画三角iphone

Question

我如何在iphone中绘制三角形.....这有什么api吗？你可以发一些代码......

Answer 1

您应该看一下Apple Documentation 中的QuartzDemo,它有很多绘图示例.

使用此演示,您可以在Polygon演示中将de star(6条边)更改为三角形(3条边).只需更改QuartzPolygons.m循环中的增量数,只需注释"//将星形添加到当前路径".例如,以下是等边三角形的代码:

-(void)drawInContext:(CGContextRef)context
{
    // Drawing with a white stroke color
    CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
    // Drawing 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);

    CGPoint center;

    // Add a triangle to the current path
    center = CGPointMake(90.0, 90.0);
    CGContextMoveToPoint(context, center.x, center.y + 60.0);
    for(int i = 1; i < 3; ++i)
    {
        CGFloat x = 60.0 * sinf(i * 4.0 * M_PI / 3.0);
        CGFloat y = 60.0 * cosf(i * 4.0 * M_PI / 3.0);
        CGContextAddLineToPoint(context, center.x + x, center.y + y);
    }
    // And close the subpath.
    CGContextClosePath(context);

    // Now draw the triangle with the current drawing mode.
    CGContextDrawPath(context, drawingMode);
}