diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 3a7b39e..a71e7cc 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -85,6 +85,8 @@
         <attr name="slidingKeyInputEnable" format="boolean" />
         <attr name="slidingKeyInputPreviewColor" format="color" />
         <attr name="slidingKeyInputPreviewWidth" format="dimension" />
+        <attr name="slidingKeyInputPreviewBodyRatio" format="integer" />
+        <attr name="slidingKeyInputPreviewShadowRatio" format="integer" />
         <!-- Key repeat start timeout -->
         <attr name="keyRepeatStartTimeout" format="integer" />
         <!-- Key repeat interval in millisecond. -->
@@ -115,6 +117,8 @@
         <attr name="gesturePreviewTrailColor" format="color" />
         <attr name="gesturePreviewTrailStartWidth" format="dimension" />
         <attr name="gesturePreviewTrailEndWidth" format="dimension" />
+        <attr name="gesturePreviewTrailBodyRatio" format="integer" />
+        <attr name="gesturePreviewTrailShadowRatio" format="integer" />
         <!-- Delay after gesture input and gesture floating preview text dismissing in millisecond -->
         <attr name="gestureFloatingPreviewTextLingerTimeout" format="integer" />
         <!-- Attributes for GestureFloatingPreviewText -->
diff --git a/java/res/values/config.xml b/java/res/values/config.xml
index a90ba80..d4fff62 100644
--- a/java/res/values/config.xml
+++ b/java/res/values/config.xml
@@ -58,6 +58,9 @@
     <bool name="config_sliding_key_input_enabled">true</bool>
     <!-- Sliding key input preview parameters -->
     <dimen name="config_sliding_key_input_preview_width">8.0dp</dimen>
+    <!-- Percentages of sliding key input preview body and shadow, in proportion to the width. -->
+    <integer name="config_sliding_key_input_preview_body_ratio">80</integer>
+    <integer name="config_sliding_key_input_preview_shadow_ratio">50</integer>
     <integer name="config_key_repeat_start_timeout">400</integer>
     <integer name="config_key_repeat_interval">50</integer>
     <integer name="config_default_longpress_key_timeout">300</integer>  <!-- milliseconds -->
diff --git a/java/res/values/dimens.xml b/java/res/values/dimens.xml
index dd42acf..db33ad8 100644
--- a/java/res/values/dimens.xml
+++ b/java/res/values/dimens.xml
@@ -103,6 +103,9 @@
     <!-- Gesture preview trail parameters -->
     <dimen name="gesture_preview_trail_start_width">10.0dp</dimen>
     <dimen name="gesture_preview_trail_end_width">2.5dp</dimen>
+    <!-- Percentages of gesture preview taril body and shadow, in proportion to the trail width. -->
+    <integer name="gesture_preview_trail_body_ratio">80</integer>
+    <integer name="gesture_preview_trail_shadow_ratio">50</integer>
     <!-- Gesture floating preview text parameters -->
     <dimen name="gesture_floating_preview_text_size">24dp</dimen>
     <dimen name="gesture_floating_preview_text_offset">73dp</dimen>
diff --git a/java/res/values/styles.xml b/java/res/values/styles.xml
index fb59c74..436e080 100644
--- a/java/res/values/styles.xml
+++ b/java/res/values/styles.xml
@@ -70,6 +70,8 @@
         <item name="gesturePreviewTrailColor">@color/highlight_color_default</item>
         <item name="gesturePreviewTrailStartWidth">@dimen/gesture_preview_trail_start_width</item>
         <item name="gesturePreviewTrailEndWidth">@dimen/gesture_preview_trail_end_width</item>
+        <item name="gesturePreviewTrailBodyRatio">@integer/gesture_preview_trail_body_ratio</item>
+        <item name="gesturePreviewTrailShadowRatio">@integer/gesture_preview_trail_shadow_ratio</item>
         <!-- Common attributes of MainKeyboardView -->
         <item name="keyHysteresisDistance">@dimen/config_key_hysteresis_distance</item>
         <item name="keyHysteresisDistanceForSlidingModifier">@dimen/config_key_hysteresis_distance_for_sliding_modifier</item>
@@ -78,6 +80,8 @@
         <item name="slidingKeyInputEnable">@bool/config_sliding_key_input_enabled</item>
         <item name="slidingKeyInputPreviewColor">@color/highlight_translucent_color_default</item>
         <item name="slidingKeyInputPreviewWidth">@dimen/config_sliding_key_input_preview_width</item>
+        <item name="slidingKeyInputPreviewBodyRatio">@integer/config_sliding_key_input_preview_body_ratio</item>
+        <item name="slidingKeyInputPreviewShadowRatio">@integer/config_sliding_key_input_preview_shadow_ratio</item>
         <item name="keyRepeatStartTimeout">@integer/config_key_repeat_start_timeout</item>
         <item name="keyRepeatInterval">@integer/config_key_repeat_interval</item>
         <item name="longPressShiftLockTimeout">@integer/config_longpress_shift_lock_timeout</item>
diff --git a/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java b/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
index f682b51..0c05061 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
@@ -51,6 +51,9 @@
         public final int mTrailColor;
         public final float mTrailStartWidth;
         public final float mTrailEndWidth;
+        public final float mTrailBodyRatio;
+        public boolean mTrailShadowEnabled;
+        public final float mTrailShadowRatio;
         public final int mFadeoutStartDelay;
         public final int mFadeoutDuration;
         public final int mUpdateInterval;
@@ -64,6 +67,14 @@
                     R.styleable.MainKeyboardView_gesturePreviewTrailStartWidth, 0.0f);
             mTrailEndWidth = mainKeyboardViewAttr.getDimension(
                     R.styleable.MainKeyboardView_gesturePreviewTrailEndWidth, 0.0f);
+            final int PERCENTAGE_INT = 100;
+            mTrailBodyRatio = (float)mainKeyboardViewAttr.getInt(
+                    R.styleable.MainKeyboardView_gesturePreviewTrailBodyRatio, PERCENTAGE_INT)
+                    / (float)PERCENTAGE_INT;
+            final int trailShadowRatioInt = mainKeyboardViewAttr.getInt(
+                    R.styleable.MainKeyboardView_gesturePreviewTrailShadowRatio, 0);
+            mTrailShadowEnabled = (trailShadowRatioInt > 0);
+            mTrailShadowRatio = (float)trailShadowRatioInt / (float)PERCENTAGE_INT;
             mFadeoutStartDelay = mainKeyboardViewAttr.getInt(
                     R.styleable.MainKeyboardView_gesturePreviewTrailFadeoutStartDelay, 0);
             mFadeoutDuration = mainKeyboardViewAttr.getInt(
@@ -219,14 +230,22 @@
                 final float r2 = getWidth(elapsedTime, params) / 2.0f;
                 // Draw trail line only when the current point isn't a down point.
                 if (!isDownEventXCoord(xCoords[i])) {
-                    final Path path = roundedLine.makePath(p1x, p1y, r1, p2x, p2y, r2);
+                    final float body1 = r1 * params.mTrailBodyRatio;
+                    final float body2 = r2 * params.mTrailBodyRatio;
+                    final Path path = roundedLine.makePath(p1x, p1y, body1, p2x, p2y, body2);
                     if (path != null) {
+                        roundedLine.getBounds(mRoundedLineBounds);
+                        if (params.mTrailShadowEnabled) {
+                            final float shadow2 = r2 * params.mTrailShadowRatio;
+                            paint.setShadowLayer(shadow2, 0.0f, 0.0f, params.mTrailColor);
+                            final int shadowInset = -(int)Math.ceil(shadow2);
+                            mRoundedLineBounds.inset(shadowInset, shadowInset);
+                        }
+                        // Take union for the bounds.
+                        outBoundsRect.union(mRoundedLineBounds);
                         final int alpha = getAlpha(elapsedTime, params);
                         paint.setAlpha(alpha);
                         canvas.drawPath(path, paint);
-                        // Take union for the bounds.
-                        roundedLine.getBounds(mRoundedLineBounds);
-                        outBoundsRect.union(mRoundedLineBounds);
                     }
                 }
                 p1x = p2x;
diff --git a/java/src/com/android/inputmethod/keyboard/internal/SlidingKeyInputPreview.java b/java/src/com/android/inputmethod/keyboard/internal/SlidingKeyInputPreview.java
index 37f4e35..33dbbaf 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/SlidingKeyInputPreview.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/SlidingKeyInputPreview.java
@@ -30,7 +30,7 @@
  * Draw rubber band preview graphics during sliding key input.
  */
 public final class SlidingKeyInputPreview extends AbstractDrawingPreview {
-    private final int mPreviewWidth;
+    private final float mPreviewBodyRadius;
 
     private boolean mShowSlidingKeyInputPreview;
     private final int[] mPreviewFrom = CoordinateUtils.newInstance();
@@ -44,8 +44,20 @@
         super(drawingView);
         final int previewColor = mainKeyboardViewAttr.getColor(
                 R.styleable.MainKeyboardView_slidingKeyInputPreviewColor, 0);
-        mPreviewWidth = mainKeyboardViewAttr.getDimensionPixelSize(
-                R.styleable.MainKeyboardView_slidingKeyInputPreviewWidth, 0);
+        final float previewRadius = mainKeyboardViewAttr.getDimension(
+                R.styleable.MainKeyboardView_slidingKeyInputPreviewWidth, 0) / 2.0f;
+        final int PERCENTAGE_INT = 100;
+        final float previewBodyRatio = (float)mainKeyboardViewAttr.getInt(
+                R.styleable.MainKeyboardView_slidingKeyInputPreviewBodyRatio, PERCENTAGE_INT)
+                / (float)PERCENTAGE_INT;
+        mPreviewBodyRadius = previewRadius * previewBodyRatio;
+        final int previewShadowRatioInt = mainKeyboardViewAttr.getInt(
+                R.styleable.MainKeyboardView_slidingKeyInputPreviewShadowRatio, 0);
+        if (previewShadowRatioInt > 0) {
+            final float previewShadowRatio = (float)previewShadowRatioInt / (float)PERCENTAGE_INT;
+            final float shadowRadius = previewRadius * previewShadowRatio;
+            mPaint.setShadowLayer(shadowRadius, 0.0f, 0.0f, previewColor);
+        }
         mPaint.setColor(previewColor);
     }
 
@@ -65,7 +77,7 @@
         }
 
         // TODO: Finalize the rubber band preview implementation.
-        final int radius = mPreviewWidth / 2;
+        final float radius = mPreviewBodyRadius;
         final Path path = mRoundedLine.makePath(
                 CoordinateUtils.x(mPreviewFrom), CoordinateUtils.y(mPreviewFrom), radius,
                 CoordinateUtils.x(mPreviewTo), CoordinateUtils.y(mPreviewTo), radius);