canvas常用方法

1.渐变填充

  // 创建线性渐变对象-线性
  const gradientLinear= ctx.createLinearGradient(0,0,0,0,0,10); //createRadialGradient(60, 60, 0, 60, 60, 50)径向

  gradientLinear.addColorStop(0,"rgba(255,255,255,1)");
  gradientLinear.addColorStop(0.3,"rgba(0,255,240,0.8)");
  gradientLinear.addColorStop(0.5,"rgba(0,2405,255,0.8)");
  gradientLinear.addColorStop(0.8,"rgba(0,208,255,0.8)");
  gradientLinear.addColorStop(1,"rgba(10,176,214,1)");

  // 填充线性渐变
  contextLinear.fillStyle = gradientLinear;
  contextLinear.fillRect(10, 10, 100, 100);

2.canvas混合模式 （globalCompositeOperation ）

context.globalCompositeOperation = type;

3.裁剪   context.clip();

4.当前元素高亮或处于选中 focus       context.drawFocusIfNeeded()

5.绘制椭圆  context.ellipse()

6.获取画布元素  context.getImageData()

7.获取当前虚线的样式    context.getLineDash()

8.检测某个点是否在当前路径中    context.isPointInPath()   

9.检测对应的点是否在描边路径上，描边越粗，检测范围越大    context.isPointInStroke()

10.画布缩放    context.scale(x, y);

11.文字描边   context.strokeText(text, x, y [, maxWidth]);