1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="fill_parent"
 4     android:layout_height="fill_parent"
 5     android:orientation="vertical" >
 6 
 7 
 8     <Button
 9         android:onClick="selectImage"
10         android:id="@+id/button1"
11         android:layout_width="fill_parent"
12         android:layout_height="wrap_content"
13         android:text="選擇圖片" />
14     <Button
15         android:onClick="saveImage"
16         android:id="@+id/button1"
17         android:layout_width="fill_parent"
18         android:layout_height="wrap_content"
19         android:text="保存圖片" />
20     <ImageView
21         android:layout_width="wrap_content"
22         android:layout_height="wrap_content"
23         android:scaleType="centerInside"
24         android:id="@+id/iv" />
25 </LinearLayout>

  1 package cn.itcast.paint;
  2 
  3 import java.io.File;
  4 import java.io.FileNotFoundException;
  5 import java.io.FileOutputStream;
  6 import java.io.InputStream;
  7 
  8 import android.app.Activity;
  9 import android.content.Intent;
 10 import android.graphics.Bitmap;
 11 import android.graphics.BitmapFactory;
 12 import android.graphics.Bitmap.CompressFormat;
 13 import android.graphics.BitmapFactory.Options;
 14 import android.graphics.Canvas;
 15 import android.graphics.Color;
 16 import android.graphics.Matrix;
 17 import android.graphics.Paint;
 18 import android.graphics.Rect;
 19 import android.net.Uri;
 20 import android.os.Bundle;
 21 import android.os.Environment;
 22 import android.view.Display;
 23 import android.view.MotionEvent;
 24 import android.view.View;
 25 import android.view.View.OnTouchListener;
 26 import android.view.WindowManager;
 27 import android.widget.ImageView;
 28 import android.widget.Toast;
 29 
 30 public class DemoActivity extends Activity {
 31     private ImageView iv;
 32     private Bitmap alterBitmap;
 33     private Canvas canvas;
 34     private Paint paint;
 35     private WindowManager wm;
 36     private Display  display;
 37     
 38     @Override
 39     public void onCreate(Bundle savedInstanceState) {
 40         super.onCreate(savedInstanceState);
 41         setContentView(R.layout.main);
 42         iv = (ImageView) findViewById(R.id.iv);
 43         paint = new Paint();
 44         paint.setColor(Color.GREEN);
 45         paint.setStrokeWidth(10);
 46         wm = getWindowManager();
 47         //獲取手機的屏幕寬高
 48         display = wm.getDefaultDisplay();
 49         iv.setOnTouchListener(new OnTouchListener() {
 50             int startx;
 51             int starty;
 52             @Override
 53             public boolean onTouch(View v, MotionEvent event) {
 54                 switch (event.getAction()) {
 55                 case MotionEvent.ACTION_DOWN://手指第一次觸摸屏幕
 56                     startx = (int) event.getX();
 57                     starty = (int) event.getY();
 58                     
 59                     break;
 60                 case MotionEvent.ACTION_MOVE: //手指在imageview上中移動
 61                     int x = (int) event.getX();
 62                     int y = (int) event.getY();
 63                     canvas.drawLine(startx, starty, x, y, paint);
 64                     startx = (int) event.getX();
 65                     starty = (int) event.getY();
 66                     iv.invalidate();
 67                     break;
 68                 }
 69                 
 70                 
 71                 
 72                 return true;
 73             }
 74         });
 75     }
 76     
 77     
 78     public void selectImage(View view){
 79         Intent intent = new Intent();
 80         intent.setAction(Intent.ACTION_PICK);
 81         intent.addCategory("android.intent.category.DEFAULT");
 82         intent.setType("image/*");
 83         startActivityForResult(intent, 0);
 84     }
 85     
 86     
 87     @Override
 88     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
 89         try {
 90             if (data != null) {
 91                 // 得到點擊圖片的uri
 92                 Uri uri = data.getData();
 93                 //對 要加載的圖片進行縮放
 94                 //1.得到圖片的寬度和高度.
 95                 //由于我們只想得到圖片的寬度和高度,這個時候 只需要解析圖片的頭信息
 96                 BitmapFactory.Options opts = new Options();
 97                 opts.inJustDecodeBounds = true;//讓 bimapfactory假的解析這個位圖,只獲取位圖的邊框信息
 98                 InputStream is = getContentResolver().openInputStream(uri);
 99                 BitmapFactory.decodeStream(is, new Rect(), opts);
100                 
101                 int bitmapHeight =     opts.outHeight;
102                 int bitmapWidth = opts.outWidth;
103                 
104                 int windowHeight = display.getHeight();
105                 int windowWidth = display.getWidth();
106                 //獲取水平和垂直方向的縮放比
107                 int scaley = bitmapHeight / windowHeight;
108                 int scalex = bitmapWidth / windowWidth;
109                 
110                 
111                 
112                 if(scalex>scaley&&scaley>1){
113                     opts.inSampleSize = scalex;
114                 }
115                 if(scaley>scalex&&scalex>1){
116                     opts.inSampleSize = scaley;
117                 }
118                 opts.inJustDecodeBounds = false;// 由于已經得到了縮放比例 ,讓位圖工廠真正的解析這個位圖
119                 // 由于前面 我們已經解析了這個輸入流, 需要重新初始化這個輸入流
120                 is = getContentResolver().openInputStream(uri);
121                 Bitmap bitmap =  BitmapFactory.decodeStream(is, new Rect(), opts);
122                 System.out.println("位圖的高度:"+bitmap.getHeight());
123                 System.out.println("位圖的寬度:"+bitmap.getWidth());
124                 
125                 
126                 alterBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
127                 
128                 canvas = new Canvas(alterBitmap);
129                 
130                 canvas.drawBitmap(bitmap, new Matrix(), new Paint());
131                 
132                 //設置的是原圖在內存中的拷貝
133                 iv.setImageBitmap(alterBitmap);
134             }
135         } catch (Exception e) {
136             e.printStackTrace();
137         }
138         super.onActivityResult(requestCode, resultCode, data);
139     }
140     
141     public void saveImage(View view){
142         try {
143             File file = new File(Environment.getExternalStorageDirectory(),System.currentTimeMillis()+".jpg");
144             FileOutputStream stream = new FileOutputStream(file);
145             alterBitmap.compress(CompressFormat.JPEG, 100, stream);
146             Toast.makeText(this, "保存成功", 1).show();
147             // 模擬系統發送一個 sd卡掛載的廣播 
148             Intent intent = new Intent();
149             intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
150             intent.setData(Uri.parse("file:"+Environment.getExternalStorageDirectory().getAbsolutePath()));
151             sendBroadcast(intent); 
152         } catch (FileNotFoundException e) {
153             Toast.makeText(this, "保存失敗", 1).show();
154             e.printStackTrace();
155         }
156     }
157 }