How to resolve error: invalid use of incomplete type ‘GdkSurface {aka struct _GdkSurface}’?

Question

关于 incomplete type 错误的问题已经经常在这里被问到，但是那里提供的所有解决方案对我的情况都没有帮助。添加前向声明没有意义，因为 GdkSurface 已经在 Gdk headers 中被前向声明。包括适当的 headers 已经完成。在产生错误的代码部分之后 + includes.

#include <gdkmm/display.h>
#include <gdkmm/surface.h>

extern "C" {
#include <gdk/x11/gdkx.h>
#include <gdk/gdk.h>
}

extern "C" {
    void surface_move(Gdk::Surface* psurface, int x, int y) {
        #ifdef GDK_WINDOWING_X11
        GdkSurface* surface = psurface->gobj();
        GdkSurface *impl = GDK_X11_SURFACE(surface);
        XMoveWindow(GDK_SURFACE_XDISPLAY (surface), GDK_SURFACE_XID (surface), x * impl->surface_scale, y * impl->surface_scale);
        #endif
    }
}

以下是完整的错误：

src/utils.cpp: In function ‘void Gdk::surface_move(Gdk::Surface*, int, int)’:
src/utils.cpp:9:83: error: invalid use of incomplete type ‘GdkSurface {aka struct _GdkSurface}’
 (GDK_SURFACE_XDISPLAY (surface), GDK_SURFACE_XID (surface), x * impl->surface_scale, y * impl->surface_scale);
                                                                     ^~
In file included from /home/user/.local/built/include/gtk-4.0/gdk/gdkapplaunchcontext.h:29:0,
                 from /home/user/.local/built/include/gtk-4.0/gdk/gdk.h:30,
                 from /home/user/.local/built/include/gtkmm-4.0/gdkmm/enums.h:29,
                 from /home/user/.local/built/include/gtkmm-4.0/gdkmm/event.h:29,
                 from /home/user/.local/built/include/gtkmm-4.0/gdkmm/display.h:30,
                 from ./include/libgdp/utils.hpp:3,
                 from src/utils.cpp:1:
/home/user/.local/built/include/gtk-4.0/gdk/gdktypes.h:97:16: note: forward declaration of ‘GdkSurface {aka struct _GdkSurface}’
 typedef struct _GdkSurface             GdkSurface;
                ^~~~~~~~~~~
src/utils.cpp:9:108: error: invalid use of incomplete type ‘GdkSurface {aka struct _GdkSurface}’
 rface), GDK_SURFACE_XID (surface), x * impl->surface_scale, y * impl->surface_scale);
                                                                     ^~
In file included from /home/user/.local/built/include/gtk-4.0/gdk/gdkapplaunchcontext.h:29:0,
                 from /home/user/.local/built/include/gtk-4.0/gdk/gdk.h:30,
                 from /home/user/.local/built/include/gtkmm-4.0/gdkmm/enums.h:29,
                 from /home/user/.local/built/include/gtkmm-4.0/gdkmm/event.h:29,
                 from /home/user/.local/built/include/gtkmm-4.0/gdkmm/display.h:30,
                 from ./include/libgdp/utils.hpp:3,
                 from src/utils.cpp:1:
/home/user/.local/built/include/gtk-4.0/gdk/gdktypes.h:97:16: note: forward declaration of ‘GdkSurface {aka struct _GdkSurface}’
 typedef struct _GdkSurface             GdkSurface;
                ^~~~~~~~~~~

我用 JHbuild 构建了 Gdk、Gtk、Gdkmm 和 Gtkmm。

Answer 1

似乎这种类型在设计上是 GDK 私有的（只提供了前向声明）。来自 GDK4 documentation:

The GdkSurface struct contains only private fields and should not be accessed directly.

参见 here 以了解定义它的 header（未分发）。这就是你得到这些错误的原因，你所拥有的只是一个前向声明来传递指针和引用。禁止对数据成员的所有访问。

要解决这个问题，您必须使用在表面（即 public）上工作的函数，例如 gdk_surface_get_scale_factor 或类似的东西，而不是尝试直接访问数据成员。

How to resolve error: invalid use of incomplete type ‘GdkSurface {aka struct _GdkSurface}’?

How to resolve error: invalid use of incomplete type ‘GdkSurface {aka struct _GdkSurface}’?

c++

gtk

gtkmm

gdk

incomplete-type