Question

我试图在我的应用程序中使用XFT，但是第二次尝试在同一进程中使用新的显示连接绘制文本时崩溃了。以下是我的用例的简化版本。

while true
do
    OpenDisplay
    LoadFont
    Draw Text
    Close Font   
    Close Display
end

我在一些论坛上看到XCloseDisplay也会关闭字体，但是当我尝试加载多个字体时，我注意到了内存泄漏。

我试图调试这个问题，这些是我的观察，

评论XftDrawText，崩溃消失
评论XftFontClose，崩溃消失但内存泄漏

以下是我用来重现此代码的代码。任何帮助将不胜感激。

#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <cstring>
#include <iostream>
#include <X11/Xft/Xft.h>

using namespace std;

const char fontNames[5][50] = { "helvetica", "arial", "courier", "times", "utopia" };
int sizes[5] = {10, 20, 30, 40, 50};
int numFonts = 5;

void TestXft(Display* display, Window& win, GC& gc, const char *fontName, int size);

Window create_simple_window(Display* display, int width, int height, int x, int y)
{
    int screen_num = DefaultScreen(display);
    int win_border_width = 2;
    Window win;
    win = XCreateSimpleWindow(display, RootWindow(display, screen_num), x, y,
            width, height, win_border_width,
            BlackPixel(display, screen_num),
            WhitePixel(display, screen_num));

    XMapWindow(display, win);

    XFlush(display);

    return win;
}

GC create_gc(Display* display, Window win)
{
    GC gc;
    unsigned long valuemask = 0;
    XGCValues values;

    gc = XCreateGC(display, win, valuemask, &values);

    if (gc < 0)
    {
        fprintf(stderr, "XCreateGC: \n");
    }
    return gc;
}

int main(int argc, char* argv[])
{
    int screen_num;
    Window win;
    unsigned int display_width, display_height;
    GC gc;
    unsigned long count = 0;

    while(true)
    {       
        cout << "\nIteration: " << ++count << endl;

        Display* display = XOpenDisplay(NULL);
        if (display == NULL)
        {
            printf("Cannot connect to X server\n");
            exit(1);
        }

        screen_num = DefaultScreen(display);
        display_width = 500;
        display_height = 500;

        win = create_simple_window(display, display_width, display_height, 0, 0);
        XMapWindow(display, win);

        XMoveWindow(display, win, 1000, 600);

        gc = create_gc(display, win);

        for(int i = 0; i < numFonts; i++)
        {
            TestXft(display, win, gc, fontNames[i], sizes[i]);
        }

        XUnmapWindow(display, win);
        XFreeGC(display, gc);
        XSync(display, false);
        XCloseDisplay(display);
    }
    return 0;
}

void TestXft(Display* display, Window& win, GC& gc, const char *fontName, int size)
{
    XftFont      *font = NULL;
    XftDraw      *xftdraw = NULL;
    XRenderColor xrcolor;
    XftColor     xftcolor;
    font = NULL;

    Colormap colormap = XCreateColormap(display, win, DefaultVisual(display, DefaultScreen(display)), AllocNone);

    font = XftFontOpen(display, DefaultScreen(display), XFT_FAMILY, XftTypeString, fontName,
                                XFT_SIZE, XftTypeDouble, (double) size,
                                XFT_SCALE, XftTypeDouble, 2.0,
                                NULL);
    if (!font)
    {
        printf("Font not Found.\n");
        return;
    }

    xftdraw = XftDrawCreate(display, win, DefaultVisual(display,0), colormap);

    xrcolor.red = 65535;
    xrcolor.green= 0;
    xrcolor.blue = 0;
    xrcolor.alpha= 65535;
    XftColorAllocValue(display, DefaultVisual(display,0), colormap, &xrcolor, &xftcolor);

    const char *text = "RCB...RCB...RCB";
    XftDrawString8(xftdraw, &xftcolor, font, 200, 300 , (XftChar8 *) text, strlen(text));

    XftColorFree(display, DefaultVisual(display,0), colormap, &xftcolor);
    XftDrawDestroy(xftdraw);
    XftFontClose(display, font);
    XFreeColormap(display, colormap);
}

Answer 1

这是Xft库中的一个错误，它阻止它在多次打开和关闭显示时有用。

将XOpenDisplay和XCloseDisplay移出循环，添加对XDestroyWindow的调用，它会起作用。

在同一应用程序进程中使用XFT字体第二次使用新的显示连接绘制文本时崩溃

1 个答案: