如何捕捉 X 错误?

问题描述

我尝试在网上搜索，但我必须注意，要找到有关 X 编程这方面的资料并不容易.

I tried searching the web, but I must note that finding materials about this aspect of X programming is not really easy.

我使用 X 和 GLX 来创建 OpenGL 上下文.我已经知道我当前的显卡驱动程序最多只支持 OpenGL API 3.3 版，但我希望我的应用程序能够尝试使用任何类型的版本创建上下文(因为它可以在其他计算机上运行).我的代码是这样的:

I use X with GLX to create OpenGL contexts. I already know my current graphics card driver only supports up to OpenGL API version 3.3, but I want my application to be able to try to create a context with any kind of version (as it could run on other computers). My code goes like this :

• 版本
• 创建上下文:
  • 如果版本是3.x或4.x，使用glXCreateContextAttribsARB
  • 否则使用 glXCreateContext
  • Version <- requested OpenGL Version (by example : 3.3)
  • Create a context :
    • if Version is 3.x or 4.x, use glXCreateContextAttribsARB
    • else use glXCreateContext

    我的代码没问题，但我想在检索 X/GLX 启动的错误的方式上更清晰，至于目前，如果我使用 glXCreateContextAttribARB 创建一个 4.4版本(记住，我的显卡最多只支持3.3)，我显然得到:

    My code is OK, but I'd like to be more clean on the way I retrieve the errors launched by X/GLX, as for the moment, if I use glXCreateContextAttribARB to create a 4.4 version (remember, my graphics card only supports up to 3.3), I obviously get :

    X Error of failed request:  BadMatch (invalid parameter attributes)
      Major opcode of failed request:  153 (GLX)
      Minor opcode of failed request:  34 ()
      Serial number of failed request:  33
      Current serial number in output stream:  34
    

    我想在我的代码中插入 X 的错误处理来处理它.X 是 C，不是 C++，异常在这个阶段不可用.这是我创建上下文的地方(我故意删除了不是直接创建上下文的内容):

    I'd like to insert error handling for X in my code to handle it. X being C, not C++, exceptions are not usable at this stage. Here is where I create the context (I intentionally removed what does not directly is context creation) :

    // Notes :
    // mGLXContext : The GLX context we want to create
    // vDepthSize, vAntialiasingLevel, vStencilSize are here to customize mGLXContext
    // vTryVersion : a pointer to the API version {major, minor} we want to create
    // vSharedContext : a pointer to an other (existing) context for data sharing.
    // mXDisplay : the X Display
    
    
    // Get the proc
    const GLubyte* vProcName = reinterpret_cast<const GLubyte*>("glXCreateContextAttribsARB");
    PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB =
        reinterpret_cast<PFNGLXCREATECONTEXTATTRIBSARBPROC>(glXGetProcAddress(vProcName));
    
    if(glXCreateContextAttribsARB) {
    
        // Create the FB attributes
        int vFBAttributes[] = {
            GLX_DEPTH_SIZE, (int)(vDepthSize),
            GLX_STENCIL_SIZE, (int)(vStencilSize),
            GLX_SAMPLE_BUFFERS, vAntialiasingLevel > 0,
            GLX_SAMPLES, (int)(vAntialiasingLevel),
            GLX_RED_SIZE, 8,
            GLX_GREEN_SIZE, 8,
            GLX_BLUE_SIZE, 8,
            GLX_ALPHA_SIZE, pDepth == 32 ? 8 : 0,
            GLX_DOUBLEBUFFER, True,
            GLX_X_RENDERABLE, True,
            GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
            GLX_RENDER_TYPE, GLX_RGBA_BIT,
            GLX_CONFIG_CAVEAT, GLX_NONE,
            None
        };
    
    
        // Get the FB configs
        int vNbXConfigs = 0;
        ::GLXFBConfig* vGLXFBConfig = glXChooseFBConfig(mXDisplay, DefaultScreen(mXDisplay), vFBAttributes, &vNbXConfigs);
    
        if(vGLXFBConfig && vNbXConfigs) {
    
            // Create the context attributes
            int vAttributes[] = {
                GLX_CONTEXT_MAJOR_VERSION_ARB, static_cast<int>(vTryVersion->major),
                GLX_CONTEXT_MINOR_VERSION_ARB, static_cast<int>(vTryVersion->minor),
                0, 0
            };
    
            // Create the context : Error is generated by GLX here
            mGLXContext = glXCreateContextAttribsARB(mXDisplay, vGLXFBConfig[0], vSharedContext, true, vAttributes);
    
        }
    }
    

    所以我的问题是如何捕获 X 错误并查询它们?

    So my question is how can I catch X error and query them ?

    感谢阅读:)

    推荐答案

    您需要使用 XSetErrorHandler 来指定错误处理程序，例如

    You need to use XSetErrorHandler to specify an error handler e.g.

    XSetErrorHandler(handler);
    

    错误处理程序是

    int handler(Display * d, XErrorEvent * e)
    {
        std::cerr << "Error code: " << e->error_code << std::endl;
        return 0;
    }
    

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