From 0709051effbcdeb2513df6f4d2c639ca56296bd4 Mon Sep 17 00:00:00 2001
From: juha <juha@lazarus-ide.org>
Date: Wed, 4 Sep 2013 00:22:36 +0000
Subject: [PATCH] OpenGLControl: Implement release context method. Issue
 #24925, patch from Anton Kavalenka

git-svn-id: trunk@42582 -
---
 components/opengl/glcarbonaglcontext.pas |  6 ++++++
 components/opengl/glgtkglxcontext.pas    | 10 ++++++++++
 components/opengl/glqtcontext.pas        | 15 +++++++++++++++
 components/opengl/glwin32wglcontext.pas  |  6 ++++++
 components/opengl/openglcontext.pas      |  8 ++++++++
 5 files changed, 45 insertions(+)

diff --git a/components/opengl/glcarbonaglcontext.pas b/components/opengl/glcarbonaglcontext.pas
index 5b631ef498..27d5142851 100644
--- a/components/opengl/glcarbonaglcontext.pas
+++ b/components/opengl/glcarbonaglcontext.pas
@@ -24,6 +24,7 @@ uses
 procedure LOpenGLViewport(Left, Top, Width, Height: integer);
 procedure LOpenGLSwapBuffers(Handle: HWND);
 function LOpenGLMakeCurrent(Handle: HWND): boolean;
+function LOpenGLReleaseContext(Handle: HWND): boolean;
 procedure LOpenGLClip(Handle: HWND);
 function LOpenGLCreateContext(AWinControl: TWinControl;
               {%H-}WSPrivate: TWSPrivateClass; SharedControl: TWinControl;
@@ -82,6 +83,11 @@ begin
   Result:=aglSetCurrentContext(AGLContext)<>0;
 end;
 
+function LOpenGLReleaseContext(Handle: HWND): boolean;
+begin
+  Result := aglSetCurrentContext(nil)<>GL_FALSE;
+end;
+
 procedure LOpenGLClip(Handle: HWND);
 var
   AGLContext: TAGLContext;
diff --git a/components/opengl/glgtkglxcontext.pas b/components/opengl/glgtkglxcontext.pas
index 2b7d019c46..bd38b1c324 100644
--- a/components/opengl/glgtkglxcontext.pas
+++ b/components/opengl/glgtkglxcontext.pas
@@ -157,6 +157,7 @@ function gdk_x11_get_default_screen:gint;cdecl;external;
 procedure LOpenGLViewport(Left, Top, Width, Height: integer);
 procedure LOpenGLSwapBuffers(Handle: HWND);
 function LOpenGLMakeCurrent(Handle: HWND): boolean;
+function LOpenGLReleaseContext(Handle: HWND): boolean;
 function LOpenGLCreateContext(AWinControl: TWinControl;
              WSPrivate: TWSPrivateClass; SharedControl: TWinControl;
              DoubleBuffered, RGBA: boolean;
@@ -907,6 +908,15 @@ begin
   Result:=gtk_gl_area_make_current(glarea);
 end;
 
+function LOpenGLReleaseContext(Handle: HWND): boolean;
+var pd:PDIsplay;
+begin
+  Result := false;
+  pd := glXGetCurrentDisplay();
+  if Assigned(pd) then
+  Result := glXMakeCurrent(pd, 0, nil);
+end;
+
 {$IFDEF LCLGtk2}
 function gtkglarea_size_allocateCB(Widget: PGtkWidget; Size: pGtkAllocation;
   Data: gPointer): GBoolean; cdecl;
diff --git a/components/opengl/glqtcontext.pas b/components/opengl/glqtcontext.pas
index f601c95a6d..c0a8e85f25 100644
--- a/components/opengl/glqtcontext.pas
+++ b/components/opengl/glqtcontext.pas
@@ -62,6 +62,7 @@ type
 procedure LOpenGLViewport(Left, Top, Width, Height: integer);
 procedure LOpenGLSwapBuffers(Handle: HWND);
 function LOpenGLMakeCurrent(Handle: HWND): boolean;
+function LOpenGLReleaseContext(Handle: HWND): boolean;
 function LOpenGLCreateContext(AWinControl: TWinControl;
              WSPrivate: TWSPrivateClass; SharedControl: TWinControl;
              DoubleBuffered, RGBA: boolean;
@@ -177,6 +178,20 @@ begin
                                  Widget.glxcontext));
 end;
 
+function LOpenGLReleaseContext(Handle: HWND): boolean;
+var
+  Widget: TQtGLWidget;
+begin
+  Result := false;
+  if Handle=0 then
+    RaiseGDBException('LOpenGLSwapBuffers Handle=0');
+
+  Widget:=TQtGLWidget(Handle);
+  Result := glXMakeCurrent(Widget.xdisplay, 0, nil);
+end;
+
+end;
+
 function LOpenGLCreateContext(AWinControl: TWinControl;
   WSPrivate: TWSPrivateClass; SharedControl: TWinControl;
   DoubleBuffered, RGBA: boolean;
diff --git a/components/opengl/glwin32wglcontext.pas b/components/opengl/glwin32wglcontext.pas
index 711e7f2e30..793ef73bcd 100644
--- a/components/opengl/glwin32wglcontext.pas
+++ b/components/opengl/glwin32wglcontext.pas
@@ -20,6 +20,7 @@ uses
 procedure LOpenGLViewport(Left, Top, Width, Height: integer);
 procedure LOpenGLSwapBuffers(Handle: HWND);
 function LOpenGLMakeCurrent(Handle: HWND): boolean;
+function LOpenGLReleaseContext(Handle: HWND): boolean;
 function LOpenGLCreateContext(AWinControl: TWinControl;
                     WSPrivate: TWSPrivateClass; SharedControl: TWinControl;
                     DoubleBuffered, RGBA: boolean;
@@ -246,6 +247,11 @@ begin
   Result:=wglMakeCurrent(Info^.DC,Info^.WGLContext);
 end;
 
+function LOpenGLReleaseContext(Handle: HWND): boolean;
+begin
+  Result:=wglMakeCurrent(0,0);
+end;
+
 function GlWindowProc(Window: HWnd; Msg: UInt; WParam: Windows.WParam;
     LParam: Windows.LParam): LResult; stdcall;
 var
diff --git a/components/opengl/openglcontext.pas b/components/opengl/openglcontext.pas
index 646d609a80..99916c3150 100644
--- a/components/opengl/openglcontext.pas
+++ b/components/opengl/openglcontext.pas
@@ -148,6 +148,7 @@ type
     procedure DoOnPaint; virtual;
     procedure SwapBuffers; virtual;
     function MakeCurrent(SaveOldToStack: boolean = false): boolean; virtual;
+    function ReleaseContext: boolean; virtual;
     function RestoreOldOpenGLControl: boolean;
     function SharingControlCount: integer;
     property SharingControls[Index: integer]: TCustomOpenGLControl read GetSharingControls;
@@ -548,6 +549,13 @@ begin
   end;
 end;
 
+function TCustomOpenGLControl.ReleaseContext: boolean;
+begin
+  Result:=false;
+  if not HandleAllocated then exit;
+  Result:=LOpenGLReleaseContext(Handle);
+end;
+
 function TCustomOpenGLControl.RestoreOldOpenGLControl: boolean;
 var
   RestoredControl: TCustomOpenGLControl;