// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file defines utility functions for X11 (Linux only). This code has been
// ported from XCB since we can't use XCB on Ubuntu while its 32-bit support
// remains woefully incomplete.

#include "chrome/common/x11_util.h"
#include "chrome/common/x11_util_internal.h"

#include <string.h>

#include <gdk/gdk.h>
#include <gdk/gdkx.h>
#include <gtk/gtk.h>

#include <sys/ipc.h>
#include <sys/shm.h>

#include "base/logging.h"
#include "base/gfx/size.h"

namespace x11_util {

Display* GetXDisplay() {
  static Display* display = NULL;

  if (!display)
    display = gdk_x11_get_default_xdisplay();

  return display;
}

static bool DoQuerySharedMemorySupport(Display* dpy) {
  int dummy;
  Bool pixmaps_supported;
  // Query the server's support for shared memory
  if (!XShmQueryVersion(dpy, &dummy, &dummy, &pixmaps_supported))
    return false;
  // If the server doesn't support shared memory, give up. (Note that if
  // |shared_pixmaps| is true, it just means that the server /supports/ shared
  // memory, not that it will work on this connection.)
  if (!pixmaps_supported)
    return false;

  // Next we probe to see if shared memory will really work
  int shmkey = shmget(IPC_PRIVATE, 1, 0666);
  if (shmkey == -1)
    return false;
  void* address = shmat(shmkey, NULL, 0);
  // Mark the shared memory region for deletion
  shmctl(shmkey, IPC_RMID, NULL);

  XShmSegmentInfo shminfo;
  memset(&shminfo, 0, sizeof(shminfo));
  shminfo.shmid = shmkey;

  gdk_error_trap_push();
  bool result = XShmAttach(dpy, &shminfo);
  XSync(dpy, False);
  if (gdk_error_trap_pop())
    result = false;
  shmdt(address);
  if (!result)
    return false;

  XShmDetach(dpy, &shminfo);
  return true;
}

bool QuerySharedMemorySupport(Display* dpy) {
  static bool shared_memory_support = false;
  static bool shared_memory_support_cached = false;

  if (shared_memory_support_cached)
    return shared_memory_support;

  shared_memory_support = DoQuerySharedMemorySupport(dpy);
  shared_memory_support_cached = true;

  return shared_memory_support;
}

bool QueryRenderSupport(Display* dpy) {
  static bool render_supported = false;
  static bool render_supported_cached = false;

  if (render_supported_cached)
    return render_supported;

  // We don't care about the version of Xrender since all the features which
  // we use are included in every version.
  int dummy;
  render_supported = XRenderQueryExtension(dpy, &dummy, &dummy);
  render_supported_cached = true;

  return render_supported;
}

XID GetX11RootWindow() {
  return GDK_WINDOW_XID(gdk_get_default_root_window());
}

XID GetX11WindowFromGtkWidget(GtkWidget* widget) {
  return GDK_WINDOW_XID(widget->window);
}

void* GetVisualFromGtkWidget(GtkWidget* widget) {
  return GDK_VISUAL_XVISUAL(gtk_widget_get_visual(widget));
}

int BitsPerPixelForPixmapDepth(Display* dpy, int depth) {
  int count;
  XPixmapFormatValues* formats = XListPixmapFormats(dpy, &count);
  if (!formats)
    return -1;

  int bits_per_pixel = -1;
  for (int i = 0; i < count; ++i) {
    if (formats[i].depth == depth) {
      bits_per_pixel = formats[i].bits_per_pixel;
      break;
    }
  }

  XFree(formats);
  return bits_per_pixel;
}

XRenderPictFormat* GetRenderVisualFormat(Display* dpy, Visual* visual) {
  static XRenderPictFormat* pictformat = NULL;
  if (pictformat)
    return pictformat;

  DCHECK(QueryRenderSupport(dpy));

  pictformat = XRenderFindVisualFormat(dpy, visual);
  CHECK(pictformat) << "XRENDER does not support default visual";

  return pictformat;
}

XRenderPictFormat* GetRenderARGB32Format(Display* dpy) {
  static XRenderPictFormat* pictformat = NULL;
  if (pictformat)
    return pictformat;

  // First look for a 32-bit format which ignores the alpha value
  XRenderPictFormat templ;
  templ.depth = 32;
  templ.type = PictTypeDirect;
  templ.direct.red = 16;
  templ.direct.green = 8;
  templ.direct.blue = 0;
  templ.direct.redMask = 0xff;
  templ.direct.greenMask = 0xff;
  templ.direct.blueMask = 0xff;
  templ.direct.alphaMask = 0;

  static const unsigned long kMask =
    PictFormatType | PictFormatDepth |
    PictFormatRed | PictFormatRedMask |
    PictFormatGreen | PictFormatGreenMask |
    PictFormatBlue | PictFormatBlueMask |
    PictFormatAlphaMask;

  pictformat = XRenderFindFormat(dpy, kMask, &templ, 0 /* first result */);

  if (!pictformat) {
    // Not all X servers support xRGB32 formats. However, the XRENDER spec says
    // that they must support an ARGB32 format, so we can always return that.
    pictformat = XRenderFindStandardFormat(dpy, PictStandardARGB32);
    CHECK(pictformat) << "XRENDER ARGB32 not supported.";
  }

  return pictformat;
}

XID AttachSharedMemory(Display* display, int shared_memory_key) {
  DCHECK(QuerySharedMemorySupport(display));

  XShmSegmentInfo shminfo;
  memset(&shminfo, 0, sizeof(shminfo));
  shminfo.shmid = shared_memory_key;

  // This function is only called if QuerySharedMemorySupport returned true. In
  // which case we've already succeeded in having the X server attach to one of
  // our shared memory segments.
  if (!XShmAttach(display, &shminfo))
    NOTREACHED();

  return shminfo.shmseg;
}

void DetachSharedMemory(Display* display, XID shmseg) {
  DCHECK(QuerySharedMemorySupport(display));

  XShmSegmentInfo shminfo;
  memset(&shminfo, 0, sizeof(shminfo));
  shminfo.shmseg = shmseg;

  if (!XShmDetach(display, &shminfo))
    NOTREACHED();
}

XID CreatePictureFromSkiaPixmap(Display* display, XID pixmap) {
  XID picture = XRenderCreatePicture(
      display, pixmap, GetRenderARGB32Format(display), 0, NULL);

  return picture;
}

void FreePicture(Display* display, XID picture) {
  XRenderFreePicture(display, picture);
}

void FreePixmap(Display* display, XID pixmap) {
  XFreePixmap(display, pixmap);
}

}  // namespace x11_util