Question

我使用以下代码从Bitmap获取View：

private static Bitmap loadBitmapFromView(View yourView) {
        Bitmap snapshot = null;
        Drawable drawable = null;
        yourView.setDrawingCacheEnabled(true);
        yourView.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH); //Quality of the snpashot
        try {
            snapshot = Bitmap.createBitmap(yourView.getDrawingCache());
            drawable = new BitmapDrawable(snapshot);
        } finally {
            yourView.setDrawingCacheEnabled(false);
        }
        return snapshot;
    }

但我在下一行收到NullPointerException：

snapshot = Bitmap.createBitmap(yourView.getDrawingCache());

以下是Logcat：

09-19 15:39:15.481: E/AndroidRuntime(8704): FATAL EXCEPTION: main
09-19 15:39:15.481: E/AndroidRuntime(8704): java.lang.NullPointerException
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.graphics.Bitmap.createBitmap(Bitmap.java:455)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at com.scb.bonuspartner.utils.MapUtility.loadBitmapFromView(MapUtility.java:85)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at com.scb.bonuspartner.utils.MapUtility.createMarker(MapUtility.java:74)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at com.scb.bonuspartner.offeractivity.fragments.MapOfferFragment.onLocationChanged(MapOfferFragment.java:70)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:227)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:160)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:176)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.os.Looper.loop(Looper.java:154)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at android.app.ActivityThread.main(ActivityThread.java:4624)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at java.lang.reflect.Method.invokeNative(Native Method)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at java.lang.reflect.Method.invoke(Method.java:511)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
09-19 15:39:15.481: E/AndroidRuntime(8704):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

试试这种方式

private static Bitmap loadBitmapFromView(View yourView) {
        Bitmap snapshot = null;
        Drawable drawable = null;
        yourView.setDrawingCacheEnabled(true);
        yourView.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH); //Quality of the snpashot
        try {
            yourView.buildDrawingCache(); // UPDATE HERE
            snapshot = Bitmap.createBitmap(yourView.getDrawingCache());
            drawable = new BitmapDrawable(snapshot);
        } finally {
            yourView.setDrawingCacheEnabled(false);
        }
        return snapshot;
    }

说明：

知识位图是最终的类。因此，垃圾收集器（GC）的优先级非常低并且内存非常昂贵。默认视图不会从画布创建位图，因为如果这样做，将在内存中生成一个位图每个视图都膨胀，它可能会导致buildDrawingCache。因此，buildDrawingCache()方法可以在需要时生成位图。

Answer 2

代码应该

snapshot = snapshot.createBitmap(yourView.getDrawingCache());

因为你已经将快照转换为Bitmap

Bitmap snapshot = null;

来自View的createBitmap（）中的NullPointerException

2 个答案: