sample add TriggerParentHotspot

sample/src/main/java/io/noties/markwon/sample/recycler/TriggerParentHotspot.java

@@ -0,0 +1,149 @@
+package io.noties.markwon.sample.recycler;
+
+import android.graphics.Canvas;
+import android.graphics.ColorFilter;
+import android.graphics.PixelFormat;
+import android.graphics.Point;
+import android.graphics.Rect;
+import android.graphics.drawable.Drawable;
+import android.os.Build;
+import android.util.StateSet;
+import android.view.View;
+import android.view.ViewTreeObserver;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+
+public class TriggerParentHotspot {
+
+    public static void init(@NonNull final View parent, @NonNull final View view) {
+        final Drawable background = parent.getBackground();
+        if (background == null) {
+            view.setBackground(null);
+            return;
+        }
+
+        final Wrapper wrapper = ensureWrapper(view);
+        wrapper.wrapped = background;
+
+        view.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
+            @Override
+            public boolean onPreDraw() {
+                final Point point = relativeTo(parent, view, POINT);
+                wrapper.offsetHorizontal = point.x;
+                wrapper.offsetVertical = point.y;
+                view.getViewTreeObserver().removeOnPreDrawListener(this);
+                return true;
+            }
+        });
+    }
+
+    private static final Point POINT = new Point();
+
+    @NonNull
+    private static Wrapper ensureWrapper(@NonNull View view) {
+        final Drawable drawable = view.getBackground();
+        if (!(drawable instanceof Wrapper)) {
+            final Wrapper wrapper = new Wrapper();
+            view.setBackground(wrapper);
+            return wrapper;
+        }
+        return (Wrapper) drawable;
+    }
+
+    @NonNull
+    private static Point relativeTo(@NonNull View parent, @NonNull View who, @NonNull Point point) {
+        point.x += who.getLeft();
+        point.y += who.getTop();
+        if (who != parent
+                && who.getParent() instanceof View) {
+            relativeTo(parent, (View) who.getParent(), point);
+        }
+        return point;
+    }
+
+    private static class Wrapper extends Drawable {
+
+        private Drawable wrapped;
+
+        private int offsetHorizontal;
+        private int offsetVertical;
+
+        @Override
+        public void draw(@NonNull Canvas canvas) {
+            // no op
+        }
+
+        @Override
+        public void setAlpha(int alpha) {
+            // no op
+        }
+
+        @Override
+        public void setColorFilter(@Nullable ColorFilter colorFilter) {
+            // no op
+        }
+
+        @Override
+        public int getOpacity() {
+            if (wrapped == null) {
+                return PixelFormat.TRANSPARENT;
+            }
+            return wrapped.getOpacity();
+        }
+
+        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
+        @Override
+        public void setHotspot(float x, float y) {
+            if (wrapped != null) {
+                wrapped.setHotspot(x + offsetHorizontal, y + offsetVertical);
+            }
+        }
+
+        @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
+        @Override
+        public void setHotspotBounds(int left, int top, int right, int bottom) {
+            if (wrapped != null) {
+                wrapped.setHotspotBounds(
+                        left + offsetHorizontal,
+                        top + offsetVertical,
+                        right + offsetHorizontal,
+                        bottom + offsetVertical
+                );
+            }
+        }
+
+        @RequiresApi(Build.VERSION_CODES.M)
+        @Override
+        public void getHotspotBounds(@NonNull Rect outRect) {
+            if (wrapped != null) {
+                wrapped.getHotspotBounds(outRect);
+                if (!outRect.isEmpty()) {
+                    outRect.set(
+                            outRect.left - offsetHorizontal,
+                            outRect.top - offsetVertical,
+                            outRect.right - offsetHorizontal,
+                            outRect.bottom - offsetVertical
+                    );
+                }
+            }
+        }
+
+        @Override
+        public boolean isStateful() {
+            return wrapped != null && wrapped.isStateful();
+        }
+
+        @Override
+        public boolean setState(@NonNull int[] stateSet) {
+            return wrapped != null && wrapped.setState(stateSet);
+        }
+
+        @NonNull
+        @Override
+        public int[] getState() {
+            return wrapped != null ? wrapped.getState() : StateSet.WILD_CARD;
+        }
+    }
+}