tdf#127529 vertical text not drawn in slideshow canvas

because the canvas text drawing impl falls back to using an OutputDevice view
of the canvas to use the vcl text drawing apis to achieve vertical text

To get an OutputDevice view of the canvas there is a specific VirtualDevice
ctor available to create a VirtualDevice that, unlike the normal case, doesn't
have its own specific backing buffer, but instead draws to the underlying target
provided via the SystemGraphicsData arg

The svp/gtk impl missed that understanding and provided an ordinary
VirtualDevice with its own backing buffer, not a VirtualDevice that would draw
to the expected target surface of the canvas. So the vertical text was drawn to
a different surface than the intended one, and was just discarded.

The cairo use in the canvas long precedes the use of cairo in vcl itself.

Seeing as text is now rendered with cairo in all cases where the canvas uses
cairo its probably now pointless for canvas to have its own text rendering
path.

Change-Id: Ie3b0a43ca2b746cbfe25e2d0415315b3d5403cd2
Reviewed-on: https://gerrit.libreoffice.org/80162
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

9 files changed, 75 insertions, 24 deletions

diff --git a/include/vcl/sysdata.hxx b/include/vcl/sysdata.hxx
index 28f991db4878..722c223f5e19 100644
--- a/include/vcl/sysdata.hxx
+++ b/include/vcl/sysdata.hxx
@@ -143,7 +143,8 @@ struct SystemGraphicsData
     long            hDrawable;      // a drawable
     void*           pVisual;        // the visual in use
     int             nScreen;        // the current screen of the drawable
-    void*           pXRenderFormat;  // render format for drawable
+    void*           pXRenderFormat; // render format for drawable
+    void*           pSurface;       // the cairo surface when using svp-based backends
 #endif
     SystemGraphicsData()
         : nSize( sizeof( SystemGraphicsData ) )
@@ -162,6 +163,7 @@ struct SystemGraphicsData
         , pVisual( nullptr )
         , nScreen( 0 )
         , pXRenderFormat( nullptr )
+        , pSurface( nullptr )
 #endif
     { }
 };
diff --git a/vcl/headless/svpinst.cxx b/vcl/headless/svpinst.cxx
index 2070f68e1663..6b415d39135f 100644
--- a/vcl/headless/svpinst.cxx
+++ b/vcl/headless/svpinst.cxx
@@ -240,14 +240,18 @@ void SvpSalInstance::DestroyObject( SalObject* pObject )
 
 #ifndef IOS
 
-std::unique_ptr<SalVirtualDevice> SvpSalInstance::CreateVirtualDevice( SalGraphics* pGraphics,
+std::unique_ptr<SalVirtualDevice> SvpSalInstance::CreateVirtualDevice(SalGraphics* pGraphics,
                                                        long &nDX, long &nDY,
                                                        DeviceFormat eFormat,
-                                                       const SystemGraphicsData* /* pData */ )
+                                                       const SystemGraphicsData* pGd)
 {
     SvpSalGraphics *pSvpSalGraphics = dynamic_cast<SvpSalGraphics*>(pGraphics);
     assert(pSvpSalGraphics);
-    std::unique_ptr<SalVirtualDevice> pNew(new SvpSalVirtualDevice(eFormat, pSvpSalGraphics->getSurface()));
+    // tdf#127529 normally pPreExistingTarget is null and we are a true virtualdevice drawing to a backing buffer.
+    // Occasionally, for canvas/slideshow, pPreExistingTarget is pre-provided as a hack to use the vcl drawing
+    // apis to render onto a preexisting cairo surface. The necessity for that precedes the use of cairo in vcl proper
+    cairo_surface_t* pPreExistingTarget = pGd ? static_cast<cairo_surface_t*>(pGd->pSurface) : nullptr;
+    std::unique_ptr<SalVirtualDevice> pNew(new SvpSalVirtualDevice(eFormat, pSvpSalGraphics->getSurface(), pPreExistingTarget));
     pNew->SetSize( nDX, nDY );
     return pNew;
 }
diff --git a/vcl/headless/svpvd.cxx b/vcl/headless/svpvd.cxx
index 686587f9deab..70ac5785ec71 100644
--- a/vcl/headless/svpvd.cxx
+++ b/vcl/headless/svpvd.cxx
@@ -31,17 +31,19 @@
 
 using namespace basegfx;
 
-SvpSalVirtualDevice::SvpSalVirtualDevice(DeviceFormat eFormat, cairo_surface_t* pRefSurface)
+SvpSalVirtualDevice::SvpSalVirtualDevice(DeviceFormat eFormat, cairo_surface_t* pRefSurface, cairo_surface_t* pPreExistingTarget)
     : m_eFormat(eFormat)
     , m_pRefSurface(pRefSurface)
-    , m_pSurface(nullptr)
+    , m_pSurface(pPreExistingTarget)
+    , m_bOwnsSurface(!pPreExistingTarget)
 {
     cairo_surface_reference(m_pRefSurface);
 }
 
 SvpSalVirtualDevice::~SvpSalVirtualDevice()
 {
-    cairo_surface_destroy(m_pSurface);
+    if (m_bOwnsSurface)
+        cairo_surface_destroy(m_pSurface);
     cairo_surface_destroy(m_pRefSurface);
 }
 
@@ -70,8 +72,6 @@ bool SvpSalVirtualDevice::SetSize( long nNewDX, long nNewDY )
 
 void SvpSalVirtualDevice::CreateSurface(long nNewDX, long nNewDY, sal_uInt8 *const pBuffer)
 {
-    m_aFrameSize = basegfx::B2IVector(nNewDX, nNewDY);
-
     if (m_pSurface)
     {
         cairo_surface_destroy(m_pSurface);
@@ -121,7 +121,10 @@ bool SvpSalVirtualDevice::SetSizeUsingBuffer( long nNewDX, long nNewDY,
     {
         m_aFrameSize = basegfx::B2IVector(nNewDX, nNewDY);
 
-        CreateSurface(nNewDX, nNewDY, pBuffer);
+        if (m_bOwnsSurface)
+            CreateSurface(nNewDX, nNewDY, pBuffer);
+
+        assert(m_pSurface);
 
         // update device in existing graphics
         for (auto const& graphic : m_aGraphics)
diff --git a/vcl/inc/headless/svpvd.hxx b/vcl/inc/headless/svpvd.hxx
index b069c63286d1..9f83026c77db 100644
--- a/vcl/inc/headless/svpvd.hxx
+++ b/vcl/inc/headless/svpvd.hxx
@@ -34,6 +34,7 @@ class VCL_DLLPUBLIC SvpSalVirtualDevice : public SalVirtualDevice
     DeviceFormat const                  m_eFormat;
     cairo_surface_t* const              m_pRefSurface;
     cairo_surface_t*                    m_pSurface;
+    bool                                m_bOwnsSurface; // nearly always true, except for edge case of tdf#127529
     basegfx::B2IVector                  m_aFrameSize;
     std::vector< SvpSalGraphics* >      m_aGraphics;
 
@@ -43,7 +44,7 @@ protected:
     SvpSalGraphics* AddGraphics(SvpSalGraphics* aGraphics);
 
 public:
-    SvpSalVirtualDevice(DeviceFormat eFormat, cairo_surface_t* pRefSurface);
+    SvpSalVirtualDevice(DeviceFormat eFormat, cairo_surface_t* pRefSurface, cairo_surface_t* pPreExistingTarget);
     virtual ~SvpSalVirtualDevice() override;
 
     // SalVirtualDevice
diff --git a/vcl/qt5/Qt5Instance.cxx b/vcl/qt5/Qt5Instance.cxx
index 64481b64108e..129eb8e5c221 100644
--- a/vcl/qt5/Qt5Instance.cxx
+++ b/vcl/qt5/Qt5Instance.cxx
@@ -288,16 +288,20 @@ void Qt5Instance::DestroyObject(SalObject* pObject)
     }
 }
 
-std::unique_ptr<SalVirtualDevice>
-Qt5Instance::CreateVirtualDevice(SalGraphics* pGraphics, long& nDX, long& nDY, DeviceFormat eFormat,
-                                 const SystemGraphicsData* /* pData */)
+std::unique_ptr<SalVirtualDevice> Qt5Instance::CreateVirtualDevice(SalGraphics* pGraphics,
+                                                                   long& nDX, long& nDY,
+                                                                   DeviceFormat eFormat,
+                                                                   const SystemGraphicsData* pGd)
 {
     if (m_bUseCairo)
     {
         SvpSalGraphics* pSvpSalGraphics = dynamic_cast<Qt5SvpGraphics*>(pGraphics);
         assert(pSvpSalGraphics);
+        // tdf#127529 see SvpSalInstance::CreateVirtualDevice for the rare case of a non-null pPreExistingTarget
+        cairo_surface_t* pPreExistingTarget
+            = pGd ? static_cast<cairo_surface_t*>(pGd->pSurface) : nullptr;
         std::unique_ptr<SalVirtualDevice> pVD(
-            new Qt5SvpVirtualDevice(eFormat, pSvpSalGraphics->getSurface()));
+            new Qt5SvpVirtualDevice(eFormat, pSvpSalGraphics->getSurface(), pPreExistingTarget));
         pVD->SetSize(nDX, nDY);
         return pVD;
     }
diff --git a/vcl/qt5/Qt5SvpSurface.cxx b/vcl/qt5/Qt5SvpSurface.cxx
index 3e300755a992..21e0ca03b5b2 100644
--- a/vcl/qt5/Qt5SvpSurface.cxx
+++ b/vcl/qt5/Qt5SvpSurface.cxx
@@ -19,6 +19,18 @@
 #include <vcl/window.hxx>
 #include <basegfx/vector/b2isize.hxx>
 
+namespace
+{
+Size get_surface_size(cairo_surface_t* surface)
+{
+    cairo_t* cr = cairo_create(surface);
+    double x1, x2, y1, y2;
+    cairo_clip_extents(cr, &x1, &y1, &x2, &y2);
+    cairo_destroy(cr);
+    return Size(x2 - x1, y2 - y1);
+}
+}
+
 namespace cairo
 {
 Qt5SvpSurface::Qt5SvpSurface(const CairoSurfaceSharedPtr& pSurface)
@@ -65,8 +77,13 @@ void Qt5SvpSurface::flush() const
 
 VclPtr<VirtualDevice> Qt5SvpSurface::createVirtualDevice() const
 {
-    //TODO allow creating a VirtualDevice to draw to the current surface
-    return VclPtrInstance<VirtualDevice>(DeviceFormat::DEFAULT);
+    SystemGraphicsData aSystemGraphicsData;
+
+    aSystemGraphicsData.nSize = sizeof(SystemGraphicsData);
+    aSystemGraphicsData.pSurface = m_pSurface.get();
+
+    return VclPtr<VirtualDevice>::Create(aSystemGraphicsData, get_surface_size(m_pSurface.get()),
+                                         DeviceFormat::DEFAULT);
 }
 
 } // namespace cairo
diff --git a/vcl/qt5/Qt5SvpVirtualDevice.hxx b/vcl/qt5/Qt5SvpVirtualDevice.hxx
index 75c446bafb33..0eb4ed26ed2f 100644
--- a/vcl/qt5/Qt5SvpVirtualDevice.hxx
+++ b/vcl/qt5/Qt5SvpVirtualDevice.hxx
@@ -25,8 +25,9 @@
 class VCL_DLLPUBLIC Qt5SvpVirtualDevice : public SvpSalVirtualDevice
 {
 public:
-    Qt5SvpVirtualDevice(DeviceFormat eFormat, cairo_surface_t* pRefSurface)
-        : SvpSalVirtualDevice(eFormat, pRefSurface)
+    Qt5SvpVirtualDevice(DeviceFormat eFormat, cairo_surface_t* pRefSurface,
+                        cairo_surface_t* pPreExistingTarget)
+        : SvpSalVirtualDevice(eFormat, pRefSurface, pPreExistingTarget)
     {
     }
 
diff --git a/vcl/unx/gtk3/cairo_gtk3_cairo.cxx b/vcl/unx/gtk3/cairo_gtk3_cairo.cxx
index 9b273ea16cf5..5f0e0b7a136f 100644
--- a/vcl/unx/gtk3/cairo_gtk3_cairo.cxx
+++ b/vcl/unx/gtk3/cairo_gtk3_cairo.cxx
@@ -19,6 +19,18 @@
 
 #include <unx/gtk/gtkgdi.hxx>
 
+namespace
+{
+    Size get_surface_size(cairo_surface_t *surface)
+    {
+        cairo_t *cr = cairo_create(surface);
+        double x1, x2, y1, y2;
+        cairo_clip_extents(cr, &x1, &y1, &x2, &y2);
+        cairo_destroy(cr);
+        return Size(x2 - x1, y2 - y1);
+    }
+}
+
 namespace cairo
 {
     /**
@@ -108,10 +120,15 @@ namespace cairo
 
     VclPtr<VirtualDevice> Gtk3Surface::createVirtualDevice() const
     {
-        //TODO allow creating a VirtualDevice to draw to the current surface
-        return VclPtrInstance<VirtualDevice>(DeviceFormat::DEFAULT);
-    }
+        SystemGraphicsData aSystemGraphicsData;
 
+        aSystemGraphicsData.nSize = sizeof(SystemGraphicsData);
+        aSystemGraphicsData.pSurface = mpSurface.get();
+
+        return VclPtr<VirtualDevice>::Create(aSystemGraphicsData,
+                              get_surface_size(mpSurface.get()),
+                              DeviceFormat::DEFAULT);
+    }
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/unx/gtk3/gtk3gtkinst.cxx b/vcl/unx/gtk3/gtk3gtkinst.cxx
index 544145d906dc..fd8db4675ff3 100644
--- a/vcl/unx/gtk3/gtk3gtkinst.cxx
+++ b/vcl/unx/gtk3/gtk3gtkinst.cxx
@@ -322,12 +322,14 @@ void GtkYieldMutex::ThreadsLeave()
 std::unique_ptr<SalVirtualDevice> GtkInstance::CreateVirtualDevice( SalGraphics *pG,
                                                     long &nDX, long &nDY,
                                                     DeviceFormat eFormat,
-                                                    const SystemGraphicsData* /*pGd*/ )
+                                                    const SystemGraphicsData* pGd )
 {
     EnsureInit();
     SvpSalGraphics *pSvpSalGraphics = dynamic_cast<SvpSalGraphics*>(pG);
     assert(pSvpSalGraphics);
-    std::unique_ptr<SalVirtualDevice> pNew(new SvpSalVirtualDevice(eFormat, pSvpSalGraphics->getSurface()));
+    // tdf#127529 see SvpSalInstance::CreateVirtualDevice for the rare case of a non-null pPreExistingTarget
+    cairo_surface_t* pPreExistingTarget = pGd ? static_cast<cairo_surface_t*>(pGd->pSurface) : nullptr;
+    std::unique_ptr<SalVirtualDevice> pNew(new SvpSalVirtualDevice(eFormat, pSvpSalGraphics->getSurface(), pPreExistingTarget));
     pNew->SetSize( nDX, nDY );
     return pNew;
 }