Fix typo: the x offset was assigned to the y coordinate.

Also remove a couple of useless casts.
diff --git a/core/java/com/android/internal/service/wallpaper/ImageWallpaper.java b/core/java/com/android/internal/service/wallpaper/ImageWallpaper.java
index 3f2979f..c4eb31f 100644
--- a/core/java/com/android/internal/service/wallpaper/ImageWallpaper.java
+++ b/core/java/com/android/internal/service/wallpaper/ImageWallpaper.java
@@ -21,7 +21,6 @@
 import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
 import android.service.wallpaper.WallpaperService;
-import android.util.Log;
 import android.view.MotionEvent;
 import android.view.SurfaceHolder;
 import android.content.Context;
@@ -87,14 +86,13 @@
         @Override
         public void onTouchEvent(MotionEvent event) {
             super.onTouchEvent(event);
-            Log.i("foo", "Touch event: " + event);
         }
 
         @Override
         public void onOffsetsChanged(float xOffset, float yOffset,
                 int xPixels, int yPixels) {
             mXOffset = xOffset;
-            mYOffset = xOffset;
+            mYOffset = yOffset;
             drawFrame();
         }
 
@@ -128,9 +126,9 @@
                     final int availw = bw-dw;
                     final int availh = bh-dh;
                     int xPixels = availw > 0
-                            ? -(int)(availw*mXOffset+.5f) : -(int)(availw/2);
+                            ? -(int)(availw*mXOffset+.5f) : -(availw/2);
                     int yPixels = availh > 0
-                            ? -(int)(availh*mYOffset+.5f) : -(int)(availh/2);
+                            ? -(int)(availh*mYOffset+.5f) : -(availh/2);
                     c.translate(xPixels, yPixels);
                     c.drawColor(0xff000000);
                     background.draw(c);