Screenshot shows black

问题:

I'm taking snapshots and creat thumbnails and then share this image. But the thumbnail shows all black. I have used the following code

Bitmap bitmap;
View v1 = v.getRootView();
v1.setDrawingCacheEnabled(true);
bitmap = Bitmap.createBitmap(v1.getDrawingCache());
String url = Images.Media.insertImage(
mContext.getContentResolver(), bitmap, "title", null);

Can anyone tell me what is wrong with this code.

EDIT

private View.OnClickListener shareListener = new View.OnClickListener() {
        public void onClick(View v) {
            Bitmap bitmap;
            View v1 = v.getRootView();
            v1.setDrawingCacheEnabled(true);
            bitmap = Bitmap.createBitmap(v1.getDrawingCache());
            String url = Images.Media.insertImage(
                    mContext.getContentResolver(), bitmap, "title", null);
            v1.setDrawingCacheEnabled(false);
            Activity activity = (Activity) getContext();
            Intent share = new Intent(Intent.ACTION_SEND);
            share.setType("image/jpeg");
            share.putExtra(Intent.EXTRA_STREAM, Uri.parse(url));
            activity.startActivity(Intent.createChooser(share,
                    "Share"));

        }

    };

Black Image

回答1:

Use following code it may work for you. Thanks

SCREENSHOTS_LOCATIONS = Environment.getExternalStorageDirectory().toString() + "/screenshots/";
// Get root view
View view = activity.getWindow().getDecorView().getRootView();
// Create the bitmap to use to draw the screenshot
final Bitmap bitmap = Bitmap.createBitmap(screenWidth, screenHeight, Bitmap.Config.ARGB_8888);
final Canvas canvas = new Canvas(bitmap);

// Get current theme to know which background to use
final Theme theme = activity.getTheme();
final TypedArray ta = theme
    .obtainStyledAttributes(new int[] { android.R.attr.windowBackground });
final int res = ta.getResourceId(0, 0);
final Drawable background = activity.getResources().getDrawable(res);

// Draw background
background.draw(canvas);

// Draw views
view.draw(canvas);

// Save the screenshot to the file system
FileOutputStream fos = null;
try {
    final File sddir = new File(SCREENSHOTS_LOCATIONS);
    if (!sddir.exists()) {
        sddir.mkdirs();
    }
    fos = new FileOutputStream(SCREENSHOTS_LOCATIONS
            + System.currentTimeMillis() + ".jpg");
    if (fos != null) {
        if (!bitmap.compress(Bitmap.CompressFormat.JPEG, 90, fos)) {
            Log.d("ScreenShot", "Compress/Write failed");
        }
        fos.flush();
        fos.close();
    }

} catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

回答2:

try

v1.setDrawingCacheEnabled(true);

// this is the important code :)  
// Without it the view will have a dimension of 0,0 and the bitmap will be null          
v1.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
v1.layout(0, 0, v1.getMeasuredWidth(), v1.getMeasuredHeight()); 
//Forces the drawing cache to be built if the drawing cache is invalid.
v1.buildDrawingCache(true);
Bitmap b = Bitmap.createBitmap(v1.getDrawingCache());
v1.setDrawingCacheEnabled(false); // clear drawing cache

回答3:

Try applying this code:

private File takeScreenshot(boolean showToast) {
    View v = getWindow().getDecorView();

    v.setDrawingCacheEnabled(true);
    Bitmap cachedBitmap = v.getDrawingCache();
    Bitmap copyBitmap = cachedBitmap.copy(Bitmap.Config.RGB_565, true);
    FileOutputStream output = null;
    File file = null;
    try {
        File path = Places.getScreenshotFolder();
        Calendar cal = Calendar.getInstance();

        file = new File(path,

        cal.get(Calendar.YEAR) + "_" + (1 + cal.get(Calendar.MONTH)) + "_"
                + cal.get(Calendar.DAY_OF_MONTH) + "_"
                + cal.get(Calendar.HOUR_OF_DAY) + "_"
                + cal.get(Calendar.MINUTE) + "_" + cal.get(Calendar.SECOND)
                + ".png");
        output = new FileOutputStream(file);
        copyBitmap.compress(CompressFormat.PNG, 100, output);
    } catch (FileNotFoundException e) {
        file = null;
        e.printStackTrace();
    } finally {
        if (output != null) {
            try {
                output.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

    if (file != null) {
        if (showToast)
            Toast.makeText(getApplicationContext(),
                    "Saved " + file.getAbsolutePath(),
                    Toast.LENGTH_LONG).show();
        // sending a broadcast to the media scanner so it will scan the new
        // screenshot.
        Intent requestScan = new Intent(
                Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        requestScan.setData(Uri.fromFile(file));
        sendBroadcast(requestScan);

        return file;
    } else {
        return null;
    }
}

This works perfectly for me. Hope this will help you.

回答4:

Maybe this happens because your area is marked as secure. While the icons are shown, the view displaying your contents displays black because it's secure:

the user may see a blank region on the screen instead of the contents of secure surfaces or protected buffers.

http://developer.android.com/reference/android/view/Display.html#FLAG_SECURE

回答5:

Try this code.. It should be work.

linearLayout.setDrawingCacheEnabled(true);
    linearLayout.measure(MeasureSpec.makeMeasureSpec(linearLayout.getWidth(), MeasureSpec.AT_MOST),MeasureSpec.makeMeasureSpec(linearLayout.getHeight(), MeasureSpec.EXACTLY));
    linearLayout.layout(0, 0, linearLayout.getMeasuredWidth(), linearLayout.getMeasuredHeight());

    Bitmap b1 =linearLayout.getDrawingCache();


    Bitmap bigbitmap    = Bitmap.createBitmap(linearLayout.getMeasuredWidth(), linearLayout.getMeasuredHeight(), Bitmap.Config.ARGB_4444);
    Canvas bigcanvas    = new Canvas(bigbitmap);

    Paint paint = new Paint();
    bigcanvas.drawBitmap(b1, 0, 0, paint);


    int Measuredwidth = 0;
    int Measuredheight = 0;
    Point size = new Point();
    WindowManager w = getWindowManager();

      if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2){
            w.getDefaultDisplay().getSize(size);

            Measuredwidth = size.x;
            Measuredheight = size.y; 
          }else{
            Display d = w.getDefaultDisplay(); 
            Measuredwidth = d.getWidth(); 
            Measuredheight = d.getHeight(); 
          }
      Log.e(DEB_TAG, ""+Measuredwidth);
      Log.e(DEB_TAG, ""+Measuredheight);
     bigbitmap = Bitmap.createScaledBitmap(bigbitmap, Measuredwidth, Measuredheight, true);

     visiterCoverFlow.setScreenCache(bigbitmap);