XtDisplayInitialize(3)

💅 XtDisplayInitialize — the XT FUNCTIONS girlies (manual page 3, bestie)

okay so real talk, this is the page for XtDisplayInitialize, XtOpenDisplay, XtDatabase, XtScreenDatabase, and XtCloseDisplay — aka the whole "boot up ur display, open it, close it, grab the resource database" saga. it's giving foundational. it's giving main character. let's go 🦋

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✨ NAME ✨

XtDisplayInitialize, XtOpenDisplay, XtDatabase, XtScreenDatabase, XtCloseDisplay — initialize, open, or close a display 💖

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🌸 SYNTAX 🌸

#include <X11/Intrinsic.h>

void XtDisplayInitialize(XtAppContext app_context, Display *display,
       const char *application_name, const char *application_class,
       XrmOptionDescRec *options, Cardinal num_options, int *argc, char
       **argv);

Display *XtOpenDisplay(XtAppContext app_context, const char
       *display_string, const char *application_name, const char
       *application_class, XrmOptionDescRec *options, Cardinal
       num_options, int *argc, char **argv);

void XtCloseDisplay(Display *display);

XrmDatabase XtDatabase(Display *display);

XrmDatabase XtScreenDatabase(Screen* screen);

like, that's a lot of signature but it's fine, we're fine 🫶

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🎀 ARGUMENTS 🎀

• argc — a pointer to the number of command line parameters. yes a pointer. she's mutable, she's getting edited, respect her 💅
• argv — the command line parameters themselves.
• app_context — the application context. ur whole vibe container ✨
• application_class — the class name of this application, which usually is the generic name for all instances of this application. like the family name, not the first name.
• application_name — the name of the application instance. this specific one. the individual.
• display — the display. 🚨 note that a display can be in at most one application context. one display, one app context. that's the rule. no sharing, no polyamory, periodt.
• num_options — how many entries are in the options list.
• options — how to parse the command line for any application-specific resources. this argument gets passed as a parameter to XrmParseCommand. want the deep lore? go read Xlib - C Language X Interface. 📚
• screen — the screen whose resource database is to be returned.

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💖 DESCRIPTION 💖

okay bestie, buckle in, this is the long part but it's so worth it.

🧚 XtDisplayInitialize

XtDisplayInitialize builds the resource database, calls the Xlib XrmParseCommand function to parse the command line, and does a bunch of other per display initialization. the way it just handles things. iconic.

once XrmParseCommand has been called, argc and argv contain only those parameters that were not in the standard option table or in the table specified by the options argument. so like, the leftovers. the unclaimed ones.

if the modified argc is not zero, most applications simply print out the modified argv along with a message listing the allowable options. (translation: "hey u typed something weird, here's what u can type" 😭)

on UNIX-based systems, the application name is usually the final component of argv[0]. lowkey important detail, don't sleep on it.

if the synchronize resource is True for the specified application, XtDisplayInitialize calls the Xlib XSynchronize function to put Xlib into synchronous mode for this display connection. 🔥

if the reverseVideo resource is True, the Intrinsics exchange XtDefaultForeground and XtDefaultBackground for widgets created on this display. (see Section 9.6.1.) 🌈

🦋 XtOpenDisplay

XtOpenDisplay calls XOpenDisplay the specified display name.

if display_string is NULL, XtOpenDisplay uses the current value of the -display option specified in argv, and if no display is specified in argv, it uses the user's default display — and on UNIX-based systems, that's the value of the DISPLAY environment variable. ✨

if this succeeds, it then calls XtDisplayInitialize and passes it the opened display and the value of the -name option specified in argv as the application name. if no name option is specified, it uses the application name passed to XtOpenDisplay. and if the application name is NULL, it uses the last component of argv[0]. 🎯

XtOpenDisplay returns the newly opened display, or NULL if it failed. 💀

XtOpenDisplay is provided as a convenience to the application programmer. that's literally it, she's a helper, she's a bestie doing u a favor 🫶

🌸 XtCloseDisplay

XtCloseDisplay closes the specified display as soon as it is safe to do so.

if it's called from within an event dispatch (for example, a callback procedure), XtCloseDisplay does not close the display until the dispatch is complete. she waits. she's polite. she has manners. 💅

note: applications need only call XtCloseDisplay if they are to continue executing after closing the display; otherwise, they should call XtDestroyApplicationContext or just exit. like fr fr, if ur done, just leave. don't overthink it.

💜 XtDatabase

XtDatabase returns the fully merged resource database that was built by XtDisplayInitialize, associated with the display that was passed in.

🚨 if this display has not been initialized by XtDisplayInitialize, the results are not defined. do not test her. she will not be nice about it. undefined behavior is not a vibe.

⭐ XtScreenDatabase

XtScreenDatabase returns the fully merged resource database associated with the specified screen.

🚨 if the screen does not belong to a Display initialized by XtDisplayInitialize, the results are undefined. same energy. same warning. same consequences. 👑

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👑 SEE ALSO 👑

• XtAppCreateShell(3)
• XtCreateApplicationContext(3)
• X Toolkit Intrinsics - C Language Interface
• Xlib - C Language X Interface

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and that's the whole page bestie, u ate that 🍓 go forth and initialize ur displays responsibly. this was X Version 11, libXt 1.3.1, page XtDisplayInitialize(3) — mwah, take care of her 💖✨🎀