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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=8 et :
*/
/* 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/. */
#ifndef mozilla_X11Util_h
#define mozilla_X11Util_h
// Utilities common to all X clients, regardless of UI toolkit.
#if defined(MOZ_WIDGET_GTK)
# include <gdk/gdk.h>
# include <gdk/gdkx.h>
# include "X11UndefineNone.h"
#else
# error Unknown toolkit
#endif
#include <string.h> // for memset
#include "mozilla/Scoped.h" // for SCOPED_TEMPLATE
namespace mozilla {
/**
* Return the default X Display created and used by the UI toolkit.
*/
inline Display*
DefaultXDisplay()
{
#if defined(MOZ_WIDGET_GTK)
return GDK_DISPLAY_XDISPLAY(gdk_display_get_default());
#endif
}
/**
* Sets *aVisual to point to aDisplay's Visual struct corresponding to
* aVisualID, and *aDepth to its depth. When aVisualID is None, these are set
* to nullptr and 0 respectively. Both out-parameter pointers are assumed
* non-nullptr.
*/
void
FindVisualAndDepth(Display* aDisplay, VisualID aVisualID,
Visual** aVisual, int* aDepth);
/**
* Ensure that all X requests have been processed.
*
* This is similar to XSync, but doesn't need a round trip if the previous
* request was synchronous or if events have been received since the last
* request. Subsequent FinishX calls will be noops if there have been no
* intermediate requests.
*/
void
FinishX(Display* aDisplay);
/**
* Invoke XFree() on a pointer to memory allocated by Xlib (if the
* pointer is nonnull) when this class goes out of scope.
*/
template <typename T>
struct ScopedXFreePtrTraits
{
typedef T *type;
static T *empty() { return nullptr; }
static void release(T *ptr) { if (ptr != nullptr) XFree(ptr); }
};
SCOPED_TEMPLATE(ScopedXFree, ScopedXFreePtrTraits)
/**
* On construction, set a graceful X error handler that doesn't crash the application and records X errors.
* On destruction, restore the X error handler to what it was before construction.
*
* The SyncAndGetError() method allows to know whether a X error occurred, optionally allows to get the full XErrorEvent,
* and resets the recorded X error state so that a single X error will be reported only once.
*
* Nesting is correctly handled: multiple nested ScopedXErrorHandler's don't interfere with each other's state. However,
* if SyncAndGetError is not called on the nested ScopedXErrorHandler, then any X errors caused by X calls made while the nested
* ScopedXErrorHandler was in place may then be caught by the other ScopedXErrorHandler. This is just a result of X being
* asynchronous and us not doing any implicit syncing: the only method in this class what causes syncing is SyncAndGetError().
*
* This class is not thread-safe at all. It is assumed that only one thread is using any ScopedXErrorHandler's. Given that it's
* not used on Mac, it should be easy to make it thread-safe by using thread-local storage with __thread.
*/
class ScopedXErrorHandler
{
public:
// trivial wrapper around XErrorEvent, just adding ctor initializing by zero.
struct ErrorEvent
{
XErrorEvent mError;
ErrorEvent()
{
memset(this, 0, sizeof(ErrorEvent));
}
};
private:
// this ScopedXErrorHandler's ErrorEvent object
ErrorEvent mXError;
// static pointer for use by the error handler
static ErrorEvent* sXErrorPtr;
// what to restore sXErrorPtr to on destruction
ErrorEvent* mOldXErrorPtr;
// what to restore the error handler to on destruction
int (*mOldErrorHandler)(Display *, XErrorEvent *);
public:
static int
ErrorHandler(Display *, XErrorEvent *ev);
/**
* @param aAllowOffMainThread whether to warn if used off main thread
*/
explicit ScopedXErrorHandler(bool aAllowOffMainThread = false);
~ScopedXErrorHandler();
/** \returns true if a X error occurred since the last time this method was called on this ScopedXErrorHandler object,
* or since the creation of this ScopedXErrorHandler object if this method was never called on it.
*
* \param ev this optional parameter, if set, will be filled with the XErrorEvent object. If multiple errors occurred,
* the first one will be returned.
*/
bool SyncAndGetError(Display *dpy, XErrorEvent *ev = nullptr);
};
class OffMainThreadScopedXErrorHandler : public ScopedXErrorHandler
{
public:
OffMainThreadScopedXErrorHandler()
: ScopedXErrorHandler(true)
{
}
};
} // namespace mozilla
#endif // mozilla_X11Util_h
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