X11 X图像处理

Question

我正在尝试从我的全新 window 中选取一张图像，然后将其绘制回相同的 window，只是为了在 XLib 上进行训练。

这是我的代码：

#include<stdio.h>
#include<stdlib.h>
#include<stdint.h>
#include<X11/Xlib.h>
#include<X11/Xutil.h>
#include<sys/stat.h>
#include<sys/time.h>
#include<sys/types.h>
#include<unistd.h>

int main(int argc, char *argv[]) {
    fd_set eventset;
    fd_set zeroset;
//  struct timeval timeout = {0, 0};

    Display *display = 0;
    int screen;
    Window wnd;
    XVisualInfo vinfo;
    XSetWindowAttributes attr;
    XEvent event;
    XImage *bg;

    Atom WM_message[2];

    int run = 1;

    FD_ZERO(&eventset);
    FD_ZERO(&zeroset);

    if(!(display = XOpenDisplay(0))) {
        /* Display not found */
        printf("Fail display.\n");
        return 0;
    }

    screen = XDefaultScreen(display);

    if(!XMatchVisualInfo(display, screen, 32, TrueColor, &vinfo)) {
        if(!XMatchVisualInfo(display, screen, 24, TrueColor, &vinfo)) {
            /* No proper color depth available */
            XCloseDisplay(display); /* Close X communication */
            printf("No found color display. Sorry.\n");
            return 0;
        }
    }

    attr.colormap = XCreateColormap(display, DefaultRootWindow(display), vinfo.visual, AllocNone);
    attr.border_pixel = 0;
    attr.background_pixel = 0x80000000;
    attr.bit_gravity = NorthWestGravity;
    attr.win_gravity = NorthWestGravity;

    wnd = XCreateWindow(display, DefaultRootWindow(display), 0, 0, 300, 300, 0,
        vinfo.depth, InputOutput, vinfo.visual,
        CWColormap | CWBorderPixel | CWBackPixel | CWBitGravity | CWWinGravity, &attr);

    /* Subscribe to window closing event */
    WM_message[0] = XInternAtom(display, "WM_PROTOCOLS", 1);
    WM_message[1] = XInternAtom(display, "WM_DELETE_WINDOW", 1);
    XSetWMProtocols(display, wnd, WM_message, 2);

    XFreeColormap(display, attr.colormap);
    XSelectInput(display, wnd, ExposureMask | ButtonPressMask | KeyPressMask);

    XMapWindow(display, wnd);

    bg = XGetImage(display, XDefaultRootWindow(display), 0, 0, 300, 300, AllPlanes, ZPixmap);
//  bg = XGetImage(display, wnd, 100, 100, 100, 100, AllPlanes, ZPixmap);
/*  int x;
    for(x = 0; x < 10000; x++) {
        bg->data[x] = 0x80;
    } */
    XPutImage(display, wnd, XDefaultGC(display, screen), bg, 0, 0, 0, 0, 300, 300);
//  XPutImage(display, wnd, XDefaultGC(display, screen), bg, 100, 100, 100, 100, 100, 100);

    XMapWindow(display, wnd);
    XFlush(display);

    while(run) {
        XNextEvent(display, &event);
        switch(event.type) {
            case Expose:
                printf("w = %d, h = %d\n", event.xexpose.width, event.xexpose.height);              
                break;

            case DestroyNotify:
                run = 0;
                break;

            case ClientMessage:
                {
                    if(event.xclient.message_type == WM_message[0]) {
                        if(event.xclient.data.l[0] == WM_message[1]) {
                            run = 0;
                        }
                    }
                }
            default:;
            }
    }
    XDestroyImage(bg);
    XDestroyWindow(display, wnd);
    XCloseDisplay(display);

    return 0;
}

这使我的程序在 porteus 和 mobaxterm 上崩溃。

但是这一行：

//  bg = XGetImage(display, wnd, 100, 100, 100, 100, AllPlanes, ZPixmap);
/*  int x;
    for(x = 0; x < 10000; x++) {
        bg->data[x] = 0x80;
    } */
//  XPutImage(display, wnd, XDefaultGC(display, screen), bg, 100, 100, 100, 100, 100, 100);

不会使我的程序崩溃...它只是什么也不渲染。

有人可以帮助我理解为什么我要试验 X 的这种奇怪行为吗？

这是我收到的错误消息：

X Error of failed request: BadMatch (invalid parameter attributes) Major opcode of failed request: 72 (X_PutImage) Serial number of failed request: 16 Current serial number in output stream: 18

Answer 1

经过进一步的研究和尝试，我终于找到了两个事实：

首先我的 post 是错误的：这不会崩溃：

XPutImage(display, XDefaultRootWindow(display), XDefaultGC(display, screen), bg, 100, 100, 100, 100, 100, 100);

那些行崩溃了：

XPutImage(display, wnd, XDefaultGC(display, screen), bg, 0, 0, 0, 0, 300, 300);
XPutImage(display, wnd, XDefaultGC(display, screen), bg, 100, 100, 100, 100, 100, 100);

第二个：

在rootwindow上用default gc写是可以的，因为default gc是默认rootwindow.

对应的gc

但是将此 GC 用于我自己的 window 是一个错误，因为我使用的颜色深度可能不同于根 window。

所以我现在运行很好：

#include<stdio.h>
#include<stdlib.h>
#include<stdint.h>
#include<X11/Xlib.h>
#include<X11/Xutil.h>
#include<sys/stat.h>
#include<sys/time.h>
#include<sys/types.h>
#include<unistd.h>

int main(int argc, char *argv[]) {
    fd_set eventset;
    fd_set zeroset;
//  struct timeval timeout = {0, 0};

    Display *display = 0;
    int screen;
    Window wnd;
    XVisualInfo vinfo;
    XSetWindowAttributes attr;
    XEvent event;
    XImage *bg;
    GC mainGC;

    Atom WM_message[2];

    int run = 1;

    FD_ZERO(&eventset);
    FD_ZERO(&zeroset);

    if(!(display = XOpenDisplay(0))) {
        /* Display not found */
        printf("Fail display.\n");
        return 0;
    }

    screen = XDefaultScreen(display);

    if(!XMatchVisualInfo(display, screen, 32, TrueColor, &vinfo)) {
        if(!XMatchVisualInfo(display, screen, 24, TrueColor, &vinfo)) {
            /* No proper color depth available */
            XCloseDisplay(display); /* Close X communication */
            printf("No found color display. Sorry.\n");
            return 0;
        }
    }

    attr.colormap = XCreateColormap(display, DefaultRootWindow(display), vinfo.visual, AllocNone);
    attr.border_pixel = 0;
    attr.background_pixel = 0x80000000;
    attr.bit_gravity = NorthWestGravity;
    attr.win_gravity = NorthWestGravity;

    wnd = XCreateWindow(display, DefaultRootWindow(display), 0, 0, 300, 300, 0,
        vinfo.depth, InputOutput, vinfo.visual,
        CWColormap | CWBorderPixel | CWBackPixel | CWBitGravity | CWWinGravity, &attr);

    /* Subscribe to window closing event */
    WM_message[0] = XInternAtom(display, "WM_PROTOCOLS", 1);
    WM_message[1] = XInternAtom(display, "WM_DELETE_WINDOW", 1);
    XSetWMProtocols(display, wnd, WM_message, 2);

    XFreeColormap(display, attr.colormap);
    XSelectInput(display, wnd, ExposureMask | ButtonPressMask | KeyPressMask);

    XMapWindow(display, wnd);
    XFlush(display);

    mainGC = XCreateGC(display, wnd, 0, 0);

    bg = XGetImage(display, wnd, 0, 0, 100, 100, AllPlanes, ZPixmap);
    int x;
    for(x = 0; x < 10000; x++) {
        bg->data[x] = 0x80;
    }
    XPutImage(display, wnd, mainGC, bg, 0, 0, 100, 100, 100, 100);

    while(run) {
        XNextEvent(display, &event);
        switch(event.type) {
            case Expose:
                printf("w = %d, h = %d\n", event.xexpose.width, event.xexpose.height);              
                break;

            case DestroyNotify:
                run = 0;
                break;

            case ClientMessage:
                {
                    if(event.xclient.message_type == WM_message[0]) {
                        if(event.xclient.data.l[0] == WM_message[1]) {
                            run = 0;
                        }
                    }
                }
            default:;
            }
    }
    XDestroyImage(bg);
    XDestroyWindow(display, wnd);
    XCloseDisplay(display);

    return 0;
}

X11 X图像处理

X11 XImage manipulation

c

x11