[DocsUI M3] Restyle drag drop badge for M3

* When there are multiple dragging files:
  * add an additional drag layer
  * add a file counter
* Update drag show (radius/offset) to match the new M3 spec.
* drag shadow view is an isolated view without the theme
  context, so M3 color attributes like "?attr/colorXXX"
  can't be used directly, instead, system color tokens are
  being used in light/dark mode. Since system color tokens
  are only available in SDK 31, fallback static colors are
  being used in the original colors.xml.

Check the attached bug for demo.

Bug: 377771158
Test: m DocumentsUIGoogle && manual inspection
Flag: com.android.documentsui.flags.use_material3
Change-Id: Ia00bb0037a19813b4137d9d6cd7a42441b7f255e

2 files changed, 138 insertions, 14 deletions

diff --git a/src/com/android/documentsui/DragAndDropManager.java b/src/com/android/documentsui/DragAndDropManager.java
index bed8764ae..158d43c95 100644
--- a/src/com/android/documentsui/DragAndDropManager.java
+++ b/src/com/android/documentsui/DragAndDropManager.java
@@ -16,6 +16,8 @@
 
 package com.android.documentsui;
 
+import static com.android.documentsui.util.FlagUtils.isUseMaterial3FlagEnabled;
+
 import android.content.ClipData;
 import android.content.Context;
 import android.graphics.drawable.Drawable;
@@ -277,7 +279,9 @@ public interface DragAndDropManager {
             final Drawable icon;
 
             final int size = srcs.size();
-            if (size == 1) {
+            // If use_material3 flag is ON, we always show the icon/title for the first file even
+            // when we have multiple files.
+            if (size == 1 || isUseMaterial3FlagEnabled()) {
                 DocumentInfo doc = srcs.get(0);
                 title = doc.displayName;
                 icon = iconHelper.getDocumentIcon(mContext, doc);
@@ -287,6 +291,10 @@ public interface DragAndDropManager {
                 icon = mDefaultShadowIcon;
             }
 
+            if (isUseMaterial3FlagEnabled()) {
+                mShadowBuilder.updateDragFileCount(size);
+            }
+
             mShadowBuilder.updateTitle(title);
             mShadowBuilder.updateIcon(icon);
 
diff --git a/src/com/android/documentsui/DragShadowBuilder.java b/src/com/android/documentsui/DragShadowBuilder.java
index 10a0106d5..be76302e8 100644
--- a/src/com/android/documentsui/DragShadowBuilder.java
+++ b/src/com/android/documentsui/DragShadowBuilder.java
@@ -16,7 +16,7 @@
 
 package com.android.documentsui;
 
-import com.android.documentsui.DragAndDropManager.State;
+import static com.android.documentsui.util.FlagUtils.isUseMaterial3FlagEnabled;
 
 import android.content.Context;
 import android.graphics.Canvas;
@@ -29,6 +29,12 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.widget.TextView;
 
+import androidx.annotation.Nullable;
+
+import com.android.documentsui.DragAndDropManager.State;
+
+import java.text.NumberFormat;
+
 class DragShadowBuilder extends View.DragShadowBuilder {
 
     private final View mShadowView;
@@ -37,8 +43,18 @@ class DragShadowBuilder extends View.DragShadowBuilder {
     private final int mWidth;
     private final int mHeight;
     private final int mShadowRadius;
-    private int mPadding;
+    private final int mPadding;
     private Paint paint;
+    // This will be null if use_material3 flag is OFF.
+    private final @Nullable View mAdditionalShadowView;
+    // This will always be 0 if the use_material3 flag is OFF.
+    private int mDragFileCount = 0;
+    // The following 5 dimensions will be 0 if the use_material3 flag is OFF.
+    private final int mDragContentRadius;
+    private final int mAdditionalLayerOffset;
+    private final int mDragFileCounterOffset;
+    private final int mShadow2Radius;
+    private final int mShadowYOffset;
 
     DragShadowBuilder(Context context) {
         mWidth = context.getResources().getDimensionPixelSize(R.dimen.drag_shadow_width);
@@ -49,6 +65,28 @@ class DragShadowBuilder extends View.DragShadowBuilder {
         mShadowView = LayoutInflater.from(context).inflate(R.layout.drag_shadow_layout, null);
         mTitle = (TextView) mShadowView.findViewById(android.R.id.title);
         mIcon = (DropBadgeView) mShadowView.findViewById(android.R.id.icon);
+        if (isUseMaterial3FlagEnabled()) {
+            mAdditionalShadowView =
+                    LayoutInflater.from(context).inflate(R.layout.additional_drag_shadow, null);
+            mDragContentRadius =
+                    context.getResources().getDimensionPixelSize(R.dimen.drag_content_radius);
+            mAdditionalLayerOffset =
+                    context.getResources()
+                            .getDimensionPixelSize(R.dimen.drag_additional_layer_offset);
+            mDragFileCounterOffset =
+                    context.getResources().getDimensionPixelSize(R.dimen.drag_file_counter_offset);
+            mShadow2Radius =
+                    context.getResources().getDimensionPixelSize(R.dimen.drag_shadow_2_radius);
+            mShadowYOffset =
+                    context.getResources().getDimensionPixelSize(R.dimen.drag_shadow_y_offset);
+        } else {
+            mAdditionalShadowView = null;
+            mDragContentRadius = 0;
+            mAdditionalLayerOffset = 0;
+            mDragFileCounterOffset = 0;
+            mShadow2Radius = 0;
+            mShadowYOffset = 0;
+        }
 
         // Important for certain APIs
         mShadowView.setLayerType(View.LAYER_TYPE_SOFTWARE, paint);
@@ -67,23 +105,86 @@ class DragShadowBuilder extends View.DragShadowBuilder {
         Rect r = canvas.getClipBounds();
         // Calling measure is necessary in order for all child views to get correctly laid out.
         mShadowView.measure(
-                View.MeasureSpec.makeMeasureSpec(r.right- r.left, View.MeasureSpec.EXACTLY),
+                View.MeasureSpec.makeMeasureSpec(r.right - r.left, View.MeasureSpec.EXACTLY),
                 View.MeasureSpec.makeMeasureSpec(r.bottom - r.top , View.MeasureSpec.EXACTLY));
         mShadowView.layout(r.left, r.top, r.right, r.bottom);
 
         // Since DragShadow is not an actual view drawn in hardware-accelerated window,
         // android:elevation does not work; we need to draw the shadow ourselves manually.
         paint.setColor(Color.TRANSPARENT);
-        // Shadow 1
-        int opacity = (int) (255 * 0.1);
-        paint.setShadowLayer(mShadowRadius, 0, 0, Color.argb(opacity, 0, 0, 0));
-        canvas.drawRect(r.left + mPadding, r.top + mPadding, r.right - mPadding,
-                r.bottom - mPadding, paint);
-        // Shadow 2
-        opacity = (int) (255 * 0.24);
-        paint.setShadowLayer(mShadowRadius, 0, mShadowRadius, Color.argb(opacity, 0, 0, 0));
-        canvas.drawRect(r.left + mPadding, r.top + mPadding, r.right - mPadding,
-                r.bottom - mPadding, paint);
+
+        // Layers on the canvas (from bottom to top):
+        // 1. Two shadows for the additional drag layer (if drag file count > 1)
+        // 2. The additional layer view itself (if drag file count > 1)
+        // 3. Two shadows for the drag content layer (icon, title)
+        // 4. The drag content layer itself
+        final int shadowOneOpacity = (int) (255 * 0.15);
+        final int shadowTwoOpacity = (int) (255 * 0.30);
+        if (mAdditionalShadowView != null && mDragFileCount > 1) {
+            mAdditionalShadowView.measure(
+                    View.MeasureSpec.makeMeasureSpec(r.right - r.left, View.MeasureSpec.EXACTLY),
+                    View.MeasureSpec.makeMeasureSpec(r.bottom - r.top , View.MeasureSpec.EXACTLY));
+            mAdditionalShadowView.layout(r.left, r.top, r.right, r.bottom);
+            // Shadow 1
+            paint.setShadowLayer(
+                    mShadowRadius, 0, mShadowYOffset, Color.argb(shadowOneOpacity, 0, 0, 0));
+            canvas.drawRoundRect(
+                    r.left + mShadowRadius,
+                    r.top + mDragFileCounterOffset + mAdditionalLayerOffset,
+                    r.right - mDragFileCounterOffset - mAdditionalLayerOffset,
+                    r.bottom - mShadowRadius,
+                    mDragContentRadius,
+                    mDragContentRadius,
+                    paint);
+            // Shadow 2
+            paint.setShadowLayer(
+                    mShadow2Radius, 0, mShadowYOffset, Color.argb(shadowTwoOpacity, 0, 0, 0));
+            canvas.drawRoundRect(
+                    r.left + mShadowRadius,
+                    r.top + mDragFileCounterOffset + mAdditionalLayerOffset,
+                    r.right - mDragFileCounterOffset - mAdditionalLayerOffset,
+                    r.bottom - mShadowRadius,
+                    mDragContentRadius,
+                    mDragContentRadius,
+                    paint);
+            mAdditionalShadowView.draw(canvas);
+        }
+
+        if (isUseMaterial3FlagEnabled()) {
+            // Shadow 1
+            paint.setShadowLayer(
+                    mShadowRadius, 0, mShadowYOffset, Color.argb(shadowOneOpacity, 0, 0, 0));
+            canvas.drawRoundRect(
+                    r.left + mShadowRadius + mAdditionalLayerOffset,
+                    r.top + mDragFileCounterOffset,
+                    r.right - mDragFileCounterOffset,
+                    r.bottom - mShadowRadius - mAdditionalLayerOffset,
+                    mDragContentRadius,
+                    mDragContentRadius,
+                    paint);
+            // Shadow 2
+            paint.setShadowLayer(
+                    mShadow2Radius, 0, mShadowYOffset, Color.argb(shadowTwoOpacity, 0, 0, 0));
+            canvas.drawRoundRect(
+                    r.left + mShadowRadius + mAdditionalLayerOffset,
+                    r.top + mDragFileCounterOffset,
+                    r.right - mDragFileCounterOffset,
+                    r.bottom - mShadowRadius - mAdditionalLayerOffset,
+                    mDragContentRadius,
+                    mDragContentRadius,
+                    paint);
+        } else {
+            // Shadow 1
+            int opacity = (int) (255 * 0.1);
+            paint.setShadowLayer(mShadowRadius, 0, 0, Color.argb(opacity, 0, 0, 0));
+            canvas.drawRect(r.left + mPadding, r.top + mPadding, r.right - mPadding,
+                    r.bottom - mPadding, paint);
+            // Shadow 2
+            opacity = (int) (255 * 0.24);
+            paint.setShadowLayer(mShadowRadius, 0, mShadowRadius, Color.argb(opacity, 0, 0, 0));
+            canvas.drawRect(r.left + mPadding, r.top + mPadding, r.right - mPadding,
+                    r.bottom - mPadding, paint);
+        }
         mShadowView.draw(canvas);
     }
 
@@ -98,4 +199,19 @@ class DragShadowBuilder extends View.DragShadowBuilder {
     void onStateUpdated(@State int state) {
         mIcon.updateState(state);
     }
+
+    void updateDragFileCount(int count) {
+        if (!isUseMaterial3FlagEnabled()) {
+            return;
+        }
+        mDragFileCount = count;
+        TextView dragFileCountView = mShadowView.findViewById(R.id.drag_file_counter);
+        if (dragFileCountView != null) {
+            dragFileCountView.setVisibility(count > 1 ? View.VISIBLE : View.GONE);
+            if (count > 1) {
+                NumberFormat numberFormat = NumberFormat.getInstance();
+                dragFileCountView.setText(numberFormat.format(count));
+            }
+        }
+    }
 }