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/* Copyright (C) 2000 Damir Zucic */
/*=============================================================================
disp_color_cap.c
Purpose:
Find display depth. Check is the TrueColor visual class supported.
Prepare the colormap. Prepare the parameters for color allocation.
TrueColor is the only visual class suitable for garlic. A server
which is capable to support DirectColor should be capable to
support TrueColor also. Some X servers do not support this visual
at 8 bits per pixel: increase the color depth and try again!
Input:
(1) Pointer to GUIS structure (with GUI data).
Output:
(1) Data stored to GUIS structure.
(2) Return value.
Return value:
(1) Positive on success.
(2) Negative on failure.
=============================================================================*/
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include "defines.h"
#include "typedefs.h"
/*======function prototypes:=================================================*/
void ErrorMessage_ (char *, char *, char *,
char *, char *, char *, char *);
int PrepareColorShifts_ (GUIS *);
/*======retrieve display color capabilities:=================================*/
int DisplayColorCapabilities_ (GUIS *guiSP)
{
Status status;
Window root_windowID;
int n;
/*------depth:---------------------------------------------------------------*/
/* Default depth for default screen (maximal number of bits per pixel). */
/* Note: it is not possible to distinguish gray-scale and color screen */
/* by the number of bits per pixel; XVisualInfo structure must be used. */
guiSP->depth = DefaultDepth (guiSP->displaySP, guiSP->screenID);
if (guiSP->depth <= 0)
{
ErrorMessage_ ("garlic", "DisplayColorCapabilities_", "",
"Default depth <= 0\n", "", "", "");
return -1;
}
/*------visual:--------------------------------------------------------------*/
/* Check is TrueColor visual class supported */
/* by X server; if it is, prepare the visual: */
status = XMatchVisualInfo (guiSP->displaySP, guiSP->screenID,
guiSP->depth, TrueColor, &guiSP->visual_infoS);
if (status == 0)
{
fprintf (stdout,
"Sorry, garlic refuses to work if TrueColor");
fprintf (stdout,
" visual is not supported!\n");
fprintf (stdout,
"The current color depth is %d bits per pixel.\n",
guiSP->depth);
fprintf (stdout,
"Your X server does not support the TrueColor visual");
fprintf (stdout,
" at this color depth.\n");
if (guiSP->depth <= 8)
{
fprintf (stdout, "Switch to at least 12 bits per pixel");
fprintf (stdout, " (or more -> 24 is recommended)!\n");
}
return -2;
}
else guiSP->visualSP = guiSP->visual_infoS.visual;
/*------colormap:------------------------------------------------------------*/
/* Prepare the colormap: */
root_windowID = RootWindow (guiSP->displaySP, guiSP->screenID);
guiSP->colormapID = XCreateColormap (guiSP->displaySP, root_windowID,
guiSP->visualSP, AllocNone);
/*------parameters for fast color allocation:--------------------------------*/
n = PrepareColorShifts_ (guiSP);
/*---------------------------------------------------------------------------*/
/* Return positive value on success: */
return 1;
}
/*===========================================================================*/
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