Smooth opening animation by modifying interpolation curve.

bug:5367032
Change-Id: I15ad839ede723591f081be200c1c16a8a9a901d0
diff --git a/src/com/android/gallery3d/ui/PositionController.java b/src/com/android/gallery3d/ui/PositionController.java
index 1be601e..9797ce9 100644
--- a/src/com/android/gallery3d/ui/PositionController.java
+++ b/src/com/android/gallery3d/ui/PositionController.java
@@ -54,7 +54,7 @@
         600,  // ANIM_KIND_SNAPBACK
         400,  // ANIM_KIND_SLIDE
         300,  // ANIM_KIND_ZOOM
-        600,  // ANIM_KIND_OPENING
+        400,  // ANIM_KIND_OPENING
         0,    // ANIM_KIND_FLING (the duration is calculated dynamically)
         800,  // ANIM_KIND_CAPTURE
     };
@@ -1212,10 +1212,12 @@
                 case ANIM_KIND_SCALE:
                     progress = 1 - f * f;  // quadratic
                     break;
+                case ANIM_KIND_OPENING:
+                    progress = 1 - f * f * f;  // x^3
+                    break;
                 case ANIM_KIND_SNAPBACK:
                 case ANIM_KIND_ZOOM:
                 case ANIM_KIND_SLIDE:
-                case ANIM_KIND_OPENING:
                     progress = 1 - f * f * f * f * f; // x^5
                     break;
             }