NullPointerException trying to draw bitmap

Question

I have a NullPointerException being thrown in my code:

canvas.drawBitmap(icon, null, rect, null);

I have a Log statement right above there to make sure the canvas is not null. I'm guessing the 2nd Rect being null is the problem? I thought it was ok to leave it as null.

Here is the logCat output:

07-22 21:34:16.807: E/AndroidRuntime(19340): FATAL EXCEPTION: Thread-3384
07-22 21:34:16.807: E/AndroidRuntime(19340): java.lang.NullPointerException
07-22 21:34:16.807: E/AndroidRuntime(19340):    at
android.view.GLES20RecordingCanvas.drawBitmap(GLES20RecordingCanvas.java:118)
07-22 21:34:16.807: E/AndroidRuntime(19340):    at   
com.live.LedgeView$DrawLedgeThread.run(LedgeView.java:88)

Are you calling `canvas.drawBitmap()` from inside onDraw()? Can you post the Logcat? — Vikram, Jul 23 '13 at 01:34
No, I actually have onDraw() kicking of a thread, to which I pass the canvas. the thread is calling canvas.drawBitmap(). Could that be the problem? — user1154644, Jul 23 '13 at 01:35
Check these out: http://code.google.com/p/android/issues/detail?id=21364, http://code.google.com/p/android/issues/detail?id=24830 — Pang, Jul 23 '13 at 01:44
Yes, seems like a not fixed bug. You need to pass a not null source. — type-a1pha, Jul 23 '13 at 01:48
why you put canvas.drawBitmap() in thread? it has to be called in UI thread — yushulx, Jul 23 '13 at 01:50
and if you use multi-thread to operate your bitmap.be careful of bitmap recycling — yushulx, Jul 23 '13 at 01:53
Right, it will throw a RuntimeException in that case. As already said, do all the UI updates in the UIThread, thst's the safest way and the way recommended in the API Guide. — type-a1pha, Jul 23 '13 at 02:05

score 1 · Answer 1 · edited May 23 '17 at 12:29

1

Yes. Please make sure the "icon" bitmap is not null and "rect" also,

 Bitmap icon= BitmapFactory.decodeResource(getResources(),
                            R.drawable.icon);

Please refer these link. It may help you out. Click Here to see sample 1

Click here to see sample 2

edited May 23 '17 at 12:29

Community

1
1

answered Jul 23 '13 at 05:22

Srinivasan

4,481
3
28
36

type-a1pha · Answer 2 · 2013-07-23T01:44:17.883

From the Android source code:

public void drawBitmap(Bitmap bitmap, Rect src, RectF dst, Paint paint) {
    if (dst == null) {
        throw new NullPointerException();
    }
    throwIfRecycled(bitmap);
    native_drawBitmap(mNativeCanvas, bitmap.ni(), src, dst,
                      aint != null ? paint.mNativePaint : 0,
                      mScreenDensity, bitmap.mDensity);
}

So...are you sure dst is not null?

In any case post the logcat stack trace.

Edit: In response to one of your comments, never update UI components from outside the UI Thread. Use AsyncTask if you need to fetch the Bitmap asynchronously.

new AsyncTask(Void,Void,Bitmap){

    protected Bitmap doInBackground(Void... voids){
        //fetch Bitmap
        return bitmap;
    }

    protected void onPostExecute(Bitmap bitmap){
        //fetch Bitmap
        canvas.drawBitmap(bitmap,...);
    }

}

I'm initializing it right above: rect = new Rect(blx, bly, trx, trx); — user1154644, Jul 23 '13 at 01:40
the only ui component being updated is the canvas itself, and since that is done via a thread started in onDraw(), shouldnt that be ok? — user1154644, Jul 23 '13 at 01:49

score 0 · Answer 3 · answered Jul 23 '13 at 02:02

0

usually, I do this way. I decode bitmap by a thread, and put it into a queue. synchronize the queue with UI thread. the UI thread gets bitmap from the queue, and draw it. all UI stuff should be done in UI thread.

answered Jul 23 '13 at 02:02

yushulx

11,695
8
37
64

score 0 · Answer 4 · answered May 08 '14 at 19:54

I had a Null Pointer Ex. in android.view.GLES20RecordingCanvas.drawBitmap

I read that you must do the "drawBitmap" inside of your onDraw method (in your view class).

for me, i used the invalidate() method for trigger onDraw. Before calling invalidate() i set some parameters to my object (of view class), so, when onDraw is called, it uses the parameters I put.

Hope it works :)

Leonardo.

score 0 · Answer 5 · answered Sep 05 '14 at 08:43

public void drawBitmap(Bitmap bitmap, Rect src, RectF dst, Paint paint) {
    if (dst == null) {
        throw new NullPointerException();
    }
    throwIfRecycled(bitmap);
    native_drawBitmap(mNativeCanvas, bitmap.ni(), src, dst,
            aint != null ? paint.mNativePaint : 0, mScreenDensity,
            bitmap.mDensity);
}

I have fixed this issue by checking dst for null before sending to that method. If dst is null i have used local variable that i have stored every time on the method "onBoundsChange". This resolve my issue.

NullPointerException trying to draw bitmap

5 Answers5