Support elevation overlays for BottomNavigationView.

PiperOrigin-RevId: 238729801
material-components · Mar 22, 2019 · d6cb349 · d6cb349
1 parent ca07e5f
commit d6cb349
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Showing 2 changed files with 27 additions and 6 deletions.
diff --git a/lib/java/com/google/android/material/bottomnavigation/BottomNavigationView.java b/lib/java/com/google/android/material/bottomnavigation/BottomNavigationView.java
@@ -177,14 +177,15 @@ public BottomNavigationView(Context context, AttributeSet attrs, int defStyleAtt
       setItemTextColor(a.getColorStateList(R.styleable.BottomNavigationView_itemTextColor));
     }
 
+    if (getBackground() == null) {
+      // Add a MaterialShapeDrawable as background that supports tinting in every API level.
+      ViewCompat.setBackground(this, createMaterialShapeDrawableBackground(context));
+    }
+
     if (a.hasValue(R.styleable.BottomNavigationView_elevation)) {
       ViewCompat.setElevation(
           this, a.getDimensionPixelSize(R.styleable.BottomNavigationView_elevation, 0));
     }
-    // Add a drawable as background that supports tinting in every API level.
-    if (getBackground() == null) {
-      ViewCompat.setBackground(this, new MaterialShapeDrawable());
-    }
 
     ColorStateList backgroundTint =
         MaterialResources.getColorStateList(
@@ -234,6 +235,26 @@ public void onMenuModeChange(MenuBuilder menu) {}
         });
   }
 
+  private MaterialShapeDrawable createMaterialShapeDrawableBackground(Context context) {
+    MaterialShapeDrawable materialShapeDrawable = new MaterialShapeDrawable();
+    materialShapeDrawable.initializeElevationOverlay(context);
+    return materialShapeDrawable;
+  }
+
+  /**
+   * Sets the base elevation of this view, in pixels.
+   *
+   * @attr ref android.R.styleable#View_elevation
+   */
+  @Override
+  public void setElevation(float elevation) {
+    super.setElevation(elevation);
+    Drawable background = getBackground();
+    if (background instanceof MaterialShapeDrawable) {
+      ((MaterialShapeDrawable) background).setElevation(elevation);
+    }
+  }
+
   /**
    * Set a listener that will be notified when a bottom navigation item is selected. This listener
    * will also be notified when the currently selected item is reselected, unless an {@link

diff --git a/lib/java/com/google/android/material/bottomnavigation/res/values/styles.xml b/lib/java/com/google/android/material/bottomnavigation/res/values/styles.xml
@@ -30,9 +30,9 @@
        Use the default style to get the default bottom navigation bar with a colorSurface background and
        colorPrimary for the icon and text colors. -->
   <style name="Widget.MaterialComponents.BottomNavigationView" parent="Widget.Design.BottomNavigationView">
-    <item name="android:background">?attr/colorSurface</item>
     <item name="enforceTextAppearance">true</item>
     <item name="enforceMaterialTheme">true</item>
+    <item name="android:background">?attr/colorSurface</item>
     <item name="itemBackground">@null</item>
     <item name="itemHorizontalTranslationEnabled">false</item>
     <item name="itemIconTint">@color/mtrl_bottom_nav_item_tint</item>
@@ -46,9 +46,9 @@
        Use the colored style to get a bottom navigation bar with a colorPrimary background and
        percentages of colorOnPrimary for the icon and text colors. -->
   <style name="Widget.MaterialComponents.BottomNavigationView.Colored">
-    <item name="android:background">?attr/colorPrimary</item>
     <item name="enforceTextAppearance">true</item>
     <item name="enforceMaterialTheme">true</item>
+    <item name="android:background">?attr/colorPrimary</item>
     <item name="itemIconTint">@color/mtrl_bottom_nav_colored_item_tint</item>
     <item name="itemRippleColor">@color/mtrl_bottom_nav_colored_ripple_color</item>
     <item name="itemTextAppearanceInactive">?attr/textAppearanceCaption</item>