Android canvas 详解

1. Android利用canvas画各种图形(点、直线、弧、圆、椭圆、文字、矩形、多边形、曲线、圆角矩形)

2. Android Canvas 方法总结

3. 自定义控件之绘图篇（四）：canvas变换与操作  (必看)

4. Android之canvas详解  

简记

显示所画东西的屏幕就是Canvas，其实这是一个非常错误的理解

canvas的变换与操作其实是参考坐标系的变换（不是屏幕的绝对坐标系，需要仔细了解）

@Override   
        protected void onDraw(Canvas canvas) {   

            Path path = new Path(); //定义一条路径   
            path.moveTo(10, 10); //移动到 坐标10,10   
            path.lineTo(50, 60);   
            path.lineTo(200,80);   
            path.lineTo(10, 10);   

//          canvas.drawPath(path, paint);   
            canvas.drawTextOnPath("Android777开发者博客", path, 10, 10, paint);   

        }

@Override   
protected void onDraw(Canvas canvas) {   

    paint.setAntiAlias(true);   
    paint.setStyle(Style.STROKE);   
    canvas.translate(canvas.getWidth()/2, 200); //将位置移动画纸的坐标点:150,150   
    canvas.drawCircle(0, 0, 100, paint); //画圆圈   

    //使用path绘制路径文字   
    canvas.save();   
    canvas.translate(-75, -75);   
    Path path = new Path();   
    path.addArc(new RectF(0,0,150,150), -180, 180);   
    Paint citePaint = new Paint(paint);   
    citePaint.setTextSize(14);   
    citePaint.setStrokeWidth(1);   
    canvas.drawTextOnPath("http://www.android777.com", path, 28, 0, citePaint);   
    canvas.restore();   

    Paint tmpPaint = new Paint(paint); //小刻度画笔对象   
    tmpPaint.setStrokeWidth(1);   

    float  y=100;   
    int count = 60; //总刻度数   

    for(int i=0 ; i