“平台”是一个包含 SDL2 的 C++ DLL 项目。该项目配置有 SDL2 包含和库目录。 “Sample”是一个控制台应用程序,包含并链接到“Platform”,但不涉及 SDL2;除了我隐含地包含一个包含该库的东西之外。 “Sample”无法在“Platform”中的 cpp 文件上编译,错误是找不到 SDL2 的头文件。
我可以将 SDL2 包含目录添加到“Sample”项目中,但这会产生一种耦合,这似乎违背了我首先将“Platform”与“Sample”分开的原因。我查看了预编译的头文件,但这似乎解决了另一个问题;而且我无论如何也不知道如何让“样本”包含“平台”PCH。
错误:
Severity Code Description Project File Line Suppression State
Error C1083 Cannot open include file: 'SDL.h': No such file or directory Sample C:\Users\danie\Source\SingleScreen\Platform\display.h 6
示例.cpp:#include "platform.h"
int main(int argc, char** argv)
{
Display_Configuration* display_configuration = new Display_Configuration();
display_configuration->window_title = "Sandbox";
display_configuration->dimension_x = 1280;
display_configuration->dimension_y = 720;
display_configuration->color_depth = 24;
display_configuration->is_fullscreen = false;
Platform* platform = new Platform(display_configuration);
return 0;
}
平台.h:#ifndef SINGLESCREEN_PLATFORM_PLATFORM_H
#define SINGLESCREEN_PLATFORM_PLATFORM_H
#ifdef PLATFORM_EXPORTS
#define PLATFORM_API __declspec(dllexport)
#else
#define PLATFORM_API __declspec(dllimport)
#endif
#include "display.h"
#include "controller.h"
#include "synthesizer.h"
#include "sampler.h"
extern PLATFORM_API class Platform
{
private:
Display* _display;
Controller* _controller;
Synthesizer* _synthesizer;
Sampler* _sampler;
public:
Platform(Display_Configuration* display_configuration);
~Platform();
};
#endif //SINGLESCREEN_PLATFORM_PLATFORM_H
平台.cpp:#include "pch.h"
#include "platform.h"
Platform::Platform(Display_Configuration* display_configuration)
{
_display = new Display(display_configuration);
_controller = new Controller();
_synthesizer = new Synthesizer();
_sampler = new Sampler();
}
Platform::~Platform()
{
delete _display;
delete _controller;
delete _synthesizer;
delete _sampler;
}
显示.h:#ifndef SINGLESCREEN_PLATFORM_DISPLAY_H
#define SINGLESCREEN_PLATFORM_DISPLAY_H
#include <vector>
#include <string>
#include "SDL.h"
struct Display_Configuration
{
std::string window_title;
bool is_fullscreen;
int dimension_x;
int dimension_y;
int color_depth;
};
class Display
{
private:
std::string _window_title;
bool _is_fullscreen;
int _dimension_x;
int _dimension_y;
int _color_depth;
SDL_Window* _window;
SDL_Surface* _surface;
public:
Display(Display_Configuration* display_configuration);
~Display();
bool initialize();
};
#endif //SINGLESCREEN_PLATFORM_DISPLAY_H
显示.cpp:#include "pch.h"
#include <iostream>
#include "display.h"
Display::Display(Display_Configuration* display_configuration)
{
_window_title = display_configuration->window_title;
_is_fullscreen = display_configuration->is_fullscreen;
_dimension_x = display_configuration->dimension_x;
_dimension_y = display_configuration->dimension_y;
_color_depth = display_configuration->color_depth;
}
Display::~Display()
{
}
bool Display::initialize()
{
_window = NULL;
_surface = NULL;
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
std::cout << "Failed to initialize the video subsystem. The error was:" << std::endl << SDL_GetError() << std::endl;
return false;
}
_window = SDL_CreateWindow(
_window_title.c_str(),
SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
_dimension_x, _dimension_y,
SDL_WINDOW_SHOWN | ( _is_fullscreen ? SDL_WINDOW_FULLSCREEN_DESKTOP : NULL )
);
if (_window == NULL) {
std::cout << "Failed to create a rendering window. The error was:" << std::endl << SDL_GetError() << std:: endl;
return false;
}
_surface = SDL_GetWindowSurface(_window);
if (_surface == NULL) {
std::cout << "Failed to create a rendering surface. The error was:" << std::endl << SDL_GetError() << std::endl;
return false;
}
return true;
}
最佳答案
TL;博士:
SDL_Window
和 SDL_Surface
从您的个人资料来看,您最近决定学习编程。别担心,这很酷,你会弄清楚的。
为什么我会这么认为?我花了一点时间才理解你的问题,因为 [Y] 你似乎对正确的词不知所措。
您要问的是如何在 C++ 中正确隐藏实现细节。据我了解,您正在使用 SDL 开发库。并且您希望在不直接使用 SDL 的应用程序中使用此库。
别担心,你可以做到的。你只需要解决两件事:
#include "SDL.h"
从任何公共(public)标题并将该行放入需要它的 cpp 文件中。如果它们打算由另一个目标(例如您的示例)使用,则 header 被认为是公开的。 向前看?
编译器具有这样的性质,他们想知道一切。如果他们不明白这一点,您将被编译错误所困扰。
当涉及到
SDL_Window
等类型时,编译器想知道:幸运的是,我们可以通过使用所谓的“前向声明”来告诉爱管闲事的编译器不要管它自己的事情。我转发声明如下所示:
// Example for your Display class.
class Display;
// Example for SDL
struct SDL_Window;
struct SDL_Surface;
使用前向声明,我们做出 promise ,类型 Display
, SDL_Window
和 SDL_Surface
存在,但不包括它们的标题,它们将在其他地方定义。这允许我们存储指向这些类型实例的指针(或引用)。这样包含
#include "SDL.h"
可以从标题 display.h
中移动到源display.cpp
.您的样本不需要知道 SDL 的下落。重要的!没有定义就不能使用前向声明的类型。
假设你转发声明了你自己的类
display
在一个文件中;即像这样:class display;
int main() {
auto size = sizeof(display); // Nope!
auto ptr = new display{}; // Nope!
ptr->initialize(); // Nope!
display object_from_somewhere_else;
display* ptr2 = &object_from_somewhere_else; // Yes!
return 0;
};
为了使类型再次可用,我们需要包含定义类型的 header 。class display;
#include "display.h"
或者#include "display.h"
class display;
int main() {
auto size = sizeof(display); // Yes!
auto ptr = new display{}; // Yes!
ptr->initialize(); // Yes!
display object_from_somewhere_else;
display* ptr2 = &object_from_somewhere_else; // Yes!
return 0;
};
我知道这一次可能很多。再忍耐一下,让我们看看最终结果会是什么样子:
显示.h
#ifndef SINGLESCREEN_PLATFORM_DISPLAY_H
#define SINGLESCREEN_PLATFORM_DISPLAY_H
#include <vector>
#include <string>
struct SDL_Window;
struct SDL_Surface;
struct Display_Configuration
{
std::string window_title;
bool is_fullscreen;
int dimension_x;
int dimension_y;
int color_depth;
};
class Display
{
private:
std::string _window_title;
bool _is_fullscreen;
int _dimension_x;
int _dimension_y;
int _color_depth;
SDL_Window* _window;
SDL_Surface* _surface;
public:
Display(Display_Configuration* display_configuration);
~Display();
bool initialize();
};
#endif //SINGLESCREEN_PLATFORM_DISPLAY_H
显示.cpp#include "pch.h"
#include <iostream>
#include "display.h"
#include "SDL.h"
Display::Display(Display_Configuration* display_configuration)
{
_window_title = display_configuration->window_title;
_is_fullscreen = display_configuration->is_fullscreen;
_dimension_x = display_configuration->dimension_x;
_dimension_y = display_configuration->dimension_y;
_color_depth = display_configuration->color_depth;
}
Display::~Display()
{
}
bool Display::initialize()
{
_window = NULL;
_surface = NULL;
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
std::cout << "Failed to initialize the video subsystem. The error was:" << std::endl << SDL_GetError() << std::endl;
return false;
}
_window = SDL_CreateWindow(
_window_title.c_str(),
SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
_dimension_x, _dimension_y,
SDL_WINDOW_SHOWN | ( _is_fullscreen ? SDL_WINDOW_FULLSCREEN_DESKTOP : NULL )
);
if (_window == NULL) {
std::cout << "Failed to create a rendering window. The error was:" << std::endl << SDL_GetError() << std:: endl;
return false;
}
_surface = SDL_GetWindowSurface(_window);
if (_surface == NULL) {
std::cout << "Failed to create a rendering surface. The error was:" << std::endl << SDL_GetError() << std::endl;
return false;
}
return true;
}
关于c++ - 如何解耦 C++ 项目 header 依赖项?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/63856394/