[BottomAppBar] Add fab end margin attribute

PiperOrigin-RevId: 456907281

docs/components/BottomAppBar.md

@@ -238,6 +238,7 @@ Element                          | Attribute                          | Related
 **Cradle margin**                | `app:fabCradleMargin`              | `setFabCradleMargin`<br>`getFabCradleMargin`                           | `6dp`
 **Cradle rounded corner radius** | `app:fabCradleRoundedCornerRadius` | `setFabCradleRoundedCornerRadius`<br>`getFabCradleRoundedCornerRadius` | `4dp`
 **Cradle vertical offset**       | `app:fabCradleVerticalOffset`      | `setCradleVerticalOffset`<br>`getCradleVerticalOffset`                 | `12dp`
+**End margin**                   | `app:fabAlignmentModeEndMargin`    | `setFabAlignmentModeEndMargin` <br> `getFabAlignmentModeEndMargin`     | N/A
 
 See the
 [FAB documentation](https://github.com/material-components/material-components-android/tree/master/docs/components/FloatingActionButton.md)

lib/java/com/google/android/material/bottomappbar/BottomAppBar.java

@@ -180,15 +180,21 @@ public class BottomAppBar extends Toolbar implements AttachedBehavior {
   public @interface MenuAlignmentMode {}
 
   @Nullable private Integer navigationIconTint;
-  private final int fabOffsetEndMode;
   private final MaterialShapeDrawable materialShapeDrawable = new MaterialShapeDrawable();
 
   @Nullable private Animator modeAnimator;
   @Nullable private Animator menuAnimator;
+  @MenuAlignmentMode private int menuAlignmentMode;
   @FabAlignmentMode private int fabAlignmentMode;
   @FabAnimationMode private int fabAnimationMode;
   @FabAnchorMode private int fabAnchorMode;
-  @MenuAlignmentMode private int menuAlignmentMode;
+
+  /** No end margin for the FAB. */
+  private static final int NO_FAB_END_MARGIN = -1;
+
+  private final int fabOffsetEndMode;
+  @Px private int fabAlignmentModeEndMargin;
+
   private boolean hideOnScroll;
   private final boolean paddingBottomSystemWindowInsets;
   private final boolean paddingLeftSystemWindowInsets;
@@ -328,6 +334,9 @@ public BottomAppBar(@NonNull Context context, @Nullable AttributeSet attrs, int
         a.getBoolean(R.styleable.BottomAppBar_paddingLeftSystemWindowInsets, false);
     paddingRightSystemWindowInsets =
         a.getBoolean(R.styleable.BottomAppBar_paddingRightSystemWindowInsets, false);
+    fabAlignmentModeEndMargin =
+        a.getDimensionPixelOffset(
+            R.styleable.BottomAppBar_fabAlignmentModeEndMargin, NO_FAB_END_MARGIN);
 
     a.recycle();
 
@@ -600,6 +609,29 @@ public void setCradleVerticalOffset(@Dimension float verticalOffset) {
     }
   }
 
+  /**
+   * Returns the {@link FloatingActionButton} end margin pixel offset for the fab if it is set.
+   *
+   * <p>An end margin of -1 indicates that the default margin will be used.
+   */
+  @Px
+  public int getFabAlignmentModeEndMargin() {
+    return fabAlignmentModeEndMargin;
+  }
+
+  /**
+   * Sets the end margin, in pixels, of the {@link FloatingActionButton}. This will only have an
+   * effect if the fab alignment mode is {@link #FAB_ALIGNMENT_MODE_END}.
+   *
+   * <p>An offset of -1 will use the default margin.
+   */
+  public void setFabAlignmentModeEndMargin(@Px int margin) {
+    if (fabAlignmentModeEndMargin != margin) {
+      fabAlignmentModeEndMargin = margin;
+      setCutoutStateAndTranslateFab();
+    }
+  }
+
   /**
    * Returns true if the {@link BottomAppBar} should hide when a {@link
    * androidx.core.view.NestedScrollingChild} is scrolled. This is handled by {@link
@@ -994,8 +1026,17 @@ private float getFabTranslationY() {
   private float getFabTranslationX(@FabAlignmentMode int fabAlignmentMode) {
     boolean isRtl = ViewUtils.isLayoutRtl(this);
     if (fabAlignmentMode == FAB_ALIGNMENT_MODE_END) {
+      View fab = findDependentView();
       int systemEndInset = isRtl ? leftInset : rightInset;
-      int totalEndInset = fabOffsetEndMode + systemEndInset;
+      int totalEndInset = systemEndInset;
+      if (fabAlignmentModeEndMargin != NO_FAB_END_MARGIN && fab != null) {
+        totalEndInset += fab.getMeasuredWidth() / 2 + fabAlignmentModeEndMargin;
+      } else {
+        // If no fab end margin is specified, it follows the previous behaviour of
+        // translating by fabOffsetEndMode instead of a clear-cut margin.
+        // This will result in a different padding for different FAB sizes.
+        totalEndInset += fabOffsetEndMode;
+      }
       return (getMeasuredWidth() / 2 - totalEndInset) * (isRtl ? -1 : 1);
     } else {
       return 0;

lib/java/com/google/android/material/bottomappbar/res-public/values/public.xml

@@ -22,6 +22,7 @@
   <public name="fabCradleMargin" type="attr"/>
   <public name="fabCradleRoundedCornerRadius" type="attr"/>
   <public name="fabCradleVerticalOffset" type="attr"/>
+  <public name="fabAlignmentModeEndMargin" type="attr"/>
   <public name="menuAlignmentMode" type="attr"/>
   <public name="hideOnScroll" type="attr"/>
   <public name="Widget.MaterialComponents.BottomAppBar" type="style"/>

lib/java/com/google/android/material/bottomappbar/res/values/attrs.xml

@@ -50,6 +50,8 @@
     <attr name="fabCradleRoundedCornerRadius" format="dimension"/>
     <!-- The vertical offset between the fab from the cradle. -->
     <attr name="fabCradleVerticalOffset" format="dimension"/>
+    <!-- The end margin of the fab when the fab is end-aligned. -->
+    <attr name="fabAlignmentModeEndMargin" format="dimension"/>
     <!-- Whether the BottomAppBar should hide when a NestedScrollView is scrolled. -->
     <attr name="hideOnScroll" format="boolean"/>
     <!-- Whether the BottomAppBar should apply padding to be above the bottom window insets. -->