Fixed bug with multi-touch in Viewport when drag is blocked and made some methods const

modules/juce_gui_basics/components/juce_Component.h

@@ -2234,12 +2234,12 @@ public:
         Viewport with drag-to-scroll functionality enabled. This is useful for Components such as sliders that
         should not move their parent Viewport when dragged.
     */
-    void setViewportIgnoreDragFlag (bool ignoreDrag) { flags.viewportIgnoreDragFlag = ignoreDrag; };
+    void setViewportIgnoreDragFlag (bool ignoreDrag) noexcept { flags.viewportIgnoreDragFlag = ignoreDrag; };
 
     /** Retrieves the current state of the Viewport drag-to-scroll functionality flag.
         @see setViewportIgnoreDragFlag
     */
-    bool getViewportIgnoreDragFlag() { return flags.viewportIgnoreDragFlag; }
+    bool getViewportIgnoreDragFlag() const noexcept { return flags.viewportIgnoreDragFlag; }
 
     //==============================================================================
     // These methods are deprecated - use localPointToGlobal, getLocalPoint, getLocalPoint, etc instead.

modules/juce_gui_basics/layout/juce_Viewport.cpp

@@ -193,7 +193,7 @@ struct Viewport::DragToScrollListener   : private MouseListener,
                                           private ViewportDragPosition::Listener
 {
     DragToScrollListener (Viewport& v)
-        : viewport (v), numTouches (0), isDragging (false)
+        : viewport (v), numTouches (0), isDragging (false), isViewportDragBlocked (false)
     {
         viewport.contentHolder.addMouseListener (this, true);
         offsetX.addListener (this);
@@ -213,16 +213,15 @@ struct Viewport::DragToScrollListener   : private MouseListener,
 
     void mouseDown (const MouseEvent& e) override
     {
-        for (auto c = e.eventComponent; c != nullptr && c != &viewport; c = c->getParentComponent())
-            if (c->getViewportIgnoreDragFlag())
-                return;
+        if (doesMouseEventComponentBlockViewportDrag (e.eventComponent))
+            isViewportDragBlocked = true;
 
         ++numTouches;
     }
 
     void mouseDrag (const MouseEvent& e) override
     {
-        if (numTouches == 1)
+        if (numTouches == 1 && ! isViewportDragBlocked)
         {
             Point<float> totalOffset = e.getOffsetFromDragStart().toFloat();
 
@@ -245,8 +244,11 @@ struct Viewport::DragToScrollListener   : private MouseListener,
         }
     }
 
-    void mouseUp (const MouseEvent&) override
+    void mouseUp (const MouseEvent& e) override
     {
+        if (doesMouseEventComponentBlockViewportDrag (e.eventComponent))
+            isViewportDragBlocked = false;
+
         if (--numTouches <= 0)
         {
             offsetX.endDrag();
@@ -256,12 +258,23 @@ struct Viewport::DragToScrollListener   : private MouseListener,
         }
     }
 
+    bool doesMouseEventComponentBlockViewportDrag (const Component* eventComp)
+    {
+        for (auto c = eventComp; c != nullptr && c != &viewport; c = c->getParentComponent())
+            if (c->getViewportIgnoreDragFlag())
+                return true;
+
+        return false;
+    }
+
     Viewport& viewport;
     ViewportDragPosition offsetX, offsetY;
     Point<int> originalViewPos;
     int numTouches;
     bool isDragging;
 
+    bool isViewportDragBlocked;
+
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (DragToScrollListener)
 };