Out of Memory error with Bitmap

问题:

During runtime, I am trying to put an image in the surface view. When I tried using the image from the Drawable folder I got Out of memory error. After a quick search in the stackoverflow, I found that there will be some relief if we access the image from the asset folder. But still I get the Out of memory error during runtime.

I have analyzed and found that scaling will help in resolving this kind of memory related issues. The thing is that I have the image size of 1280 x 720 and the device size also the same. Hence I feel like the scaling will not have any effect.

As we have experts in this community, I would appreciate if you can help me with some suggestions/examples to resolve this kind of issue.

Scenario 1:

Using the Bitmap from Drawable folder.

backgoundImage = Bitmap.createScaledBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.backgroundhomepage), (int) dWidth, (int) dHeight, true);

    /***********************************************************************************************************************************************************
    1.  To get the image from asset library
     **************************************************************************************************************************************************************/ 

    public  Bitmap getAssetImage(Context context, String filename) throws IOException {
        AssetManager assets = context.getResources().getAssets();
        InputStream buffer = new BufferedInputStream((assets.open("drawable/" + filename + ".png")));
        Bitmap bitmap = BitmapFactory.decodeStream(buffer);
        return bitmap;
    }

Scenario 2:

Using the Bitmap from Assets folder

backgoundImage = Bitmap.createScaledBitmap(getAssetImage(context,"backgroundhomepage"), (int) dWidth, (int) dHeight, true);

回答1:

OutofMemory occurs when your app exceeds memory allocated in heap. The bitmap is too large to fit in memory ie heap. In such a case you run out of memory. You need to scale down the bitmap and then use the same. For that check the link below

http://developer.android.com/training/displaying-bitmaps/load-bitmap.html.

There is also a blog @ http://android-developers.blogspot.in/2009/01/avoiding-memory-leaks.html (avoiding memory leaks)

 public static Bitmap decodeFile(File f,int WIDTH,int HIGHT){
 try {
     //Decode image size
     BitmapFactory.Options o = new BitmapFactory.Options();
     o.inJustDecodeBounds = true;
     BitmapFactory.decodeStream(new FileInputStream(f),null,o);

     //The new size we want to scale to
     final int REQUIRED_WIDTH=WIDTH;
     final int REQUIRED_HIGHT=HIGHT;
     //Find the correct scale value. It should be the power of 2.
     int scale=1;
     while(o.outWidth/scale/2>=REQUIRED_WIDTH && o.outHeight/scale/2>=REQUIRED_HIGHT)
         scale*=2;

     //Decode with inSampleSize
     BitmapFactory.Options o2 = new BitmapFactory.Options();
     o2.inSampleSize=scale;
     return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
 } catch (FileNotFoundException e) {}
 return null;
}

Quoting from the docs

The BitmapFactory class provides several decoding methods (decodeByteArray(), decodeFile(), decodeResource(), etc.) for creating a Bitmap from various sources. Choose the most appropriate decode method based on your image data source. These methods attempt to allocate memory for the constructed bitmap and therefore can easily result in an OutOfMemory exception. Each type of decode method has additional signatures that let you specify decoding options via the BitmapFactory.Options class.

Setting the inJustDecodeBounds property to true while decoding avoids memory allocation, returning null for the bitmap object but setting outWidth, outHeight and outMimeType. This technique allows you to read the dimensions and type of the image data prior to construction (and memory allocation) of the bitmap.

Also check this link for memory management.

https://www.youtube.com/watch?v=_CruQY55HOk

回答2:

Got a quick Solution

<application
     android:largeHeap="true" >

put into appplication tag in manifest file.

回答3:

You can use the following code to load the bitmap from file:

private Bitmap decodeFile(File f,int req_Height,int req_Width){
    try {
        //decode image size
        BitmapFactory.Options o1 = new BitmapFactory.Options();
        o1.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f),null,o1);


        //Find the correct scale value. It should be the power of 2.
        int width_tmp = o1.outWidth;
        int height_tmp = o1.outHeight;
        int scale = 1;

        if(width_tmp > req_Width || height_tmp > req_Height)
        {
             int heightRatio = Math.round((float) height_tmp / (float) req_Height);
             int widthRatio = Math.round((float) width_tmp / (float) req_Width);


             scale = heightRatio < widthRatio ? heightRatio : widthRatio;
        }

        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        o2.inScaled = false;
        return BitmapFactory.decodeFile(f.getAbsolutePath(),o2);
    } 
    catch(Exception e) 
    {
      e.printStackTrace();
    }
    return null;
}

It should resolve your out of memory exception. Link here has a good detailed explanation of your answer.