keep just one shared reference to Skia shared GrContext

This should make it easier to keep the reference without having
to keep references all over the place, especially when the shared GrContext
starts to be used also for GPU-backed surfaces elsewhere.

Change-Id: Icf3f6eb849ebc5eb63b1836f9caeb6f5e5e58ca6
Reviewed-on: https://gerrit.libreoffice.org/84560
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

8 files changed, 119 insertions, 36 deletions

diff --git a/include/vcl/skia/SkiaHelper.hxx b/include/vcl/skia/SkiaHelper.hxx
index d27cffd650f3..8cb76c653600 100644
--- a/include/vcl/skia/SkiaHelper.hxx
+++ b/include/vcl/skia/SkiaHelper.hxx
@@ -14,26 +14,28 @@
 
 #include <config_features.h>
 
-// All member functions static and VCL_DLLPUBLIC. Basically a glorified namespace.
-struct VCL_DLLPUBLIC SkiaHelper
+namespace SkiaHelper
 {
-    SkiaHelper() = delete; // Should not be instantiated
-
-public:
-    static bool isVCLSkiaEnabled();
+VCL_DLLPUBLIC bool isVCLSkiaEnabled();
 
 #if HAVE_FEATURE_SKIA
-    // Which Skia backend to use.
-    enum RenderMethod
-    {
-        RenderRaster,
-        RenderVulkan
-    };
-    static RenderMethod renderMethodToUse();
-    static void disableRenderMethod(RenderMethod method);
-#endif
+
+// Which Skia backend to use.
+enum RenderMethod
+{
+    RenderRaster,
+    RenderVulkan
 };
 
-#endif
+VCL_DLLPUBLIC RenderMethod renderMethodToUse();
+
+// Clean up before exit.
+VCL_DLLPUBLIC void cleanup();
+
+#endif // HAVE_FEATURE_SKIA
+
+} // namespace
+
+#endif // INCLUDED_VCL_SKIA_SKIAHELPER_HXX
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/inc/skia/gdiimpl.hxx b/vcl/inc/skia/gdiimpl.hxx
index e61ee6cfb787..7365d58f9173 100644
--- a/vcl/inc/skia/gdiimpl.hxx
+++ b/vcl/inc/skia/gdiimpl.hxx
@@ -28,7 +28,7 @@
 #include <SkSurface.h>
 
 #include <prewin.h>
-#include <tools/sk_app/VulkanWindowContext.h>
+#include <tools/sk_app/WindowContext.h>
 #include <postwin.h>
 
 class SkiaFlushIdle;
@@ -263,7 +263,6 @@ protected:
     /// Pointer to the SalFrame or SalVirtualDevice
     SalGeometryProvider* mProvider;
     std::unique_ptr<sk_app::WindowContext> mWindowContext;
-    sk_app::VulkanWindowContext::SharedGrContext mOffscreenGrContext;
     // The Skia surface that is target of all the rendering.
     sk_sp<SkSurface> mSurface;
     bool mIsGPU; // whether the surface is GPU-backed
diff --git a/vcl/inc/skia/salbmp.hxx b/vcl/inc/skia/salbmp.hxx
index ed0f374162d6..0b0e1aa5439c 100644
--- a/vcl/inc/skia/salbmp.hxx
+++ b/vcl/inc/skia/salbmp.hxx
@@ -101,6 +101,6 @@ private:
     int mScanlineSize; // size of one row in mBuffer
 };
 
-#endif // INCLUDED_VCL_INC_OPENGL_SALBMP_H
+#endif // INCLUDED_VCL_INC_SKIA_SALBMP_H
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/inc/skia/utils.hxx b/vcl/inc/skia/utils.hxx
new file mode 100644
index 000000000000..5d824400030a
--- /dev/null
+++ b/vcl/inc/skia/utils.hxx
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#ifndef INCLUDED_VCL_INC_SKIA_UTILS_H
+#define INCLUDED_VCL_INC_SKIA_UTILS_H
+
+#include <vcl/skia/SkiaHelper.hxx>
+
+#include <tools/sk_app/VulkanWindowContext.h>
+
+namespace SkiaHelper
+{
+// Get the one shared GrContext instance.
+GrContext* getSharedGrContext();
+
+void disableRenderMethod(RenderMethod method);
+
+} // namespace
+
+#endif // INCLUDED_VCL_INC_SKIA_UTILS_H
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/SkiaHelper.cxx b/vcl/skia/SkiaHelper.cxx
index 040f189be74f..471d47f01f69 100644
--- a/vcl/skia/SkiaHelper.cxx
+++ b/vcl/skia/SkiaHelper.cxx
@@ -14,10 +14,21 @@
 #include <officecfg/Office/Common.hxx>
 
 #if !HAVE_FEATURE_SKIA
-bool SkiaHelper::isVCLSkiaEnabled() { return false; }
+
+namespace SkiaHelper
+{
+bool isVCLSkiaEnabled() { return false; }
+
+} // namespace
 
 #else
 
+#include <skia/utils.hxx>
+
+#include <tools/sk_app/VulkanWindowContext.h>
+
+namespace SkiaHelper
+{
 static bool supportsVCLSkia()
 {
     static bool bDisableSkia = !!getenv("SAL_DISABLESKIA");
@@ -26,7 +37,7 @@ static bool supportsVCLSkia()
     return !bDisableSkia && !bBlacklisted;
 }
 
-bool SkiaHelper::isVCLSkiaEnabled()
+bool isVCLSkiaEnabled()
 {
     /**
      * The !bSet part should only be called once! Changing the results in the same
@@ -84,7 +95,7 @@ bool SkiaHelper::isVCLSkiaEnabled()
     return bRet;
 }
 
-static SkiaHelper::RenderMethod methodToUse = SkiaHelper::RenderRaster;
+static RenderMethod methodToUse = RenderRaster;
 
 static bool initRenderMethodToUse()
 {
@@ -92,15 +103,15 @@ static bool initRenderMethodToUse()
     {
         if (strcmp(env, "raster") == 0)
         {
-            methodToUse = SkiaHelper::RenderRaster;
+            methodToUse = RenderRaster;
             return true;
         }
     }
-    methodToUse = SkiaHelper::RenderVulkan;
+    methodToUse = RenderVulkan;
     return true;
 }
 
-SkiaHelper::RenderMethod SkiaHelper::renderMethodToUse()
+RenderMethod renderMethodToUse()
 {
     static bool methodToUseInited = initRenderMethodToUse();
     if (methodToUseInited) // Used just to ensure thread-safe one-time init.
@@ -108,7 +119,7 @@ SkiaHelper::RenderMethod SkiaHelper::renderMethodToUse()
     abort();
 }
 
-void SkiaHelper::disableRenderMethod(RenderMethod method)
+void disableRenderMethod(RenderMethod method)
 {
     if (renderMethodToUse() != method)
         return;
@@ -116,6 +127,38 @@ void SkiaHelper::disableRenderMethod(RenderMethod method)
     methodToUse = RenderRaster;
 }
 
+static sk_app::VulkanWindowContext::SharedGrContext* sharedGrContext;
+
+GrContext* getSharedGrContext()
+{
+    assert(renderMethodToUse() == RenderVulkan);
+    if (sharedGrContext)
+        return sharedGrContext->getGrContext();
+    // TODO mutex?
+    // Setup the shared GrContext from Skia's (patched) VulkanWindowContext, if it's been
+    // already set up.
+    sk_app::VulkanWindowContext::SharedGrContext context
+        = sk_app::VulkanWindowContext::getSharedGrContext();
+    GrContext* grContext = context.getGrContext();
+    if (grContext)
+    {
+        sharedGrContext = new sk_app::VulkanWindowContext::SharedGrContext(context);
+        return grContext;
+    }
+    // TODO
+    // SkiaSalGraphicsImpl::createOffscreenSurface() creates the shared context using a dummy window,
+    // but we do not have a window here. Is it worth it to try to do it here?
+    return nullptr;
+}
+
+void cleanup()
+{
+    delete sharedGrContext;
+    sharedGrContext = nullptr;
+}
+
+} // namespace
+
 #endif // HAVE_FEATURE_SKIA
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/gdiimpl.cxx b/vcl/skia/gdiimpl.cxx
index 9c8d7c497ba2..6a977ab6b598 100644
--- a/vcl/skia/gdiimpl.cxx
+++ b/vcl/skia/gdiimpl.cxx
@@ -25,6 +25,7 @@
 #include <vcl/svapp.hxx>
 #include <vcl/lazydelete.hxx>
 #include <vcl/skia/SkiaHelper.hxx>
+#include <skia/utils.hxx>
 
 #include <SkCanvas.h>
 #include <SkPath.h>
@@ -182,7 +183,6 @@ SkiaSalGraphicsImpl::~SkiaSalGraphicsImpl()
 {
     assert(!mSurface);
     assert(!mWindowContext);
-    assert(!mOffscreenGrContext);
 }
 
 void SkiaSalGraphicsImpl::Init() {}
@@ -243,8 +243,7 @@ void SkiaSalGraphicsImpl::createOffscreenSurface()
     {
         case SkiaHelper::RenderVulkan:
         {
-            mOffscreenGrContext = sk_app::VulkanWindowContext::getSharedGrContext();
-            GrContext* grContext = mOffscreenGrContext.getGrContext();
+            GrContext* grContext = SkiaHelper::getSharedGrContext();
             // We may not get a GrContext if called before any onscreen window is created.
             if (!grContext)
             {
@@ -253,14 +252,10 @@ void SkiaSalGraphicsImpl::createOffscreenSurface()
                 // Create temporary WindowContext with no window. That will fail,
                 // but it will initialize the shared GrContext.
                 createWindowContext();
-                // Keep a reference.
-                sk_app::VulkanWindowContext::SharedGrContext context
-                    = sk_app::VulkanWindowContext::getSharedGrContext();
+                // This will use the temporarily created context.
+                grContext = SkiaHelper::getSharedGrContext();
                 // Destroy the temporary WindowContext.
                 destroySurface();
-                // Keep a reference until the surface is destroyed.
-                mOffscreenGrContext = context;
-                grContext = mOffscreenGrContext.getGrContext();
             }
             if (grContext)
             {
@@ -309,7 +304,6 @@ void SkiaSalGraphicsImpl::destroySurface()
     mSurface.reset();
     mWindowContext.reset();
     mIsGPU = false;
-    mOffscreenGrContext.reset();
 }
 
 void SkiaSalGraphicsImpl::DeInit() { destroySurface(); }
diff --git a/vcl/unx/generic/app/salinst.cxx b/vcl/unx/generic/app/salinst.cxx
index 3c39a1addbd9..f253f70d7d93 100644
--- a/vcl/unx/generic/app/salinst.cxx
+++ b/vcl/unx/generic/app/salinst.cxx
@@ -79,6 +79,10 @@ X11SalInstance::~X11SalInstance()
     // would be done in a static destructor else which is
     // a little late
     GetGenericUnixSalData()->Dispose();
+
+#if HAVE_FEATURE_SKIA
+    SkiaHelper::cleanup();
+#endif
 }
 
 SalX11Display* X11SalInstance::CreateDisplay() const
diff --git a/vcl/win/app/salinst.cxx b/vcl/win/app/salinst.cxx
index 43cc8e8e6a85..cd9332e0c728 100644
--- a/vcl/win/app/salinst.cxx
+++ b/vcl/win/app/salinst.cxx
@@ -407,6 +407,9 @@ WinSalInstance::~WinSalInstance()
 {
     ImplFreeSalGDI();
     DestroyWindow( mhComWnd );
+#if HAVE_FEATURE_SKIA
+    SkiaHelper::cleanup();
+#endif
 }
 
 static LRESULT ImplSalDispatchMessage( const MSG* pMsg )