Merge "Cleanup how we set back button alpha" into ub-launcher3-edmonton

quickstep/src/com/android/launcher3/uioverrides/BackButtonAlphaHandler.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.launcher3.uioverrides;
+
+import android.animation.ValueAnimator;
+
+import com.android.launcher3.Launcher;
+import com.android.launcher3.LauncherState;
+import com.android.launcher3.LauncherStateManager;
+import com.android.launcher3.anim.AnimatorSetBuilder;
+import com.android.quickstep.OverviewInteractionState;
+
+public class BackButtonAlphaHandler implements LauncherStateManager.StateHandler {
+
+    private static final String TAG = "BackButtonAlphaHandler";
+
+    private final Launcher mLauncher;
+    private final OverviewInteractionState mOverviewInteractionState;
+
+    public BackButtonAlphaHandler(Launcher launcher) {
+        mLauncher = launcher;
+        mOverviewInteractionState = OverviewInteractionState.getInstance(mLauncher);
+    }
+
+    @Override
+    public void setState(LauncherState state) {
+        UiFactory.onLauncherStateOrFocusChanged(mLauncher);
+    }
+
+    @Override
+    public void setStateWithAnimation(LauncherState toState,
+            AnimatorSetBuilder builder, LauncherStateManager.AnimationConfig config) {
+        if (!config.playNonAtomicComponent()) {
+            return;
+        }
+        float fromAlpha = mOverviewInteractionState.getBackButtonAlpha();
+        float toAlpha = toState.hideBackButton ? 0 : 1;
+        if (Float.compare(fromAlpha, toAlpha) != 0) {
+            ValueAnimator anim = ValueAnimator.ofFloat(fromAlpha, toAlpha);
+            anim.setDuration(config.duration);
+            anim.addUpdateListener(valueAnimator -> {
+                final float alpha = (float) valueAnimator.getAnimatedValue();
+                mOverviewInteractionState.setBackButtonAlpha(alpha, false);
+            });
+            builder.play(anim);
+        }
+    }
+}

quickstep/src/com/android/launcher3/uioverrides/UiFactory.java

@@ -78,11 +78,13 @@ public class UiFactory {
     }
 
     public static StateHandler[] getStateHandler(Launcher launcher) {
-        return new StateHandler[] {
-                launcher.getAllAppsController(), launcher.getWorkspace(),
-                new RecentsViewStateController(launcher)};
+        return new StateHandler[] {launcher.getAllAppsController(), launcher.getWorkspace(),
+                new RecentsViewStateController(launcher), new BackButtonAlphaHandler(launcher)};
     }
 
+    /**
+     * Sets the back button visibility based on the current state/window focus.
+     */
     public static void onLauncherStateOrFocusChanged(Launcher launcher) {
         boolean shouldBackButtonBeHidden = launcher != null
                 && launcher.getStateManager().getState().hideBackButton
@@ -96,10 +98,6 @@ public class UiFactory {
                 .setBackButtonAlpha(shouldBackButtonBeHidden ? 0 : 1, true /* animate */);
     }
 
-    public static void setBackButtonAlpha(Launcher launcher, float alpha, boolean animate) {
-         OverviewInteractionState.getInstance(launcher).setBackButtonAlpha(alpha,animate);
-    }
-
     public static void resetOverview(Launcher launcher) {
         RecentsView recents = launcher.getOverviewPanel();
         recents.reset();

quickstep/src/com/android/quickstep/OverviewInteractionState.java

@@ -91,6 +91,7 @@ public class OverviewInteractionState {
     // These are updated on the background thread
     private ISystemUiProxy mISystemUiProxy;
     private boolean mSwipeUpEnabled = true;
+    private float mBackButtonAlpha = 1;
 
     private Runnable mOnSwipeUpSettingChangedListener;
 
@@ -117,7 +118,14 @@ public class OverviewInteractionState {
         return mSwipeUpEnabled;
     }
 
+    public float getBackButtonAlpha() {
+        return mBackButtonAlpha;
+    }
+
     public void setBackButtonAlpha(float alpha, boolean animate) {
+        if (!mSwipeUpEnabled) {
+            alpha = 1;
+        }
         mUiHandler.removeMessages(MSG_SET_BACK_BUTTON_ALPHA);
         mUiHandler.obtainMessage(MSG_SET_BACK_BUTTON_ALPHA, animate ? 1 : 0, 0, alpha)
                 .sendToTarget();
@@ -128,6 +136,9 @@ public class OverviewInteractionState {
     }
 
     private boolean handleUiMessage(Message msg) {
+        if (msg.what == MSG_SET_BACK_BUTTON_ALPHA) {
+            mBackButtonAlpha = (float) msg.obj;
+        }
         mBgHandler.obtainMessage(msg.what, msg.arg1, msg.arg2, msg.obj).sendToTarget();
         return true;
     }