Flicker-Free Grabbers and Mic/Speaker icons.

Previously we were clearing in Erase Background, giving lots of flicker when resizing some toolbar.
Also fixed a mac Slider background painting issue.

src/toolbars/DeviceToolBar.cpp

@@ -44,6 +44,7 @@
 #include "../widgets/Grabber.h"
 #include "../DeviceManager.h"
 #include "../widgets/ErrorDialog.h"
+#include "../widgets/Grabber.h"
 
 #if wxUSE_ACCESSIBILITY
 #include "../widgets/WindowAccessible.h"
@@ -104,7 +105,7 @@ void DeviceToolBar::Populate()
    Add(mHost, 0, wxALIGN_CENTER);
 
    // Input device
-   Add(safenew wxStaticBitmap(this,
+   Add(safenew AStaticBitmap(this,
                           wxID_ANY,
                           theTheme.Bitmap(bmpMic)), 0, wxALIGN_CENTER);
    mInput = safenew wxChoice(this,
@@ -128,7 +129,7 @@ void DeviceToolBar::Populate()
    Add(mInputChannels, 0, wxALIGN_CENTER);
 
    // Output device
-   Add(safenew wxStaticBitmap(this,
+   Add(safenew AStaticBitmap(this,
                           wxID_ANY,
                           theTheme.Bitmap(bmpSpeaker)), 0, wxALIGN_CENTER);
    mOutput = safenew wxChoice(this,

src/toolbars/MixerToolBar.cpp

@@ -39,6 +39,7 @@
 #include "../Project.h"
 #include "../Theme.h"
 #include "../widgets/ASlider.h"
+#include "../widgets/Grabber.h"
 
 IMPLEMENT_CLASS(MixerToolBar, ToolBar);
 
@@ -74,7 +75,7 @@ void MixerToolBar::Populate()
 {
    SetBackgroundColour( theTheme.Colour( clrMedium  ) );
    // Recording icon and slider
-   Add(safenew wxStaticBitmap(this,
+   Add(safenew AStaticBitmap(this,
                           wxID_ANY,
                           theTheme.Bitmap(bmpMic)), 0, wxALIGN_CENTER);
    mInputSlider = safenew ASlider(this, wxID_ANY, _("Recording Volume"),
@@ -83,7 +84,7 @@ void MixerToolBar::Populate()
    Add(mInputSlider, 0, wxALIGN_CENTER);
 
    // Playback icon and slider
-   Add(safenew wxStaticBitmap(this,
+   Add(safenew AStaticBitmap(this,
                           wxID_ANY,
                           theTheme.Bitmap(bmpSpeaker)), 0, wxALIGN_CENTER);
    mOutputSlider = safenew ASlider(this, wxID_ANY, _("Playback Volume"),

src/toolbars/ToolBar.cpp

@@ -860,8 +860,8 @@ void ToolBar::OnErase( wxEraseEvent & WXUNUSED(event) )
 //
 void ToolBar::OnPaint( wxPaintEvent & event )
 {
-   wxPaintDC dc( (wxWindow *) event.GetEventObject() );
-
+   //wxPaintDC dc( (wxWindow *) event.GetEventObject() );
+   wxPaintDC dc( this );
    // Start with a clean background
    //
    // Under GTK, we specifically set the toolbar background to the background

src/widgets/ASlider.cpp

@@ -573,12 +573,12 @@ void LWSlider::OnPaint(wxDC &dc, bool highlight)
       thumbPos += 8-mThumbHeight/2;
    }
 
-#if !defined(__WXMAC__)
+   // Previously not done on mac, but with wx3.1.1. it
+   // needs to be.
    if( mHW )
    {
       dc.Clear();
    }
-#endif
 
    dc.DrawBitmap(*mBitmap, mLeft, mTop, true);
    const auto &thumbBitmap =

src/widgets/Grabber.cpp

@@ -45,6 +45,7 @@ BEGIN_EVENT_TABLE(Grabber, wxWindow)
    EVT_ENTER_WINDOW(Grabber::OnEnter)
    EVT_LEAVE_WINDOW(Grabber::OnLeave)
    EVT_LEFT_DOWN(Grabber::OnLeftDown)
+   EVT_ERASE_BACKGROUND( Grabber::OnErase )
    EVT_PAINT(Grabber::OnPaint)
    EVT_KEY_DOWN(Grabber::OnKeyDown)
 END_EVENT_TABLE()
@@ -238,6 +239,11 @@ void Grabber::OnLeave(wxMouseEvent & WXUNUSED(event))
    }
 }
 
+void Grabber::OnErase( wxEraseEvent & WXUNUSED(event) )
+{
+   // Ignore it to prevent flashing
+}
+
 //
 // Handle the paint events
 //
@@ -260,3 +266,11 @@ void Grabber::OnKeyDown(wxKeyEvent &event)
       SendEvent(EVT_GRABBER_CLICKED, wxPoint{ -1, -1 }, true);
    }
 }
+
+// Piggy back in same source file as Grabber.
+// Audcaity Flicker-free StaticBitmap.
+BEGIN_EVENT_TABLE(AStaticBitmap,wxStaticBitmap)
+    EVT_ERASE_BACKGROUND(AStaticBitmap::OnErase)
+END_EVENT_TABLE()
+
+

src/widgets/Grabber.h

@@ -30,6 +30,7 @@ around to NEW positions.
 #include "wx/event.h"
 #include "wx/gdicmn.h"
 #include "wx/window.h"
+#include <wx/statbmp.h>
 
 ////////////////////////////////////////////////////////////
 /// Grabber Class
@@ -118,6 +119,7 @@ class Grabber final : public wxWindow
    void OnLeftDown(wxMouseEvent & event);
    void OnEnter(wxMouseEvent & event);
    void OnLeave(wxMouseEvent & event);
+   void OnErase(wxEraseEvent & event);
    void OnPaint(wxPaintEvent & event);
    void OnKeyDown(wxKeyEvent & event);
 
@@ -135,4 +137,32 @@ class Grabber final : public wxWindow
    DECLARE_EVENT_TABLE()
 };
 
+// Piggy back in same source file as Grabber.
+// Audcaity Flicker-free StaticBitmap.
+class AStaticBitmap : public wxStaticBitmap {
+  public:
+    AStaticBitmap(wxWindow *parent,
+                   wxWindowID id,
+                   const wxBitmap& label,
+                   const wxPoint& pos = wxDefaultPosition,
+                   const wxSize& size = wxDefaultSize,
+                   long style = 0,
+                   const wxString& name = wxStaticBitmapNameStr) :
+
+    wxStaticBitmap(parent,
+                   id,
+                   label,
+                   pos ,
+                   size ,
+                   style,
+                   name )
+    {};
+    void OnErase(wxEraseEvent& event) {
+       static_cast<void>(event);
+    };
+    DECLARE_EVENT_TABLE()
+};
+
+
+
 #endif