View中的createBitmap（）中的NullPointerException

Question

我正在使用以下代碼從View獲取Bitmap ：

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;
    }

但是我在下面的行中收到NullPointerException ：

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

這是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

試試這個

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;
    }

說明：

就知識而言，位圖是最終課程。 因此， 垃圾回收器（GC）的優先級非常低，而且內存占用很大。默認情況下，視圖不會從畫布創建位圖，因為如果這樣做，則會為每個放大的視圖在內存中生成一個位圖，這可能會導致buildDrawingCache。 因此，使用buildDrawingCache()方法可以在需要時生成位圖。

Answer 2

代碼應該是

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

因為您已經將快照投射為Bitmap

Bitmap snapshot = null;

？