How to load large images in Android and avoiding t

问题:

I'm working on an app that uses large images (1390 × 870 : 150kb - 50kb). I'm adding images as I tap a trigger/ImageView.

At a certain point I'm getting an out of memory error:

java.lang.OutOfMemoryError
E/AndroidRuntime(23369): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
E/AndroidRuntime(23369): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:613)
E/AndroidRuntime(23369): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:378)

To resize the image I'm doing this:

Bitmap productIndex = null;
final String imageLoc = IMAGE_LOCATION;
InputStream imageStream;
try {
     imageStream = new FileInputStream(imageLoc);
     productIndex = decodeSampledBitmapFromResource(getResources(), imageLoc, 400, 400);

     productIV.setImageBitmap(productIndex);
     } catch (FileNotFoundException e1) {
          // TODO Auto-generated catch block
          e1.printStackTrace();
     }
}


public static Bitmap decodeSampledBitmapFromResource(Resources res, String resId, int reqWidth, int reqHeight) {

// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(resId, options);

// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(resId, options);
}

public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;

if (height > reqHeight || width > reqWidth) {

    final int halfHeight = height / 3;
    final int halfWidth = width / 3;

    // Calculate the largest inSampleSize value that is a power of 2 and keeps both
    // height and width larger than the requested height and width.
    while ((halfHeight / inSampleSize) > reqHeight
            && (halfWidth / inSampleSize) > reqWidth) {
        inSampleSize *= 2;
    }
}

return inSampleSize;
}

I got this way of resizing to save space from the Android Docs: Loading Large Bitmaps Efficiently

According to the log this like is the culprit in the decodeSampledBitmapFromResource method :

return BitmapFactory.decodeFile(resId, options);

----- edit ----- Here is how I'm adding each item to the FrameLayout.

for(int ps=0;ps<productSplit.size();ps++){
    //split each product by the equals sign
    List<String> productItem = Arrays.asList(productSplit.get(ps).split("="));

    String tempCarID = productItem.get(0);
    tempCarID = tempCarID.replace(" ", "");
    if(String.valueOf(carID).equals(tempCarID)){

        ImageView productIV = new ImageView(Configurator.this);
        LayoutParams productParams = new LayoutParams(
                LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        productIV.setId(Integer.parseInt(partIdsList.get(x)));
        productIV.setLayoutParams(productParams);

        final String imageLoc = productItem.get(2);

        InputStream imageStream;
        try {
            imageStream = new FileInputStream(imageLoc);
            productIndex = decodeSampledBitmapFromResource(getResources(), imageLoc, 400, 400);
            productIV.setImageBitmap(productIndex);
        } catch (FileNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        productLayers.addView(productIV);

    }
}

回答1:

You can use another bitmap-config to heavily decrease the size of the images. The default is RGB-config ARGB8888 which means four 8-bit channels are used (red, green, blue, alhpa). Alpha is transparency of the bitmap. This occupy a lot of memory - imagesize X 4. So if the imagesize is 4 megapixel 16 megabytes will immidiately be allocated on the heap - quickly exhausting the memory.

Instead - use RGB_565 which to some extent deteriorate the quality - but to compensate this you can dither the images.

So - to your method decodeSampledBitmapFromResource - add the following snippets:

 options.inPreferredConfig = Config.RGB_565;
 options.inDither = true;

In your code:

 public static Bitmap decodeSampledBitmapFromResource(Resources res, String resId, int    reqWidth, int reqHeight) {

 // First decode with inJustDecodeBounds=true to check dimensions
 final BitmapFactory.Options options = new BitmapFactory.Options();
 options.inJustDecodeBounds = true;
 BitmapFactory.decodeFile(resId, options);

 // Calculate inSampleSize
 options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

 // Decode bitmap with inSampleSize set
 options.inJustDecodeBounds = false;
 options.inPreferredConfig = Config.RGB_565;
 options.inDither = true;
 return BitmapFactory.decodeFile(resId, options);
 }

References:

http://developer.android.com/reference/android/graphics/Bitmap.Config.html#ARGB_8888

回答2:

High resolution devices such as S4 usually run out of memory if you do not have your image in the proper folder which is drawable-xxhdpi. You can also put your image into drawable-nodpi. The reason it would run out of memorey if your image just in drawable that the android would scale the image thinking that the image was designed for low resolution.

回答3:

You can use this beautiful library https://github.com/davemorrissey/subsampling-scale-image-view

回答4:

Here is how I'm adding each item to the FrameLayout that's the problem, the code keep adding and adding more images, and doesn't matter how well you resize or how much memory the device have, at certain point it WILL run out of memory. That's because every image you add it's keeping in memory.

For this type of situation what the apps do is to use a ViewGroup that can recycle views. I don't know your layout, but usually is a ListView, GridView or a ViewPager, by recycling views you re-use the layout and can dispose re-load images as necessary.

For the specific purpose of loading and resizing images I strongly advise use Picasso library as it is VERY well written, simple to use and stable.

回答5:

You are still going to need to manage the bitmap memory as I wouldn't try to allocate a total space more than 3x the size of the screen (if you think about it makes sense for scrolling behavior). If you are overlaying one image on top of another, at some point, you're hitting an Out Of Memory error. You may need to look at capturing the prior screen image as a single background image to make sure you still fit within the available memory. Or when a new image overlaps an existing image only load and render the visible portion. If performance becomes an issue, then you may need to consider OpenGL Textures but the memory allocation problem is still the same.

Do go through all of the Displaying Bitmaps Training as it should give you some additional ideas of how to handle display.

回答6:

Use Fresco library to load large images will avoid this error. in xml layout

<com.facebook.drawee.view.SimpleDraweeView
    android:id="@+id/my_image_view"
    android:layout_width="1300dp"
    android:layout_height="1300dp"
    fresco:placeholderImage="@drawable/my_drawable"
  />

and in javacode

Uri uri = Uri.parse("https://image.png");
SimpleDraweeView draweeView = (SimpleDraweeView) findViewById(R.id.my_image_view);
draweeView.setImageURI(uri);