【Android自定义View】绘图之Path篇（二）

前言

上一篇，咱们说了绘制基本的几何图形，这一篇咱们说说绘制路径（Path）

• 【Android自定义View】目录

这里主要用到的方法是 canvas.drawPath(path, paint);

1.直线

主要用到的方法

moveTo(float x, float y) 起始点

lineTo(float x, float y)当前点直线的结束点，也是下条直线的起始点

close()闭合

Paint paint = new Paint();
        paint.setColor(Color.RED);
        paint.setStrokeWidth(10);
        paint.setStyle(Paint.Style.FILL);

        Path path = new Path();
        path.moveTo(20, 20); //设定起始点
        path.lineTo(300, 100);//第1条直线
        path.lineTo(300, 300);//第2条直线
        path.close();//闭合
        canvas.drawPath(path, paint);
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2.矩形

addRect(RectF rect, Direction dir)

addRect(float left, float top, float right, float bottom, Direction dir)

RectF和float left, float top, float right, float bottom是同样的，Direction有2种方式，CW和CCW，其中CW表示顺时针，CCW表示逆时针

Path ccw = new Path();
        RectF rect1 =  new RectF(50, 50, 300, 300);
        ccw.addRect(rect1, Path.Direction.CCW);//逆时针

        Path cw = new Path();
        RectF rect2 =  new RectF(350, 50, 600, 300);
        cw.addRect(rect2, Path.Direction.CW);//顺时针

        canvas.drawPath(ccw, paint);
        canvas.drawPath(cw, paint);
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看上去好像是同样的？实际上是过程不同，结果同样，细节的话，咱们后面再说。

3.圆角矩形

addRoundRect(RectF rect, float rx, float ry, Direction dir)

addRoundRect(float left, float top, float right, float bottom, float rx, float ry, Direction dir)

addRoundRect(RectF rect, float[] radii, Direction dir)

addRoundRect(float left, float top, float right, float bottom, float[] radii,Direction dir)

其中，radii只能传入8个数值，多于8个不会有效果，rx表示x方向的半径，ry表示y方向的半径

Path ccw = new Path();
        RectF rect1 = new RectF(50, 50, 500, 500);
        float[] radii = {5, 20, 50, 100, 150, 200, 250, 300};
        ccw.addRoundRect(rect1, radii, Path.Direction.CCW);


        Path cw = new Path();
        RectF rect2 = new RectF(550, 50, 1000, 500);
        cw.addRoundRect(rect2, 10, 100, Path.Direction.CCW);

        canvas.drawPath(ccw, paint);

        paint.setColor(Color.BLUE);
        canvas.drawPath(cw, paint);
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4.圆形

addCircle(float x, float y, float radius, Direction dir)

Path cw = new Path();
        cw.addCircle(200, 200, 100, Path.Direction.CW);
        canvas.drawPath(cw, paint);
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5.椭圆

addOval(RectF oval, Direction dir)

addOval(float left, float top, float right, float bottom, Direction dir)

Path cw = new Path();
        RectF rect1 = new RectF(50, 50, 500, 300);
        cw.addOval(rect1, Path.Direction.CW);
        canvas.drawPath(cw, paint);
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6.弧形

addArc(RectF oval, float startAngle, float sweepAngle)

addArc(float left, float top, float right, float bottom, float startAngle, float sweepAngle)

startAngle 开始的角度，X轴正方向为0度

sweepAngel 持续的度数

Path cw = new Path();
        RectF rect1 = new RectF(50, 50, 500, 300);
        cw.addArc(rect1, 0, 180);
        canvas.drawPath(cw, paint);
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7.带轨迹的文字

drawTextOnPath(String text, Path path, float hOffset,float vOffset, Paint paint)

drawTextOnPath(char[] text, int index, int count, Path path, float hOffset, float vOffset, Paint paint)

index 表示开始位置

count 表示结束位置，能够对文字进行截取

hOffset 表示绘制位置离开始位置的偏移量

vOffset 表示绘制位置离开路径的偏移量

String text = "ABCDEFGHIJKLMNOPQRSTYVWXYZ";
        paint.setTextSize(72);

        Path ccw = new Path();
        RectF rect1 = new RectF(50, 50, 500, 500);
        ccw.addRect(rect1, Path.Direction.CCW);//逆时针

        Path cw = new Path();
        RectF rect2 = new RectF(650, 50, 1100, 500);
        cw.addRect(rect2, Path.Direction.CW);//顺时针

        canvas.drawPath(ccw, paint);
        canvas.drawPath(cw, paint);

        canvas.drawTextOnPath(text, ccw, 0, 0, paint);

        canvas.drawTextOnPath(text, cw, 0, 0, paint);
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这里就能够明显的看出 CCW和 CW的区别了

修改hOffset和vOffset

String text = "ABCDEFGHIJKLMNOPQRSTYVWXYZ";
        paint.setTextSize(72);

        Path ccw = new Path();
        RectF rect1 = new RectF(50, 50, 500, 500);
        ccw.addRect(rect1, Path.Direction.CCW);//逆时针

        Path cw = new Path();
        RectF rect2 = new RectF(650, 50, 1100, 500);
        cw.addRect(rect2, Path.Direction.CW);//顺时针

        canvas.drawPath(ccw, paint);
        canvas.drawPath(cw, paint);

        canvas.drawTextOnPath(text, ccw, 100, 0, paint);

        canvas.drawTextOnPath(text, cw, 0, 100, paint);
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能够看到，hOffset 表示绘制位置离开始位置的偏移量，vOffset 表示绘制位置离开路径的偏移量，vOffset 越大，离圆心越近。

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