android - 避免位图内存不足错误的建议

Question

我正在开发一个安卓应用程序。该应用程序有一个包含大量图像的 View 。我有一个错误，我会尽量提供尽可能多的信息，希望有人能给我一些建议。

该应用程序在所有本地测试中运行良好。但是，我收到了很多来自用户的崩溃:java.lang.OutOfMemoryError: bitmap size超出VM budget

这是堆栈跟踪

0       java.lang.OutOfMemoryError: bitmap size exceeds VM budget
1   at  android.graphics.Bitmap.nativeCreate(Native Method)
2   at  android.graphics.Bitmap.createBitmap(Bitmap.java:507)
3   at  android.graphics.Bitmap.createBitmap(Bitmap.java:474)
4   at  android.graphics.Bitmap.createScaledBitmap(Bitmap.java:379)
5   at  android.graphics.BitmapFactory.finishDecode(BitmapFactory.java:498)
6   at  android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:473)
7   at  android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:336)
8   at  android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:359)
9   at  android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:385)

我最大的问题是即使在旧设备上我也无法在本地重现该问题。

我已经实现了很多东西来尝试解决这个问题:

1. 没有内存泄漏:我确保完全没有内存泄漏。当我不需要 View 时，我删除了它们。我还回收了所有位图并确保垃圾收集器正常工作。我在 onDestroy() 方法中实现了所有必要的步骤
2. 正确缩放图像尺寸:在获取图像之前，我会先获取其尺寸并计算 inSampleSize。
3. 堆大小:我还在获取图像之前检测最大堆大小并确保有足够的空间。如果不够，我会相应地重新缩放图像。

计算正确 inSampleSize 的代码

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)
      {
         if(width > height)
         {
            inSampleSize = Math.round((float) height / (float) reqHeight);
         }
         else
         {
            inSampleSize = Math.round((float) width / (float) reqWidth);
         }
      }
      return inSampleSize;
   }

获取位图的代码

    // decodes image and scales it to reduce memory consumption
   private static Bitmap decodeFile(File file, int newWidth, int newHeight)
   {// target size
      try
      {

         Bitmap bmp = MediaStore.Images.Media.getBitmap(getContext().getContentResolver(), Uri.fromFile(file));
         if(bmp == null)
         {
            // avoid concurrence
            // Decode image size
            BitmapFactory.Options option = new BitmapFactory.Options();

            // option = getBitmapOutput(file);

            option.inDensity = res.getDisplayMetrics().densityDpi < DisplayMetrics.DENSITY_HIGH ? 120 : 240;
            option.inTargetDensity = res.getDisplayMetrics().densityDpi;

            if(newHeight > 0 && newWidth > 0) 
                option.inSampleSize = calculateInSampleSize(option, newWidth, newWidth);

            option.inJustDecodeBounds = false;
            byte[] decodeBuffer = new byte[12 * 1024];
            option.inTempStorage = decodeBuffer;
            option.inPurgeable = true;
            option.inInputShareable = true;
            option.inScaled = true;

            bmp = BitmapFactory.decodeStream(new FileInputStream(file), null, option);
            if(bmp == null)
            {
               return null;
            }

         }
         else
         {
            int inDensity = res.getDisplayMetrics().densityDpi < DisplayMetrics.DENSITY_HIGH ? 120 : 240;
            int inTargetDensity = res.getDisplayMetrics().densityDpi;
            if(inDensity != inTargetDensity)
            {
               int newBmpWidth = (bmp.getWidth() * inTargetDensity) / inDensity;
               int newBmpHeight = (bmp.getHeight() * inTargetDensity) / inDensity;
               bmp = Bitmap.createScaledBitmap(bmp, newBmpWidth, newBmpHeight, true);
            }
         }

         return bmp;
      }
      catch(Exception e)
      {
         Log.e("Error calling Application.decodeFile Method params: " + Arrays.toString(new Object[]{file }), e);
      }
      return null;
   }

根据旧设备的堆大小计算图像大小的代码

private void calculateImagesSize()
   {
      // only for android older than HoneyComb that does not support large heap
      if(Build.VERSION.SDK_INT < Constants.HONEYCOMB)
      {
         long maxHeapSize = Runtime.getRuntime().maxMemory();
         long maxImageHeap = maxHeapSize - 10485760;
         if(Application.getResource().getDisplayMetrics().densityDpi >= DisplayMetrics.DENSITY_XHIGH)
         {
            maxImageHeap -= 12 * 1048576;
         }
         if(maxImageHeap < (30 * 1048576))
         {
            int screenHeight = Math.min(Application.getResource().getDisplayMetrics().heightPixels, Application.getResource()
               .getDisplayMetrics().widthPixels);
            long maxImageSize = maxImageHeap / 100;
            long maxPixels = maxImageSize / 4;
            long maxHeight = (long) Math.sqrt(maxPixels / 1.5);
            if(maxHeight < screenHeight)
            {
               drawableHeight = (int) maxHeight;
               drawableWidth = (int) (drawableHeight * 1.5);
            }
         }
      }
   }

我认为问题出在堆上，也许有时操作系统不允许应用程序使用 maxheapsize。另外我最大的问题是我无法重现该问题，因此当我尝试修复时，我必须稍等片刻，看看用户是否仍然收到错误。

我还可以尝试避免内存不足问题吗？任何建议将不胜感激。非常感谢

Answer 1

只需使用此功能解码...这是您错误的完美解决方案..因为我也遇到同样的错误并且我得到了这个解决方案..

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;
 }