ghostty/src/apprt/gtk/x11.zig
2024-01-07 16:54:01 +01:00

151 lines
5.8 KiB
Zig

/// Utility functions for X11 handling.
const std = @import("std");
const c = @import("c.zig");
const input = @import("../../input.zig");
const log = std.log.scoped(.gtk_x11);
/// Returns true if the passed in display is an X11 display.
pub fn is_display(display: ?*c.GdkDisplay) bool {
return c.g_type_check_instance_is_a(
@ptrCast(@alignCast(display orelse return false)),
c.gdk_x11_display_get_type(),
) != 0;
}
/// Returns true if the app is running on X11
pub fn is_current_display_server() bool {
const display = c.gdk_display_get_default();
return is_display(display);
}
pub const Xkb = struct {
base_event_code: c_int,
funcs: Funcs,
/// Initialize an Xkb struct, for the given GDK display. If the display
/// isn't backed by X then this will return null.
pub fn init(display_: ?*c.GdkDisplay) !?Xkb {
// Display should never be null but we just treat that as a non-X11
// display so that the caller can just ignore it and not unwrap it.
const display = display_ orelse return null;
// If the display isn't X11, then we don't need to do anything.
if (!is_display(display)) return null;
log.debug("Xkb.init: initializing Xkb", .{});
const xdisplay = c.gdk_x11_display_get_xdisplay(display);
var result: Xkb = .{
.base_event_code = 0,
.funcs = try Funcs.init(),
};
log.debug("Xkb.init: running XkbQueryExtension", .{});
var opcode: c_int = 0;
var base_error_code: c_int = 0;
var major = c.XkbMajorVersion;
var minor = c.XkbMinorVersion;
if (result.funcs.XkbQueryExtension(
xdisplay,
&opcode,
&result.base_event_code,
&base_error_code,
&major,
&minor,
) == 0) {
log.err("Fatal: error initializing Xkb extension: error executing XkbQueryExtension", .{});
return error.XkbInitializationError;
}
log.debug("Xkb.init: running XkbSelectEventDetails", .{});
if (result.funcs.XkbSelectEventDetails(
xdisplay,
c.XkbUseCoreKbd,
c.XkbStateNotify,
c.XkbModifierStateMask,
c.XkbModifierStateMask,
) == 0) {
log.err("Fatal: error initializing Xkb extension: error executing XkbSelectEventDetails", .{});
return error.XkbInitializationError;
}
return result;
}
/// Checks for an immediate pending XKB state update event, and returns the
/// keyboard state based on if it finds any. This is necessary as the
/// standard GTK X11 API (and X11 in general) does not include the current
/// key pressed in any modifier state snapshot for that event (e.g. if the
/// pressed key is a modifier, that is not necessarily reflected in the
/// modifiers).
///
/// Returns null if there is no event. In this case, the caller should fall
/// back to the standard GDK modifier state (this likely means the key
/// event did not result in a modifier change).
pub fn modifier_state_from_notify(self: Xkb, display_: ?*c.GdkDisplay) ?input.Mods {
const display = display_ orelse return null;
// Shoutout to Mozilla for figuring out a clean way to do this, this is
// paraphrased from Firefox/Gecko in widget/gtk/nsGtkKeyUtils.cpp.
const xdisplay = c.gdk_x11_display_get_xdisplay(display);
if (self.funcs.XEventsQueued(xdisplay, c.QueuedAfterReading) == 0) return null;
var nextEvent: c.XEvent = undefined;
_ = self.funcs.XPeekEvent(xdisplay, &nextEvent);
if (nextEvent.type != self.base_event_code) return null;
const xkb_event: *c.XkbEvent = @ptrCast(&nextEvent);
if (xkb_event.any.xkb_type != c.XkbStateNotify) return null;
const xkb_state_notify_event: *c.XkbStateNotifyEvent = @ptrCast(xkb_event);
// Check the state according to XKB masks.
const lookup_mods = xkb_state_notify_event.lookup_mods;
var mods: input.Mods = .{};
log.debug("X11: found extra XkbStateNotify event w/lookup_mods: {b}", .{lookup_mods});
if (lookup_mods & c.ShiftMask != 0) mods.shift = true;
if (lookup_mods & c.ControlMask != 0) mods.ctrl = true;
if (lookup_mods & c.Mod1Mask != 0) mods.alt = true;
if (lookup_mods & c.Mod2Mask != 0) mods.super = true;
if (lookup_mods & c.LockMask != 0) mods.caps_lock = true;
return mods;
}
};
/// The functions that we load dynamically from libX11.so.
const Funcs = struct {
XkbQueryExtension: XkbQueryExtensionType,
XkbSelectEventDetails: XkbSelectEventDetailsType,
XEventsQueued: XEventsQueuedType,
XPeekEvent: XPeekEventType,
const XkbQueryExtensionType = *const fn (?*c.struct__XDisplay, [*c]c_int, [*c]c_int, [*c]c_int, [*c]c_int, [*c]c_int) callconv(.C) c_int;
const XkbSelectEventDetailsType = *const fn (?*c.struct__XDisplay, c_uint, c_uint, c_ulong, c_ulong) callconv(.C) c_int;
const XEventsQueuedType = *const fn (?*c.struct__XDisplay, c_int) callconv(.C) c_int;
const XPeekEventType = *const fn (?*c.struct__XDisplay, [*c]c.union__XEvent) callconv(.C) c_int;
pub fn init() !Funcs {
var libX11 = try std.DynLib.open("libX11.so");
defer libX11.close();
var result: Funcs = undefined;
inline for (@typeInfo(Funcs).Struct.fields) |field| {
const name = comptime name: {
const null_term = field.name ++ .{0};
break :name null_term[0..field.name.len :0];
};
@field(result, field.name) = libX11.lookup(
field.type,
name,
) orelse {
log.err(" error dynamic loading libX11: missing symbol {s}", .{field.name});
return error.XkbInitializationError;
};
}
return result;
}
};