Tk\_GetColormap(3) Tk Library Procedures Tk\_GetColormap(3)

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# [NAME](#NAME)

Tk\_GetColormap, Tk\_PreserveColormap, Tk\_FreeColormap - allocate and free colormaps

# [SYNOPSIS](#SYNOPSIS)

```
#include <tk.h>

Colormap
Tk_GetColormap(interp, tkwin, string)

Tk_PreserveColormap(display, colormap)

Tk_FreeColormap(display, colormap)
```

# [ARGUMENTS](#ARGUMENTS)

Tcl\_Interp *\*interp* (in)

Interpreter to use for error reporting.

Tk\_Window *tkwin* (in)

Token for window in which colormap will be used.

const char *\*string* (in)

Selects a colormap: either **new** or the name of a window with the same screen and visual as *tkwin*.

Display *\*display* (in)

Display for which *colormap* was allocated.

Colormap *colormap* (in)

Colormap to free or preserve; must have been returned by a previous call to **Tk\_GetColormap** or **Tk\_GetVisual**.

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# [DESCRIPTION](#DESCRIPTION)

These procedures are used to manage colormaps. **Tk\_GetColormap** returns a colormap suitable for use in *tkwin*. If its *string* argument is **new** then a new colormap is created; otherwise *string* must be the name of another window with the same screen and visual as *tkwin*, and the colormap from that window is returned. If *string* does not make sense, or if it refers to a window on a different screen from *tkwin* or with a different visual than *tkwin*, then **Tk\_GetColormap** returns **None** and leaves an error message in *interp*'s result.

**Tk\_PreserveColormap** increases the internal reference count for a colormap previously returned by **Tk\_GetColormap**, which allows the colormap to be stored in several locations without knowing which order they will be released.

**Tk\_FreeColormap** should be called when a colormap returned by **Tk\_GetColormap** is no longer needed. Tk maintains a reference count for each colormap returned by **Tk\_GetColormap**, so there should eventually be one call to **Tk\_FreeColormap** for each call to **Tk\_GetColormap** and each call to **Tk\_PreserveColormap**. When a colormap's reference count becomes zero, Tk releases the X colormap.

**Tk\_GetVisual** and **Tk\_GetColormap** work together, in that a new colormap created by **Tk\_GetVisual** may later be returned by **Tk\_GetColormap**. The reference counting mechanism for colormaps includes both procedures, so callers of **Tk\_GetVisual** must also call **Tk\_FreeColormap** to release the colormap. 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 be used in other windows by calling **Tk\_GetColormap** with the original window's name as *string*.

# [KEYWORDS](#KEYWORDS)

colormap, visual

4.0 Tk

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Document: Tk_FreeColormap(3) from tk 9.1.0-r0 (Chainguard OS)
Source: https://downloads.sourceforge.net/sourceforge/tcl/tk9.1.0-src.tar.gz