线

private void drawLine(Canvas canvas,
                          float startX,float startY,float stopX,float stopY,
                          float width,int color){
    Paint paint = new Paint();
    paint.setAntiAlias(true);//抗锯齿
    paint.setStyle(Paint.Style.STROKE);//不加这个不显示
    paint.setColor(color);
    paint.setStrokeWidth(width);
    Path mPath = new Path();
    mPath.moveTo(startX, startY);
    mPath.lineTo(stopX, stopY);
    mPath.close();



    //***************旋转线
    //1.
    canvas.save();
    canvas.translate(startX, startY);//根据指定坐标旋转
    //水平翻转
    canvas.scale(-1,1);
    //垂直翻转
    canvas.scale(1,-1);
    canvas.translate(-startX, -startY);
    //2.
    canvas.rotate(90, startX, startY);//根据指定角度、坐标来旋转

    canvas.drawPath(mPath, paint);

    canvas.restore();
}

矩形

private void drawRectangle(Canvas canvas,boolean choose,
                               float left,float top,float right,float bottom,int color){
    Paint paint = new Paint();
    paint.setAntiAlias(true);//抗锯齿
    paint.setColor(color);
    if (choose){
        //设置实心矩形
        paint.setStyle(Paint.Style.FILL);
    }else{
       //设置空心矩形
       paint.setStyle(Paint.Style.STROKE);
    }
    //使用画笔在画布上画矩形
    canvas.drawRect(left,top,right,bottom,paint);
}

圆形

private void drawYuan(Canvas canvas,boolean choose,
                          float startX,float startY,float radius,int color){
    Paint paint = new Paint();
    paint.setAntiAlias(true);//抗锯齿
    paint.setColor(color);
    if (choose){
       //设置实心圆
       paint.setStyle(Paint.Style.FILL);
    }else{
       //设置空心圆
       paint.setStyle(Paint.Style.STROKE);
    }
    //X、Y坐标，radius半径
   canvas.drawCircle(startX, startY, radius, paint);
}

三角形

private void drawTriangle(Canvas canvas,boolean choose,
                              float startX,float startY,
                              float afterX,float afterY,
                              float stopX,float stopY,
                              float width,int color){
    Paint paint = new Paint();
    paint.setAntiAlias(true);//抗锯齿
    paint.setStrokeWidth(width);
    paint.setColor(color);
    if (choose){
       //设置实心三角形
       paint.setStyle(Paint.Style.FILL);
    }else{
       //设置空心三角形
       paint.setStyle(Paint.Style.STROKE);
    }
    Path mPath = new Path();
    mPath.moveTo(startX, startY);
    mPath.lineTo(afterX, afterY);
    mPath.lineTo(stopX, stopY);
    //将mpath封闭，也可以写 mpath.lineTo(100, 100);代替
    mPath.close();
    //绘制path路径
    canvas.drawPath(mPath, paint);
}

旋转文字

private void drawText(Canvas canvas,String str,int size,float degrees,float startX,float             
                     startY,int color){
    Paint paint = new Paint();
    paint.setAntiAlias(true);//抗锯齿        
    paint.setColor(color);
    paint.setTypeface(Typeface.DEFAULT_BOLD);//字体
    Typeface font = Typeface.create(Typeface.SANS_SERIF, Typeface.NORMAL);//字体风格
    paint.setTypeface(font);
    paint.setTextSize(size);
    //Paint设置水平居中
    paint.setTextAlign(Paint.Align.CENTER);
    float length = paint.measureText(str);//获取字体的长度
    float ncenterx = startX + (size - length) / 2;
    if (degrees!=0){
       //以指定坐标点旋转指定角度
       canvas.rotate(degrees, ncenterx, startY);
     }
     canvas.drawText(str, ncenterx,startY,paint);
}

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