Android Api Demos登頂之路（九十四）Graphics-->Xfermodes

/*
 * 這個demon演示了圖像的整合模式
 */
public class MainActivity extends Activity {

    private Bitmap makeDest(int w, int h) {
        Bitmap bm = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(bm);
        Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
        p.setColor(0xffffcc44);
        c.drawOval(new RectF(0, 0, w * 3 / 4, h * 3 / 4), p);
        return bm;
    }

    private Bitmap makeSrc(int w, int h) {
        Bitmap bm = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(bm);
        Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
        p.setColor(0xff66aaff);
        c.drawRect(w / 3, h / 3, w * 19 / 20, h * 19 / 20, p);
        return bm;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }

    private class SampleView extends View {
        private static final int W = 64;
        private static final int H = 64;
        private static final int ROW_MAX = 4;

        private Bitmap mSrcB;
        private Bitmap mDstB;
        private Shader mBG;

        private Xfermode[] sModes = {
                new PorterDuffXfermode(PorterDuff.Mode.CLEAR),
                new PorterDuffXfermode(PorterDuff.Mode.SRC),
                new PorterDuffXfermode(PorterDuff.Mode.DST),
                new PorterDuffXfermode(PorterDuff.Mode.SRC_OVER),
                new PorterDuffXfermode(PorterDuff.Mode.DST_OVER),
                new PorterDuffXfermode(PorterDuff.Mode.SRC_IN),
                new PorterDuffXfermode(PorterDuff.Mode.DST_IN),
                new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT),
                new PorterDuffXfermode(PorterDuff.Mode.DST_OUT),
                new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP),
                new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP),
                new PorterDuffXfermode(PorterDuff.Mode.XOR),
                new PorterDuffXfermode(PorterDuff.Mode.DARKEN),
                new PorterDuffXfermode(PorterDuff.Mode.LIGHTEN),
                new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY),
                new PorterDuffXfermode(PorterDuff.Mode.SCREEN) };

        private String[] sLabels = { "Clear", "Src", "Dst", "SrcOver",
                "DstOver", "SrcIn", "DstIn", "SrcOut", "DstOut", "SrcATop",
                "DstATop", "Xor", "Darken", "Lighten", "Multiply", "Screen" };

        public SampleView(Context context) {
            super(context);

            mSrcB = makeSrc(W, H);
            mDstB = makeDest(W, H);
            // 創建一個位圖圖案，用於作爲背景，寬和高爲2個像素第1個顏色值表示第一行第一個像素點，第二個顏色值表示第一行第二個像素點
            // 第三個顏色值表示第二行第一個像素點，第四個顏色值表示第二行第二個像素點
            Bitmap bm = Bitmap.createBitmap(new int[] { 0xffffffff, 0xffcccccc,
                    0xffcccccc, 0xffffffff }, 2, 2, Bitmap.Config.RGB_565);

            mBG = new BitmapShader(bm, Shader.TileMode.REPEAT,
                    Shader.TileMode.REPEAT);
            Matrix m = new Matrix();
            // 將圖案放大6倍
            m.setScale(6, 6);
            mBG.setLocalMatrix(m);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);
            Paint paint = new Paint();
            // 關閉圖像過濾，如果打開會使背景變得模糊，因爲我們需要得到清晰、邊緣分明的背景，所以不需要濾波
            paint.setFilterBitmap(false);
            // paint.setAntiAlias(true);
            canvas.translate(15, 35);

            Paint labelP=new Paint(Paint.ANTI_ALIAS_FLAG);
            labelP.setTextAlign(Paint.Align.CENTER);

            int x = 0;
            int y = 0;
            //canvas.drawBitmap(mSrcB, 0, 0, paint);
            for (int i = 0; i < sModes.length; i++) {
                //畫邊框
                paint.setStyle(Paint.Style.STROKE);
                paint.setShader(null);
                canvas.drawRect(x - 0.5f, y - 0.5f, x + W + 0.5f, y + H + 0.5f,
                        paint);
                //畫背景
                paint.setStyle(Paint.Style.FILL);
                paint.setShader(mBG);
                canvas.drawRect(x, y, x + W, y + H, paint);

                int sc = canvas.saveLayer(x, y, x + W, y + H, null,
                        Canvas.MATRIX_SAVE_FLAG |
                        Canvas.CLIP_SAVE_FLAG |
                        Canvas.HAS_ALPHA_LAYER_SAVE_FLAG |
                        Canvas.FULL_COLOR_LAYER_SAVE_FLAG |
                        Canvas.CLIP_TO_LAYER_SAVE_FLAG);
                canvas.translate(x, y);
                //繪製目標圖形
                canvas.drawBitmap(mDstB, 0, 0, paint);
                //設置整合模式
                paint.setXfermode(sModes[i]);
                //繪製源圖形
                canvas.drawBitmap(mSrcB, 0, 0, paint);
                paint.setXfermode(null);
                canvas.restoreToCount(sc);

                //繪製說明文字
                canvas.drawText(sLabels[i], x+W/2, y-labelP.getTextSize()/2, labelP);

                x+=W+10;
                if((i%ROW_MAX)==ROW_MAX-1){
                    x=0;
                    y+=H+30;
                }
            }
        }

    }

}