android - 在 ImageView 中使用位图时出现 OutOfMemory 问题

Question

我的 android 应用程序中有超过 8 个 Activity ，所有屏幕都有很多 imageView，它们将使用位图图像呈现

当我们打开所有屏幕( Activity )时，它会正常工作几次，然后会出现内存不足错误，应用程序崩溃

这是我的代码如何显示图像，请建议如何避免这个/管理这个内存不足的问题

XML:

<?xml version="1.0" encoding="utf-8"?>    
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
    android:layout_width="match_parent"    
    android:layout_height="match_parent"    
    android:orientation="vertical"    
    android:background="@drawable/img_background">    

   <ImageView    
        android:layout_width="match_parent"   
        android:layout_height="match_parent"    
        android:scaleType="fitCenter"    
        android:adjustViewBounds="true"       
        android:id="@+id/artifactImage"      
        android:onClick="displayFullScreenImage"/>      

</LinearLayout>    

Activity :

ImageView artifact_Image = (ImageView) gridView.findViewById(R.id.artifactImage);     
artifact_Image.setImageBitmap(artifactImages[position]);       
artifact_Image.setDrawingCacheEnabled(false);

Answer 1

可能您显示的图像占用了整个内存空间，这就是您收到此错误的原因。您可能想查看有关如何显示位图的文档:

http://developer.android.com/training/displaying-bitmaps/index.html

在您的情况下，您应该加载图像的缩小版本。查看此链接以获取示例代码:

http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

为了方便起见，我也将示例代码复制到这里。

计算样本量:

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;
}

解码位图:

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);
}

最后设置缩放后的位图

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