Added an option to Viewport to allow mouse-wheel scrolling when scrollbars are disabled.

modules/juce_gui_basics/layout/juce_Viewport.cpp

@@ -30,6 +30,8 @@ Viewport::Viewport (const String& name)
     showHScrollbar (true),
     showVScrollbar (true),
     deleteContent (true),
+    allowScrollingWithoutScrollbarV (false),
+    allowScrollingWithoutScrollbarH (false),
     verticalScrollBar (true),
     horizontalScrollBar (false)
 {
@@ -234,31 +236,23 @@ void Viewport::updateVisibleArea()
 
     Point<int> visibleOrigin (-contentBounds.getPosition());
 
-    if (hBarVisible)
-    {
-        horizontalScrollBar.setBounds (0, contentArea.getHeight(), contentArea.getWidth(), scrollbarWidth);
-        horizontalScrollBar.setRangeLimits (0.0, contentBounds.getWidth());
-        horizontalScrollBar.setCurrentRange (visibleOrigin.x, contentArea.getWidth());
-        horizontalScrollBar.setSingleStepSize (singleStepX);
-        horizontalScrollBar.cancelPendingUpdate();
-    }
-    else if (canShowHBar)
-    {
+    horizontalScrollBar.setBounds (0, contentArea.getHeight(), contentArea.getWidth(), scrollbarWidth);
+    horizontalScrollBar.setRangeLimits (0.0, contentBounds.getWidth());
+    horizontalScrollBar.setCurrentRange (visibleOrigin.x, contentArea.getWidth());
+    horizontalScrollBar.setSingleStepSize (singleStepX);
+    horizontalScrollBar.cancelPendingUpdate();
+
+    if (canShowHBar && ! hBarVisible)
         visibleOrigin.setX (0);
-    }
 
-    if (vBarVisible)
-    {
-        verticalScrollBar.setBounds (contentArea.getWidth(), 0, scrollbarWidth, contentArea.getHeight());
-        verticalScrollBar.setRangeLimits (0.0, contentBounds.getHeight());
-        verticalScrollBar.setCurrentRange (visibleOrigin.y, contentArea.getHeight());
-        verticalScrollBar.setSingleStepSize (singleStepY);
-        verticalScrollBar.cancelPendingUpdate();
-    }
-    else if (canShowVBar)
-    {
+    verticalScrollBar.setBounds (contentArea.getWidth(), 0, scrollbarWidth, contentArea.getHeight());
+    verticalScrollBar.setRangeLimits (0.0, contentBounds.getHeight());
+    verticalScrollBar.setCurrentRange (visibleOrigin.y, contentArea.getHeight());
+    verticalScrollBar.setSingleStepSize (singleStepY);
+    verticalScrollBar.cancelPendingUpdate();
+
+    if (canShowVBar && ! vBarVisible)
         visibleOrigin.setY (0);
-    }
 
     // Force the visibility *after* setting the ranges to avoid flicker caused by edge conditions in the numbers.
     horizontalScrollBar.setVisible (hBarVisible);
@@ -301,8 +295,13 @@ void Viewport::setSingleStepSizes (const int stepX, const int stepY)
 }
 
 void Viewport::setScrollBarsShown (const bool showVerticalScrollbarIfNeeded,
-                                   const bool showHorizontalScrollbarIfNeeded)
+                                   const bool showHorizontalScrollbarIfNeeded,
+                                   const bool allowVerticalScrollingWithoutScrollbar,
+                                   const bool allowHorizontalScrollingWithoutScrollbar)
 {
+    allowScrollingWithoutScrollbarV = allowVerticalScrollingWithoutScrollbar;
+    allowScrollingWithoutScrollbarH = allowHorizontalScrollingWithoutScrollbar;
+
     if (showVScrollbar != showVerticalScrollbarIfNeeded
          || showHScrollbar != showHorizontalScrollbarIfNeeded)
     {
@@ -347,47 +346,44 @@ void Viewport::mouseWheelMove (const MouseEvent& e, const MouseWheelDetails& whe
         Component::mouseWheelMove (e, wheel);
 }
 
+static float rescaleMouseWheelDistance (float distance, int singleStepSize) noexcept
+{
+    if (distance == 0)
+        return 0;
+
+    distance *= 14.0f * singleStepSize;
+
+    return distance < 0 ? jmin (distance, -1.0f)
+                        : jmax (distance,  1.0f);
+}
+
 bool Viewport::useMouseWheelMoveIfNeeded (const MouseEvent& e, const MouseWheelDetails& wheel)
 {
     if (! (e.mods.isAltDown() || e.mods.isCtrlDown() || e.mods.isCommandDown()))
     {
-        const bool hasVertBar = verticalScrollBar.isVisible();
-        const bool hasHorzBar = horizontalScrollBar.isVisible();
+        const bool canScrollVert = (allowScrollingWithoutScrollbarV || verticalScrollBar.isVisible());
+        const bool canScrollHorz = (allowScrollingWithoutScrollbarH || horizontalScrollBar.isVisible());
 
-        if (hasHorzBar || hasVertBar)
+        if (canScrollHorz || canScrollVert)
         {
-            float wheelIncrementX = wheel.deltaX;
-            float wheelIncrementY = wheel.deltaY;
-
-            if (wheelIncrementX != 0)
-            {
-                wheelIncrementX *= 14.0f * singleStepX;
-                wheelIncrementX = (wheelIncrementX < 0) ? jmin (wheelIncrementX, -1.0f)
-                                                        : jmax (wheelIncrementX, 1.0f);
-            }
-
-            if (wheelIncrementY != 0)
-            {
-                wheelIncrementY *= 14.0f * singleStepY;
-                wheelIncrementY = (wheelIncrementY < 0) ? jmin (wheelIncrementY, -1.0f)
-                                                        : jmax (wheelIncrementY, 1.0f);
-            }
+            float wheelIncrementX = rescaleMouseWheelDistance (wheel.deltaX, singleStepX);
+            float wheelIncrementY = rescaleMouseWheelDistance (wheel.deltaY, singleStepY);
 
             Point<int> pos (getViewPosition());
 
-            if (wheelIncrementX != 0 && wheelIncrementY != 0 && hasHorzBar && hasVertBar)
+            if (wheelIncrementX != 0 && wheelIncrementY != 0 && canScrollHorz && canScrollVert)
             {
                 pos.setX (pos.x - roundToInt (wheelIncrementX));
                 pos.setY (pos.y - roundToInt (wheelIncrementY));
             }
-            else if (hasHorzBar && (wheelIncrementX != 0 || e.mods.isShiftDown() || ! hasVertBar))
+            else if (canScrollHorz && (wheelIncrementX != 0 || e.mods.isShiftDown() || ! canScrollVert))
             {
-                if (wheelIncrementX == 0 && ! hasVertBar)
+                if (wheelIncrementX == 0 && ! canScrollVert)
                     wheelIncrementX = wheelIncrementY;
 
                 pos.setX (pos.x - roundToInt (wheelIncrementX));
             }
-            else if (hasVertBar && wheelIncrementY != 0)
+            else if (canScrollVert && wheelIncrementY != 0)
             {
                 pos.setY (pos.y - roundToInt (wheelIncrementY));
             }

modules/juce_gui_basics/layout/juce_Viewport.h

@@ -191,9 +191,15 @@ public:
 
         If set to false, the scrollbars won't ever appear. When true (the default)
         they will appear only when needed.
+
+        The allowVerticalScrollingWithoutScrollbar parameters allow you to enable
+        mouse-wheel scrolling even when there the scrollbars are hidden. When the
+        scrollbars are visible, these parameters are ignored.
     */
     void setScrollBarsShown (bool showVerticalScrollbarIfNeeded,
-                             bool showHorizontalScrollbarIfNeeded);
+                             bool showHorizontalScrollbarIfNeeded,
+                             bool allowVerticalScrollingWithoutScrollbar = false,
+                             bool allowHorizontalScrollingWithoutScrollbar = false);
 
     /** True if the vertical scrollbar is enabled.
         @see setScrollBarsShown
@@ -258,9 +264,9 @@ private:
     int scrollBarThickness;
     int singleStepX, singleStepY;
     bool showHScrollbar, showVScrollbar, deleteContent;
+    bool allowScrollingWithoutScrollbarV, allowScrollingWithoutScrollbarH;
     Component contentHolder;
-    ScrollBar verticalScrollBar;
-    ScrollBar horizontalScrollBar;
+    ScrollBar verticalScrollBar, horizontalScrollBar;
     Point<int> viewportPosToCompPos (Point<int>) const;
 
     void updateVisibleArea();