如何在Android中使用Canvas Paint在弧顶上绘制线路径

Question

I am working in an android application where i need to draw a graph like this.

I have drawn the arc using paint and canvas but i didn't know how to draw the line path along with the text as mentioned in below picture!

Any heads up on this would be really helpful for me. Thanks in advance.

Answer 1

In order to keep direction of the line truly, you have to use many trigonometric functions and calculus. However, for such cases you can use canvas.rotate() for tricky solution. For the solution, first you calculate angle of line according to a value. For example, assume your arc represents total value of 200. The left side is 0 and the right side is 200, then you get the value of 80. With these values, you can calculate the angle like that 180degree * (80f)/(200 - 0) it gives 72 degree. Then you can rotate the canvas for drawing canvas.rotate(70f,centerX,centerY) . CenterX and CenterY are values of the center point of the arc. After that, you can draw your line as you draw to line at the left-bottom corner of the canvas canvas.drawLine(0,100,20,100,paint) .

canvas.save()
canvas.rotate(70f,centerX,centerY)
canvas.drawLine(0,100,20,100,paint)
canvas.restore()