android中簡單的圖片翻頁效果

參考http://www.blogjava.net/wangxinsh55/archive/2011/09/21/359146.html實現，具體代碼如下：

public class PageWidget extends View {    private Bitmap foreImage;    private Bitmap bgImage;    private PointF touchPt;    private int screenWidth;    private int screenHeight;    private GradientDrawable shadowDrawableRL;    private GradientDrawable shadowDrawableLR;    private ColorMatrixColorFilter mColorMatrixFilter;    private Scroller mScroller;    private int lastTouchX;        public PageWidget(Context context) {        super(context);        // TODO Auto-generated constructor stub        touchPt = new PointF(-1,-1);            //ARGB A(0-透明,255-不透明)        int[] color = { 0xb0333333 ,0x00333333};        shadowDrawableRL = new GradientDrawable(GradientDrawable.Orientation.RIGHT_LEFT, color);        shadowDrawableRL.setGradientType(GradientDrawable.LINEAR_GRADIENT);        shadowDrawableLR = new GradientDrawable(GradientDrawable.Orientation.LEFT_RIGHT, color);        shadowDrawableLR.setGradientType(GradientDrawable.LINEAR_GRADIENT);                 float array[] = { 0.55f,    0,    0,     0, 80.0f,                    0    ,0.55f,    0,     0, 80.0f,                      0    ,    0,0.55f,     0, 80.0f,                    0    ,    0,    0,  0.2f, 0};        ColorMatrix cm = new ColorMatrix();        cm.set(array);        /*         * |A*0.55 + 80|         * |R*0.55 + 80|         * |G*0.55 + 80|         * |B*0.2|         *///      cm.setSaturation(0);        mColorMatrixFilter = new ColorMatrixColorFilter(cm);        //利用捲軸來實現接觸點放開後的動畫效果        mScroller = new Scroller(context);    }    @Override    public void computeScroll() {        // TODO Auto-generated method stub        if (mScroller.computeScrollOffset()) {            touchPt.x = mScroller.getCurrX();            touchPt.y = mScroller.getCurrY();                        postInvalidate();        }        else{//            touchPt.x = -1;//            touchPt.y = -1;                    }        super.computeScroll();    }    public void SetScreen(int screenWidth,int screenHeight){        this.screenWidth = screenWidth;        this.screenHeight = screenHeight;    }        public Bitmap getForeImage() {        return foreImage;    }    public void setForeImage(Bitmap foreImage) {        this.foreImage = foreImage;    }    public Bitmap getBgImage() {        return bgImage;    }    public void setBgImage(Bitmap bgImage) {        this.bgImage = bgImage;    }        @Override    protected void onDraw(Canvas canvas) {        // TODO Auto-generated method stub        drawPageEffect(canvas);        super.onDraw(canvas);    }    /**     * 畫前景圖片     * @param canvas     */    private void drawForceImage(Canvas canvas) {        // TODO Auto-generated method stub        Paint mPaint = new Paint();                if (foreImage!=null) {            canvas.drawBitmap(foreImage, 0, 0, mPaint);        }            }    /**     * 畫背景圖片     * @param canvas     */    private void drawBgImage(Canvas canvas,Path path) {        // TODO Auto-generated method stub        Paint mPaint = new Paint();                if (bgImage!=null) {            canvas.save();                        //只在與路徑相交處畫圖            canvas.clipPath(path,Op.INTERSECT);            canvas.drawBitmap(bgImage, 0, 0, mPaint);            canvas.restore();        }    }    /**     * 畫翻頁效果     * @param canvas     */    private void drawPageEffect(Canvas canvas) {        // TODO Auto-generated method stub        drawForceImage(canvas);        Paint mPaint = new Paint();        if (touchPt.x!=-1 && touchPt.y!=-1) {            //翻頁左側書邊            canvas.drawLine(touchPt.x, 0, touchPt.x,screenHeight, mPaint);                        //左側書邊畫陰影            shadowDrawableRL.setBounds((int)touchPt.x - 20, 0 ,(int)touchPt.x, screenHeight);            shadowDrawableRL.draw(canvas);                        //翻頁對摺處            float halfCut = touchPt.x + (screenWidth - touchPt.x)/2;            canvas.drawLine(halfCut, 0, halfCut, screenHeight, mPaint);                        //對摺處左側畫翻頁頁圖片背面            Rect backArea = new Rect((int)touchPt.x,0,(int)halfCut,screenHeight);            Paint backPaint = new Paint();            backPaint.setColor(0xffdacab0);            canvas.drawRect(backArea, backPaint);                        //將翻頁圖片正面進行處理水平翻轉並平移到touchPt.x點            Paint fbPaint = new Paint();            fbPaint.setColorFilter(mColorMatrixFilter);            Matrix matrix = new Matrix();                        matrix.preScale(-1,1);            matrix.postTranslate(foreImage.getWidth() + touchPt.x,0);                        canvas.save();            canvas.clipRect(backArea);            canvas.drawBitmap(foreImage, matrix, fbPaint);            canvas.restore();                        //對摺處畫左側陰影            shadowDrawableRL.setBounds((int)halfCut - 50, 0 ,(int)halfCut, screenHeight);            shadowDrawableRL.draw(canvas);                        Path bgPath = new Path();                        //可以顯示背景圖的地區            bgPath.addRect(new RectF(halfCut,0,screenWidth,screenHeight), Direction.CW);                        //對摺出右側畫背景            drawBgImage(canvas,bgPath);                        //對摺處畫右側陰影            shadowDrawableLR.setBounds((int)halfCut, 0 ,(int)halfCut + 50, screenHeight);            shadowDrawableLR.draw(canvas);        }    }        @Override    public boolean onTouchEvent(MotionEvent event) {        // TODO Auto-generated method stub        if (event.getAction() == MotionEvent.ACTION_DOWN) {            touchPt.x = event.getX();            touchPt.y =    event.getY();        }        else if(event.getAction() == MotionEvent.ACTION_MOVE){            lastTouchX = (int)touchPt.x;            touchPt.x = event.getX();            touchPt.y =    event.getY();                        postInvalidate();        }        else if(event.getAction() == MotionEvent.ACTION_UP){            int dx,dy;                        dy = 0;                        //向右滑動            if (lastTouchX<touchPt.x) {                dx = foreImage.getWidth() - (int)touchPt.x + 30;            }            else{             //向左滑動                dx = -(int)touchPt.x - foreImage.getWidth();            }                        mScroller.startScroll((int)touchPt.x,(int)touchPt.y,dx,dy,1000);            postInvalidate();        }                //必須為true，否則無法擷取ACTION_MOVE及ACTION_UP事件        return true;    }}public class PageActivity extends Activity {    protected void onCreate(android.os.Bundle savedInstanceState) {        requestWindowFeature(Window.FEATURE_NO_TITLE);                PageWidget pageWidget = new PageWidget(this);        Display display = getWindowManager().getDefaultDisplay();        int width  = display.getWidth();        int height = display.getHeight();        pageWidget.SetScreen(width, height);        Bitmap bm1 = BitmapFactory.decodeResource(getResources(), R.drawable.pre7);        Bitmap bm2 = BitmapFactory.decodeResource(getResources(), R.drawable.after7);        Bitmap foreImage = Bitmap.createScaledBitmap(bm1, width, height,false);        Bitmap bgImage = Bitmap.createScaledBitmap(bm2, width, height,false);        pageWidget.setBgImage(bgImage);        pageWidget.setForeImage(foreImage);        setContentView(pageWidget);                super.onCreate(savedInstanceState);    };}