[chronojump] CairoGeneric handles better disposing of surface

[Xavier de Blas <xaviblas src gnome org>]

commit 02f355c3d4d91fe9954bf11f9618e7505605b4ea
Author: Xavier de Blas <xaviblas gmail com>
Date:   Tue Mar 15 16:42:48 2022 +0100

    CairoGeneric handles better disposing of surface

 src/gui/cairo/generic.cs | 40 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 37 insertions(+), 3 deletions(-)
---
diff --git a/src/gui/cairo/generic.cs b/src/gui/cairo/generic.cs
index aea47e7b1..15e487f77 100644
--- a/src/gui/cairo/generic.cs
+++ b/src/gui/cairo/generic.cs
@@ -51,18 +51,19 @@ public abstract class CairoGeneric
                https://www.mono-project.com/docs/tools+libraries/libraries/Mono.Cairo/
                eg. on Linux can do the writeCoordinatesOfMouseClick() without disposing, but on win and mac 
does not work, so dispose always.
         */
-
+       /*
+          debug cairo disposing problems calling Chronojump like this:
+          MONO_CAIRO_DEBUG_DISPOSE=1 chronojump
+          */
        protected void endGraphDisposing(Cairo.Context g, ImageSurface surface, Gdk.Window window)
        {
                if(surface != null)
                {
-                       //using (Context gArea = Gdk.CairoHelper.Create (area.GdkWindow))
                        using (Context gArea = Gdk.CairoHelper.Create (window))
                        {
                                gArea.SetSource (surface);
                                gArea.Paint ();
 
-                               surface.Dispose();
                                gArea.GetTarget().Dispose ();
                                gArea.Dispose ();
                        }
@@ -70,6 +71,12 @@ public abstract class CairoGeneric
 
                g.GetTarget().Dispose ();
                g.Dispose ();
+
+               if(surface != null)
+               {
+                       surface.Dispose(); //dispose surface here when all the attached stuff has been 
disposed
+                       //hardDisposeSurface(surface); //aixo diu 1
+               }
        }
        protected void endGraphDisposing(Cairo.Context g)
        {
@@ -77,6 +84,33 @@ public abstract class CairoGeneric
                g.Dispose ();
        }
 
+       /*
+          https://www.debugcn.com/en/article/59607062.html
+          but unused, the problem was finishing the DoSendingList with a return without a previous 
endGraphDisposing
+          fixed forcing it: see raceAnalyzer and encoder
+       private static void hardDisposeSurface (Surface surface)
+       {
+               var handle = surface.Handle;
+               long refCount = surface.ReferenceCount;
+               LogB.Information("hardDisposeSurface refCount pre: " + refCount.ToString());
+               surface.Dispose ();
+               refCount--;
+               if (refCount <= 0)
+                       return;
+
+               var asm = typeof (Surface).Assembly;
+               var nativeMethods = asm.GetType ("Cairo.NativeMethods");
+               var surfaceDestroy = nativeMethods.GetMethod ("cairo_surface_destroy",
+                               System.Reflection.BindingFlags.Static | 
System.Reflection.BindingFlags.NonPublic);
+               try {
+                       for (long i = refCount; i > 0; i--)
+                               surfaceDestroy.Invoke (null, new object [] { handle });
+               } catch {
+                       LogB.Information("catched on hardDisposeSurface");
+               }
+       }
+       */
+
        //0 - 255
        protected static Cairo.Color colorFromRGB(int red, int green, int blue)
        {