1，点击按钮，指定action和uri，设定结果码(ResultCode).到达手机默认相册的Gallery.

代码如下：
 
1. public void onClick(View v) {
2.         // TODO Auto-generated method stub
3.         Intent intent = new Intent(Intent.ACTION_PICK,
4.                 android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);// 启动照片Gallery
5.         startActivityForResult(intent, 0);
6.     }
2，选择图片，返回所选照片uri信息
代码如下：
 
1. @Override
2.     protected void onActivityResult(int requestCode, int resultCode,
3.             Intent intent) {
4.         // TODO Auto-generated method stub
5.         super.onActivityResult(requestCode, resultCode, intent);
6. 
7.         if (resultCode == RESULT_OK) {// 操作成功 www.2cto.com
8.             Uri imgFileUri = intent.getData();// 获得所选照片的信息
3，处理图片，设定合适的尺寸（正好适应屏幕）
设定BitmapFactory.Options 参数inJustDecodeBounds = true，即不创建bitmap，但可获取bitmap的相关属性。以宽高比例差距 最大者为基准。
代码如下：
 
1. // 由于返回的图像可能太大而无法完全加载到内存中。系统有限制，需要处理。
2.             Display currentDisplay = getWindowManager().getDefaultDisplay();
3.             int defaultHeight = currentDisplay.getHeight();
4.             int defaultWidth = currentDisplay.getWidth();
5. 
6.             BitmapFactory.Options bitmapFactoryOptions = new BitmapFactory.Options();
7.             bitmapFactoryOptions.inJustDecodeBounds = true;// /只是为获取原始图片的尺寸，而不返回Bitmap对象
8.             // 注上：If set to true, the decoder will return null (no bitmap), but
9.             // the out... fields will still be set,
10.             // allowing the caller to query the bitmap without having to
11.             // allocate the memory for its pixels
12.             try {
13.                 Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver()
14.                         .openInputStream(imgFileUri), null,
15.                         bitmapFactoryOptions);
16.                 int outHeight = bitmapFactoryOptions.outHeight;
17.                 int outWidth = bitmapFactoryOptions.outWidth;
18.                 int heightRatio = (int) Math.ceil((float) outHeight
19.                         / defaultHeight);
20.                 int widthRatio = (int) Math.ceil((float) outWidth
21.                         / defaultWidth);
22. 
23.                 if (heightRatio > 1 || widthRatio > 1) {
24.                     if (heightRatio > widthRatio) {
25.                         bitmapFactoryOptions.inSampleSize = heightRatio;
26.                     } else {
27.                         bitmapFactoryOptions.inSampleSize = widthRatio;
28.                     }
29.                 }
4，inJustDecodeBounds = false，创建将此bitmap赋给第一个ImageView。
代码如下：
 
1. bitmapFactoryOptions.inJustDecodeBounds = false;
2.                 bitmap = BitmapFactory.decodeStream(getContentResolver()
3.                         .openInputStream(imgFileUri), null,
4.                         bitmapFactoryOptions);
5. 
6.                 mImageShow.setImageBitmap(bitmap);
5，绘制bitmap(选中的图片)，赋给第二个ImageView
a, 绘制正面Bitmap
b，在此Bitmap上绘制文本
c，创建Matrix对象，指定旋转角度。
d，创建新的bitmap对象，即canvas即将要绘制的倾斜区域
e，绘制
代码如下：
 
1. // /*
2.                 // * 在位图上绘制位图
3.                 // */
4.                 //
5.                 
6.                 Bitmap bitmapAltered = Bitmap.createBitmap(bitmap.getWidth(),
7.                         bitmap.getHeight(), bitmap.getConfig());
8. 
9.                 Canvas canvas = new Canvas(bitmapAltered);// bitmap提供了画布，只在此提供了大小尺寸，偏移后并未有背景显示出来
10.                 
11.                 Paint paint = new Paint();
12.                 
13.                 canvas.drawBitmap(bitmap, 0, 0, paint);
14.                 
15.                 paint.setColor(Color.RED);
16. 
17.                 canvas.drawText("hello", 10, 10, paint);
18.                 
19.                 //先绘制正面图片，再旋转
20.                 Matrix matrix = new Matrix();
21.                 
22.                 matrix.setRotate(45, 0, 0);     
23.                 //创建一个倾斜的绘制区域
24.                 Bitmap bitmapRotated = Bitmap.createBitmap(bitmapAltered, 0, 0, bitmapAltered.getWidth(), bitmapAltered.getHeight(), matrix, false);
25.                 canvas.drawBitmap(bitmapAltered, matrix, paint);
26.                 mImageAltered.setImageBitmap(bitmapRotated);