diff --git a/src/com/hippo/ehviewer/gallery/GalleryView.java b/src/com/hippo/ehviewer/gallery/GalleryView.java
index 42ac04acf..906087e32 100644
--- a/src/com/hippo/ehviewer/gallery/GalleryView.java
+++ b/src/com/hippo/ehviewer/gallery/GalleryView.java
@@ -180,6 +180,8 @@ public class GalleryView extends GLView implements ImageSet.ImageListener,
         public void onSizeUpdate(int size);
 
         public void onSlideBottom(float dx);
+
+        public void onSlideBottomOver();
     }
 
     public interface OnTapTextListener {
@@ -1322,8 +1324,11 @@ public class GalleryView extends GLView implements ImageSet.ImageListener,
                 return false;
             if (mDoubleTapAnimating)
                 return false;
-            if (mLightnessSliding)
-                return false;
+            if (mLightnessSliding) {
+                if (mGalleryViewListener != null)
+                    mGalleryViewListener.onSlideBottomOver();
+                return true;
+            }
 
             switch (mScrollState) {
             case SCROLL_ANIME_LEFT:
diff --git a/src/com/hippo/ehviewer/ui/GalleryActivity.java b/src/com/hippo/ehviewer/ui/GalleryActivity.java
index e265d8d03..4cf039abd 100644
--- a/src/com/hippo/ehviewer/ui/GalleryActivity.java
+++ b/src/com/hippo/ehviewer/ui/GalleryActivity.java
@@ -282,11 +282,17 @@ public class GalleryActivity extends Activity
 
     @Override
     public void onSlideBottom(float dx) {
-        if (mLightnessScale == 0)
-            mLightnessScale = mMaskView.getWidth();
+        if (mLightnessScale == 0) {
+            int w = mMaskView.getWidth();
+            mLightnessScale = w > 0 ? w : 1024;
+        }
 
         mLightness = MathUtils.clamp(mLightness - (dx / mLightnessScale), -1.0f, 1.0f);
         setLightness(mLightness);
+    }
+
+    @Override
+    public void onSlideBottomOver() {
         Config.setFloat(KEY_LIGHTNESS, mLightness);
     }