Linux下如何获取当前/Alt+Tab切换后的应用程序名称？

Got it, let's break down how to get the active window name and track Alt+Tab switches on Linux—since unlike macOS, Linux relies on two main display servers (X11 and Wayland) with distinct approaches, we'll cover both scenarios.

For X11 (Traditional Desktops: Ubuntu <22.04, XFCE, KDE Plasma X11) #

X11 has well-established tools and low-level APIs for window interaction, similar to macOS's CG Graphics framework.

Quick Command-Line Solutions #

If you just need a fast way to fetch the active window name, use these pre-built tools:

• xdotool: Run xdotool getactivewindow getwindowname to directly print the active window's title.
• wmctrl: Use wmctrl -l | grep $(xdotool getactivewindow) to filter the active window from the full list of open windows.

Programmatic Approach with Xlib (C/C++) #

This is the low-level equivalent to macOS's CGWindowListCopyWindowInfo. Here's a minimal example to retrieve the active window name:

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <stdio.h>

int main() {
    Display *display = XOpenDisplay(NULL);
    if (!display) {
        fprintf(stderr, "Failed to connect to X display\n");
        return 1;
    }

    Window root = DefaultRootWindow(display);
    Window activeWindow;
    int revertMode;
    XGetInputFocus(display, &activeWindow, &revertMode);

    char *windowName;
    if (XFetchName(display, activeWindow, &windowName)) {
        printf("Current Active Window: %s\n", windowName);
        XFree(windowName);
    } else {
        printf("No title found for active window\n");
    }

    XCloseDisplay(display);
    return 0;
}

Compile with: gcc -o active_window active_window.c -lX11

Tracking Alt+Tab Window Switches #

To detect when the active window changes (like after an Alt+Tab press), listen for FocusIn events using Xlib:

1. Enable event tracking on the root window: XSelectInput(display, root, FocusChangeMask)
2. Enter an event loop, and whenever a FocusIn event triggers, re-fetch the active window name using the code above.

For Wayland (Modern Desktops: GNOME 40+, KDE Plasma Wayland, Sway) #

Wayland prioritizes security, so there's no universal "list all windows" API like X11. Instead, use desktop-specific tools or framework APIs:

GNOME Wayland #

Use D-Bus to query and monitor window activity:

• Get current active window name:

  gdbus call --session --dest org.gnome.Shell --object-path /org/gnome/Shell --method org.gnome.Shell.Eval "global.display.focus_window.get_title()"
  

• Track window switches: Monitor D-Bus signals from GNOME Shell, or use the GNOME Shell Extension API if building a GUI app.

KDE Plasma Wayland #

Leverage KDE's KWindowSystem library (part of KDE Frameworks) or command-line D-Bus calls:

# Get active window ID
qdbus org.kde.KWin /KWin activeWindow
# Get window title from ID
qdbus org.kde.KWin /KWin getWindowTitle $(qdbus org.kde.KWin /KWin activeWindow)

Wlroots-Based Compositors (Sway, Hyprland) #

Use compositor-specific tools:

• Get active window name in Sway:

  swaymsg -t get_tree | jq '.. | select(.focused == true) | .name'
  

• Track switches: Listen to Sway's IPC events with swaymsg -t subscribe '["window"]'

Cross-Desktop GUI Frameworks #

If you're building a Qt/GTK app, use their built-in APIs to abstract X11/Wayland differences:

• Qt: QGuiApplication::activeWindow()->windowTitle()
• GTK: gtk_window_get_title(gtk_window_get_active())

内容的提问来源于stack exchange，提问作者Nikhil Nilawar