SM fix element control scrollbar

The element layouting must always be done without a scrollbar, so
it can be decided, if a scrollbar is needed. If it's needed the
first paint will update the scrollbar accordingly.

This also sets the scrollbar's page size to the control height,
so clicking in an empty area will correctly scroll the widget not
just a single pixel.

Change-Id: Ib9a0eb1952bc0355f683cd8d116c61f9c9d462c4
Reviewed-on: https://gerrit.libreoffice.org/72315
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

2 files changed, 28 insertions, 12 deletions

diff --git a/starmath/inc/ElementsDockingWindow.hxx b/starmath/inc/ElementsDockingWindow.hxx
index fe712401f773..c98072143bdc 100644
--- a/starmath/inc/ElementsDockingWindow.hxx
+++ b/starmath/inc/ElementsDockingWindow.hxx
@@ -77,6 +77,7 @@ class SmElementsControl : public Control
     virtual void MouseButtonDown(const MouseEvent& rMEvt) override;
     virtual void MouseMove(const MouseEvent& rMEvt) override;
     virtual void RequestHelp(const HelpEvent& rHEvt) override;
+    virtual void Resize() override;
 
     SmDocShell*   mpDocShell;
     SmFormat      maFormat;
@@ -88,6 +89,7 @@ class SmElementsControl : public Control
     Size          maMaxElementDimensions;
     bool          mbVerticalMode;
     VclPtr< ScrollBar > mxScroll;
+    bool mbFirstPaintAfterLayout;
 
     void addElement(const OUString& aElementVisual, const OUString& aElementSource, const OUString& aHelpText);
 
diff --git a/starmath/source/ElementsDockingWindow.cxx b/starmath/source/ElementsDockingWindow.cxx
index ab0ad7dd689e..36af328f1ced 100644
--- a/starmath/source/ElementsDockingWindow.cxx
+++ b/starmath/source/ElementsDockingWindow.cxx
@@ -238,6 +238,7 @@ SmElementsControl::SmElementsControl(vcl::Window *pParent)
     , mpCurrentElement(nullptr)
     , mbVerticalMode(true)
     , mxScroll(VclPtr<ScrollBar>::Create(this, WB_VERT))
+    , mbFirstPaintAfterLayout(false)
 {
     set_id("element_selector");
     SetMapMode( MapMode(MapUnit::Map100thMM) );
@@ -248,7 +249,6 @@ SmElementsControl::SmElementsControl(vcl::Window *pParent)
     maFormat.SetBaseSize(PixelToLogic(Size(0, SmPtsTo100th_mm(12))));
 
     mxScroll->SetScrollHdl( LINK(this, SmElementsControl, ScrollHdl) );
-    mxScroll->Show();
 }
 
 SmElementsControl::~SmElementsControl()
@@ -268,14 +268,19 @@ void SmElementsControl::setVerticalMode(bool bVerticalMode)
     mbVerticalMode = bVerticalMode;
 }
 
+/**
+ * !pContext => layout only
+ *
+ * Layouting is always done without a scrollbar and will show or hide it.
+ * The first paint (mbFirstPaintAfterLayout) therefore needs to update a
+ * visible scrollbar, because the layouting was wrong.
+ **/
 void SmElementsControl::LayoutOrPaintContents(vcl::RenderContext *pContext)
 {
-    bool bOldVisibleState = mxScroll->IsVisible();
-
-    sal_Int32 nScrollbarWidth = bOldVisibleState ? GetSettings().GetStyleSettings().GetScrollBarSize() : 0;
-
-    sal_Int32 nControlWidth = GetOutputSizePixel().Width() - nScrollbarWidth;
-    sal_Int32 nControlHeight = GetOutputSizePixel().Height();
+    const sal_Int32 nScrollbarWidth = GetSettings().GetStyleSettings().GetScrollBarSize();
+    const sal_Int32 nControlWidth = GetOutputSizePixel().Width()
+                                    - (pContext && mxScroll->IsVisible() ? nScrollbarWidth : 0);
+    const sal_Int32 nControlHeight = GetOutputSizePixel().Height();
 
     sal_Int32 boxX = maMaxElementDimensions.Width()  + 10;
     sal_Int32 boxY = maMaxElementDimensions.Height() + 10;
@@ -379,15 +384,21 @@ void SmElementsControl::LayoutOrPaintContents(vcl::RenderContext *pContext)
     }
 
     if (pContext)
-        return;
+    {
+        if (!mbFirstPaintAfterLayout || !mxScroll->IsVisible())
+            return;
+        mbFirstPaintAfterLayout = false;
+    }
+    else
+        mbFirstPaintAfterLayout = true;
 
     sal_Int32 nTotalControlHeight = y + boxY + mxScroll->GetThumbPos();
-
     if (nTotalControlHeight > GetOutputSizePixel().Height())
     {
         mxScroll->SetRangeMax(nTotalControlHeight);
         mxScroll->SetPosSizePixel(Point(nControlWidth, 0), Size(nScrollbarWidth, nControlHeight));
         mxScroll->SetVisibleSize(nControlHeight);
+        mxScroll->SetPageSize(nControlHeight);
         mxScroll->Show();
     }
     else
@@ -397,6 +408,12 @@ void SmElementsControl::LayoutOrPaintContents(vcl::RenderContext *pContext)
     }
 }
 
+void SmElementsControl::Resize()
+{
+     Window::Resize();
+     LayoutOrPaintContents(nullptr);
+}
+
 void SmElementsControl::ApplySettings(vcl::RenderContext& rRenderContext)
 {
     rRenderContext.SetBackground(COL_WHITE);
@@ -461,7 +478,6 @@ void SmElementsControl::MouseMove( const MouseEvent& rMouseEvent )
     mpCurrentElement = nullptr;
     if (rMouseEvent.IsLeaveWindow())
     {
-        LayoutOrPaintContents();
         Invalidate();
         return;
     }
@@ -476,7 +492,6 @@ void SmElementsControl::MouseMove( const MouseEvent& rMouseEvent )
                 if (pPrevElement != element)
                 {
                     mpCurrentElement = element;
-                    LayoutOrPaintContents();
                     Invalidate();
                     return;
                 }
@@ -541,7 +556,6 @@ void SmElementsControl::DoScroll(long nDelta)
     aRect.AdjustRight( -(mxScroll->GetSizePixel().Width()) );
     Scroll( 0, -nDelta, aRect );
     mxScroll->SetPosPixel(aNewPoint);
-    LayoutOrPaintContents();
     Invalidate();
 }