我有一个循环使用bitmap的问题。我有所有null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());
错误讯息：
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)
解码为位图降低分辨率的类。
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;
}
}
不知道它在哪里获得循环位图
答案 0 :(得分：10)
您的源位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：
尽可能从现有位图缩放创建新位图。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，并且不会创建新的位图。