3等效于progrmr的答案：
override func draw(_ rect: CGRect) {
guard let context = UIGraphicsGetCurrentContext() else { return }
context.beginPath()
context.move(to: CGPoint(x: rect.minX, y: rect.minY))
context.addLine(to: CGPoint(x: rect.maxX, y: rect.midY))
context.addLine(to: CGPoint(x: (rect.minX), y: rect.maxY))
context.closePath()
context.setFillColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)
context.fillPath()
}
回答by Anna Korr
- (void)drawRect:(CGRect)rect {
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextClearRect(ctx, rect);
// Draw a triangle
CGContextSetRGBFillColor(ctx, 255, 160, 122, 1);
CGContextBeginPath(ctx);
CGContextMoveToPoint (ctx, 290, 35); // top
CGContextAddLineToPoint(ctx, 350, 165); // right
CGContextAddLineToPoint(ctx, 230,165); // left
CGContextClosePath(ctx);
CGContextSetRGBFillColor(ctx, 1, 1, 1, 1);
CGContextFillPath(ctx);
}
