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 
26 public class BitmapMesh extends GraphicsActivity {
27 
28     @Override
onCreate(Bundle savedInstanceState)29     protected void onCreate(Bundle savedInstanceState) {
30         super.onCreate(savedInstanceState);
31         setContentView(new SampleView(this));
32     }
33 
34     private static class SampleView extends View {
35         private static final int WIDTH = 20;
36         private static final int HEIGHT = 20;
37         private static final int COUNT = (WIDTH + 1) * (HEIGHT + 1);
38 
39         private final Bitmap mBitmap;
40         private final float[] mVerts = new float[COUNT*2];
41         private final float[] mOrig = new float[COUNT*2];
42 
43         private final Matrix mMatrix = new Matrix();
44         private final Matrix mInverse = new Matrix();
45 
setXY(float[] array, int index, float x, float y)46         private static void setXY(float[] array, int index, float x, float y) {
47             array[index*2 + 0] = x;
48             array[index*2 + 1] = y;
49         }
50 
SampleView(Context context)51         public SampleView(Context context) {
52             super(context);
53             setFocusable(true);
54 
55             mBitmap = BitmapFactory.decodeResource(getResources(),
56                                                      R.drawable.beach);
57 
58             float w = mBitmap.getWidth();
59             float h = mBitmap.getHeight();
60             // construct our mesh
61             int index = 0;
62             for (int y = 0; y <= HEIGHT; y++) {
63                 float fy = h * y / HEIGHT;
64                 for (int x = 0; x <= WIDTH; x++) {
65                     float fx = w * x / WIDTH;
66                     setXY(mVerts, index, fx, fy);
67                     setXY(mOrig, index, fx, fy);
68                     index += 1;
69                 }
70             }
71 
72             mMatrix.setTranslate(10, 10);
73             mMatrix.invert(mInverse);
74         }
75 
onDraw(Canvas canvas)76         @Override protected void onDraw(Canvas canvas) {
77             canvas.drawColor(0xFFCCCCCC);
78 
79             canvas.concat(mMatrix);
80             canvas.drawBitmapMesh(mBitmap, WIDTH, HEIGHT, mVerts, 0,
81                                   null, 0, null);
82         }
83 
warp(float cx, float cy)84         private void warp(float cx, float cy) {
85             final float K = 10000;
86             float[] src = mOrig;
87             float[] dst = mVerts;
88             for (int i = 0; i < COUNT*2; i += 2) {
89                 float x = src[i+0];
90                 float y = src[i+1];
91                 float dx = cx - x;
92                 float dy = cy - y;
93                 float dd = dx*dx + dy*dy;
94                 float d = (float) Math.sqrt(dd);
95                 float pull = K / (dd + 0.000001f);
96 
97                 pull /= (d + 0.000001f);
98              //   android.util.Log.d("skia", "index " + i + " dist=" + d + " pull=" + pull);
99 
100                 if (pull >= 1) {
101                     dst[i+0] = cx;
102                     dst[i+1] = cy;
103                 } else {
104                     dst[i+0] = x + dx * pull;
105                     dst[i+1] = y + dy * pull;
106                 }
107             }
108         }
109 
110         private int mLastWarpX = -9999; // don't match a touch coordinate
111         private int mLastWarpY;
112 
onTouchEvent(MotionEvent event)113         @Override public boolean onTouchEvent(MotionEvent event) {
114             float[] pt = { event.getX(), event.getY() };
115             mInverse.mapPoints(pt);
116 
117             int x = (int)pt[0];
118             int y = (int)pt[1];
119             if (mLastWarpX != x || mLastWarpY != y) {
120                 mLastWarpX = x;
121                 mLastWarpY = y;
122                 warp(pt[0], pt[1]);
123                 invalidate();
124             }
125             return true;
126         }
127     }
128 }
129 
130