Tk_GetColormap(3tk)

💖 Tk_GetColormap — allocate and free colormaps 💖

okay bestie, so this is the Tk_GetColormap(3tk) page from the Tk Library Procedures and it's literally all about colormaps: grabbing them, holding onto them, and letting them go. three little functions, one big vibe. let's get into it 🎀

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✨ SYNOPSIS ✨

#include <tk.h>

Colormap
Tk_GetColormap(interp, tkwin, string)

Tk_PreserveColormap(display, colormap)

Tk_FreeColormap(display, colormap)

like, that's the whole thing. short king behavior tbh 👑

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🫶 ARGUMENTS 🫶

• Tcl_Interp *interp (in) — the interpreter we use for error reporting, so if something goes sideways, the tea gets spilled right here.
• Tk_Window tkwin (in) — a token for the window where the colormap is gonna be used.
• const char *string (in) — picks the colormap for you: either new, or the name of a window that has the same screen and visual as tkwin.
• Display *display (in) — the display the colormap was allocated for.
• Colormap colormap (in) — the colormap to free or preserve; it must have been returned by an earlier call to Tk_GetColormap or Tk_GetVisual.

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🌈 DESCRIPTION 🌈

So these procedures manage colormaps, periodt. Tk_GetColormap hands you back a colormap that's suitable for use in tkwin. If its string argument is new, then a brand-new colormap gets created 🦋. Otherwise, string has to be the name of another window with the same screen and visual as tkwin, and the colormap from that window is what you get back. And if string doesn't make sense? or if it points at a window on a different screen than tkwin, or one with a different visual than tkwin? then Tk_GetColormap returns None and leaves an error message in interp's result. no cap. 💀

Tk_PreserveColormap bumps up the internal reference count for a colormap that was previously returned by Tk_GetColormap. why do you care? because it lets you stash that colormap in several different places without needing to know which order they'll get released in. it's giving organized chaos, but make it correct 🧚

Tk_FreeColormap is the one you call when a colormap returned by Tk_GetColormap is no longer needed. Tk keeps a reference count for every colormap that Tk_GetColormap returns, so eventually there should be one call to Tk_FreeColormap for each call to Tk_GetColormap and each call to Tk_PreserveColormap. the way that math has to balance out... iconic. and when a colormap's reference count hits zero, Tk releases the X colormap. bye boo 👋

not me stressing that mismatched counts are a whole thing — keep your gets and your frees matching, bestie, fr fr.

Tk_GetVisual and Tk_GetColormap are besties, they work together 🫂: a new colormap created by Tk_GetVisual may later be returned by Tk_GetColormap. The reference counting mechanism for colormaps covers both procedures, so callers of Tk_GetVisual must also call Tk_FreeColormap to release the colormap. don't forget that part, it's lowkey the whole plot twist.

And one more thing ✨: if Tk_GetColormap is called with a string value of new, then the resulting colormap will never be returned by Tk_GetVisual. However, it can still be used in other windows — you just call Tk_GetColormap with the original window's name as string. slay, it's shareable 💅

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🔑 KEYWORDS 🔑

colormap, visual

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and that's the page, babe 🌸 this was Tk version 4.0, Tk_GetColormap(3tk), from the Tk Library Procedures — go forth and manage those colormaps responsibly, you main character 👑💜