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());
    }
}