速读原著-Android应用开发入门教程(记录绘制的过程)

    private static class SampleView extends View {
        private Picture mPicture;
        private Drawable mDrawable;
        static void drawSomething(Canvas canvas) { // 绘制的过程
            Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
            p.setColor(0x88FF0000);
            canvas.drawCircle(50, 50, 40, p);
            p.setColor(Color.GREEN);
            p.setTextSize(30);
            canvas.drawText("Pictures", 60, 60, p);
        }
        public SampleView(Context context) {
            super(context);
            setFocusable(true);
            setFocusableInTouchMode(true);
            mPicture = new Picture();
            drawSomething(mPicture.beginRecording(200, 100)); // 开始记录绘制的过程
            mPicture.endRecording(); // 结束记录绘制的过程

            mDrawable = new PictureDrawable(mPicture); // 创建一个可绘制物
        }

        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);
            canvas.drawPicture(mPicture); // 绘制第 1 次
            canvas.drawPicture(mPicture, new RectF(0, 100, getWidth(), 200));
            // 绘制第 2 次
            mDrawable.setBounds(0, 200, getWidth(), 300);
            mDrawable.draw(canvas); // 绘制第 3 次

            ByteArrayOutputStream os = new ByteArrayOutputStream();
            mPicture.writeToStream(os);
            InputStream is = new ByteArrayInputStream(os.toByteArray());
            canvas.translate(0, 300);
            canvas.drawPicture(Picture.createFromStream(is)); // 绘制第 4 次
        }
    }