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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.apis.graphics;
     18 
     19 import com.example.android.apis.R;
     20 
     21 import android.content.Context;
     22 import android.graphics.*;
     23 import android.os.Bundle;
     24 import android.view.*;
     25 import android.util.FloatMath;
     26 
     27 public class BitmapMesh extends GraphicsActivity {
     28 
     29     @Override
     30     protected void onCreate(Bundle savedInstanceState) {
     31         super.onCreate(savedInstanceState);
     32         setContentView(new SampleView(this));
     33     }
     34 
     35     private static class SampleView extends View {
     36         private static final int WIDTH = 20;
     37         private static final int HEIGHT = 20;
     38         private static final int COUNT = (WIDTH + 1) * (HEIGHT + 1);
     39 
     40         private final Bitmap mBitmap;
     41         private final float[] mVerts = new float[COUNT*2];
     42         private final float[] mOrig = new float[COUNT*2];
     43 
     44         private final Matrix mMatrix = new Matrix();
     45         private final Matrix mInverse = new Matrix();
     46 
     47         private static void setXY(float[] array, int index, float x, float y) {
     48             array[index*2 + 0] = x;
     49             array[index*2 + 1] = y;
     50         }
     51 
     52         public SampleView(Context context) {
     53             super(context);
     54             setFocusable(true);
     55 
     56             mBitmap = BitmapFactory.decodeResource(getResources(),
     57                                                      R.drawable.beach);
     58 
     59             float w = mBitmap.getWidth();
     60             float h = mBitmap.getHeight();
     61             // construct our mesh
     62             int index = 0;
     63             for (int y = 0; y <= HEIGHT; y++) {
     64                 float fy = h * y / HEIGHT;
     65                 for (int x = 0; x <= WIDTH; x++) {
     66                     float fx = w * x / WIDTH;
     67                     setXY(mVerts, index, fx, fy);
     68                     setXY(mOrig, index, fx, fy);
     69                     index += 1;
     70                 }
     71             }
     72 
     73             mMatrix.setTranslate(10, 10);
     74             mMatrix.invert(mInverse);
     75         }
     76 
     77         @Override protected void onDraw(Canvas canvas) {
     78             canvas.drawColor(0xFFCCCCCC);
     79 
     80             canvas.concat(mMatrix);
     81             canvas.drawBitmapMesh(mBitmap, WIDTH, HEIGHT, mVerts, 0,
     82                                   null, 0, null);
     83         }
     84 
     85         private void warp(float cx, float cy) {
     86             final float K = 10000;
     87             float[] src = mOrig;
     88             float[] dst = mVerts;
     89             for (int i = 0; i < COUNT*2; i += 2) {
     90                 float x = src[i+0];
     91                 float y = src[i+1];
     92                 float dx = cx - x;
     93                 float dy = cy - y;
     94                 float dd = dx*dx + dy*dy;
     95                 float d = FloatMath.sqrt(dd);
     96                 float pull = K / (dd + 0.000001f);
     97 
     98                 pull /= (d + 0.000001f);
     99              //   android.util.Log.d("skia", "index " + i + " dist=" + d + " pull=" + pull);
    100 
    101                 if (pull >= 1) {
    102                     dst[i+0] = cx;
    103                     dst[i+1] = cy;
    104                 } else {
    105                     dst[i+0] = x + dx * pull;
    106                     dst[i+1] = y + dy * pull;
    107                 }
    108             }
    109         }
    110 
    111         private int mLastWarpX = -9999; // don't match a touch coordinate
    112         private int mLastWarpY;
    113 
    114         @Override public boolean onTouchEvent(MotionEvent event) {
    115             float[] pt = { event.getX(), event.getY() };
    116             mInverse.mapPoints(pt);
    117 
    118             int x = (int)pt[0];
    119             int y = (int)pt[1];
    120             if (mLastWarpX != x || mLastWarpY != y) {
    121                 mLastWarpX = x;
    122                 mLastWarpY = y;
    123                 warp(pt[0], pt[1]);
    124                 invalidate();
    125             }
    126             return true;
    127         }
    128     }
    129 }
    130 
    131