我有一个使用XLib的C++应用程序。在这个应用程序中,我使用ctime库访问日期和时间,并在Expose事件中创建一个字符串并将其放置在窗口中央。我的问题是,只有当窗口被调整大小时,时间才会更新。例如,除非我不断地调整窗口大小,否则秒数不会改变。以下是代码:
#include <stdio.h>
#include <cstdio>
#include <stdlib.h>
#include <string.h>
#include <X11/Xlib.h>
#include <ctime>
int main (int argc, char *argv[])
{
Display *display;
Visual *visual;
int depth;
int text_x;
int text_y;
XSetWindowAttributes frame_attributes;
Window frame_window;
XFontStruct *fontinfo;
XGCValues gr_values;
GC graphical_context;
XKeyEvent event;
char contents[80] = " ";
time_t rawtime;
struct tm *timeinfo;
int contents_length = strlen(contents);
display = XOpenDisplay(NULL);
visual = DefaultVisual(display, 0);
depth = DefaultDepth(display, 0);
frame_attributes.background_pixel = XWhitePixel(display, 0);
/* create the application window */
frame_window = XCreateWindow(display, XRootWindow(display, 0),
0, 0, 500, 50, 5, depth,
InputOutput, visual, CWBackPixel,
&frame_attributes);
XStoreName(display, frame_window, "Fly Taskbar");
XSelectInput(display, frame_window, ExposureMask | StructureNotifyMask);
fontinfo = XLoadQueryFont(display, "10x20");
gr_values.font = fontinfo->fid;
gr_values.foreground = XBlackPixel(display, 0);
graphical_context = XCreateGC(display, frame_window,
GCFont+GCForeground, &gr_values);
XMapWindow(display, frame_window);
while ( 1 ) {
XNextEvent(display, (XEvent *)&event);
switch ( event.type ) {
case Expose:
{
XClearWindow(display, frame_window);
// Upkeep of interface usefulness.
Window returned_root, returned_parent;
Window* top_level_windows;
unsigned int nwin = 0;
XQueryTree(
display,
XDefaultRootWindow(display),
&returned_root,
&returned_parent,
&top_level_windows,
&nwin);
time(&rawtime);
timeinfo = localtime(&rawtime);
strftime(contents, 80, "%a %d %b, %T %p", timeinfo);
sprintf(contents, "%s [%d]", contents, nwin);
XWindowAttributes window_attributes;
int font_direction, font_ascent, font_descent;
XCharStruct text_structure;
XTextExtents(fontinfo, contents, contents_length,
&font_direction, &font_ascent, &font_descent,
&text_structure);
XGetWindowAttributes(display, frame_window, &window_attributes);
text_x = (window_attributes.width - text_structure.width) + 5;
text_y = (window_attributes.height -
(text_structure.ascent+text_structure.descent))/2;
XDrawString(display, frame_window, graphical_context,
text_x, text_y, contents, contents_length);
break;
}
default:
break;
}
}
return 0;
}
< p > 如果你们中有人想知道这个工具的目的是什么,我正在编写一个窗口管理器(实际上我已经非常进展了,比如你可以打开应用程序、移动和调整它们的大小),这是我需要的一个调试工具。存储库在这里