Fix Discord streaming for OpenGL

Check if the OpenGL context is valid on every operation, and if not
re-initialize it. Also rebind the textures every time the frame is
drawn.

Also rename the SetCurrent method to SetContext, which is clearer.

Fix #643
Fix #767
Fix #840
Fix #843

Signed-off-by: Rafael Kitover <rkitover@gmail.com>

src/wx/drawing.h

@@ -38,10 +38,11 @@ protected:
     void DrawArea(wxWindowDC& dc);
     void OnSize(wxSizeEvent& ev);
     void AdjustViewport();
+    void RefreshGL();
 #ifndef wxGL_IMPLICIT_CONTEXT
-    wxGLContext* ctx;
+    wxGLContext* ctx = nullptr;
 #endif
-    bool SetCurrent();
+    bool SetContext();
     void DrawingPanelInit();
     GLuint texid, vlist;
     int texsize;

src/wx/panel.cpp

@@ -2183,9 +2183,26 @@ static int glopts[] = {
     WX_GL_RGBA, WX_GL_DOUBLEBUFFER, 0
 };
 
-bool GLDrawingPanel::SetCurrent()
+bool GLDrawingPanel::SetContext()
 {
 #ifndef wxGL_IMPLICIT_CONTEXT
+    // Check if the current context is valid
+    if (!ctx
+#if wxCHECK_VERSION(3, 1, 0)
+            || !ctx->IsOK()
+#endif
+    )
+    {
+        // Delete the old context
+        if (ctx) {
+            delete ctx;
+            ctx = nullptr;
+        }
+
+        // Create a new context
+        ctx = new wxGLContext(this);
+        DrawingPanelInit();
+    }
     return wxGLCanvas::SetCurrent(*ctx);
 #else
     return wxGLContext::SetCurrent(*this);
@@ -2198,11 +2215,7 @@ GLDrawingPanel::GLDrawingPanel(wxWindow* parent, int _width, int _height)
           wxFULL_REPAINT_ON_RESIZE | wxWANTS_CHARS)
 {
     widgets::RequestHighResolutionOpenGlSurfaceForWindow(this);
-#ifndef wxGL_IMPLICIT_CONTEXT
+    SetContext();
-    ctx = new wxGLContext(this);
-#endif
-    SetCurrent();
-    if (!did_init) DrawingPanelInit();
 }
 
 GLDrawingPanel::~GLDrawingPanel()
@@ -2211,7 +2224,7 @@ GLDrawingPanel::~GLDrawingPanel()
     // it's also unsafe if panel no longer displayed
     if (did_init)
     {
-        SetCurrent();
+        SetContext();
         glDeleteLists(vlist, 1);
         glDeleteTextures(1, &texid);
     }
@@ -2223,7 +2236,7 @@ GLDrawingPanel::~GLDrawingPanel()
 
 void GLDrawingPanel::DrawingPanelInit()
 {
-    SetCurrent();
+    SetContext();
 
     DrawingPanelBase::DrawingPanelInit();
 
@@ -2361,7 +2374,6 @@ void GLDrawingPanel::DrawingPanelInit()
 
 void GLDrawingPanel::OnSize(wxSizeEvent& ev)
 {
-    SetCurrent();
     AdjustViewport();
 
     // Temporary hack to backport 800d6ed69b from wxWidgets until 3.2.2 is released.
@@ -2373,7 +2385,7 @@ void GLDrawingPanel::OnSize(wxSizeEvent& ev)
 
 void GLDrawingPanel::AdjustViewport()
 {
-    SetCurrent();
+    SetContext();
 
     int x, y;
     widgets::GetRealPixelClientSize(this, &x, &y);
@@ -2387,10 +2399,20 @@ void GLDrawingPanel::AdjustViewport()
 #endif
 }
 
+void GLDrawingPanel::RefreshGL()
+{
+    SetContext();
+
+    // Rebind any textures or other OpenGL resources here
+
+    glBindTexture(GL_TEXTURE_2D, texid);
+}
+
 void GLDrawingPanel::DrawArea(wxWindowDC& dc)
 {
     (void)dc; // unused params
-    SetCurrent();
+    SetContext();
+    RefreshGL();
 
     if (!did_init)
         DrawingPanelInit();