将图像加载到位图对象时出现奇怪的OutOfMemory问题 [英] Strange OutOfMemory issue while loading an image to a Bitmap object

问题描述

我有一个 ListView ，每行上都有几个图像按钮.当用户单击列表行时，它将启动一个新活动.由于相机布局存在问题，我不得不构建自己的标签.为结果而启动的活动是地图.如果单击我的按钮以启动图像预览(将图像从SD卡加载)，则应用程序将从活动返回到 ListView 活动并返回到结果处理程序，以重新启动我的新活动不仅仅是图片小部件.

I have a ListView with a couple of image buttons on each row. When user click the list row, it launches a new activity. I have had to build my own tabs because of an issue with the camera layout. The activity that gets launched for the result is a map. If I click on my button to launch the image preview (load an image off the SD card) the application returns from the activity back to the ListView activity to the result handler to relaunch my new activity which is nothing more than an image widget.

ListView 上的图像预览是使用光标和 ListAdapter 完成的.这非常简单，但是我不确定如何放置调整大小后的图像(即，较小的位大小而不是像素作为飞行中图像按钮的 src .因此，我只是调整了图像的大小从手机相机上掉下来了.

The image preview on the ListView is being done with the cursor and ListAdapter. This makes it pretty simple, but I am not sure how I can put a resized image (I.e. Smaller bit size not pixel as the src for the image button on the fly. So I just resized the image that came off the phone camera.

问题在于，当我尝试返回并重新启动第二项活动时，出现了 OutOfMemoryError .

The issue is that I get an OutOfMemoryError when it tries to go back and re-launch the 2nd activity.

• 有没有一种方法可以轻松地逐行构建列表适配器，从而可以即时调整大小(明智的)?

这将是更可取的，因为我还需要对每行中的小部件/元素的属性进行一些更改，因为由于焦点问题而无法使用触摸屏选择一行.(我可以使用滚珠.)

This would be preferable as I also need to make some changes to the properties of the widgets/elements in each row as I am unable to select a row with the touch screen because of the focus issue. (I can use roller ball.)

• 我知道我可以进行带外调整大小并保存图像，但这并不是我真正想做的，但是一些示例代码会很不错.

一旦我禁用了 ListView 上的图像，它又可以正常工作.

As soon as I disabled the image on the ListView it worked fine again.

仅供参考:这就是我的做法:

FYI: This is how I was doing it:

String[] from = new String[] { DBHelper.KEY_BUSINESSNAME, DBHelper.KEY_ADDRESS,
    DBHelper.KEY_CITY, DBHelper.KEY_GPSLONG, DBHelper.KEY_GPSLAT,
    DBHelper.KEY_IMAGEFILENAME  + ""};
int[] to = new int[] { R.id.businessname, R.id.address, R.id.city, R.id.gpslong,
    R.id.gpslat, R.id.imagefilename };
notes = new SimpleCursorAdapter(this, R.layout.notes_row, c, from, to);
setListAdapter(notes);

其中 R.id.imagefilename 是 ButtonImage .

这是我的LogCat:

Here is my LogCat:

01-25 05:05:49.877: ERROR/dalvikvm-heap(3896): 6291456-byte external allocation too large for this process.
01-25 05:05:49.877: ERROR/(3896): VM wont let us allocate 6291456 bytes
01-25 05:05:49.877: ERROR/AndroidRuntime(3896): Uncaught handler: thread main exiting due to uncaught exception
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): java.lang.OutOfMemoryError: bitmap size exceeds VM budget
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:304)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:149)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:174)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.graphics.drawable.Drawable.createFromPath(Drawable.java:729)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.ImageView.resolveUri(ImageView.java:484)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.ImageView.setImageURI(ImageView.java:281)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.SimpleCursorAdapter.setViewImage(SimpleCursorAdapter.java:183)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.SimpleCursorAdapter.bindView(SimpleCursorAdapter.java:129)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.CursorAdapter.getView(CursorAdapter.java:150)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.AbsListView.obtainView(AbsListView.java:1057)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.ListView.makeAndAddView(ListView.java:1616)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.ListView.fillSpecific(ListView.java:1177)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.ListView.layoutChildren(ListView.java:1454)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.AbsListView.onLayout(AbsListView.java:937)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1108)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.LinearLayout.onLayout(LinearLayout.java:922)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.FrameLayout.onLayout(FrameLayout.java:294)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.LinearLayout.layoutVertical(LinearLayout.java:999)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.LinearLayout.onLayout(LinearLayout.java:920)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.widget.FrameLayout.onLayout(FrameLayout.java:294)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.ViewRoot.performTraversals(ViewRoot.java:771)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1103)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.os.Handler.dispatchMessage(Handler.java:88)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.os.Looper.loop(Looper.java:123)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at android.app.ActivityThread.main(ActivityThread.java:3742)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at java.lang.reflect.Method.invokeNative(Native Method)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at java.lang.reflect.Method.invoke(Method.java:515)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:497)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896):     at dalvik.system.NativeStart.main(Native Method)
01-25 05:10:01.127: ERROR/AndroidRuntime(3943): ERROR: thread attach failed 

显示图像时我也遇到了一个新错误:

I also have a new error when displaying an image:

22:13:18.594: DEBUG/skia(4204): xxxxxxxxxxx jpeg error 20 Improper call to JPEG library in state %d
22:13:18.604: INFO/System.out(4204): resolveUri failed on bad bitmap uri: 
22:13:18.694: ERROR/dalvikvm-heap(4204): 6291456-byte external allocation too large for this process.
22:13:18.694: ERROR/(4204): VM won't let us allocate 6291456 bytes
22:13:18.694: DEBUG/skia(4204): xxxxxxxxxxxxxxxxxxxx allocPixelRef failed

推荐答案

Android培训类，"有效显示位图"，为理解和处理 java异常提供了一些很好的信息.lang.OutOfMemoryError:加载位图时，位图大小超出了VM预算.

The Android Training class, "Displaying Bitmaps Efficiently", offers some great information for understanding and dealing with the exception java.lang.OutOfMemoryError: bitmap size exceeds VM budget when loading Bitmaps.

BitmapFactory 类提供了几种解码方法( decodeByteArray()， decodeFile()， decodeResource()等)，以从各种来源创建位图.根据您的图像数据源选择最合适的解码方法.这些方法尝试为构造的位图分配内存，因此很容易导致 OutOfMemory 异常.每种解码方法都有附加的签名，可让您通过 BitmapFactory.Options 类指定解码选项.在解码时将 inJustDecodeBounds 属性设置为 true 可以避免内存分配，为位图对象返回 null ，但设置为 outWidth ， outHeight 和 outMimeType .这种技术使您可以在位图的构造(和内存分配)之前读取图像数据的尺寸和类型.

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.

BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;

为避免 java.lang.OutOfMemory 异常，请在解码位图之前检查位图的尺寸，除非您完全相信该源可为您提供可预测大小的图像数据，且该图像数据可以舒适地容纳在可用内存中

To avoid java.lang.OutOfMemory exceptions, check the dimensions of a bitmap before decoding it, unless you absolutely trust the source to provide you with predictably sized image data that comfortably fits within the available memory.

既然图像尺寸是已知的，它们就可以用来决定是否应将完整图像加载到内存中，或者是否应该加载子采样版本.以下是一些要考虑的因素:

Now that the image dimensions are known, they can be used to decide if the full image should be loaded into memory or if a subsampled version should be loaded instead. Here are some factors to consider:

• 估计将完整映像加载到内存中的内存使用情况.
• 在应用程序有其他内存需求的情况下，您愿意承诺加载此映像的内存量.
• 要将图像加载到其中的目标ImageView或UI组件的尺寸.
• 当前设备的屏幕尺寸和密度.

例如，如果将1024x768像素的图像最终显示在 ImageView 中的128x96像素的缩略图中，则不值得将其加载到内存中.

For example, it’s not worth loading a 1024x768 pixel image into memory if it will eventually be displayed in a 128x96 pixel thumbnail in an ImageView.

要告诉解码器对图像进行二次采样，将较小的版本加载到内存中，请在您的 BitmapFactory.Options 对象中将 inSampleSize 设置为 true ..例如，以 inSampleSize 为4解码的分辨率为2048x1536的图像会生成大约512x384的位图.将其加载到内存中需要使用0.75MB而不是12MB的完整图像(假设 ARGB_8888 的位图配置).这是一种根据目标宽度和高度计算样本大小值(是2的幂)的方法:

To tell the decoder to subsample the image, loading a smaller version into memory, set inSampleSize to true in your BitmapFactory.Options object. For example, an image with resolution 2048x1536 that is decoded with an inSampleSize of 4 produces a bitmap of approximately 512x384. Loading this into memory uses 0.75MB rather than 12MB for the full image (assuming a bitmap configuration of ARGB_8888). Here’s a method to calculate a sample size value that is a power of two based on a target width and height:

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 / 2;
        final int halfWidth = width / 2;

        // 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;
}

注意:由于解码器使用根据四舍五入取整到最接近的2的幂 inSampleSize 文档.

Note: A power of two value is calculated because the decoder uses a final value by rounding down to the nearest power of two, as per the inSampleSize documentation.

要使用此方法，请先将 inJustDecodeBounds 设置为 true 进行解码，然后传递选项，然后使用新的 inSampleSize 值再次进行解码和 inJustDecodeBounds 设置为 false :

To use this method, first decode with inJustDecodeBounds set to true, pass the options through and then decode again using the new inSampleSize value and inJustDecodeBounds set to false:

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

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

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

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

此方法可以轻松地将任意大尺寸的位图加载到显示100x100像素缩略图的 ImageView 中，如以下示例代码所示:

This method makes it easy to load a bitmap of arbitrarily large size into an ImageView that displays a 100x100 pixel thumbnail, as shown in the following example code:

mImageView.setImageBitmap(
    decodeSampledBitmapFromResource(getResources(), R.id.myimage, 100, 100));

您可以按照类似的过程，通过根据需要替换适当的 BitmapFactory.decode * 方法来解码其他来源的位图.

You can follow a similar process to decode bitmaps from other sources, by substituting the appropriate BitmapFactory.decode* method as needed.

这篇关于将图像加载到位图对象时出现奇怪的OutOfMemory问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！