HPUX GetColor[3]
GetColor in anderen Kapiteln des hpux Handbuch:
Tk_GetColor(3) Tk Tk_GetColor(3)
Tk Library Procedures Tk Library Procedures
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NAME
Tk_GetColor, Tk_GetColorByValue, Tk_NameOfColor Tk_FreeColor -
maintain database of colors
SYNOPSIS
#include <tk.h>
XColor *
Tk_GetColor(interp, tkwin, colorMap, nameId)
XColor *
Tk_GetColorByValue(interp, tkwin, colorMap, prefPtr)
char *
Tk_NameOfColor(colorPtr)
Tk_FreeColor(colorPtr)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use for error
reporting.
Tk_Window tkwin (in) Token for window in which color
will be used.
Colormap colormap (in) Colormap from which to allocate
color. If None, then the default
colormap for tkwin's screen is
used.
Tk_Uid nameId (in) Textual description of desired
color.
XColor *prefPtr (in) Indicates red, green, and blue
intensities of desired color.
XColor *colorPtr (in) Pointer to X color information.
Must have been allocated by
previous call to Tk_GetColor or
Tk_GetColorByValue, except when
passed to Tk_NameOfColor.
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DESCRIPTION
The Tk_GetColor and Tk_GetColorByValue procedures locate pixel values
that may be used to render particular colors in the window given by
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Tk_GetColor(3) Tk Tk_GetColor(3)
Tk Library Procedures Tk Library Procedures
tkwin using the colormap given by colormap. In Tk_GetColor the
desired color is specified with a Tk_Uid (nameId), which may have any
of the following forms:
colorname Any of the valid textual names for a color defined
in the server's color database file, such as red
or PeachPuff.
#RGB
#RRGGBB
#RRRGGGBBB
#RRRRGGGGBBBB A numeric specification of the red, green, and
blue intensities to use to display the color.
Each R, G, or B represents a single hexadecimal
digit. The four forms permit colors to be
specified with 4-bit, 8-bit, 12-bit or 16-bit
values. When fewer than 16 bits are provided for
each color, they represent the most significant
bits of the color. For example, #3a7 is the same
as #3000a0007000. In Tk_GetColorByValue, the
desired color is indicated with the red, green,
and blue fields of the structure pointed to by
colorPtr.
If Tk_GetColor or Tk_GetColorByValue is successful in allocating the
desired color, then it returns a pointer to an XColor structure; the
structure indicates the exact intensities of the allocated color
(which may differ slightly from those requested, depending on the
limitations of the screen) and a pixel value from colormap that may be
used to draw in the color. If an error occurs in allocating a color
then NULL is returned and an error message will be stored in interp-
>result.
Tk_GetColor and Tk_GetColorByValue maintain a database of all the
colors currently in use. If the same nameId is requested multiple
times from Tk_GetColor (e.g. by different windows), or if the same
intensities are requested multiple times from Tk_GetColorByValue, then
existing pixel values will be re-used. Re-using an existing pixel
avoids any interaction with the X server, which makes the allocation
much more efficient. For this reason, you should generally use
Tk_GetColor or Tk_GetColorByValue instead of Xlib procedures like
XAllocColor, XAllocNamedColor, or XParseColor.
Since different calls to Tk_GetColor or Tk_GetColorByValue may return
the same shared pixel value, callers should never change the color of
a pixel returned by the procedures. If you need to change a color
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Tk_GetColor(3) Tk Tk_GetColor(3)
Tk Library Procedures Tk Library Procedures
value dynamically, you should use XAllocColorCells to allocate the
pixel value for the color.
The procedure Tk_NameOfColor is roughly the inverse of Tk_GetColor.
If its colorPtr argument was created by Tk_GetColor, then the return
value is the nameId string that was passed to Tk_GetColor to create
the color. If colorPtr was created by a call to Tk_GetColorByValue,
or by any other mechanism, then the return value is a string that
could be passed to Tk_GetColor to return the same color. Note: the
string returned by Tk_NameOfColor is only guaranteed to persist until
the next call to Tk_NameOfColor.
When a pixel value returned by Tk_GetColor or Tk_GetColorByValue is no
longer needed, Tk_FreeColor should be called to release the color.
There should be exactly one call to Tk_FreeColor for each call to
Tk_GetColor or Tk_GetColorByValue. When a pixel value is no longer in
use anywhere (i.e. it has been freed as many times as it has been
gotten) Tk_FreeColor will release it to the X server and delete it
from the database.
KEYWORDS
color, intensity, pixel value
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