使用CGContextAddArcToPoint()绘制弧时,(x1,y1)和(x2,y2)是什么意思? [英] When drawing an arc using CGContextAddArcToPoint(), what does (x1,y1) and (x2,y2) mean?
问题描述
您可以使用以下代码使用Quartz绘制弧:
You can use the following code to draw an arc using Quartz:
CGContextMoveToPoint(context2, x, y);
CGContextAddArcToPoint(context2, x1, y1, x2, y2, r);
在这些函数中,(x,y)
是起点, r
是圆弧半径但是(x1,y1)
和(x2,y2)
?
In these functions, (x,y)
is the starting point and r
is the arc radius but what are (x1,y1)
and (x2,y2)
?
推荐答案
x1
:用户空间坐标中第一条切线终点的x值。第一条切线从当前点绘制到(x1,y1)。
x1
: The x-value, in user space coordinates, for the end point of the first tangent line. The first tangent line is drawn from the current point to (x1,y1).
y1
:y-用户空间坐标中的值,表示第一条切线的终点。第一条切线从当前点绘制到(x1,y1)。
y1
: The y-value, in user space coordinates, for the end point of the first tangent line. The first tangent line is drawn from the current point to (x1,y1).
x2
:x-用户空间坐标中的值,用于第二条切线的终点。第二条切线从(x1,y1)到(x2,y2)。
x2
: The x-value, in user space coordinates, for the end point of the second tangent line. The second tangent line is drawn from (x1,y1) to (x2,y2).
y2
:用户空间坐标中的y值,表示第二条切线的终点。第二条切线从(x1,y1)到(x2,y2)绘制。
y2
: The y-value, in user space coordinates, for the end point of the second tangent line. The second tangent line is drawn from (x1,y1) to (x2,y2).
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