GTK/DFB中的WaitCursor

GTK/DFB中的WaitCursor

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作者联系方式：李先静 <xianjimli at hotmail dot com>

虽然我们实现了单实例应用程序，即在应用程序第二次运行时自动激活第一个实例，并将参数传递给第一个运行实例。但如果在桌面连续点击应用程序的起动图标，会让应用程序起动过过程变得更慢，为了避免这种情况出现，有必要实现类似WaitCursor机制。GTK+-2.6/DFB中没有实现WaitCursor，新版本中好像也没有，只好自己动手了：

• 在gdkwindow.h文件中增加两个函数：

gint          gdk_window_begin_wait_cursor(GdkWindow   *window);
gint          gdk_window_end_wait_cursor(GdkWindow   *window);

• 在_GdkWindowObject结构中增加waitcursor的信息。

  struct
  {
    gint ref;
    gint elapsed;
    gint timeout_id;
  }wait_cursor;

• 在gdkwindow-directfb.c中实现这两个函数，很简单，就是实现一个定时器，每隔一段时间更新一下Cursor。

gint gdk_window_begin_wait_cursor(GdkWindow   *window)
{
  GdkWindowObject *private = GDK_WINDOW_OBJECT (window);
  g_return_val_if_fail(private != NULL, 0);

  private->wait_cursor.ref++;

  if(private->wait_cursor.ref == 1 && update_wait_cursor(window))
  {
    private->wait_cursor.elapsed = 0;
    private->wait_cursor.timeout_id = g_timeout_add(250, update_wait_cursor, window);
#ifndef LINUX_I386  
    gdk_directfb_display->layer->EnableCursor(gdk_directfb_display->layer, 1);
#endif
  }

  return private->wait_cursor.ref;
}

gint gdk_window_end_wait_cursor(GdkWindow   *window)
{
  GdkWindowObject *private = GDK_WINDOW_OBJECT (window);
  if(private == NULL || private->wait_cursor.ref <=0)
  {
    return 0;
  }
  private->wait_cursor.ref--;
#ifndef LINUX_I386  
  gdk_directfb_display->layer->EnableCursor(gdk_directfb_display->layer, private->wait_cursor.ref != 0);
#endif

  return private->wait_cursor.ref;
}

static gboolean update_wait_cursor(gpointer user_data)
{
  GdkWindow   *window = user_data;
  GdkWindowObject *private = GDK_WINDOW_OBJECT (window);
  g_return_val_if_fail(private != NULL, FALSE);

  int cursor_type = GDK_WAIT_BEGIN +
(private->wait_cursor.elapsed)%(GDK_WAIT_END - GDK_WAIT_BEGIN + 1);
  GdkCursor* cursor = gdk_cursor_new_for_display (gdk_display_get_default(),
cursor_type);
  gdk_window_set_cursor(window, cursor);
  gdk_cursor_unref(cursor);

  private->wait_cursor.elapsed++;
  if(private->wait_cursor.ref <= 0)
  {
    private->wait_cursor.elapsed = 0;
    private->wait_cursor.timeout_id = 0;
    gdk_window_set_cursor(window, NULL);
  }

  return private->wait_cursor.ref > 0;
}

在gdkcursor-directfb.c中加载Cursor图片，Cursor图片与主题关联：

static GdkCursor *
gdk_cursor_load_wait_cursor(GdkDisplay    *display,
                            GdkCursorType  cursor_type)
{
  GdkCursor* cursor = NULL;
  if(cursor_type >= GDK_WAIT_BEGIN && cursor_type <= GDK_WAIT_END)
  {
    int index = 0;
    GValue value = {0};
    char* theme = NULL;
    char filename[260] = {0};
    GObject* setting = g_object_get_data (G_OBJECT (gdk_screen_get_default()),
"gtk-settings");
    g_return_val_if_fail(setting != NULL, NULL);

    g_value_init(&value, G_TYPE_STRING);
    g_object_get_property (setting, "gtk-icon-theme-name", &value);
    theme = g_value_get_string(&value);
    index = cursor_type-GDK_WAIT_BEGIN + 1;
    snprintf(filename, sizeof(filename), WAITCURSOR, theme, index);
    if((cursor = gdk_cursor_new_from_name(display, filename)) == NULL)
    {
        snprintf(filename, sizeof(filename), WAITCURSOR, "hicolor", index);
        cursor = gdk_cursor_new_from_name(display, filename);
        g_debug("load %p %s", cursor, filename);
    }
    g_value_reset(&value);
  }

  return cursor;
}

• 要注意的是gdk_cursor_new_from_pixbuf有点问题，pixbuf中的格式居然是GBRA而不是代码中要求的ARGB，要修改一下这个函数，否则无法实现透明效果。

• 为了避免enable/disable时闪现一下传统的cursor，修改gdk_cursor_new_for_display,让alpha=0，让传统cursor全透明。

• 出现WaitCursor时，丢弃按键和笔点事件，修改gdk_event_translate：

  if(private->wait_cursor.ref > 0)
  {
    switch (dfbevent->type)
    {
      case DWET_BUTTONDOWN:
      case DWET_BUTTONUP:
      case DWET_MOTION:
      case DWET_KEYDOWN:
      case DWET_KEYUP:
            return NULL;
      default:break;
    }
  }

在手机上和PC上有点不问，手机上平时不能显示cursor，而且waitcursor的位置要居中，所以还要修改DirectFB:

• 在dfb_layer_context_create_window中禁止cursor，把以前的dfb_windowstack_cursor_enable(core, stack, true )改为dfb_windowstack_cursor_enable( core, stack, false )
  

• 在wm_update_cursor里让位置居中：

#ifndef LINUX_I386
     if(context->stack->cursor.enabled && (flags & CCUF_POSITION))
     {
          stack->cursor.hot.x = stack->cursor.x - (context->width/2 -
stack->cursor.size.w);
          stack->cursor.hot.y = stack->cursor.y - (context->height/2 -
stack->cursor.size.h);
     }
#endif

测试了一下，基本功能正常。

～～end～～