android - 无法压缩回收位图

Question

我有回收位图的问题。我有所有的空值并从代码中回收。不确定我做错了什么。

我的代码:

ByteArrayOutputStream stream = new ByteArrayOutputStream();               
bmp = DecodeImage.decodeFile(imgpath, 450, 450, true);
bmp.compress(Bitmap.CompressFormat.JPEG, 100 , stream);     
Image img = Image.getInstance(stream.toByteArray()); 

错误信息:

07-12 15:44:11.924: E/AndroidRuntime(415): FATAL EXCEPTION: Thread-9850
07-12 15:44:11.924: E/AndroidRuntime(415): java.lang.IllegalStateException: Can't compress 
a recycled bitmap
07-12 15:44:11.924: E/AndroidRuntime(415):  at 
android.graphics.Bitmap.checkRecycled(Bitmap.java:272)
07-12 15:44:11.924: E/AndroidRuntime(415):  at 
android.graphics.Bitmap.compress(Bitmap.java:896)
07-12 15:44:11.924: E/AndroidRuntime(415):  at com.multiprvt.PDF$1.run(PDF.java:329)
07-12 15:44:11.924: E/AndroidRuntime(415):  at java.lang.Thread.run(Thread.java:856)

降低位图分辨率的解码类。

    public class DecodeImage
       {

       //decodes image and scales it to reduce memory consumption
         public static Bitmap decodeFile(File bitmapFile, int requiredWidth, int 
    requiredHeight,     boolean quickAndDirty)
   {
    try
    {
        //Decode image size
        BitmapFactory.Options bitmapSizeOptions = new BitmapFactory.Options();
        bitmapSizeOptions.inJustDecodeBounds = true;
      BitmapFactory.decodeStream(new FileInputStream(bitmapFile), null,  
    bitmapSizeOptions);

        // load image using inSampleSize adapted to required image size
        BitmapFactory.Options bitmapDecodeOptions = new BitmapFactory.Options();
        bitmapDecodeOptions.inTempStorage = new byte[16 * 1024];
     bitmapDecodeOptions.inSampleSize = computeInSampleSize(bitmapSizeOptions, 
    requiredWidth, requiredHeight, false);
        bitmapDecodeOptions.inPurgeable = true;
        bitmapDecodeOptions.inDither = !quickAndDirty;
       bitmapDecodeOptions.inPreferredConfig = quickAndDirty ? Bitmap.Config.RGB_565 : 
     Bitmap.Config.ARGB_8888;

         Bitmap decodedBitmap = BitmapFactory.decodeStream(new 
    FileInputStream(bitmapFile), null, bitmapDecodeOptions);

        // scale bitmap to mathc required size (and keep aspect ratio)

        float srcWidth = (float) bitmapDecodeOptions.outWidth;
        float srcHeight = (float) bitmapDecodeOptions.outHeight;

        float dstWidth = (float) requiredWidth;
        float dstHeight = (float) requiredHeight;

        float srcAspectRatio = srcWidth / srcHeight;
        float dstAspectRatio = dstWidth / dstHeight;

    // recycleDecodedBitmap is used to know if we must recycle intermediary 
   'decodedBitmap'
    // (DO NOT recycle it right away: wait for end of bitmap manipulation process to avoid
    // java.lang.RuntimeException: Canvas: trying to use a recycled bitmap 
   android.graphics.Bitmap@416ee7d8
        // I do not excatly understand why, but this way it's OK

        boolean recycleDecodedBitmap = false;

        Bitmap scaledBitmap = decodedBitmap;
        if (srcAspectRatio < dstAspectRatio)
        {       scaledBitmap = getScaledBitmap(decodedBitmap, (int) dstWidth, (int)  
  (srcHeight * (dstWidth / srcWidth)));
            // will recycle recycleDecodedBitmap
            recycleDecodedBitmap = true;
        }
        else if (srcAspectRatio > dstAspectRatio)
        {
            scaledBitmap = getScaledBitmap(decodedBitmap, (int) (srcWidth * (dstHeight / 
  srcHeight)), (int) dstHeight);
            recycleDecodedBitmap = true;
        }

        // crop image to match required image size

        int scaledBitmapWidth = scaledBitmap.getWidth();
        int scaledBitmapHeight = scaledBitmap.getHeight();

        Bitmap croppedBitmap = scaledBitmap;



        if (recycleDecodedBitmap)
        {
            decodedBitmap.recycle();
        }
        decodedBitmap = null;

        scaledBitmap = null;
        return croppedBitmap;

    }
    catch (Exception ex)
    {
        ex.printStackTrace();
    }
    return null;
   }

   /**
    * compute powerOf2 or exact scale to be used as {@link   
   BitmapFactory.Options#inSampleSize} value (for subSampling)
   * 
   * @param requiredWidth
   * @param requiredHeight
   * @param powerOf2
   *            weither we want a power of 2 sclae or not
 * @return
 */
  public static int computeInSampleSize(BitmapFactory.Options options, int dstWidth, int 
  dstHeight, boolean powerOf2)
  {
    int inSampleSize = 1;

    // Raw height and width of image
    final int srcHeight = options.outHeight;
    final int srcWidth = options.outWidth;

    if (powerOf2)
    {
        //Find the correct scale value. It should be the power of 2.

        int tmpWidth = srcWidth, tmpHeight = srcHeight;
        while (true)
        {
            if (tmpWidth / 2 < dstWidth || tmpHeight / 2 < dstHeight)
                break;
            tmpWidth /= 2;
            tmpHeight /= 2;
            inSampleSize *= 2;
        }
    }
    else
    {
        // Calculate ratios of height and width to requested height and width
        final int heightRatio = Math.round((float) srcHeight / (float) dstHeight);
        final int widthRatio = Math.round((float) srcWidth / (float) dstWidth);

        // Choose the smallest ratio as inSampleSize value, this will guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
   }

     public static Bitmap drawableToBitmap(Drawable drawable)
    {
    if (drawable instanceof BitmapDrawable)
    {
        return ((BitmapDrawable) drawable).getBitmap();
    }

    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), 
     drawable.getIntrinsicHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);

    return bitmap;
   }

    public static Bitmap getScaledBitmap(Bitmap bitmap, int newWidth, int newHeight)
   {
    int width = bitmap.getWidth();
    int height = bitmap.getHeight();
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;

    // CREATE A MATRIX FOR THE MANIPULATION
    Matrix matrix = new Matrix();
    // RESIZE THE BIT MAP
    matrix.postScale(scaleWidth, scaleHeight);

    // RECREATE THE NEW BITMAP
         Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix,                
    false);
    return resizedBitmap;
   } 

   }

不确定从哪里获取回收位图

Answer 1

您的源位图和缩放位图是相同的。在回收源之前检查是否相等。

Bitmap scaled = Bitmap.createScaledBitmap(src, ...):
if (src != scaled) {
    src.recycle();
}
return scaled;

来自 Bitmap.createScaledBitmap(...) 的文档:

如果可能，创建一个新的位图，从现有的位图缩放。如果指定的宽度和高度与源位图的当前宽度和高度相同，则返回源位图并且不创建新位图。