Custom view converting to bitmap returning black image

Question

I need to create a custom view and then save it to png file into sdcard. Right now I am getting black colour images in sdcard. I couldn't trace out the issue in code. Can anyone please help me out.

layout file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:background="@android:color/white"
    android:orientation="vertical" >
        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@android:color/black" />

        <TextView
            android:id="@+id/address"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@android:color/black" />
</LinearLyout>

In my java file, I have inflated linear layout and set data to textviews and then I am calling:

private Bitmap convertViewToBitmap(LinearLayout layout) {
    layout.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
    int width = layout.getMeasuredWidth();
    int height = layout.getMeasuredHeight();

    //Create the bitmap
    Bitmap bitmap = Bitmap.createBitmap(width, 
            height, 
            Bitmap.Config.ARGB_8888);
    //Create a canvas with the specified bitmap to draw into
    Canvas c = new Canvas(bitmap);

    //Render this view (and all of its children) to the given Canvas
    view.draw(c);
    return bitmap;
}

After getting bitmap I am saving it to sdcard as follows:

private void saveBitmapTpSdCard(Bitmap bitmap, String fileName) {
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 40, bytes);

        File f = new File(Environment.getExternalStorageDirectory()
                + File.separator + getString(R.string.app_name));

        try {
            if(!f.exists()) {
                f.mkdirs();
            }
            File imageFile = new File(f, fileName + ".png");
            FileOutputStream fo = new FileOutputStream(imageFile);
            fo.write(bytes.toByteArray());
            fo.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
}

Are you trying to get the snapshot of lnearlayout's content? — Glenn, May 08 '14 at 07:46
http://stackoverflow.com/questions/7200535/how-to-convert-views-to-bitmap — Glenn, May 08 '14 at 07:58
@Glenn-- I had tried this. But layout.getDrawingCache(); is returning null — Anju, May 08 '14 at 08:09
Let us see the updated code (your code with the drawing cache method) ? — Glenn, May 08 '14 at 08:16
Btw, you can just call `bitmap.compress` with `FileOutputStream` directly instead of dancing with `ByteArrayOutputStream` (which you don't need here) — Dmitry Zaytsev, May 08 '14 at 08:16

score 5 · Accepted Answer · answered May 08 '14 at 10:23

5

I got it worked by adding this line:

view.layout(0, 0, width, height);

before creating Bitmap using Bitmap.createBitmap

answered May 08 '14 at 10:23

Anju

9,379
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I was wondering why the method is returning null but, good job! – Glenn May 09 '14 at 00:00

Abdul Mohsin · Answer 2 · 2014-05-08T08:29:03.407

0

try the following code to convert a custom view to Bitmap Object:

    LinearLayout layout = (LinearLayout) findViewById(R.id.layout_main_for_bitmap);
    layout.setDrawingCacheEnabled(true);
    layout.buildDrawingCache();
    Bitmap bitmap = layout.getDrawingCache();

edited May 08 '14 at 08:29

answered May 08 '14 at 08:04

Abdul Mohsin

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I passed layout to method after inflating and setting values – Anju May 08 '14 at 08:31

Dmitry Zaytsev · Answer 3 · 2014-05-08T10:30:48.183

0

The fact that LinearLayout was measured by you manually doesn't means that it was layouted (i.e. layout wasn't invoked). Therefore children are not getting layouted, therefore they don't receive correct position on a ViewGroup, therefore they're not visible.

Instead of trying to mimic drawing lifecycle, I would suggest you to call linearLayout.post() on your LinearLayout (if it's added to view hierarchy of course) and inside Runnable invoke your "snapping" workflow.

Alternatively you can invoke layout manually.

edited May 08 '14 at 10:30

answered May 08 '14 at 08:10

Dmitry Zaytsev

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@Mathew so my first thought was correct :) Congrats! – Dmitry Zaytsev May 08 '14 at 10:30

Custom view converting to bitmap returning black image

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