XtAllocateGC(3)

✨ XtAllocateGC — the libXt function that gets you a shareable GC 💅

okay bestie, gather round, because we're talking about XtAllocateGC(3) from the X Toolkit Intrinsics (that's the XT FUNCTIONS section of the manual, mwah) 🎀

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🌸 NAME 🌸

XtAllocateGC — obtain a shareable GC with modifiable fields 💖

Like. It hands you a graphics context that other people can share too, and you're allowed to poke at some of its fields. Iconic behaviour, no cap.

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✨ SYNTAX ✨

#include <X11/Intrinsic.h>

GC XtAllocateGC(Widget w, Cardinal depth, XtGCMask value_mask, XGCValues
       *values, XtGCMask dynamic_mask, XtGCMask unused_mask);

There she is. Six arguments, zero notes, absolutely ate 🫶

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🦋 ARGUMENTS 🦋

• values — the actual values for this GC, like, literally the real ones bestie.
• value_mask — tells you which fields of values are actually specified.
• w — the widget. the main character of this whole operation 👑
• depth — the depth for which the returned GC is valid, or 0. yes, zero is allowed, it's giving "you decide for me".
• dynamic_mask — the fields of the GC that you, the caller, are gonna modify later. you're the problem and you're proud of it 💀
• unused_mask — the fields of the GC that you will not be needing. not your business, not your vibe.

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💜 DESCRIPTION 💜

So. The XtAllocateGC function returns a shareable GC that may be modified by the client. Yep, may be modified, that's the whole point, that's the tea ☕

The screen field of the specified widget — or of the nearest widget ancestor of the specified object — plus the depth argument you passed, together supply the root and drawable depths for which the GC is to be valid. If depth is zero, the depth gets taken from the depth field of the specified widget, or of the nearest widget ancestor of the specified object. lowkey elegant, honestly 🌈

Now the masks, because this is where people get confused and I refuse to let that be you:

The value_mask argument specifies the fields of the GC that will be initialized with the respective members of the values structure. Simple. Clean. We love her.

The dynamic_mask argument specifies fields that the caller intends to modify during program execution. ⚠️ And here's the part that matters: the caller must ensure that the corresponding GC field is set prior to each use of the GC. Every. Single. Use. Not optional. Do not skip this step, I'm begging 🙈

The unused_mask argument specifies fields of the GC that are of no interest to the caller. And the caller may make no assumptions about the contents of any fields specified in unused_mask. None. Zero. Don't look at them. Don't think about them. They're not yours 💅

The caller may assume that at all times all fields not specified in either dynamic_mask or unused_mask have their default value — if they're not specified in value_mask or given by values, that is.

If a field is specified in both value_mask and dynamic_mask, the effect is as if it were specified only in dynamic_mask and then immediately set to the value in values. Cute little tie-break, love that for us ✨

If a field is set in unused_mask and also in either value_mask or dynamic_mask, the specification in unused_mask is ignored. sorry bestie, the other masks win that argument 🥲

and finally, the efficiency slay: XtAllocateGC tries to minimize the number of unique GCs created by comparing the arguments with those of previous calls and returning an existing GC when there are no conflicts. reuse, reduce, recycle, periodt ♻️

⚠️ but heads up: XtAllocateGC may modify and return an existing GC if it was allocated with a nonzero unused_mask. so if you lied about not needing those fields, that's on you, and it will find out 😭

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🔥 SEE ALSO 🔥

• XtGetGC
• X Toolkit Intrinsics - C Language Interface
• Xlib - C Language X Interface

iykyk, go read those too, they're the supporting cast and they deserve their flowers 🌸

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okay that's the whole page bestie, you're officially fluent in GC allocation 💖

this has been the XtAllocateGC(3) page from X Version 11, libXt 1.3.1, dated like the classic it is — and yes, the footer says XtAllocateGC(3) again because the universe loves a callback. mwah, go write some Xt code, you've got this 🫶✨🎀