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/*

 * tkUnixColor.c --

 *

 *      This file contains the platform specific color routines

 *      needed for X support.

 *

 * Copyright (c) 1996 by Sun Microsystems, Inc.

 *

 * See the file "license.terms" for information on usage and redistribution

 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.

 *

 * RCS: @(#) $Id: tkUnixColor.c,v 1.1.1.1 2002-01-16 10:26:01 markom Exp $

 */

#include <tkColor.h>

/*

 * If a colormap fills up, attempts to allocate new colors from that

 * colormap will fail.  When that happens, we'll just choose the

 * closest color from those that are available in the colormap.

 * One of the following structures will be created for each "stressed"

 * colormap to keep track of the colors that are available in the

 * colormap (otherwise we would have to re-query from the server on

 * each allocation, which would be very slow).  These entries are

 * flushed after a few seconds, since other clients may release or

 * reallocate colors over time.

 */

struct TkStressedCmap {

    Colormap colormap;                  /* X's token for the colormap. */

    int numColors;                      /* Number of entries currently active

                                         * at *colorPtr. */

    XColor *colorPtr;                   /* Pointer to malloc'ed array of all

                                         * colors that seem to be available in

                                         * the colormap.  Some may not actually

                                         * be available, e.g. because they are

                                         * read-write for another client;  when

                                         * we find this out, we remove them

                                         * from the array. */

    struct TkStressedCmap *nextPtr;     /* Next in list of all stressed

                                         * colormaps for the display. */

};

/*

 * Forward declarations for procedures defined in this file:

 */

static void             DeleteStressedCmap _ANSI_ARGS_((Display *display,

                            Colormap colormap));

static void             FindClosestColor _ANSI_ARGS_((Tk_Window tkwin,

                            XColor *desiredColorPtr, XColor *actualColorPtr));

/*

 *----------------------------------------------------------------------

 *

 * TkpFreeColor --

 *

 *      Release the specified color back to the system.

 *

 * Results:

 *      None

 *

 * Side effects:

 *      Invalidates the colormap cache for the colormap associated with

 *      the given color.

 *

 *----------------------------------------------------------------------

 */

void

TkpFreeColor(tkColPtr)

    TkColor *tkColPtr;          /* Color to be released.  Must have been

                                 * allocated by TkpGetColor or

                                 * TkpGetColorByValue. */

{

    Visual *visual;

    Screen *screen = tkColPtr->screen;

    /*

     * Careful!  Don't free black or white, since this will

     * make some servers very unhappy.  Also, there is a bug in

     * some servers (such Sun's X11/NeWS server) where reference

     * counting is performed incorrectly, so that if a color is

     * allocated twice in different places and then freed twice,

     * the second free generates an error (this bug existed as of

     * 10/1/92).  To get around this problem, ignore errors that

     * occur during the free operation.

     */

    visual = tkColPtr->visual;

    if ((visual->class != StaticGray) && (visual->class != StaticColor)

            && (tkColPtr->color.pixel != BlackPixelOfScreen(screen))

            && (tkColPtr->color.pixel != WhitePixelOfScreen(screen))) {

        Tk_ErrorHandler handler;

        handler = Tk_CreateErrorHandler(DisplayOfScreen(screen),

                -1, -1, -1, (Tk_ErrorProc *) NULL, (ClientData) NULL);

        XFreeColors(DisplayOfScreen(screen), tkColPtr->colormap,

                &tkColPtr->color.pixel, 1, 0L);

        Tk_DeleteErrorHandler(handler);

    }

    DeleteStressedCmap(DisplayOfScreen(screen), tkColPtr->colormap);

}

/*

 *----------------------------------------------------------------------

 *

 * TkpGetColor --

 *

 *      Allocate a new TkColor for the color with the given name.

 *

 * Results:

 *      Returns a newly allocated TkColor, or NULL on failure.

 *

 * Side effects:

 *      May invalidate the colormap cache associated with tkwin upon

 *      allocating a new colormap entry.  Allocates a new TkColor

 *      structure.

 *

 *----------------------------------------------------------------------

 */

TkColor *

TkpGetColor(tkwin, name)

    Tk_Window tkwin;            /* Window in which color will be used. */

    Tk_Uid name;                /* Name of color to allocated (in form

                                 * suitable for passing to XParseColor). */

{

    Display *display = Tk_Display(tkwin);

    Colormap colormap = Tk_Colormap(tkwin);

    XColor color;

    TkColor *tkColPtr;

    /*

     * Map from the name to a pixel value.  Call XAllocNamedColor rather than

     * XParseColor for non-# names: this saves a server round-trip for those

     * names.

     */

    if (*name != '#') {

        XColor screen;

        if (XAllocNamedColor(display, colormap, name, &screen,

                &color) != 0) {

            DeleteStressedCmap(display, colormap);

        } else {

            /*

             * Couldn't allocate the color.  Try translating the name to

             * a color value, to see whether the problem is a bad color

             * name or a full colormap.  If the colormap is full, then

             * pick an approximation to the desired color.

             */

            if (XLookupColor(display, colormap, name, &color,

                    &screen) == 0) {

                return (TkColor *) NULL;

            }

            FindClosestColor(tkwin, &screen, &color);

        }

    } else {

        if (XParseColor(display, colormap, name, &color) == 0) {

            return (TkColor *) NULL;

        }

        if (XAllocColor(display, colormap, &color) != 0) {

            DeleteStressedCmap(display, colormap);

        } else {

            FindClosestColor(tkwin, &color, &color);

        }

    }

    tkColPtr = (TkColor *) ckalloc(sizeof(TkColor));

    tkColPtr->color = color;

    return tkColPtr;

}

/*

 *----------------------------------------------------------------------

 *

 * TkpGetColorByValue --

 *

 *      Given a desired set of red-green-blue intensities for a color,

 *      locate a pixel value to use to draw that color in a given

 *      window.

 *

 * Results:

 *      The return value is a pointer to an TkColor structure that

 *      indicates the closest red, blue, and green intensities available

 *      to those specified in colorPtr, and also specifies a pixel

 *      value to use to draw in that color.

 *

 * Side effects:

 *      May invalidate the colormap cache for the specified window.

 *      Allocates a new TkColor structure.

 *

 *----------------------------------------------------------------------

 */

TkColor *

TkpGetColorByValue(tkwin, colorPtr)

    Tk_Window tkwin;            /* Window in which color will be used. */

    XColor *colorPtr;           /* Red, green, and blue fields indicate

                                 * desired color. */

{

    Display *display = Tk_Display(tkwin);

    Colormap colormap = Tk_Colormap(tkwin);

    TkColor *tkColPtr = (TkColor *) ckalloc(sizeof(TkColor));

    tkColPtr->color.red = colorPtr->red;

    tkColPtr->color.green = colorPtr->green;

    tkColPtr->color.blue = colorPtr->blue;

    if (XAllocColor(display, colormap, &tkColPtr->color) != 0) {

        DeleteStressedCmap(display, colormap);

    } else {

        FindClosestColor(tkwin, &tkColPtr->color, &tkColPtr->color);

    }

    return tkColPtr;

}

/*

 *----------------------------------------------------------------------

 *

 * FindClosestColor --

 *

 *      When Tk can't allocate a color because a colormap has filled

 *      up, this procedure is called to find and allocate the closest

 *      available color in the colormap.

 *

 * Results:

 *      There is no return value, but *actualColorPtr is filled in

 *      with information about the closest available color in tkwin's

 *      colormap.  This color has been allocated via X, so it must

 *      be released by the caller when the caller is done with it.

 *

 * Side effects:

 *      A color is allocated.

 *

 *----------------------------------------------------------------------

 */

static void

FindClosestColor(tkwin, desiredColorPtr, actualColorPtr)

    Tk_Window tkwin;                    /* Window where color will be used. */

    XColor *desiredColorPtr;            /* RGB values of color that was

                                         * wanted (but unavailable). */

    XColor *actualColorPtr;             /* Structure to fill in with RGB and

                                         * pixel for closest available

                                         * color. */

{

    TkStressedCmap *stressPtr;

    double tmp, distance, closestDistance;

    int i, closest, numFound;

    XColor *colorPtr;

    TkDisplay *dispPtr = ((TkWindow *) tkwin)->dispPtr;

    Colormap colormap = Tk_Colormap(tkwin);

    XVisualInfo template, *visInfoPtr;

    /*

     * Find the TkStressedCmap structure for this colormap, or create

     * a new one if needed.

     */

    for (stressPtr = dispPtr->stressPtr; ; stressPtr = stressPtr->nextPtr) {

        if (stressPtr == NULL) {

            stressPtr = (TkStressedCmap *) ckalloc(sizeof(TkStressedCmap));

            stressPtr->colormap = colormap;

            template.visualid = XVisualIDFromVisual(Tk_Visual(tkwin));

            visInfoPtr = XGetVisualInfo(Tk_Display(tkwin),

                    VisualIDMask, &template, &numFound);

            if (numFound < 1) {

                panic("FindClosestColor couldn't lookup visual");

            }

            stressPtr->numColors = visInfoPtr->colormap_size;

            XFree((char *) visInfoPtr);

            stressPtr->colorPtr = (XColor *) ckalloc((unsigned)

                    (stressPtr->numColors * sizeof(XColor)));

            for (i = 0; i  < stressPtr->numColors; i++) {

                stressPtr->colorPtr[i].pixel = (unsigned long) i;

            }

            XQueryColors(dispPtr->display, colormap, stressPtr->colorPtr,

                    stressPtr->numColors);

            stressPtr->nextPtr = dispPtr->stressPtr;

            dispPtr->stressPtr = stressPtr;

            break;

        }

        if (stressPtr->colormap == colormap) {

            break;

        }

    }

    /*

     * Find the color that best approximates the desired one, then

     * try to allocate that color.  If that fails, it must mean that

     * the color was read-write (so we can't use it, since it's owner

     * might change it) or else it was already freed.  Try again,

     * over and over again, until something succeeds.

     */

    while (1)  {

        if (stressPtr->numColors == 0) {

            panic("FindClosestColor ran out of colors");

        }

        closestDistance = 1e30;

        closest = 0;

        for (colorPtr = stressPtr->colorPtr, i = 0; i < stressPtr->numColors;

                colorPtr++, i++) {

            /*

             * Use Euclidean distance in RGB space, weighted by Y (of YIQ)

             * as the objective function;  this accounts for differences

             * in the color sensitivity of the eye.

             */

            tmp = .30*(((int) desiredColorPtr->red) - (int) colorPtr->red);

            distance = tmp*tmp;

            tmp = .61*(((int) desiredColorPtr->green) - (int) colorPtr->green);

            distance += tmp*tmp;

            tmp = .11*(((int) desiredColorPtr->blue) - (int) colorPtr->blue);

            distance += tmp*tmp;

            if (distance < closestDistance) {

                closest = i;

                closestDistance = distance;

            }

        }

        if (XAllocColor(dispPtr->display, colormap,

                &stressPtr->colorPtr[closest]) != 0) {

            *actualColorPtr = stressPtr->colorPtr[closest];

            return;

        }

        /*

         * Couldn't allocate the color.  Remove it from the table and

         * go back to look for the next best color.

         */

        stressPtr->colorPtr[closest] =

                stressPtr->colorPtr[stressPtr->numColors-1];

        stressPtr->numColors -= 1;

    }

}

/*

 *----------------------------------------------------------------------

 *

 * DeleteStressedCmap --

 *

 *      This procedure releases the information cached for "colormap"

 *      so that it will be refetched from the X server the next time

 *      it is needed.

 *

 * Results:

 *      None.

 *

 * Side effects:

 *      The TkStressedCmap structure for colormap is deleted;  the

 *      colormap is no longer considered to be "stressed".

 *

 * Note:

 *      This procedure is invoked whenever a color in a colormap is

 *      freed, and whenever a color allocation in a colormap succeeds.

 *      This guarantees that TkStressedCmap structures are always

 *      deleted before the corresponding Colormap is freed.

 *

 *----------------------------------------------------------------------

 */

static void

DeleteStressedCmap(display, colormap)

    Display *display;           /* Xlib's handle for the display

                                 * containing the colormap. */

    Colormap colormap;          /* Colormap to flush. */

{

    TkStressedCmap *prevPtr, *stressPtr;

    TkDisplay *dispPtr = TkGetDisplay(display);

    for (prevPtr = NULL, stressPtr = dispPtr->stressPtr; stressPtr != NULL;

            prevPtr = stressPtr, stressPtr = stressPtr->nextPtr) {

        if (stressPtr->colormap == colormap) {

            if (prevPtr == NULL) {

                dispPtr->stressPtr = stressPtr->nextPtr;

            } else {

                prevPtr->nextPtr = stressPtr->nextPtr;

            }

            ckfree((char *) stressPtr->colorPtr);

            ckfree((char *) stressPtr);

            return;

        }

    }

}

/*

 *----------------------------------------------------------------------

 *

 * TkpCmapStressed --

 *

 *      Check to see whether a given colormap is known to be out

 *      of entries.

 *

 * Results:

 *      1 is returned if "colormap" is stressed (i.e. it has run out

 *      of entries recently), 0 otherwise.

 *

 * Side effects:

 *      None.

 *

 *----------------------------------------------------------------------

 */

int

TkpCmapStressed(tkwin, colormap)

    Tk_Window tkwin;            /* Window that identifies the display

                                 * containing the colormap. */

    Colormap colormap;          /* Colormap to check for stress. */

{

    TkStressedCmap *stressPtr;

    for (stressPtr = ((TkWindow *) tkwin)->dispPtr->stressPtr;

            stressPtr != NULL; stressPtr = stressPtr->nextPtr) {

        if (stressPtr->colormap == colormap) {

            return 1;

        }

    }

    return 0;

}