(C++) 适用于 Linux 的 MessageBox 就像在 MS Windows 中一样

Question

我需要为 Linux (SDL) 应用程序实现一个简单的图形消息框，类似于 C++ (gcc/g++ 4.4.0) 中的 Windows MessageBox。它所需要做的就是显示标题、消息和确定或关闭按钮，并在单击该按钮时返回到调用函数。

SDL 只是使用 X(11) 打开一个窗口进行 (OpenGL) 渲染。

我查看了有关 GTK 实现的类似线程，但该实现似乎无法正常工作。

我也尝试过 wxWidgets 的 wxMessageBox 函数，但是编译头文件会使编译器抛出有关 include/c++/4.4.0/bits/stl_algobase.h 中语法错误的错误消息（openSuSE 11.1 32 位上的 gcc 4.4.0 32 位）。使用 wxWidgets 还意味着必须链接大量的库，将 STL 添加到我的应用程序中（否则不需要），谁知道还有什么，所以我不想使用 wxWidgets。

X11/motif (openmotif) 有我需要的东西 (XmCreate{Error|Warning|InfoDialog)，但是这些需要一个父窗口小部件（例如顶级窗口），而我没有，并且不接受它们的 NULL 参数。

所以我现在很困惑。有没有一种简单的方法可以做我想做的事？或者至少是一半简单/容易/直接的？如果是，是哪一个（提供尽可能多的详细信息将不胜感激）。

Answer 1

在 SDL2 中，您现在可以显示消息框：

http://wiki.libsdl.org/SDL_ShowSimpleMessageBox

int SDL_ShowSimpleMessageBox(Uint32      flags,
                             const char* title,
                             const char* message,
                             SDL_Window* window)

http://wiki.libsdl.org/SDL_ShowMessageBox

int SDL_ShowMessageBox(const SDL_MessageBoxData* messageboxdata,
                       int*                      buttonid)

Answer 2

我个人使用Qt4的QMessageBox。

例子：

QMessageBox mb(QMessageBox::Question, "Title", "Message",  QMessageBox::Ok | QMessageBox::Cancel);
if(mb.exec() == QMessageBox::Ok) { do_stuff(); }

Answer 3

看起来您必须创建一个顶级 X11/Motif 窗口。这里有一些代码可以帮助您入门：

#include <Xm/Xm.h> 
#include <Xm/PushB.h>

/* Prototype Callback function */

void pushed_fn(Widget , XtPointer , 
               XmPushButtonCallbackStruct *);


main(int argc, char **argv) 

{   Widget top_wid, button;
    XtAppContext  app;

    top_wid = XtVaAppInitialize(&app, "Push", NULL, 0,
        &argc, argv, NULL, NULL);

    button = XmCreatePushButton(top_wid, "Push_me", NULL, 0);

    /* tell Xt to manage button */
                XtManageChild(button);

                /* attach fn to widget */
    XtAddCallback(button, XmNactivateCallback, pushed_fn, NULL);

    XtRealizeWidget(top_wid); /* display widget hierarchy */
    XtAppMainLoop(app); /* enter processing loop */ 

}

void pushed_fn(Widget w, XtPointer client_data, 
               XmPushButtonCallbackStruct *cbs) 
  {   
     printf("Don't Push Me!!\n");
  }

这是从此处复制的< /a> 这可能会给你更多关于这方面的指示。

Answer 4

这是我的解决方案。我选择使用 Motif (OpenMotif)，因为它需要相对较少的额外库（Xm、Xt、X11）。根据消息大小，我的实现会打开一个简单的消息框或更复杂的对话框，其中包含不可编辑的可滚动文本（后者取自 Motif 程序员手册并适合我的目的）。

包括文件和全局数据：

#include <Xm/Xm.h>
#include <Xm/MwmUtil.h>
#include <Xm/MainW.h>
#include <Xm/CascadeB.h>
#include <Xm/MessageB.h>
#include <Xm/RowColumn.h>
#include <Xm/Form.h>
#include <Xm/PushBG.h>
#include <Xm/LabelG.h>
#include <Xm/PanedW.h>
#include <Xm/Text.h>
#include <Xm/DialogS.h>
#include <Xm/Command.h>

static XtAppContext appShell;

用于确定行数和最大值的辅助函数。文本消息的列数：

static int MsgSize (char* pszMsg, int& nCols)
{
if (!(pszMsg && *pszMsg))
   return 0;
int nRows = 1;
nCols = 0;
for (char* p = pszMsg; *p && (pszMsg = strchr (p, '\n')); nRows++, p = ++pszMsg) {
   if (nCols < pszMsg - p)
      nCols = pszMsg - p;
   }
return nRows;
}

消息对话框的关闭按钮的回调函数：

void DestroyShell (Widget widget, XtPointer clientData, XtPointer callData)
{
Widget shell = (Widget) clientData;
XtDestroyWidget (shell);
// tell the application event loop to terminate w/o terminating the application
XtAppSetExitFlag (appShell);
}

构建一个包含可滚动、不可编辑的文本小部件和关闭按钮的对话框。取自 Motif 程序员手册并稍作修改（无图标，单个按钮），最小化窗口装饰）。

void XmMessageDialog (const char* pszMsg, int nRows, int nCols, bool bError)
{
    Widget       msgBox, pane, msgText, form, widget;
    void         DestroyShell(Widget, XtPointer, XtPointer);
    Arg          args [10];
    int          n = 0;
    int          i;
    Dimension    h;

// Set up a DialogShell as a popup window. Set the delete window protocol response to XmDESTROY to make sure that
// the window goes away appropriately. Otherwise, it's XmUNMAP which means it'd be lost forever, since we're not storing
// the widget globally or statically to this function.
Widget topWid = XtVaAppInitialize (&appShell, "D2X-XL", NULL, 0, &argc, argv, NULL, NULL);
XtSetArg (args [0], XmNdeleteResponse, XmDESTROY);
msgBox = XmCreateDialogShell (topWid, bError ? const_cast<char*>("Error") : const_cast<char*>("Warning"), args, 1);
XtVaGetValues (msgBox, XmNmwmDecorations, &i, NULL);
i &= ~(MWM_DECOR_ALL | MWM_DECOR_MINIMIZE | MWM_DECOR_MAXIMIZE | MWM_DECOR_MENU);
XtVaSetValues (msgBox, XmNmwmDecorations, i, NULL);
XtVaGetValues (msgBox, XmNmwmFunctions, &i, NULL);
i &= ~(MWM_FUNC_ALL | MWM_FUNC_MINIMIZE | MWM_FUNC_MAXIMIZE | MWM_FUNC_CLOSE);
XtVaSetValues (msgBox, XmNmwmFunctions, i, NULL);
// Create a PanedWindow to manage the stuff in this dialog. PanedWindow won't let us set these to 0!
XtSetArg (args [0], XmNsashWidth, 1);
// Make small so user doesn't try to resize
XtSetArg (args [1], XmNsashHeight, 1);
pane = XmCreatePanedWindow (msgBox, const_cast<char*>("pane"), args, 2);
// Create a RowColumn in the form for Label and Text widgets. This is the control area.
form = XmCreateForm (pane, const_cast<char*>("form1"), NULL, 0);
// prepare the text for display in the ScrolledText object we are about to create.
n = 0;
XtSetArg (args [n], XmNscrollVertical, True); n++;
XtSetArg (args [n], XmNscrollHorizontal, False); n++;
XtSetArg (args [n], XmNeditMode, XmMULTI_LINE_EDIT); n++;
XtSetArg (args [n], XmNeditable, False); n++;
XtSetArg (args [n], XmNcursorPositionVisible, False); n++;
XtSetArg (args [n], XmNwordWrap, True); n++;
XtSetArg (args [n], XmNvalue, pszMsg); n++;
XtSetArg (args [n], XmNrows, min (nRows, 30)); n++;
XtSetArg (args [n], XmNcolumns, min (nCols, 120)); n++;
msgText = XmCreateScrolledText (form, const_cast<char*>("help_text"), args, n);
// Attachment values must be set on the Text widget's PARENT, the ScrolledWindow. This  is the object that is positioned.
XtVaSetValues (XtParent (msgText),
               XmNleftAttachment, XmATTACH_FORM,
               XmNtopAttachment, XmATTACH_FORM,
               XmNrightAttachment, XmATTACH_FORM,
               XmNbottomAttachment, XmATTACH_FORM,
               NULL);
XtManageChild (msgText);
XtManageChild (form);
// Create another form to act as the action area for the dialog
XtSetArg (args [0], XmNfractionBase, 5);
form = XmCreateForm (pane, const_cast<char*>("form2"), args, 1);
// The OK button is under the pane's separator and is attached to the left edge of the form. It spreads from
// position 0 to 1 along the bottom (the form is split into 5 separate grids via XmNfractionBase upon creation).
widget = XmCreatePushButtonGadget (form, const_cast<char*>("Close"), NULL, 0);
XtVaSetValues (widget,
               XmNtopAttachment, XmATTACH_FORM,
               XmNbottomAttachment, XmATTACH_FORM,
               XmNleftAttachment, XmATTACH_POSITION,
               XmNleftPosition, 2,
               XmNrightAttachment, XmATTACH_POSITION,
               XmNrightPosition, 3,
               XmNshowAsDefault, True,
               XmNdefaultButtonShadowThickness, 1,
               NULL);
XtManageChild (widget);
XtAddCallback (widget, XmNactivateCallback, DestroyShell, (XtPointer) msgBox);
// Fix the action area pane to its current height -- never let it resize
XtManageChild (form);
XtVaGetValues (widget, XmNheight, &h, NULL);
XtVaSetValues (form, XmNpaneMaximum, h, XmNpaneMinimum, h, NULL);
// This also pops up the dialog, as it is the child of a DialogShell
XtManageChild (pane);
}

消息框“确定”按钮的回调函数

void XmCloseMsgBox (Widget w, XtPointer clientData, XtPointer callData)
{
XtAppSetExitFlag (appShell);
}

决定是使用简单消息框还是高级消息框，显示其中一个，并在用户单击关闭/确定按钮时删除它们。

void XmMessageBox (const char* pszMsg, bool bError)
{
   Widget   topWid;
   int      nRows, nCols;

nRows = MsgSize (const_cast<char*>(pszMsg), nCols);
if ((nRows > 3) || (nCols > 360))
   XmMessageDialog (pszMsg, nRows, nCols, bError);
else { // use the built-in message box
   topWid = XtVaAppInitialize (&appShell, "D2X-XL", NULL, 0, &argC, argv, NULL, NULL);
   // setup message box text
   Arg args [1];
   XmString xmString = XmStringCreateLocalized (const_cast<char*>(pszMsg));
   XtSetArg (args [0], XmNmessageString, xmString);
   // create and label message box
   Widget xMsgBox = bError
                    ? XmCreateErrorDialog (topWid, const_cast<char*>("Error"), args, 1)
                    : XmCreateWarningDialog (topWid, const_cast<char*>("Warning"), args, 1);
   // remove text resource
   XmStringFree (xmString);
   // remove help and cancel buttons
   XtUnmanageChild (XmMessageBoxGetChild (xMsgBox, XmDIALOG_CANCEL_BUTTON));
   XtUnmanageChild (XmMessageBoxGetChild (xMsgBox, XmDIALOG_HELP_BUTTON));
   // add callback to the "close" button that signals closing of the message box
   XtAddCallback (xMsgBox, XmNokCallback, XmCloseMsgBox, NULL);
   XtManageChild (xMsgBox);
   XtRealizeWidget (topWid);
   }
XtAppMainLoop (appShell);
XtUnrealizeWidget (topWid);
XtDestroyApplicationContext (appShell);
}

Answer 5

我建议您研究一下支持 SDL 作为后端的 GUI 库之一。 GG 就是这样一个库，它具有 ThreeButtonDlg 类。当它的 Run() 返回时，您可以查看它的 Result()。请参阅 minimal 示例中的初始方法。