support rendering a widget snapshot to an OutputDevice

Change-Id: I7beecd8f9579d5ae4b60a839f4a71c3238e0666d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/94645
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>

3 files changed, 48 insertions, 0 deletions

diff --git a/vcl/inc/salvtables.hxx b/vcl/inc/salvtables.hxx
index 6cc85731952e..86b9d0aec5bf 100644
--- a/vcl/inc/salvtables.hxx
+++ b/vcl/inc/salvtables.hxx
@@ -390,6 +390,8 @@ public:
 
     virtual void set_highlight_background() override;
 
+    virtual void draw(VirtualDevice& rOutput) override;
+
     SystemWindow* getSystemWindow();
 };
 
diff --git a/vcl/source/app/salvtables.cxx b/vcl/source/app/salvtables.cxx
index b3c9d2cfb77d..67cb4fad45e1 100644
--- a/vcl/source/app/salvtables.cxx
+++ b/vcl/source/app/salvtables.cxx
@@ -1135,6 +1135,12 @@ std::unique_ptr<weld::Container> SalInstanceWidget::weld_parent() const
     return std::make_unique<SalInstanceContainer>(pParent, m_pBuilder, false);
 }
 
+void SalInstanceWidget::draw(VirtualDevice& rOutput)
+{
+    rOutput.SetOutputSizePixel(m_xWidget->GetSizePixel());
+    m_xWidget->PaintToDevice(&rOutput, Point());
+}
+
 namespace
 {
 class SalInstanceBox : public SalInstanceContainer, public virtual weld::Box
diff --git a/vcl/unx/gtk3/gtk3gtkinst.cxx b/vcl/unx/gtk3/gtk3gtkinst.cxx
index 530a115bd96b..16b2a1ae1d7c 100644
--- a/vcl/unx/gtk3/gtk3gtkinst.cxx
+++ b/vcl/unx/gtk3/gtk3gtkinst.cxx
@@ -3065,6 +3065,46 @@ public:
         xRet->SetBackground(COL_TRANSPARENT);
         return xRet;
     }
+
+    virtual void draw(VirtualDevice& rOutput) override
+    {
+        // detect if we have to manually setup its size
+        bool bAlreadyRealized = gtk_widget_get_realized(m_pWidget);
+        // has to be visible for draw to work
+        bool bAlreadyVisible = gtk_widget_get_visible(m_pWidget);
+        // has to be mapped for draw to work
+        bool bAlreadyMapped = gtk_widget_get_mapped(m_pWidget);
+        if (!bAlreadyVisible)
+            gtk_widget_show(m_pWidget);
+
+        GtkAllocation allocation;
+
+        if (!bAlreadyRealized)
+            gtk_widget_realize(m_pWidget);
+
+        if (!bAlreadyMapped)
+            gtk_widget_map(m_pWidget);
+
+        if (GTK_IS_CONTAINER(m_pWidget))
+            gtk_container_resize_children(GTK_CONTAINER(m_pWidget));
+
+        gtk_widget_get_allocation(m_pWidget, &allocation);
+
+        rOutput.SetOutputSizePixel(Size(allocation.width, allocation.height));
+        cairo_surface_t* pSurface = get_underlying_cairo_surface(rOutput);
+        cairo_t* cr = cairo_create(pSurface);
+
+        gtk_widget_draw(m_pWidget, cr);
+
+        cairo_destroy(cr);
+
+        if (!bAlreadyVisible)
+            gtk_widget_hide(m_pWidget);
+        if (!bAlreadyMapped)
+            gtk_widget_unmap(m_pWidget);
+        if (!bAlreadyRealized)
+            gtk_widget_unrealize(m_pWidget);
+    }
 };
 
 }