Adjust action bar tab policies

Action bar tabs now stack in portrait mode on all screen sizes rather
than display embedded. This only affects apps with a targetSdkVersion
of JB or greater, as older apps may not be prepared for the different
measurement of the bar or have an appropriate stacked bar background
drawable.

Stacked action bar tabs now have a width limit. This prevents
super-wide tabs that can span the whole screen. The cluster of tabs
is centered if it does not span the full width.

Add ActionBarPolicy to give a single point to query for various action
bar measurements and behaviors that vary with configuration.

Change-Id: I01162ca009c14f6f0e712fc906b9db6382c738cd

4 files changed, 110 insertions, 23 deletions

diff --git a/core/java/com/android/internal/app/ActionBarImpl.java b/core/java/com/android/internal/app/ActionBarImpl.java
index 1ba6d43..d0071e3 100644
--- a/core/java/com/android/internal/app/ActionBarImpl.java
+++ b/core/java/com/android/internal/app/ActionBarImpl.java
@@ -16,6 +16,7 @@
 
 package com.android.internal.app;
 
+import com.android.internal.view.ActionBarPolicy;
 import com.android.internal.view.menu.MenuBuilder;
 import com.android.internal.view.menu.MenuPopupHelper;
 import com.android.internal.view.menu.SubMenuBuilder;
@@ -183,18 +184,13 @@ public class ActionBarImpl extends ActionBar {
         mContextDisplayMode = mActionView.isSplitActionBar() ?
                 CONTEXT_DISPLAY_SPLIT : CONTEXT_DISPLAY_NORMAL;
 
-        // Older apps get the home button interaction enabled by default.
-        // Newer apps need to enable it explicitly.
-        setHomeButtonEnabled(mContext.getApplicationInfo().targetSdkVersion <
-                Build.VERSION_CODES.ICE_CREAM_SANDWICH);
-
-        setHasEmbeddedTabs(mContext.getResources().getBoolean(
-                com.android.internal.R.bool.action_bar_embed_tabs));
+        ActionBarPolicy abp = ActionBarPolicy.get(mContext);
+        setHomeButtonEnabled(abp.enableHomeButtonByDefault());
+        setHasEmbeddedTabs(abp.hasEmbeddedTabs());
     }
 
     public void onConfigurationChanged(Configuration newConfig) {
-        setHasEmbeddedTabs(mContext.getResources().getBoolean(
-                com.android.internal.R.bool.action_bar_embed_tabs));
+        setHasEmbeddedTabs(ActionBarPolicy.get(mContext).hasEmbeddedTabs());
     }
 
     private void setHasEmbeddedTabs(boolean hasEmbeddedTabs) {
diff --git a/core/java/com/android/internal/view/ActionBarPolicy.java b/core/java/com/android/internal/view/ActionBarPolicy.java
new file mode 100644
index 0000000..0c6b780
--- /dev/null
+++ b/core/java/com/android/internal/view/ActionBarPolicy.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2012 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.internal.view;
+
+import com.android.internal.R;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.content.res.TypedArray;
+import android.os.Build;
+import android.view.ViewConfiguration;
+
+/**
+ * Allows components to query for various configuration policy decisions
+ * about how the action bar should lay out and behave on the current device.
+ */
+public class ActionBarPolicy {
+    private Context mContext;
+
+    public static ActionBarPolicy get(Context context) {
+        return new ActionBarPolicy(context);
+    }
+
+    private ActionBarPolicy(Context context) {
+        mContext = context;
+    }
+
+    public int getMaxActionButtons() {
+        return mContext.getResources().getInteger(R.integer.max_action_buttons);
+    }
+
+    public boolean showsOverflowMenuButton() {
+        return !ViewConfiguration.get(mContext).hasPermanentMenuKey();
+    }
+
+    public int getEmbeddedMenuWidthLimit() {
+        return mContext.getResources().getDisplayMetrics().widthPixels / 2;
+    }
+
+    public boolean hasEmbeddedTabs() {
+        final int targetSdk = mContext.getApplicationInfo().targetSdkVersion;
+        if (targetSdk >= Build.VERSION_CODES.JELLY_BEAN) {
+            return mContext.getResources().getBoolean(R.bool.action_bar_embed_tabs);
+        }
+
+        // The embedded tabs policy changed in Jellybean; give older apps the old policy
+        // so they get what they expect.
+        return mContext.getResources().getBoolean(R.bool.action_bar_embed_tabs_pre_jb);
+    }
+
+    public int getTabContainerHeight() {
+        TypedArray a = mContext.obtainStyledAttributes(null, R.styleable.ActionBar,
+                com.android.internal.R.attr.actionBarStyle, 0);
+        int height = a.getLayoutDimension(R.styleable.ActionBar_height, 0);
+        Resources r = mContext.getResources();
+        if (!hasEmbeddedTabs()) {
+            // Stacked tabs; limit the height
+            height = Math.min(height,
+                    r.getDimensionPixelSize(R.dimen.action_bar_stacked_max_height));
+        }
+        a.recycle();
+        return height;
+    }
+
+    public boolean enableHomeButtonByDefault() {
+        // Older apps get the home button interaction enabled by default.
+        // Newer apps need to enable it explicitly.
+        return mContext.getApplicationInfo().targetSdkVersion <
+                Build.VERSION_CODES.ICE_CREAM_SANDWICH;
+    }
+
+    public int getStackedTabMaxWidth() {
+        return mContext.getResources().getDimensionPixelSize(
+                R.dimen.action_bar_stacked_tab_max_width);
+    }
+}
diff --git a/core/java/com/android/internal/view/menu/ActionMenuPresenter.java b/core/java/com/android/internal/view/menu/ActionMenuPresenter.java
index dca45a9..73324c0 100644
--- a/core/java/com/android/internal/view/menu/ActionMenuPresenter.java
+++ b/core/java/com/android/internal/view/menu/ActionMenuPresenter.java
@@ -16,6 +16,7 @@
 
 package com.android.internal.view.menu;
 
+import com.android.internal.view.ActionBarPolicy;
 import com.android.internal.view.menu.ActionMenuView.ActionMenuChildView;
 
 import android.content.Context;
@@ -29,7 +30,6 @@ import android.view.MenuItem;
 import android.view.SoundEffectConstants;
 import android.view.View;
 import android.view.View.MeasureSpec;
-import android.view.ViewConfiguration;
 import android.view.ViewGroup;
 import android.widget.ImageButton;
 
@@ -79,17 +79,18 @@ public class ActionMenuPresenter extends BaseMenuPresenter
 
         final Resources res = context.getResources();
 
+        final ActionBarPolicy abp = ActionBarPolicy.get(context);
         if (!mReserveOverflowSet) {
-            mReserveOverflow = !ViewConfiguration.get(context).hasPermanentMenuKey();
+            mReserveOverflow = abp.showsOverflowMenuButton();
         }
 
         if (!mWidthLimitSet) {
-            mWidthLimit = res.getDisplayMetrics().widthPixels / 2;
+            mWidthLimit = abp.getEmbeddedMenuWidthLimit();
         }
 
         // Measure for initial configuration
         if (!mMaxItemsSet) {
-            mMaxItems = res.getInteger(com.android.internal.R.integer.max_action_buttons);
+            mMaxItems = abp.getMaxActionButtons();
         }
 
         int width = mWidthLimit;
diff --git a/core/java/com/android/internal/widget/ScrollingTabContainerView.java b/core/java/com/android/internal/widget/ScrollingTabContainerView.java
index 1767d68..83ac896 100644
--- a/core/java/com/android/internal/widget/ScrollingTabContainerView.java
+++ b/core/java/com/android/internal/widget/ScrollingTabContainerView.java
@@ -15,7 +15,7 @@
  */
 package com.android.internal.widget;
 
-import com.android.internal.R;
+import com.android.internal.view.ActionBarPolicy;
 
 import android.animation.Animator;
 import android.animation.ObjectAnimator;
@@ -23,7 +23,6 @@ import android.animation.TimeInterpolator;
 import android.app.ActionBar;
 import android.content.Context;
 import android.content.res.Configuration;
-import android.content.res.TypedArray;
 import android.graphics.drawable.Drawable;
 import android.text.TextUtils.TruncateAt;
 import android.view.Gravity;
@@ -55,6 +54,7 @@ public class ScrollingTabContainerView extends HorizontalScrollView
     private boolean mAllowCollapse;
 
     int mMaxTabWidth;
+    int mStackedTabMaxWidth;
     private int mContentHeight;
     private int mSelectedTabIndex;
 
@@ -69,10 +69,9 @@ public class ScrollingTabContainerView extends HorizontalScrollView
         super(context);
         setHorizontalScrollBarEnabled(false);
 
-        TypedArray a = getContext().obtainStyledAttributes(null, R.styleable.ActionBar,
-                com.android.internal.R.attr.actionBarStyle, 0);
-        setContentHeight(a.getLayoutDimension(R.styleable.ActionBar_height, 0));
-        a.recycle();
+        ActionBarPolicy abp = ActionBarPolicy.get(context);
+        setContentHeight(abp.getTabContainerHeight());
+        mStackedTabMaxWidth = abp.getStackedTabMaxWidth();
 
         mTabLayout = createTabLayout();
         addView(mTabLayout, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
@@ -93,6 +92,7 @@ public class ScrollingTabContainerView extends HorizontalScrollView
             } else {
                 mMaxTabWidth = MeasureSpec.getSize(widthMeasureSpec) / 2;
             }
+            mMaxTabWidth = Math.min(mMaxTabWidth, mStackedTabMaxWidth);
         } else {
             mMaxTabWidth = -1;
         }
@@ -187,6 +187,7 @@ public class ScrollingTabContainerView extends HorizontalScrollView
         final LinearLayout tabLayout = new LinearLayout(getContext(), null,
                 com.android.internal.R.attr.actionBarTabBarStyle);
         tabLayout.setMeasureWithLargestChildEnabled(true);
+        tabLayout.setGravity(Gravity.CENTER);
         tabLayout.setLayoutParams(new LinearLayout.LayoutParams(
                 LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.MATCH_PARENT));
         return tabLayout;
@@ -205,12 +206,11 @@ public class ScrollingTabContainerView extends HorizontalScrollView
     protected void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
 
+        ActionBarPolicy abp = ActionBarPolicy.get(getContext());
         // Action bar can change size on configuration changes.
         // Reread the desired height from the theme-specified style.
-        TypedArray a = getContext().obtainStyledAttributes(null, R.styleable.ActionBar,
-                com.android.internal.R.attr.actionBarStyle, 0);
-        setContentHeight(a.getLayoutDimension(R.styleable.ActionBar_height, 0));
-        a.recycle();
+        setContentHeight(abp.getTabContainerHeight());
+        mStackedTabMaxWidth = abp.getStackedTabMaxWidth();
     }
 
     public void animateToVisibility(int visibility) {