Scrollbars standarization (#1925)

app/src/common/shared/org/mozilla/vrbrowser/ui/views/CustomRecyclerView.java

@@ -0,0 +1,92 @@
+package org.mozilla.vrbrowser.ui.views;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.content.res.TypedArray;
+import android.graphics.drawable.Drawable;
+import android.graphics.drawable.StateListDrawable;
+import android.util.AttributeSet;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+import androidx.recyclerview.widget.RecyclerView;
+
+import org.mozilla.vrbrowser.R;
+
+public class CustomRecyclerView extends RecyclerView {
+
+    private CustomFastScroller mFastScroller;
+
+    public CustomRecyclerView(@NonNull Context context) {
+        this(context, null);
+    }
+
+    public CustomRecyclerView(@NonNull Context context, @Nullable AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public CustomRecyclerView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+
+        if (attrs != null) {
+            int defStyleRes = 0;
+            TypedArray a = context.obtainStyledAttributes(attrs, androidx.recyclerview.R.styleable.RecyclerView,
+                    defStyle, defStyleRes);
+            StateListDrawable verticalThumbDrawable = (StateListDrawable) a
+                    .getDrawable(androidx.recyclerview.R.styleable.RecyclerView_fastScrollVerticalThumbDrawable);
+            Drawable verticalTrackDrawable = a
+                    .getDrawable(androidx.recyclerview.R.styleable.RecyclerView_fastScrollVerticalTrackDrawable);
+            StateListDrawable horizontalThumbDrawable = (StateListDrawable) a
+                    .getDrawable(androidx.recyclerview.R.styleable.RecyclerView_fastScrollHorizontalThumbDrawable);
+            Drawable horizontalTrackDrawable = a
+                    .getDrawable(androidx.recyclerview.R.styleable.RecyclerView_fastScrollHorizontalTrackDrawable);
+            a.recycle();
+
+            TypedArray customAttributes = context.obtainStyledAttributes(attrs, R.styleable.CustomRecyclerView,
+                    defStyle, defStyleRes);
+            boolean alwaysVisible = customAttributes.getBoolean(R.styleable.CustomRecyclerView_android_fastScrollAlwaysVisible, false);
+            boolean enabled = customAttributes.getBoolean(R.styleable.CustomRecyclerView_customFastScrollEnabled, false);
+            customAttributes.recycle();
+            if (enabled) {
+                initFastScroller(alwaysVisible, verticalThumbDrawable, verticalTrackDrawable, horizontalThumbDrawable, horizontalTrackDrawable);
+            }
+
+        } else {
+            setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
+        }
+
+        getViewTreeObserver().addOnGlobalLayoutListener(() -> {
+            if (getVisibility() == VISIBLE) {
+                mFastScroller.updateScrollPosition(computeHorizontalScrollOffset(),
+                        computeVerticalScrollOffset());
+            }
+        });
+    }
+
+    String exceptionLabel() {
+        return " " + super.toString()
+                + ", adapter:" + getAdapter()
+                + ", layout:" + getLayoutManager()
+                + ", context:" + getContext();
+    }
+
+    @VisibleForTesting
+    void initFastScroller(boolean alwaysVisible, StateListDrawable verticalThumbDrawable,
+                          Drawable verticalTrackDrawable, StateListDrawable horizontalThumbDrawable,
+                          Drawable horizontalTrackDrawable) {
+        if (verticalThumbDrawable == null || verticalTrackDrawable == null
+                || horizontalThumbDrawable == null || horizontalTrackDrawable == null) {
+            throw new IllegalArgumentException(
+                    "Trying to set fast scroller without both required drawables." + exceptionLabel());
+        }
+
+        Resources resources = getContext().getResources();
+        mFastScroller = new CustomFastScroller(this, verticalThumbDrawable, verticalTrackDrawable,
+                horizontalThumbDrawable, horizontalTrackDrawable,
+                resources.getDimensionPixelSize(R.dimen.fastscroll_default_thickness),
+                resources.getDimensionPixelSize(R.dimen.fastscroll_minimum_range),
+                resources.getDimensionPixelOffset(R.dimen.fastscroll_margin), alwaysVisible);
+    }
+}