[Fix] Work around GradientDrawable missing tinting implementation on Lollipop.

Author: zhanghai

library/src/main/java/me/zhanghai/android/fastscroll/FastScrollerBuilder.java

@@ -26,7 +26,6 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.appcompat.content.res.AppCompatResources;
 import androidx.core.util.Consumer;
 import androidx.core.widget.NestedScrollView;
 import androidx.recyclerview.widget.RecyclerView;
@@ -117,17 +116,21 @@ public FastScrollerBuilder setPopupStyle(@NonNull Consumer<TextView> popupStyle)
     @NonNull
     public FastScrollerBuilder useDefaultStyle() {
         Context context = mView.getContext();
-        mTrackDrawable = AppCompatResources.getDrawable(context, R.drawable.afs_track);
-        mThumbDrawable = AppCompatResources.getDrawable(context, R.drawable.afs_thumb);
+        mTrackDrawable = Utils.getGradientDrawableWithTintAttr(R.drawable.afs_track,
+                R.attr.colorControlNormal, context);
+        mThumbDrawable = Utils.getGradientDrawableWithTintAttr(R.drawable.afs_thumb,
+                R.attr.colorControlActivated, context);
         mPopupStyle = PopupStyles.DEFAULT;
         return this;
     }
 
     @NonNull
     public FastScrollerBuilder useMd2Style() {
         Context context = mView.getContext();
-        mTrackDrawable = AppCompatResources.getDrawable(context, R.drawable.afs_md2_track);
-        mThumbDrawable = AppCompatResources.getDrawable(context, R.drawable.afs_md2_thumb);
+        mTrackDrawable = Utils.getGradientDrawableWithTintAttr(R.drawable.afs_md2_track,
+                R.attr.colorControlNormal, context);
+        mThumbDrawable = Utils.getGradientDrawableWithTintAttr(R.drawable.afs_md2_thumb,
+                R.attr.colorControlActivated, context);
         mPopupStyle = PopupStyles.MD2;
         return this;
     }

library/src/main/java/me/zhanghai/android/fastscroll/PopupStyles.java

@@ -24,7 +24,6 @@
 import android.widget.FrameLayout;
 import android.widget.TextView;
 
-import androidx.appcompat.content.res.AppCompatResources;
 import androidx.core.util.Consumer;
 
 public class PopupStyles {
@@ -42,8 +41,8 @@ private PopupStyles() {}
         layoutParams.setMarginEnd(resources.getDimensionPixelOffset(R.dimen.afs_popup_margin_end));
         popupView.setLayoutParams(layoutParams);
         Context context = popupView.getContext();
-        popupView.setBackground(new AutoMirrorDrawable(AppCompatResources.getDrawable(context,
-                R.drawable.afs_popup_background)));
+        popupView.setBackground(new AutoMirrorDrawable(Utils.getGradientDrawableWithTintAttr(
+                R.drawable.afs_popup_background, R.attr.colorControlActivated, context)));
         popupView.setEllipsize(TextUtils.TruncateAt.MIDDLE);
         popupView.setGravity(Gravity.CENTER);
         popupView.setIncludeFontPadding(false);

library/src/main/java/me/zhanghai/android/fastscroll/Utils.java

@@ -19,12 +19,17 @@
 import android.content.Context;
 import android.content.res.ColorStateList;
 import android.content.res.TypedArray;
+import android.graphics.drawable.Drawable;
+import android.graphics.drawable.GradientDrawable;
+import android.os.Build;
 
 import androidx.annotation.AttrRes;
 import androidx.annotation.ColorInt;
+import androidx.annotation.DrawableRes;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.appcompat.content.res.AppCompatResources;
+import androidx.core.graphics.drawable.DrawableCompat;
 
 class Utils {
 
@@ -49,4 +54,19 @@ public static ColorStateList getColorStateListFromAttrRes(@AttrRes int attrRes,
             a.recycle();
         }
     }
+
+    // Work around the bug that GradientDrawable didn't actually implement tinting until
+    // Lollipop MR1 (API 22).
+    @Nullable
+    public static Drawable getGradientDrawableWithTintAttr(@DrawableRes int drawableRes,
+                                                           @AttrRes int tintAttrRes,
+                                                           @NonNull Context context) {
+        Drawable drawable = AppCompatResources.getDrawable(context, drawableRes);
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP_MR1
+                && drawable instanceof GradientDrawable) {
+            drawable = DrawableCompat.wrap(drawable);
+            drawable.setTintList(getColorStateListFromAttrRes(tintAttrRes, context));
+        }
+        return drawable;
+    }
 }

library/src/main/res/drawable/afs_md2_thumb.xml

@@ -16,6 +16,10 @@
   ~ limitations under the License.
   -->
 
+<!--
+  ~ Any changes to the tint here needs to be mirrored in the call to
+  ~ Utils.getGradientDrawableWithTintAttr() as well.
+  -->
 <shape
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="rectangle"

library/src/main/res/drawable/afs_md2_track.xml

@@ -16,6 +16,10 @@
   ~ limitations under the License.
   -->
 
+<!--
+  ~ Any changes to the tint here needs to be mirrored in the call to
+  ~ Utils.getGradientDrawableWithTintAttr() as well.
+  -->
 <shape
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="rectangle"

library/src/main/res/drawable/afs_popup_background.xml

@@ -16,6 +16,10 @@
   ~ limitations under the License.
   -->
 
+<!--
+  ~ Any changes to the tint here needs to be mirrored in the call to
+  ~ Utils.getGradientDrawableWithTintAttr() as well.
+  -->
 <shape
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="rectangle"

library/src/main/res/drawable/afs_thumb.xml

@@ -16,6 +16,10 @@
   ~ limitations under the License.
   -->
 
+<!--
+  ~ Any changes to the tint here needs to be mirrored in the call to
+  ~ Utils.getGradientDrawableWithTintAttr() as well.
+  -->
 <shape
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="rectangle"

library/src/main/res/drawable/afs_thumb_stateful.xml

@@ -16,6 +16,11 @@
   ~ limitations under the License.
   -->
 
+<!--
+  ~ It was later discovered that this XML drawable doesn't work on Lollipop (API 21) due to the bug
+  ~ that GradientDrawable didn't actually implement tinting until Lollipop MR1 (API 22). So if you
+  ~ need to support API 21, you'll need to work around it yourself.
+  -->
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
 
     <item android:state_pressed="true">

library/src/main/res/drawable/afs_track.xml

@@ -16,6 +16,10 @@
   ~ limitations under the License.
   -->
 
+<!--
+  ~ Any changes to the tint here needs to be mirrored in the call to
+  ~ Utils.getGradientDrawableWithTintAttr() as well.
+  -->
 <shape
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="rectangle"

sample/src/main/java/me/zhanghai/android/fastscroll/sample/RecyclerViewListFragment.java

@@ -17,8 +17,6 @@
 package me.zhanghai.android.fastscroll.sample;
 
 import androidx.annotation.NonNull;
-import androidx.recyclerview.widget.LinearLayoutManager;
-import androidx.recyclerview.widget.RecyclerView;
 
 public class RecyclerViewListFragment extends RecyclerViewFragment {