Initial revision

1 files changed, 146 insertions, 0 deletions

diff --git a/doc/GetColor.3 b/doc/GetColor.3
new file mode 100644
index 0000000..7f89446
--- /dev/null
+++ b/doc/GetColor.3
@@ -0,0 +1,146 @@
+'\"
+'\" Copyright (c) 1990, 1991 The Regents of the University of California.
+'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\" 
+'\" SCCS: @(#) GetColor.3 1.22 96/08/27 13:21:26
+'\" 
+.so man.macros
+.TH Tk_GetColor 3 4.0 Tk "Tk Library Procedures"
+.BS
+.SH NAME
+Tk_GetColor, Tk_GetColorByValue, Tk_NameOfColor, Tk_FreeColor \- maintain database of colors
+.SH SYNOPSIS
+.nf
+\fB#include <tk.h>\fR
+.sp
+XColor *
+\fBTk_GetColor\fR(\fIinterp, tkwin, nameId\fB)\fR
+.sp
+XColor *
+\fBTk_GetColorByValue\fR(\fItkwin, prefPtr\fB)\fR
+.sp
+char *
+\fBTk_NameOfColor(\fIcolorPtr\fB)\fR
+.sp
+GC
+\fBTk_GCForColor\fR(\fIcolorPtr, drawable\fR)
+.sp
+\fBTk_FreeColor(\fIcolorPtr\fB)\fR
+.SH ARGUMENTS
+.AS "Tcl_Interp" *colorPtr
+.AP Tcl_Interp *interp in
+Interpreter to use for error reporting.
+.AP Tk_Window tkwin in
+Token for window in which color will be used.
+.AP Tk_Uid nameId in
+Textual description of desired color.
+.AP XColor *prefPtr in
+Indicates red, green, and blue intensities of desired
+color.
+.AP XColor *colorPtr in
+Pointer to X color information.  Must have been allocated by previous
+call to \fBTk_GetColor\fR or \fBTk_GetColorByValue\fR, except when passed
+to \fBTk_NameOfColor\fR.
+.AP Drawable drawable in
+Drawable in which the result graphics context will be used.  Must have
+same screen and depth as the window for which the color was allocated.
+.BE
+
+.SH DESCRIPTION
+.PP
+The \fBTk_GetColor\fR and \fBTk_GetColorByValue\fR procedures
+locate pixel values that may be used to render particular
+colors in the window given by \fItkwin\fR.  In \fBTk_GetColor\fR
+the desired color is specified with a Tk_Uid (\fInameId\fR), which
+may have any of the following forms:
+.TP 20
+\fIcolorname\fR
+Any of the valid textual names for a color defined in the
+server's color database file, such as \fBred\fR or \fBPeachPuff\fR.
+.TP 20
+\fB#\fIRGB\fR
+.TP 20
+\fB#\fIRRGGBB\fR
+.TP 20
+\fB#\fIRRRGGGBBB\fR
+.TP 20
+\fB#\fIRRRRGGGGBBBB\fR
+A numeric specification of the red, green, and blue intensities
+to use to display the color.  Each \fIR\fR, \fIG\fR, or \fIB\fR
+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.
+.PP
+In \fBTk_GetColorByValue\fR, the desired color is indicated with
+the \fIred\fR, \fIgreen\fR, and \fIblue\fR fields of the structure
+pointed to by \fIcolorPtr\fR.
+.PP
+If \fBTk_GetColor\fR or \fBTk_GetColorByValue\fR 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
+that may be used to draw in the color.
+If the colormap for \fItkwin\fR is full, \fBTk_GetColor\fR
+and \fBTk_GetColorByValue\fR will use the closest existing color
+in the colormap.
+If \fBTk_GetColor\fR encounters an error while allocating
+the color (such as an unknown color name) then NULL is returned and
+an error message is stored in \fIinterp->result\fR;
+\fBTk_GetColorByValue\fR never returns an error.
+.PP
+\fBTk_GetColor\fR and \fBTk_GetColorByValue\fR maintain a database
+of all the colors currently in use.
+If the same \fInameId\fR is requested multiple times from
+\fBTk_GetColor\fR (e.g. by different windows), or if the
+same intensities are requested multiple times from
+\fBTk_GetColorByValue\fR, 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
+\fBTk_GetColor\fR or \fBTk_GetColorByValue\fR
+instead of Xlib procedures like \fBXAllocColor\fR,
+\fBXAllocNamedColor\fR, or \fBXParseColor\fR.
+.PP
+Since different calls to \fBTk_GetColor\fR or \fBTk_GetColorByValue\fR
+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 value dynamically, you should use
+\fBXAllocColorCells\fR to allocate the pixel value for the color.
+.PP
+The procedure \fBTk_NameOfColor\fR is roughly the inverse of
+\fBTk_GetColor\fR.  If its \fIcolorPtr\fR argument was created
+by \fBTk_GetColor\fR, then the return value is the \fInameId\fR
+string that was passed to \fBTk_GetColor\fR to create the
+color.  If \fIcolorPtr\fR was created by a call to \fBTk_GetColorByValue\fR,
+or by any other mechanism, then the return value is a string
+that could be passed to \fBTk_GetColor\fR to return the same
+color.  Note:  the string returned by \fBTk_NameOfColor\fR is
+only guaranteed to persist until the next call to \fBTk_NameOfColor\fR.
+.PP
+\fBTk_GCForColor\fR returns a graphics context whose \fBForeground\fR
+field is the pixel allocated for \fIcolorPtr\fR and whose other fields
+all have default values.
+This provides an easy way to do basic drawing with a color.
+The graphics context is cached with the color and will exist only as
+long as \fIcolorPtr\fR exists;  it is freed when the last reference
+to \fIcolorPtr\fR is freed by calling \fBTk_FreeColor\fR.
+.PP
+When a pixel value returned by \fBTk_GetColor\fR or
+\fBTk_GetColorByValue\fR is no longer
+needed, \fBTk_FreeColor\fR should be called to release the color.
+There should be exactly one call to \fBTk_FreeColor\fR for
+each call to \fBTk_GetColor\fR or \fBTk_GetColorByValue\fR.
+When a pixel value is no longer in
+use anywhere (i.e. it has been freed as many times as it has been gotten)
+\fBTk_FreeColor\fR will release it to the X server and delete it from
+the database.
+
+.SH KEYWORDS
+color, intensity, pixel value