Return 1f in Log(Ac/De)celerateInterpolators on a 1f input.

In battery saver mode, animations skip directly to the final values.
For LogDecelerateInterpolator, however, an input of 1f outputs an
interpolated 0.99999994. This meant that the FirstFrameAnimatorHelper
didn't realize that this was the last frame, and messed things up.
Since any interpolator should return 1 on an input of 1, we just
short-circuit in that case for the log interpolators.

Bug: 25666809
Change-Id: I60527e3758cea383fbcf50acb95460a7bd9ab43c

src/com/android/launcher3/Launcher.java

@@ -3117,10 +3117,6 @@ public class Launcher extends Activity
         }
         oa.setDuration(getResources().getInteger(R.integer.config_folderExpandDuration));
         oa.start();
-        if (Utilities.isPowerSaverOn(this)) {
-            // Animations are disabled in battery saver mode, so just skip to the end state.
-            oa.end();
-        }
     }
 
     private void shrinkAndFadeInFolderIcon(final FolderIcon fi, boolean animate) {

src/com/android/launcher3/LogAccelerateInterpolator.java

@@ -20,6 +20,8 @@ public class LogAccelerateInterpolator implements TimeInterpolator {
 
     @Override
     public float getInterpolation(float t) {
-        return 1 - computeLog(1 - t, mBase, mDrift) * mLogScale;
+        // Due to rounding issues, the interpolation doesn't quite reach 1 even though it should.
+        // To account for this, we short-circuit to return 1 if the input is 1.
+        return Float.compare(t, 1f) == 0 ? 1f : 1 - computeLog(1 - t, mBase, mDrift) * mLogScale;
     }
 }

src/com/android/launcher3/LogDecelerateInterpolator.java

@@ -21,6 +21,8 @@ public class LogDecelerateInterpolator implements TimeInterpolator {
 
     @Override
     public float getInterpolation(float t) {
-        return computeLog(t, mBase, mDrift) * mLogScale;
+        // Due to rounding issues, the interpolation doesn't quite reach 1 even though it should.
+        // To account for this, we short-circuit to return 1 if the input is 1.
+        return Float.compare(t, 1f) == 0 ? 1f : computeLog(t, mBase, mDrift) * mLogScale;
     }
 }