Enable shadows for BottomAppBar

PiperOrigin-RevId: 218868156

Author: cketcham

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

@@ -19,6 +19,7 @@
 import com.google.android.material.R;
 
 import static com.google.android.material.internal.ThemeEnforcement.createThemedContext;
+import static com.google.android.material.shape.MaterialShapeDrawable.SHADOW_COMPAT_MODE_ALWAYS;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
@@ -137,7 +138,7 @@ public class BottomAppBar extends Toolbar implements AttachedBehavior {
   public @interface FabAnimationMode {}
 
   private final int fabOffsetEndMode;
-  private final MaterialShapeDrawable materialShapeDrawable;
+  private final MaterialShapeDrawable materialShapeDrawable = new MaterialShapeDrawable();
   private final BottomAppBarTopEdgeTreatment topEdgeTreatment;
 
   @Nullable private Animator modeAnimator;
@@ -207,6 +208,7 @@ public BottomAppBar(Context context, @Nullable AttributeSet attrs, int defStyleA
     ColorStateList backgroundTint =
         MaterialResources.getColorStateList(context, a, R.styleable.BottomAppBar_backgroundTint);
 
+    int elevation = a.getDimensionPixelSize(R.styleable.BottomAppBar_elevation, 0);
     float fabCradleMargin = a.getDimensionPixelOffset(R.styleable.BottomAppBar_fabCradleMargin, 0);
     float fabCornerRadius =
         a.getDimensionPixelOffset(R.styleable.BottomAppBar_fabCradleRoundedCornerRadius, 0);
@@ -225,12 +227,12 @@ public BottomAppBar(Context context, @Nullable AttributeSet attrs, int defStyleA
 
     topEdgeTreatment =
         new BottomAppBarTopEdgeTreatment(fabCradleMargin, fabCornerRadius, fabVerticalOffset);
-    ShapeAppearanceModel appBarModel = new ShapeAppearanceModel();
+    ShapeAppearanceModel appBarModel = materialShapeDrawable.getShapeAppearanceModel();
     appBarModel.setTopEdge(topEdgeTreatment);
-    materialShapeDrawable = new MaterialShapeDrawable(appBarModel);
+    materialShapeDrawable.setShadowCompatibilityMode(SHADOW_COMPAT_MODE_ALWAYS);
     materialShapeDrawable.setPaintStyle(Style.FILL);
     materialShapeDrawable.setPaintFlags(Paint.ANTI_ALIAS_FLAG);
-    materialShapeDrawable.setPaintShadowEnabled(true);
+    setElevation(elevation);
     DrawableCompat.setTintList(materialShapeDrawable, backgroundTint);
     ViewCompat.setBackground(this, materialShapeDrawable);
   }
@@ -356,6 +358,11 @@ public void setHideOnScroll(boolean hide) {
     hideOnScroll = hide;
   }
 
+  @Override
+  public void setElevation(float elevation) {
+    materialShapeDrawable.setShadowElevation((int) elevation);
+  }
+
   /**
    * A convenience method to replace the contents of the BottomAppBar's menu.
    *

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

@@ -109,7 +109,7 @@ public void getEdgePath(float length, float center, float interpolation, ShapePa
     float cutoutArcOffset = ARC_QUARTER - cornerRadiusArcLength;
 
     // Draw the starting line up to the left rounded corner.
-    shapePath.lineTo(/* x= */ leftRoundedCornerCircleX - roundedCornerOffset, /* y= */ 0);
+    shapePath.lineTo(/* x= */ leftRoundedCornerCircleX, /* y= */ 0);
 
     // Draw the arc for the left rounded corner circle. The bounding box is the area around the
     // circle's center which is at `(leftRoundedCornerCircleX, roundedCornerOffset)`.

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

@@ -18,6 +18,8 @@
   <declare-styleable name="BottomAppBar">
     <!-- Background for the BottomAppBar. -->
     <attr name="backgroundTint"/>
+    <!-- Elevation for the BottomAppBar. -->
+    <attr name="elevation"/>
     <!-- The alignment of the fab relative to the BottomAppBar. -->
     <attr name="fabAlignmentMode">
       <!-- Mode that aligns the fab to the center. -->

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

@@ -38,6 +38,7 @@
     <item name="fabCradleVerticalOffset">@dimen/mtrl_bottomappbar_fab_cradle_vertical_offset</item>
     <item name="android:minHeight">@dimen/mtrl_bottomappbar_height</item>
     <item name="maxButtonHeight">@dimen/mtrl_bottomappbar_height</item>
+    <item name="elevation">8dp</item>
   </style>
 
   <style name="Widget.MaterialComponents.BottomAppBar.Colored" parent="Widget.MaterialComponents.BottomAppBar">

lib/java/com/google/android/material/shape/MaterialShapeDrawable.java

@@ -116,7 +116,6 @@ public class MaterialShapeDrawable extends Drawable implements TintAwareDrawable
 
   private ShapeAppearanceModel shapeAppearanceModel;
   private int shadowCompatMode = SHADOW_COMPAT_MODE_DEFAULT;
-  private boolean paintShadowEnabled = false;
   private boolean useTintColorForShadow = false;
   private float interpolation = 1f;
   private int shadowCompatElevation = 0;
@@ -467,15 +466,6 @@ public void setShadowEnabled(boolean shadowEnabled) {
         shadowEnabled ? SHADOW_COMPAT_MODE_DEFAULT : SHADOW_COMPAT_MODE_NEVER);
   }
 
-  /** TODO: Remove the paint shadow */
-  public void setPaintShadowEnabled(boolean paintShadowEnabled) {
-    this.paintShadowEnabled = paintShadowEnabled;
-    shadowCompatMode = SHADOW_COMPAT_MODE_NEVER;
-    // Backwards compatible defaults.
-    shadowCompatElevation = 5;
-    shadowCompatRadius = 10;
-  }
-
   /**
    * Get the interpolation of the path, between 0 and 1. Ranges between 0 (none) and 1 (fully)
    * interpolated.
@@ -716,10 +706,6 @@ public void draw(Canvas canvas) {
     final int prevStrokeAlpha = strokePaint.getAlpha();
     strokePaint.setAlpha(modulateAlpha(prevStrokeAlpha, alpha));
 
-    if (shadowCompatElevation > 0 && paintShadowEnabled) {
-      fillPaint.setShadowLayer(shadowCompatRadius, 0, shadowCompatElevation, Color.BLACK);
-    }
-
     calculatePath(getBoundsInsetByStroke(), pathInsetByStroke);
     if (hasCompatShadow()) {
       // Save the canvas before changing the clip bounds.