Clarify AnimationSet docs and behavior

Two problems fixed here:
- The docs for AnimationSet were too vague and incorrect: some properties of
Animation (such as duration) are pushed from the AnimationSet down to its children, as
the current docs say. Some other properties (such as repeatCount) are ignored. Other
properties (such as startOffset) apply to the Set itself, but not to the children.
Fix: clarify this behavior for each of the properties.
- The behavior for XML resources was just busted. We would set the various properties
(e.g., duration) and then forget that we did so, since we reset the flags that marked
their existence after we loaded the resource. In fact, the duration property was
always being reset to 0, regardless of what it was set to in the xml resource.
Fix: Make it work they way it always should have: respect the values read from the XML
resource and make them behave the same way they do when set at runtime.

Change-Id: I07d68876d2259105dc5a359501d5c656ecfaa8e5

diff --git a/core/java/android/view/animation/AnimationSet.java b/core/java/android/view/animation/AnimationSet.java
index 4f2542b..58373bc 100644 (file)
--- a/core/java/android/view/animation/AnimationSet.java
+++ b/core/java/android/view/animation/AnimationSet.java
@@ -18,6 +18,7 @@ package android.view.animation;
 
 import android.content.Context;
 import android.content.res.TypedArray;
+import android.os.Build;
 import android.util.AttributeSet;
 import android.graphics.RectF;
 
@@ -31,6 +32,22 @@ import java.util.List;
  * If AnimationSet sets any properties that its children also set
  * (for example, duration or fillBefore), the values of AnimationSet
  * override the child values.
+ *
+ * <p>The way that AnimationSet inherits behavior from Animation is important to
+ * understand. Some of the Animation attributes applied to AnimationSet affect the
+ * AnimationSet itself, some are pushed down to the children, and some are ignored,
+ * as follows:
+ * <ul>
+ *     <li>duration, repeatMode, fillBefore, fillAfter: These properties, when set
+ *     on an AnimationSet object, will be pushed down to all child animations.</li>
+ *     <li>repeatCount, fillEnabled: These properties are ignored for AnimationSet.</li>
+ *     <li>startOffset, shareInterpolator: These properties apply to the AnimationSet itself.</li>
+ * </ul>
+ * Starting with {@link android.os.Build.VERSION_CODES#ICE_CREAM_SANDWICH},
+ * the behavior of these properties is the same in XML resources and at runtime (prior to that
+ * release, the values set in XML were ignored for AnimationSet). That is, calling
+ * <code>setDuration(500)</code> on an AnimationSet has the same effect as declaring
+ * <code>android:duration="500"</code> in an XML resource for an AnimationSet object.</p>
  */
 public class AnimationSet extends Animation {
     private static final int PROPERTY_FILL_AFTER_MASK         = 0x1;
@@ -69,7 +86,26 @@ public class AnimationSet extends Animation {
         setFlag(PROPERTY_SHARE_INTERPOLATOR_MASK,
                 a.getBoolean(com.android.internal.R.styleable.AnimationSet_shareInterpolator, true));
         init();
-        
+
+        if (context.getApplicationInfo().targetSdkVersion >=
+                Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
+            if (a.hasValue(com.android.internal.R.styleable.Animation_duration)) {
+                mFlags |= PROPERTY_DURATION_MASK;
+            }
+            if (a.hasValue(com.android.internal.R.styleable.Animation_fillBefore)) {
+                mFlags |= PROPERTY_FILL_BEFORE_MASK;
+            }
+            if (a.hasValue(com.android.internal.R.styleable.Animation_fillAfter)) {
+                mFlags |= PROPERTY_FILL_AFTER_MASK;
+            }
+            if (a.hasValue(com.android.internal.R.styleable.Animation_repeatMode)) {
+                mFlags |= PROPERTY_REPEAT_MODE_MASK;
+            }
+            if (a.hasValue(com.android.internal.R.styleable.Animation_startOffset)) {
+                mFlags |= PROPERTY_START_OFFSET_MASK;
+            }
+        }
+
         a.recycle();
     }
     
@@ -112,7 +148,6 @@ public class AnimationSet extends Animation {
 
     private void init() {
         mStartTime = 0;
-        mDuration = 0;
     }
 
     @Override
@@ -171,6 +206,7 @@ public class AnimationSet extends Animation {
     public void setDuration(long durationMillis) {
         mFlags |= PROPERTY_DURATION_MASK;
         super.setDuration(durationMillis);
+        mLastEnd = mStartOffset + mDuration;
     }
 
     /**
@@ -192,12 +228,16 @@ public class AnimationSet extends Animation {
             mFlags |= PROPERTY_CHANGE_BOUNDS_MASK;
         }
 
-        if (mAnimations.size() == 1) {
-            mDuration = a.getStartOffset() + a.getDuration();
+        if ((mFlags & PROPERTY_DURATION_MASK) == PROPERTY_DURATION_MASK) {
             mLastEnd = mStartOffset + mDuration;
         } else {
-            mLastEnd = Math.max(mLastEnd, a.getStartOffset() + a.getDuration());
-            mDuration = mLastEnd - mStartOffset;
+            if (mAnimations.size() == 1) {
+                mDuration = a.getStartOffset() + a.getDuration();
+                mLastEnd = mStartOffset + mDuration;
+            } else {
+                mLastEnd = Math.max(mLastEnd, a.getStartOffset() + a.getDuration());
+                mDuration = mLastEnd - mStartOffset;
+            }
         }
 
         mDirty = true;