Canvas学习笔记

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public class MyView extends View{    public MyView(Context context, AttributeSet set)    {        super(context, set);    }    @Override    // 重写该方法，进行绘图    protected void onDraw(Canvas canvas)    {        super.onDraw(canvas);        // 把整张画布绘制成白色        canvas.drawColor(Color.WHITE);        Paint paint = new Paint();        // 去锯齿        paint.setAntiAlias(true);        paint.setColor(Color.BLUE);        paint.setStyle(Paint.Style.STROKE);        paint.setStrokeWidth(3);        // 绘制圆形        canvas.drawCircle(40, 40, 30, paint);        // 绘制正方形        canvas.drawRect(10, 80, 70, 140, paint);        // 绘制矩形        canvas.drawRect(10, 150, 70, 190, paint);        RectF re1 = new RectF(10, 200, 70, 230);        // 绘制圆角矩形        canvas.drawRoundRect(re1, 15, 15, paint);        RectF re11 = new RectF(10, 240, 70, 270);        // 绘制椭圆        canvas.drawOval(re11, paint);        // 定义一个Path对象，封闭成一个三角形。        Path path1 = new Path();        path1.moveTo(10, 340);        path1.lineTo(70, 340);        path1.lineTo(40, 290);        path1.close();        // 根据Path进行绘制，绘制三角形        canvas.drawPath(path1, paint);        // 定义一个Path对象，封闭成一个五角形。        Path path2 = new Path();        path2.moveTo(26, 360);        path2.lineTo(54, 360);        path2.lineTo(70, 392);        path2.lineTo(40, 420);        path2.lineTo(10, 392);        path2.close();        // 根据Path进行绘制，绘制五角形        canvas.drawPath(path2, paint);        // ----------设置填充风格后绘制----------        paint.setStyle(Paint.Style.FILL);        paint.setColor(Color.RED);        canvas.drawCircle(120, 40, 30, paint);        //绘制正方形        canvas.drawRect(90, 80, 150, 140, paint);        //绘制矩形        canvas.drawRect(90, 150, 150, 190, paint);        RectF re2 = new RectF(90, 200, 150, 230);        //绘制圆角矩形        canvas.drawRoundRect(re2, 15, 15, paint);        RectF re21 = new RectF(90, 240, 150, 270);        // 绘制椭圆        canvas.drawOval(re21, paint);        Path path3 = new Path();        path3.moveTo(90, 340);        path3.lineTo(150, 340);        path3.lineTo(120, 290);        path3.close();        //绘制三角形        canvas.drawPath(path3, paint);        Path path4 = new Path();        path4.moveTo(106, 360);        path4.lineTo(134, 360);        path4.lineTo(150, 392);        path4.lineTo(120, 420);        path4.lineTo(90, 392);        path4.close();        //绘制五角形        canvas.drawPath(path4, paint);        // ----------设置渐变器后绘制----------        // 为Paint设置渐变器        Shader mShader = new LinearGradient(0, 0, 40, 60            , new int[] {            Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW }            , null , Shader.TileMode.REPEAT);        paint.setShader(mShader);        //设置阴影        paint.setShadowLayer(45 , 10 , 10 , Color.GRAY);        // 绘制圆形        canvas.drawCircle(200, 40, 30, paint);        // 绘制正方形        canvas.drawRect(170, 80, 230, 140, paint);        // 绘制矩形        canvas.drawRect(170, 150, 230, 190, paint);        RectF re3 = new RectF(170, 200, 230, 230);        // 绘制圆角矩形        canvas.drawRoundRect(re3, 15, 15, paint);        RectF re31 = new RectF(170, 240, 230, 270);        // 绘制椭圆        canvas.drawOval(re31, paint);        Path path5 = new Path();        path5.moveTo(170, 340);        path5.lineTo(230, 340);        path5.lineTo(200, 290);        path5.close();        // 根据Path进行绘制，绘制三角形        canvas.drawPath(path5, paint);        Path path6 = new Path();        path6.moveTo(186, 360);        path6.lineTo(214, 360);        path6.lineTo(230, 392);        path6.lineTo(200, 420);        path6.lineTo(170, 392);        path6.close();        // 根据Path进行绘制，绘制五角形        canvas.drawPath(path6, paint);        // ----------设置字符大小后绘制----------        paint.setTextSize(24);        paint.setShader(null);        // 绘制7个字符串        canvas.drawText(getResources().getString(R.string.circle), 240, 50,            paint);        canvas.drawText(getResources().getString(R.string.square), 240, 120,            paint);        canvas.drawText(getResources().getString(R.string.rect), 240, 175,            paint);        canvas.drawText(getResources().getString(R.string.round_rect), 230,            220, paint);        canvas.drawText(getResources().getString(R.string.oval), 240,            260, paint);        canvas.drawText(getResources().getString(R.string.triangle), 240, 325,            paint);        canvas.drawText(getResources().getString(R.string.pentagon), 240, 390,            paint);    }}
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