Bug 2040 - Linux: Assert on recording or generating when main Window minimised

src/Project.cpp

@@ -962,6 +962,7 @@ BEGIN_EVENT_TABLE(AudacityProject, wxFrame)
    EVT_CLOSE(AudacityProject::OnCloseWindow)
    EVT_SIZE(AudacityProject::OnSize)
    EVT_SHOW(AudacityProject::OnShow)
+   EVT_ICONIZE(AudacityProject::OnIconize)
    EVT_MOVE(AudacityProject::OnMove)
    EVT_ACTIVATE(AudacityProject::OnActivate)
    EVT_COMMAND_SCROLL_LINEUP(HSBarID, AudacityProject::OnScrollLeftButton)
@@ -2202,14 +2203,25 @@ void AudacityProject::OnIconize(wxIconizeEvent &event)
 
    unsigned int i;
 
+   // VisibileProjectCount seems to be just a counter for debugging.
+   // It's not used outside this function.
    for(i=0;i<gAudacityProjects.size();i++){
       if(gAudacityProjects[i]){
          if( !gAudacityProjects[i]->mIconized )
             VisibleProjectCount++;
       }
    }
-
    event.Skip();
+
+   // This step is to fix part of Bug 2040, where the BackingPanel
+   // size was not restored after we leave Iconized state.
+
+   // Queue up a resize event using OnShow so that we 
+   // refresh the track panel.  But skip this, if we're iconized.
+   if( mIconized )
+      return;
+   wxShowEvent Evt;
+   OnShow( Evt );
 }
 
 void AudacityProject::OnMove(wxMoveEvent & event)

src/widgets/BackedPanel.cpp

@@ -47,13 +47,13 @@ wxDC &BackedPanel::GetBackingDCForRepaint()
 
 void BackedPanel::ResizeBacking()
 {
-   // Delete the backing bitmap
    if (mBacking)
       mBackingDC.SelectObject(wxNullBitmap);
 
    wxSize sz = GetClientSize();
    mBacking = std::make_unique<wxBitmap>();
-   mBacking->Create(sz.x, sz.y,24); //, *dc);
+   // Bug 2040 - Avoid 0 x 0 bitmap when minimized.
+   mBacking->Create(std::max(sz.x,1), std::max(sz.y,1),24); //, *dc);
    mBackingDC.SelectObject(*mBacking);
 }
 
@@ -64,14 +64,15 @@ void BackedPanel::RepairBitmap(wxDC &dc, wxCoord x, wxCoord y, wxCoord width, wx
 
 void BackedPanel::DisplayBitmap(wxDC &dc)
 {
-   RepairBitmap(dc, 0, 0, mBacking->GetWidth(), mBacking->GetHeight());
+   if( mBacking ) 
+      RepairBitmap(dc, 0, 0, mBacking->GetWidth(), mBacking->GetHeight());
 }
 
-void BackedPanel::OnSize(wxSizeEvent & /* event */)
+void BackedPanel::OnSize(wxSizeEvent & event)
 {
    // Tell OnPaint() to recreate the backing bitmap
    mResizeBacking = true;
-
+   event.Skip();
    // Refresh the entire area.  Really only need to refresh when
    // expanding...is it worth the trouble?
    Refresh();

src/widgets/BackedPanel.h

@@ -15,7 +15,7 @@
 
 
 /// \brief BackedPanel is for a panel that consists of a bitmap with something drawn
-/// obver it.  It supports efficient repainting when the overlays change and
+/// over it.  It supports efficient repainting when the overlays change and
 /// recreation of the bitmap when the panel size is changed.
 class AUDACITY_DLL_API BackedPanel /* not final */ : public wxPanelWrapper {
 public:
@@ -27,15 +27,10 @@ public:
    ~BackedPanel();
 
    wxDC &GetBackingDC();
-
    wxDC &GetBackingDCForRepaint();
-
    void ResizeBacking();
-
    void RepairBitmap(wxDC &dc, wxCoord x, wxCoord y, wxCoord width, wxCoord height);
-
    void DisplayBitmap(wxDC &dc);
-
    void OnSize(wxSizeEvent & event);
 
 private: