Android从相册选取图片并裁剪

一.概述

1.选取照片并显示
启动相册的动作为

public static final java.lang.String ACTION_GET_CONTENT = "android.intent.action.GET_CONTENT"; 

隐式启动相册的代码为：

  Intent intent = new Intent(Intent.ACTION_PICK);        intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,"image/*");         startActivityForResult(intent,ACTION_CHOOSE);

注意这里没有把return-data设置为false，因为我们就是要利用data里面的值来显示图片。

最后在onActivityResult中接收

  @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode){            case ACTION_CHOOSE:                try {                if(data!=null){                    Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(data.getData()));                     Bitmap smallBmp = setScaleBitmap(photo, 2);                    imageview.setImageBitmap(smallBmp );                } catch (FileNotFoundException e) {                    e.printStackTrace();                }                break;}        }    }

为了防止图片显示不下，先把它压缩为一半，代码如下：

private Bitmap setScaleBitmap(Bitmap photo,int SCALE) {      if (photo != null) {          //为防止原始图片过大导致内存溢出，这里先缩小原图显示，然后释放原始Bitmap占用的内存          //这里缩小了1/2,但图片过大时仍然会出现加载不了,但系统中一个BITMAP最大是在10M左右,我们可以根据BITMAP的大小          //根据当前的比例缩小,即如果当前是15M,那如果定缩小后是6M,那么SCALE= 15/6          Bitmap smallBitmap = zoomBitmap(photo, photo.getWidth() / SCALE, photo.getHeight() / SCALE);          //释放原始图片占用的内存，防止out of memory异常发生          photo.recycle();          return smallBitmap;      }      return null;  }  

public Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {      int w = bitmap.getWidth();      int h = bitmap.getHeight();      Matrix matrix = new Matrix();      float scaleWidth = ((float) width / w);      float scaleHeight = ((float) height / h);      matrix.postScale(scaleWidth, scaleHeight);// 利用矩阵进行缩放不会造成内存溢出      Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);      return newbmp;  }  

但是由于data所能传递的最大值为1M，所以当我们的图片太大时，选取的图片并不会显示到ImageView中。

2.选取照片裁剪显示

启动相册，并且配置参数，将return-data设置为false,我们用uri来接收结果。

 Intent intent = new Intent(Intent.ACTION_PICK);        intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,"image/*");        intent.putExtra("crop", "true");        intent.putExtra("aspectX", 1);        intent.putExtra("aspectY", 1);        intent.putExtra("outputX", 1000);        intent.putExtra("outputY", 1000);        intent.putExtra("scale", true);        intent.putExtra("return-data", false);        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);        intent.putExtra("outputFormat", Bitmap.CompressFormat.JPEG.toString());        intent.putExtra("noFaceDetection", true);        startActivityForResult(intent,ACTION_CHOOSE);

直接从uri中获取图片，显示在ImageView里面：

   @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode){            case ACTION_CHOOSE:                try {                    Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));                    Bitmap smallBmp = setScaleBitmap(photo, 2);                    imageview.setImageBitmap(smallBmp );                } catch (FileNotFoundException e) {                    e.printStackTrace();                }                break;        }    }

看着好像没什么事情，但问题来了：在有些手机上根本出不来裁剪页面，这是为什么呢？那这里要怎么办呢？有没有一种方法能找到用户点击的图片的地址呢？如果能找到地址，那在用户点击一个图片后，再调用裁剪的Intent，从本地读取图片数据传进去裁剪Intent让它来裁剪，这样就绕过了直接通过Intent数据传递的大小限制。

3.从相册选取并裁剪(通过路径)

整体过程是这样的
先调用选择图片Intent:

 public void choosePhoto(View view){        Intent intent = new Intent(Intent.ACTION_PICK);        intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,"image/*");        startActivityForResult(intent,ACTION_CHOOSE);    }

然后在接收时，找到图片路径，生成对应的URI，转给裁剪页面：

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode){            case ACTION_CHOOSE:                    String path = Util.getImageAbsolutePath(this,data.getData());                    File file = new File(path);                    Uri uri = Uri.fromFile(file);                cropImage(uri);                break;                }

然后是裁剪：

public void cropImage(Uri uri){       Intent intent = new Intent("com.android.camera.action.CROP");       intent.setDataAndType(uri,"image/*");       intent.putExtra("crop", "true");       intent.putExtra("aspectX", 1);       intent.putExtra("aspectY", 1);       intent.putExtra("outputX", 700);       intent.putExtra("outputY", 700);       intent.putExtra("return-data", false);       intent.putExtra(MediaStore.EXTRA_OUTPUT, cropUri);       intent.putExtra("outputFormat", Bitmap.CompressFormat.JPEG.toString());       intent.putExtra("noFaceDetection", true);       startActivityForResult(intent,ACTION_CROP);

裁剪后，将图片保存在本地的uri中，在onActivityResult中接收，将Uri中的图片取出来。

 case ACTION_CROP:                try {                    Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(cropUri));                    Bitmap smallBmp = setScaleBitmap(photo, 2);                    imageview.setImageBitmap(smallBmp );                } catch (FileNotFoundException e) {                    e.printStackTrace();                }

4、从相册选择图像并显示的终极方案
过程是这样的：

启动图库：

  public void choosePhoto(View view){        Intent intent = new Intent(Intent.ACTION_PICK);        intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,"image/*");        startActivityForResult(intent,ACTION_CHOOSE);    }

在onActivityResult中接收返回来的数据，根据data获取图片的路径，然后根据路径生成uri，直接从uri中获得bitmap，显示给ImageView.

  @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode){            case ACTION_CHOOSE:            if(data!=null){                    String path = Util.getImageAbsolutePath(this,data.getData());                    File file = new File(path);                    Uri uri = Uri.fromFile(file);                try {                    Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri));                    Bitmap smallBmp = setScaleBitmap(photo, 2);                    imageview.setImageBitmap(smallBmp );                } catch (FileNotFoundException e) {                    e.printStackTrace();                }                break;        }        }    }}

最后给出根据Uri获取图片地址的代码：

  public static String getImageAbsolutePath(Activity context, Uri imageUri) {        if (context == null || imageUri == null)            return null;        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT && DocumentsContract.isDocumentUri(context, imageUri)) {            if (isExternalStorageDocument(imageUri)) {                String docId = DocumentsContract.getDocumentId(imageUri);                String[] split = docId.split(":");                String type = split[0];                if ("primary".equalsIgnoreCase(type)) {                    return Environment.getExternalStorageDirectory() + "/" + split[1];                }            } else if (isDownloadsDocument(imageUri)) {                String id = DocumentsContract.getDocumentId(imageUri);                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));                return getDataColumn(context, contentUri, null, null);            } else if (isMediaDocument(imageUri)) {                String docId = DocumentsContract.getDocumentId(imageUri);                String[] split = docId.split(":");                String type = split[0];                Uri contentUri = null;                if ("image".equals(type)) {                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;                } else if ("video".equals(type)) {                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;                } else if ("audio".equals(type)) {                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;                }                String selection = MediaStore.Images.Media._ID + "=?";                String[] selectionArgs = new String[] { split[1] };                return getDataColumn(context, contentUri, selection, selectionArgs);            }        } // MediaStore (and general)        else if ("content".equalsIgnoreCase(imageUri.getScheme())) {            // Return the remote address            if (isGooglePhotosUri(imageUri))                return imageUri.getLastPathSegment();            return getDataColumn(context, imageUri, null, null);        }        // File        else if ("file".equalsIgnoreCase(imageUri.getScheme())) {            return imageUri.getPath();        }        return null;    }    public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {        Cursor cursor = null;        String column = MediaStore.Images.Media.DATA;        String[] projection = { column };        try {            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);            if (cursor != null && cursor.moveToFirst()) {                int index = cursor.getColumnIndexOrThrow(column);                return cursor.getString(index);            }        } finally {            if (cursor != null)                cursor.close();        }        return null;    }    /**     * @param uri The Uri to check.     * @return Whether the Uri authority is ExternalStorageProvider.     */    public static boolean isExternalStorageDocument(Uri uri) {        return "com.android.externalstorage.documents".equals(uri.getAuthority());    }    /**     * @param uri The Uri to check.     * @return Whether the Uri authority is DownloadsProvider.     */    public static boolean isDownloadsDocument(Uri uri) {        return "com.android.providers.downloads.documents".equals(uri.getAuthority());    }    /**     * @param uri The Uri to check.     * @return Whether the Uri authority is MediaProvider.     */    public static boolean isMediaDocument(Uri uri) {        return "com.android.providers.media.documents".equals(uri.getAuthority());    }    /**     * @param uri The Uri to check.     * @return Whether the Uri authority is Google Photos.     */    public static boolean isGooglePhotosUri(Uri uri) {        return "com.google.android.apps.photos.content".equals(uri.getAuthority());    }}