Feature/scrollbars

app/src/main/res/layout/activity_main.xml

@@ -11,6 +11,7 @@
         android:layout_width="match_parent"
         android:layout_height="0dp"
         android:layout_weight="1"
+        android:scrollbars="horizontal|vertical"
         app:hasClickableChildren="true"
         app:horizontalPanEnabled="true"
         app:verticalPanEnabled="true"
@@ -27,7 +28,11 @@
         android:layout_width="match_parent"
         android:layout_height="0dp"
         android:layout_weight="1"
-        android:visibility="gone" />
+        android:scrollbars="horizontal|vertical"
+        android:visibility="gone"
+        app:horizontalPanEnabled="true"
+        app:verticalPanEnabled="true"
+        app:zoomEnabled="true" />
 
     <LinearLayout
         android:layout_width="match_parent"

library/src/main/java/com/otaliastudios/zoom/ZoomImageView.java

@@ -95,12 +95,34 @@ public boolean onTouchEvent(MotionEvent ev) {
     public void onUpdate(ZoomEngine helper, Matrix matrix) {
         mMatrix.set(matrix);
         setImageMatrix(mMatrix);
+
+        awakenScrollBars();
     }
 
     @Override
     public void onIdle(ZoomEngine engine) {
     }
 
+    @Override
+    protected int computeHorizontalScrollOffset() {
+        return (int) (-1 * mEngine.getPanX() * mEngine.getRealZoom());
+    }
+
+    @Override
+    protected int computeHorizontalScrollRange() {
+        return (int) (mDrawableRect.width() * mEngine.getRealZoom());
+    }
+
+    @Override
+    protected int computeVerticalScrollOffset() {
+        return (int) (-1 * mEngine.getPanY() * mEngine.getRealZoom());
+    }
+
+    @Override
+    protected int computeVerticalScrollRange() {
+        return (int) (mDrawableRect.height() * mEngine.getRealZoom());
+    }
+
     //endregion
 
     //region APIs

library/src/main/java/com/otaliastudios/zoom/ZoomLayout.java

@@ -80,6 +80,8 @@ public ZoomLayout(@NonNull Context context, @Nullable AttributeSet attrs, @AttrR
         if (minZoom > -1) setMinZoom(minZoom, minZoomMode);
         if (maxZoom > -1) setMaxZoom(maxZoom, maxZoomMode);
         setHasClickableChildren(hasChildren);
+
+        setWillNotDraw(false);
     }
 
     //region Internal
@@ -156,23 +158,48 @@ public void onUpdate(ZoomEngine helper, Matrix matrix) {
         } else {
             invalidate();
         }
+
+        awakenScrollBars();
     }
 
     @Override
     public void onIdle(ZoomEngine engine) {
     }
 
+    @Override
+    protected int computeHorizontalScrollOffset() {
+        return (int) (-1 * mEngine.getPanX() * mEngine.getRealZoom());
+    }
+
+    @Override
+    protected int computeHorizontalScrollRange() {
+        return (int) (mChildRect.width() * mEngine.getRealZoom());
+    }
+
+    @Override
+    protected int computeVerticalScrollOffset() {
+        return (int) (-1 * mEngine.getPanY() * mEngine.getRealZoom());
+    }
+
+    @Override
+    protected int computeVerticalScrollRange() {
+        return (int) (mChildRect.height() * mEngine.getRealZoom());
+    }
+
     @Override
     protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
+        boolean result;
+
         if (!mHasClickableChildren) {
             int save = canvas.save();
             canvas.setMatrix(mMatrix);
-            boolean result = super.drawChild(canvas, child, drawingTime);
+            result = super.drawChild(canvas, child, drawingTime);
             canvas.restoreToCount(save);
-            return result;
         } else {
-            return super.drawChild(canvas, child, drawingTime);
+            result = super.drawChild(canvas, child, drawingTime);
         }
+
+        return result;
     }
 
     //endregion