Canvas绘图详解：像素点、线条、圆与弧的绘制-优快云博客

本文链接：https://blog.youkuaiyun.com/yhcelebrite/article/details/11177179

这篇博客介绍了如何使用Canvas进行基础绘图，包括绘制像素点、线条、圆形和弧形。通过示例代码展示了drawPoint、drawLine、drawCircle以及drawArc的方法用法，并提供了相关参数的详细解释。

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//绘制像素点

canvas.drawPoint(float x, float y, Paint paint);
canvas.drawPoints(float[] pts, Paint paint);
canvas.drawPoints(f float[] pts, int offset, int count, paint paint);

/**

x:像素点横坐标

y:像素点纵坐标

pts:多个像素点的坐标，元素个数必须是偶数，两个一组为一个像素点的横纵坐标

paint:用来设置像素点的大小，颜色等属性

offset:drawPoints可以取pts数组中的一部分连续元素作为像素点的坐标，通过该参数指定第一个要获取的元素位置，若要获取从第三个元素开始，则设置为2

count:要获得数组的元素个数，必为偶数

**/

for example:

protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  float[] pts = {1,2,3,4,5,6,7,8};
  int offset = 4;
  int count = pts.length-4;
  Paint paint = new Paint();
  paint.setColor(Color.BLUE);
  canvas.drawPoints(pts, offset, count, paint);
}

//绘制线条和绘制像素点基本相同像素点是两个float作为一组，而线条是四个float一组；

//绘制圆形

canvas.drawCircle(x, y, 20, paint); 横纵坐标，半径；

//绘制弧

protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  float left = 1;
  float top = 1;
  float right = 100;
  float bottom = 100;
  RectF oval = new RectF(left, top, right, bottom);
  float startAngle = 10;
  float sweepAngle = 130;
  boolean useCenter = true;
  Paint paint = new Paint();
  paint.setColor(Color.BLUE);
  canvas.drawArc(oval, startAngle, sweepAngle, useCenter, paint);
}

//绘制文本

canvas.drawText(text, x, y, paint);
canvas.drawPosText(text, pos, paint);
canvas.drawPosText(text, index, count, pos, paint);