Create a quadratic Bezier curve in the WeChat applet drawing API


quadraticCurveTo

Definition

Create a quadratic Bezier curve path.

Tip: The starting point of the curve is the previous point in the path.

Parameters

QQ截图20170208143203.png

Example

const ctx = wx.createCanvasContext('myCanvas')// Draw pointsctx.beginPath()
ctx.arc(20, 20, 2, 0, 2 * Math.PI)
ctx.setFillStyle('red')
ctx.fill()

ctx.beginPath()
ctx.arc(200, 20, 2, 0, 2 * Math.PI)
ctx.setFillStyle('lightgreen')
ctx.fill()

ctx.beginPath()
ctx.arc(20, 100, 2, 0, 2 * Math.PI)
ctx.setFillStyle('blue')
ctx.fill()

ctx.setFillStyle('black')
ctx.setFontSize(12)// Draw guidesctx.beginPath()
ctx.moveTo(20, 20)
ctx.lineTo(20, 100)
ctx.lineTo(200, 20)
ctx.setStrokeStyle('#AAAAAA')
ctx.stroke()// Draw quadratic curvectx.beginPath()
ctx.moveTo(20, 20)
ctx.quadraticCurveTo(20, 100, 200, 20)
ctx.setStrokeStyle('black')
ctx.stroke()

ctx.draw()

QQ截图20170208143223.png

FormoveTo(20, 20) quadraticCurveTo(20, 100, 200, 20) The three key coordinates are as follows:

  • Red: starting point (20, 20)
  • Blue Color: Control point (20, 100)
  • Green: End point (200, 20)