From 3ca7026aa0e9ec0e8896e0890081551f72777f1e Mon Sep 17 00:00:00 2001
From: Maciej Suminski <maciej.suminski@cern.ch>
Date: Fri, 20 May 2016 12:06:08 +0200
Subject: [PATCH] More robust checks for OpenGL canvas visibility.

---
 common/draw_panel_gal.cpp                | 2 +-
 include/gal/cairo/cairo_gal.h            | 5 +++++
 include/gal/graphics_abstraction_layer.h | 5 ++++-
 include/gal/opengl/opengl_gal.h          | 7 ++++++-
 4 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/common/draw_panel_gal.cpp b/common/draw_panel_gal.cpp
index aa72e8ea6b..94654e5684 100644
--- a/common/draw_panel_gal.cpp
+++ b/common/draw_panel_gal.cpp
@@ -479,7 +479,7 @@ void EDA_DRAW_PANEL_GAL::onRefreshTimer( wxTimerEvent& aEvent )
 
 void EDA_DRAW_PANEL_GAL::onShowTimer( wxTimerEvent& aEvent )
 {
-    if( IsShownOnScreen() )
+    if( m_gal && m_gal->IsVisible() )
     {
         m_onShowTimer.Stop();
         OnShow();
diff --git a/include/gal/cairo/cairo_gal.h b/include/gal/cairo/cairo_gal.h
index 1f395f7201..bc378d4b3d 100644
--- a/include/gal/cairo/cairo_gal.h
+++ b/include/gal/cairo/cairo_gal.h
@@ -85,6 +85,11 @@ public:
 
     virtual ~CAIRO_GAL();
 
+    ///> @copydoc GAL::IsVisible()
+    bool IsVisible() const override {
+        return IsShownOnScreen();
+    }
+
     // ---------------
     // Drawing methods
     // ---------------
diff --git a/include/gal/graphics_abstraction_layer.h b/include/gal/graphics_abstraction_layer.h
index 8a2ecaa119..20f8130ba6 100644
--- a/include/gal/graphics_abstraction_layer.h
+++ b/include/gal/graphics_abstraction_layer.h
@@ -66,9 +66,12 @@ public:
     GAL();
     virtual ~GAL();
 
-   /// @brief Returns the initalization status for the canvas.
+    /// @brief Returns the initalization status for the canvas.
     virtual bool IsInitialized() const { return true; }
 
+    /// @brief Returns true if the GAL canvas is visible on the screen.
+    virtual bool IsVisible() const { return true; }
+
     // ---------------
     // Drawing methods
     // ---------------
diff --git a/include/gal/opengl/opengl_gal.h b/include/gal/opengl/opengl_gal.h
index 7fd63c43be..71619a914e 100644
--- a/include/gal/opengl/opengl_gal.h
+++ b/include/gal/opengl/opengl_gal.h
@@ -83,9 +83,14 @@ public:
 
     virtual ~OPENGL_GAL();
 
-   /// @copydoc GAL::IsInitialized()
+    /// @copydoc GAL::IsInitialized()
     virtual bool IsInitialized() const { return IsShownOnScreen(); }
 
+    ///> @copydoc GAL::IsVisible()
+    bool IsVisible() const override {
+        return IsShownOnScreen();
+    }
+
     // ---------------
     // Drawing methods
     // ---------------