gecko-dev/gfx/layers/ipc/ShadowLayerUtilsX11.cpp

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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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 * The contents of this file are subject to the Mozilla Public License Version
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 * The Initial Developer of the Original Code is
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 * Contributor(s):
 *   Chris Jones <jones.chris.g@gmail.com>
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#include "mozilla/layers/PLayers.h"
#include "mozilla/layers/ShadowLayers.h"
 
#include "gfxPlatform.h"

#include "gfxXlibSurface.h"
#include "mozilla/X11Util.h"

namespace mozilla {
namespace layers {

// Return true if we're likely compositing using X and so should use
// Xlib surfaces in shadow layers.
static PRBool
UsingXCompositing()
{
  return (gfxASurface::SurfaceTypeXlib ==
          gfxPlatform::GetPlatform()->ScreenReferenceSurface()->GetType());
}

// LookReturn a pointer to |aFormat| that lives in the Xrender library.
// All code using render formats assumes it doesn't need to copy.
static XRenderPictFormat*
GetXRenderPictFormatFromId(Display* aDisplay, PictFormat aFormatId)
{
  XRenderPictFormat tmplate;
  tmplate.id = aFormatId;
  return XRenderFindFormat(aDisplay, PictFormatID, &tmplate, 0);
}

static PRBool
TakeAndDestroyXlibSurface(SurfaceDescriptor* aSurface)
{
  nsRefPtr<gfxXlibSurface> surf =
    aSurface->get_SurfaceDescriptorX11().OpenForeign();
  surf->TakePixmap();
  *aSurface = SurfaceDescriptor();
  // the Pixmap is destroyed when |surf| goes out of scope
  return PR_TRUE;
}

SurfaceDescriptorX11::SurfaceDescriptorX11(gfxXlibSurface* aSurf)
  : mId(aSurf->XDrawable())
  , mSize(aSurf->GetSize())
  , mFormat(aSurf->XRenderFormat()->id)
{ }

already_AddRefed<gfxXlibSurface>
SurfaceDescriptorX11::OpenForeign() const
{
  Display* display = DefaultXDisplay();
  Screen* screen = DefaultScreenOfDisplay(display);

  XRenderPictFormat* format = GetXRenderPictFormatFromId(display, mFormat);
  nsRefPtr<gfxXlibSurface> surf =
    new gfxXlibSurface(screen, mId, format, mSize);
  return surf->CairoStatus() ? nsnull : surf.forget();
}

PRBool
ShadowLayerForwarder::PlatformAllocDoubleBuffer(const gfxIntSize& aSize,
                                                gfxASurface::gfxContentType aContent,
                                                SurfaceDescriptor* aFrontBuffer,
                                                SurfaceDescriptor* aBackBuffer)
{
  if (!UsingXCompositing()) {
    // If we're not using X compositing, we're probably compositing on
    // the client side, in which case X surfaces would just slow
    // things down.  Use Shmem instead.
    return PR_FALSE;
  }

  gfxPlatform* platform = gfxPlatform::GetPlatform();
  nsRefPtr<gfxASurface> front = platform->CreateOffscreenSurface(aSize, aContent);
  nsRefPtr<gfxASurface> back = platform->CreateOffscreenSurface(aSize, aContent);
  if (!front || !back ||
      front->GetType() != gfxASurface::SurfaceTypeXlib ||
      back->GetType() != gfxASurface::SurfaceTypeXlib) {
    NS_ERROR("creating Xlib front/back surfaces failed!");
    return PR_FALSE;
  }

  gfxXlibSurface* frontX = static_cast<gfxXlibSurface*>(front.get());
  gfxXlibSurface* backX = static_cast<gfxXlibSurface*>(back.get());
  // Release Pixmap ownership to the layers model
  frontX->ReleasePixmap();
  backX->ReleasePixmap();

  *aFrontBuffer = SurfaceDescriptorX11(frontX);
  *aBackBuffer = SurfaceDescriptorX11(backX);
  return PR_TRUE;
}

/*static*/ already_AddRefed<gfxASurface>
ShadowLayerForwarder::PlatformOpenDescriptor(const SurfaceDescriptor& aSurface)
{
  if (SurfaceDescriptor::TSurfaceDescriptorX11 != aSurface.type()) {
    return nsnull;
  }
  return aSurface.get_SurfaceDescriptorX11().OpenForeign();
}

PRBool
ShadowLayerForwarder::PlatformDestroySharedSurface(SurfaceDescriptor* aSurface)
{
  if (SurfaceDescriptor::TSurfaceDescriptorX11 != aSurface->type()) {
    return PR_FALSE;
  }
  return TakeAndDestroyXlibSurface(aSurface);
}

/*static*/ void
ShadowLayerForwarder::PlatformSyncBeforeUpdate()
{
  if (UsingXCompositing()) {
    // If we're using X surfaces, then we need to finish all pending
    // operations on the back buffers before handing them to the
    // parent, otherwise the surface might be used by the parent's
    // Display in between two operations queued by our Display.
    XSync(DefaultXDisplay(), False);
  }
}

/*static*/ void
ShadowLayerManager::PlatformSyncBeforeReplyUpdate()
{
  if (UsingXCompositing()) {
    // If we're using X surfaces, we need to finish all pending
    // operations on the *front buffers* before handing them back to
    // the child, even though they will be read operations.
    // Otherwise, the child might start scribbling on new back buffers
    // that are still participating in requests as old front buffers.
    XSync(DefaultXDisplay(), False);
  }
}

PRBool
ShadowLayerManager::PlatformDestroySharedSurface(SurfaceDescriptor* aSurface)
{
  if (SurfaceDescriptor::TSurfaceDescriptorX11 != aSurface->type()) {
    return PR_FALSE;
  }
  return TakeAndDestroyXlibSurface(aSurface);
}

} // namespace layers
} // namespace mozilla