Update vertical motion for TextInputLayout's error text.

Motion additions/updates in this change:
- Added animation for error text's translation down
- Updated durations and interpolators for the opacity in and out animations

These changes roll forward changes that were previously rolled back because they broke screenshot tests.

PiperOrigin-RevId: 158881906

lib/res/values/dimens.xml

@@ -36,6 +36,8 @@
     <dimen name="design_tab_text_size">14sp</dimen>
     <dimen name="design_tab_text_size_2line">12sp</dimen>
 
+    <dimen name="design_textinput_error_translate_y">5dp</dimen>
+
     <dimen name="design_snackbar_min_width">-1px</dimen>
     <dimen name="design_snackbar_max_width">-1px</dimen>
     <dimen name="design_snackbar_elevation">6dp</dimen>

lib/src/android/support/design/widget/TextInputLayout.java

@@ -18,6 +18,8 @@ package android.support.design.widget;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
+import android.animation.AnimatorSet;
+import android.animation.ObjectAnimator;
 import android.animation.ValueAnimator;
 import android.content.Context;
 import android.content.res.ColorStateList;
@@ -110,17 +112,26 @@ import android.widget.TextView;
  */
 public class TextInputLayout extends LinearLayout {
 
-  private static final int ANIMATION_DURATION = 200;
   // Duration for the label's scale up and down animations.
   private static final int LABEL_SCALE_ANIMATION_DURATION = 167;
 
+  // Duration for the error text's vertical translation animation.
+  private static final int ERROR_TRANSLATE_Y_ANIMATION_DURATION = 250;
+
+  // Durations for the error text's opacity fade animations.
+  private static final int ERROR_OPACITY_FADE_IN_ANIMATION_DURATION = 167;
+  private static final int ERROR_OPACITY_FADE_OUT_ANIMATION_DURATION = 83;
+
   private static final int INVALID_MAX_LENGTH = -1;
 
   private static final String LOG_TAG = "TextInputLayout";
 
   private final FrameLayout mInputFrame;
+  private @Nullable Animator mErrorAnimator;
   EditText mEditText;
 
+  private final float mErrorTextTranslationYPx;
+
   private boolean mHintEnabled;
   private CharSequence mHint;
 
@@ -259,6 +270,9 @@ public class TextInputLayout extends LinearLayout {
     }
 
     ViewCompat.setAccessibilityDelegate(this, new TextInputAccessibilityDelegate());
+
+    mErrorTextTranslationYPx =
+        getResources().getDimensionPixelSize(R.dimen.design_textinput_error_translate_y);
   }
 
   @Override
@@ -597,6 +611,9 @@ public class TextInputLayout extends LinearLayout {
     if (mErrorEnabled != enabled) {
       if (mErrorView != null) {
         mErrorView.animate().cancel();
+        if (mErrorAnimator != null) {
+          mErrorAnimator.cancel();
+        }
       }
 
       if (enabled) {
@@ -700,6 +717,9 @@ public class TextInputLayout extends LinearLayout {
 
     // Cancel any on-going animation
     mErrorView.animate().cancel();
+    if (mErrorAnimator != null) {
+      mErrorAnimator.cancel();
+    }
 
     if (mErrorShown) {
       mErrorView.setText(error);
@@ -710,19 +730,35 @@ public class TextInputLayout extends LinearLayout {
           // If it's currently 100% show, we'll animate it from 0
           mErrorView.setAlpha(0f);
         }
-        mErrorView
-            .animate()
-            .alpha(1f)
-            .setDuration(ANIMATION_DURATION)
-            .setInterpolator(AnimationUtils.LINEAR_OUT_SLOW_IN_INTERPOLATOR)
-            .setListener(
-                new AnimatorListenerAdapter() {
-                  @Override
-                  public void onAnimationStart(Animator animator) {
-                    mErrorView.setVisibility(VISIBLE);
-                  }
-                })
-            .start();
+
+        ObjectAnimator errorOpacityAnimator = ObjectAnimator.ofFloat(mErrorView, ALPHA, 1f);
+        ObjectAnimator errorTranslationYAnimator =
+            ObjectAnimator.ofFloat(mErrorView, TRANSLATION_Y, -mErrorTextTranslationYPx, 0);
+
+        errorOpacityAnimator
+            .setDuration(ERROR_OPACITY_FADE_IN_ANIMATION_DURATION)
+            .setInterpolator(AnimationUtils.LINEAR_INTERPOLATOR);
+        errorTranslationYAnimator
+            .setDuration(ERROR_TRANSLATE_Y_ANIMATION_DURATION)
+            .setInterpolator(AnimationUtils.LINEAR_OUT_SLOW_IN_INTERPOLATOR);
+
+        final AnimatorSet errorAnimatorSet = new AnimatorSet();
+        mErrorAnimator = errorAnimatorSet;
+
+        errorAnimatorSet.playTogether(errorOpacityAnimator, errorTranslationYAnimator);
+        errorAnimatorSet.addListener(
+            new AnimatorListenerAdapter() {
+              @Override
+              public void onAnimationEnd(Animator animation) {
+                mErrorAnimator = null;
+              }
+
+              @Override
+              public void onAnimationStart(Animator animation) {
+                mErrorView.setVisibility(VISIBLE);
+              }
+            });
+        errorAnimatorSet.start();
       } else {
         // Set alpha to 1f, just in case
         mErrorView.setAlpha(1f);
@@ -733,8 +769,8 @@ public class TextInputLayout extends LinearLayout {
           mErrorView
               .animate()
               .alpha(0f)
-              .setDuration(ANIMATION_DURATION)
-              .setInterpolator(AnimationUtils.FAST_OUT_LINEAR_IN_INTERPOLATOR)
+              .setDuration(ERROR_OPACITY_FADE_OUT_ANIMATION_DURATION)
+              .setInterpolator(AnimationUtils.LINEAR_INTERPOLATOR)
               .setListener(
                   new AnimatorListenerAdapter() {
                     @Override
@@ -750,7 +786,6 @@ public class TextInputLayout extends LinearLayout {
         }
       }
     }
-
     updateEditTextBackground();
     updateLabelState(animate);
   }