/** * Android API實(shí)現(xiàn)圖像扭曲效果 * @description： * @date 2016-7-22 下午2:19:12 */public class BitmapMesh extends GraphicsActivity { @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(new SampleView(this)); } private static class SampleView extends View {   //定義常量,指定該圖片橫向被劃分為20格  private static final int WIDTH = 20;   //定義常量,指定該圖片縱向上被劃分為20格  private static final int HEIGHT = 20;  //記錄該圖像上包含441個(gè)頂點(diǎn)  private static final int COUNT = (WIDTH + 1) * (HEIGHT + 1);  //位圖  private final Bitmap mBitmap;  //數(shù)組,記錄Bitmap上的21*21個(gè)點(diǎn)的坐標(biāo)  private final float[] mVerts = new float[COUNT * 2];   //記錄Bitmap上的21*21個(gè)點(diǎn)經(jīng)過扭曲后的坐標(biāo)  private final float[] mOrig = new float[COUNT * 2];  private final Matrix mMatrix = new Matrix();  private final Matrix mInverse = new Matrix();  private static void setXY(float[] array, int index, float x, float y) {   array[index * 2 + 0] = x;   array[index * 2 + 1] = y;  }  public SampleView(Context context) {   super(context);   setFocusable(true);   //加載圖片   mBitmap = BitmapFactory.decodeResource(getResources(), R.raw.beach);   //獲取圖像的寬度和高度   float w = mBitmap.getWidth();   float h = mBitmap.getHeight();   //構(gòu)建扭曲數(shù)據(jù)   int index = 0;   for (int y = 0; y <= HEIGHT; y++) {    float fy = h * y / HEIGHT;    for (int x = 0; x <= WIDTH; x++) {     float fx = w * x / WIDTH;      //初始化orig,verts數(shù)組     //初始化,orig,verts兩個(gè)數(shù)組均勻地保存了21 * 21個(gè)點(diǎn)的x,y坐標(biāo)　     setXY(mVerts, index, fx, fy);     setXY(mOrig, index, fx, fy);     index += 1;    }   }   //設(shè)置平移效果   mMatrix.setTranslate(10, 10);   //實(shí)現(xiàn)亂矩陣逆向坐標(biāo)映射   mMatrix.invert(mInverse);  }  @Override  protected void onDraw(Canvas canvas) {   canvas.drawColor(0xFFCCCCCC);   //對(duì)matrix的變換應(yīng)用到canvas上的所有對(duì)象.   canvas.concat(mMatrix);   /**    * bitmap　　　　 　需要扭曲的源位圖    * meshWidth 　　控制在橫向上把該源位圖劃成成多少格    * meshHeight　 　 控制在縱向上把該源位圖劃成成多少格    * verts 　　　　　 長度為(meshWidth + 1) * (meshHeight + 1) * 2的數(shù)組，它記錄了扭曲后的位圖各頂點(diǎn)位置    * vertOffset 控制verts數(shù)組中從第幾個(gè)數(shù)組元素開始才對(duì)bitmap進(jìn)行扭曲    */   canvas.drawBitmapMesh(mBitmap, WIDTH, HEIGHT, mVerts, 0, null, 0,     null);  }  //根據(jù)觸摸事件的位置計(jì)算verts數(shù)組里各元素的值  private void warp(float cx, float cy) {   final float K = 10000;   float[] src = mOrig;   float[] dst = mVerts;   for (int i = 0; i < COUNT * 2; i += 2) {    float x = src[i + 0];    float y = src[i + 1];    float dx = cx - x;    float dy = cy - y;    float dd = dx * dx + dy * dy;     //計(jì)算每個(gè)坐標(biāo)點(diǎn)與當(dāng)前點(diǎn)(cx,cy)之間的距離    float d = FloatMath.sqrt(dd);     //扭曲度，距離當(dāng)前點(diǎn)(cx,cy)越遠(yuǎn)，扭曲度越小    float pull = K / (dd + 0.000001f);    pull /= (d + 0.000001f);    //對(duì)dst數(shù)組(保存bitmap　上21 * 21個(gè)點(diǎn)經(jīng)過扭曲后的坐標(biāo))賦值    if (pull >= 1) {     dst[i + 0] = cx;     dst[i + 1] = cy;    } else {      //控制各頂點(diǎn)向觸摸事件發(fā)生點(diǎn)偏移     dst[i + 0] = x + dx * pull;     dst[i + 1] = y + dy * pull;    }   }  }  private int mLastWarpX = -9999; // don't match a touch coordinate  private int mLastWarpY;  @SuppressLint("ClickableViewAccessibility") @Override  public boolean onTouchEvent(MotionEvent event) {   float[] pt = { event.getX(), event.getY() };   //用當(dāng)前矩陣改變pts中的值，然后存儲(chǔ)在pts中，同上，pts也是存儲(chǔ)點(diǎn)的坐標(biāo)的數(shù)組   mInverse.mapPoints(pt);   int x = (int) pt[0];   int y = (int) pt[1];   if (mLastWarpX != x || mLastWarpY != y) {    mLastWarpX = x;    mLastWarpY = y;    warp(pt[0], pt[1]);    invalidate();   }   return true;  } }}