stk/Tk/unix/tkUnixScale.c

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/*
* tkUnixScale.c --
*
* This file implements the X specific portion of the scrollbar
* widget.
*
* 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.
*
* SCCS: @(#) tkUnixScale.c 1.5 96/07/31 14:22:29
*/
#include "tkScale.h"
#include "tkInt.h"
/*
* Forward declarations for procedures defined later in this file:
*/
static void DisplayHorizontalScale _ANSI_ARGS_((TkScale *scalePtr,
Drawable drawable, XRectangle *drawnAreaPtr));
static void DisplayHorizontalValue _ANSI_ARGS_((TkScale *scalePtr,
Drawable drawable, double value, int top));
static void DisplayVerticalScale _ANSI_ARGS_((TkScale *scalePtr,
Drawable drawable, XRectangle *drawnAreaPtr));
static void DisplayVerticalValue _ANSI_ARGS_((TkScale *scalePtr,
Drawable drawable, double value, int rightEdge));
/*
*----------------------------------------------------------------------
*
* TkpCreateScale --
*
* Allocate a new TkScale structure.
*
* Results:
* Returns a newly allocated TkScale structure.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
TkScale *
TkpCreateScale(tkwin)
Tk_Window tkwin;
{
return (TkScale *) ckalloc(sizeof(TkScale));
}
/*
*----------------------------------------------------------------------
*
* TkpDestroyScale --
*
* Destroy a TkScale structure.
*
* Results:
* None
*
* Side effects:
* Memory is freed.
*
*----------------------------------------------------------------------
*/
void
TkpDestroyScale(scalePtr)
TkScale *scalePtr;
{
ckfree((char *) scalePtr);
}
/*
*--------------------------------------------------------------
*
* DisplayVerticalScale --
*
* This procedure redraws the contents of a vertical scale
* window. It is invoked as a do-when-idle handler, so it only
* runs when there's nothing else for the application to do.
*
* Results:
* There is no return value. If only a part of the scale needs
* to be redrawn, then drawnAreaPtr is modified to reflect the
* area that was actually modified.
*
* Side effects:
* Information appears on the screen.
*
*--------------------------------------------------------------
*/
static void
DisplayVerticalScale(scalePtr, drawable, drawnAreaPtr)
TkScale *scalePtr; /* Widget record for scale. */
Drawable drawable; /* Where to display scale (window
* or pixmap). */
XRectangle *drawnAreaPtr; /* Initally contains area of window;
* if only a part of the scale is
* redrawn, gets modified to reflect
* the part of the window that was
* redrawn. */
{
Tk_Window tkwin = scalePtr->tkwin;
int x, y, width, height, shadowWidth;
double tickValue;
Tk_3DBorder sliderBorder;
/*
* Display the information from left to right across the window.
*/
if (!(scalePtr->flags & REDRAW_OTHER)) {
drawnAreaPtr->x = scalePtr->vertTickRightX;
drawnAreaPtr->y = scalePtr->inset;
drawnAreaPtr->width = scalePtr->vertTroughX + scalePtr->width
+ 2*scalePtr->borderWidth - scalePtr->vertTickRightX;
drawnAreaPtr->height -= 2*scalePtr->inset;
}
Tk_Fill3DRectangle(tkwin, drawable, scalePtr->bgBorder,
drawnAreaPtr->x, drawnAreaPtr->y, drawnAreaPtr->width,
drawnAreaPtr->height, 0, TK_RELIEF_FLAT);
if (scalePtr->flags & REDRAW_OTHER) {
/*
* Display the tick marks.
*/
if (scalePtr->tickInterval != 0) {
for (tickValue = scalePtr->fromValue; ;
tickValue += scalePtr->tickInterval) {
/*
* The TkRoundToResolution call gets rid of accumulated
* round-off errors, if any.
*/
tickValue = TkRoundToResolution(scalePtr, tickValue);
if (scalePtr->toValue >= scalePtr->fromValue) {
if (tickValue > scalePtr->toValue) {
break;
}
} else {
if (tickValue < scalePtr->toValue) {
break;
}
}
DisplayVerticalValue(scalePtr, drawable, tickValue,
scalePtr->vertTickRightX);
}
}
}
/*
* Display the value, if it is desired.
*/
if (scalePtr->showValue) {
DisplayVerticalValue(scalePtr, drawable, scalePtr->value,
scalePtr->vertValueRightX);
}
/*
* Display the trough and the slider.
*/
Tk_Draw3DRectangle(tkwin, drawable,
scalePtr->bgBorder, scalePtr->vertTroughX, scalePtr->inset,
scalePtr->width + 2*scalePtr->borderWidth,
Tk_Height(tkwin) - 2*scalePtr->inset, scalePtr->borderWidth,
TK_RELIEF_SUNKEN);
XFillRectangle(scalePtr->display, drawable, scalePtr->troughGC,
scalePtr->vertTroughX + scalePtr->borderWidth,
scalePtr->inset + scalePtr->borderWidth,
(unsigned) scalePtr->width,
(unsigned) (Tk_Height(tkwin) - 2*scalePtr->inset
- 2*scalePtr->borderWidth));
if (scalePtr->state == tkActiveUid) {
sliderBorder = scalePtr->activeBorder;
} else {
sliderBorder = scalePtr->bgBorder;
}
width = scalePtr->width;
height = scalePtr->sliderLength/2;
x = scalePtr->vertTroughX + scalePtr->borderWidth;
y = TkpValueToPixel(scalePtr, scalePtr->value) - height;
shadowWidth = scalePtr->borderWidth/2;
if (shadowWidth == 0) {
shadowWidth = 1;
}
Tk_Draw3DRectangle(tkwin, drawable, sliderBorder, x, y, width,
2*height, shadowWidth, scalePtr->sliderRelief);
x += shadowWidth;
y += shadowWidth;
width -= 2*shadowWidth;
height -= shadowWidth;
Tk_Fill3DRectangle(tkwin, drawable, sliderBorder, x, y, width,
height, shadowWidth, scalePtr->sliderRelief);
Tk_Fill3DRectangle(tkwin, drawable, sliderBorder, x, y+height,
width, height, shadowWidth, scalePtr->sliderRelief);
/*
* Draw the label to the right of the scale.
*/
if ((scalePtr->flags & REDRAW_OTHER) && (scalePtr->labelLength != 0)) {
Tk_FontMetrics fm;
Tk_GetFontMetrics(scalePtr->tkfont, &fm);
Tk_DrawChars(scalePtr->display, drawable, scalePtr->textGC,
scalePtr->tkfont, scalePtr->label, scalePtr->labelLength,
scalePtr->vertLabelX, scalePtr->inset + (3*fm.ascent)/2);
}
}
/*
*----------------------------------------------------------------------
*
* DisplayVerticalValue --
*
* This procedure is called to display values (scale readings)
* for vertically-oriented scales.
*
* Results:
* None.
*
* Side effects:
* The numerical value corresponding to value is displayed with
* its right edge at "rightEdge", and at a vertical position in
* the scale that corresponds to "value".
*
*----------------------------------------------------------------------
*/
static void
DisplayVerticalValue(scalePtr, drawable, value, rightEdge)
register TkScale *scalePtr; /* Information about widget in which to
* display value. */
Drawable drawable; /* Pixmap or window in which to draw
* the value. */
double value; /* Y-coordinate of number to display,
* specified in application coords, not
* in pixels (we'll compute pixels). */
int rightEdge; /* X-coordinate of right edge of text,
* specified in pixels. */
{
register Tk_Window tkwin = scalePtr->tkwin;
int y, width, length;
char valueString[PRINT_CHARS];
Tk_FontMetrics fm;
Tk_GetFontMetrics(scalePtr->tkfont, &fm);
y = TkpValueToPixel(scalePtr, value) + fm.ascent/2;
sprintf(valueString, scalePtr->format, value);
length = strlen(valueString);
width = Tk_TextWidth(scalePtr->tkfont, valueString, length);
/*
* Adjust the y-coordinate if necessary to keep the text entirely
* inside the window.
*/
if ((y - fm.ascent) < (scalePtr->inset + SPACING)) {
y = scalePtr->inset + SPACING + fm.ascent;
}
if ((y + fm.descent) > (Tk_Height(tkwin) - scalePtr->inset - SPACING)) {
y = Tk_Height(tkwin) - scalePtr->inset - SPACING - fm.descent;
}
Tk_DrawChars(scalePtr->display, drawable, scalePtr->textGC,
scalePtr->tkfont, valueString, length, rightEdge - width, y);
}
/*
*--------------------------------------------------------------
*
* DisplayHorizontalScale --
*
* This procedure redraws the contents of a horizontal scale
* window. It is invoked as a do-when-idle handler, so it only
* runs when there's nothing else for the application to do.
*
* Results:
* There is no return value. If only a part of the scale needs
* to be redrawn, then drawnAreaPtr is modified to reflect the
* area that was actually modified.
*
* Side effects:
* Information appears on the screen.
*
*--------------------------------------------------------------
*/
static void
DisplayHorizontalScale(scalePtr, drawable, drawnAreaPtr)
TkScale *scalePtr; /* Widget record for scale. */
Drawable drawable; /* Where to display scale (window
* or pixmap). */
XRectangle *drawnAreaPtr; /* Initally contains area of window;
* if only a part of the scale is
* redrawn, gets modified to reflect
* the part of the window that was
* redrawn. */
{
register Tk_Window tkwin = scalePtr->tkwin;
int x, y, width, height, shadowWidth;
double tickValue;
Tk_3DBorder sliderBorder;
/*
* Display the information from bottom to top across the window.
*/
if (!(scalePtr->flags & REDRAW_OTHER)) {
drawnAreaPtr->x = scalePtr->inset;
drawnAreaPtr->y = scalePtr->horizValueY;
drawnAreaPtr->width -= 2*scalePtr->inset;
drawnAreaPtr->height = scalePtr->horizTroughY + scalePtr->width
+ 2*scalePtr->borderWidth - scalePtr->horizValueY;
}
Tk_Fill3DRectangle(tkwin, drawable, scalePtr->bgBorder,
drawnAreaPtr->x, drawnAreaPtr->y, drawnAreaPtr->width,
drawnAreaPtr->height, 0, TK_RELIEF_FLAT);
if (scalePtr->flags & REDRAW_OTHER) {
/*
* Display the tick marks.
*/
if (scalePtr->tickInterval != 0) {
for (tickValue = scalePtr->fromValue; ;
tickValue += scalePtr->tickInterval) {
/*
* The TkRoundToResolution call gets rid of accumulated
* round-off errors, if any.
*/
tickValue = TkRoundToResolution(scalePtr, tickValue);
if (scalePtr->toValue >= scalePtr->fromValue) {
if (tickValue > scalePtr->toValue) {
break;
}
} else {
if (tickValue < scalePtr->toValue) {
break;
}
}
DisplayHorizontalValue(scalePtr, drawable, tickValue,
scalePtr->horizTickY);
}
}
}
/*
* Display the value, if it is desired.
*/
if (scalePtr->showValue) {
DisplayHorizontalValue(scalePtr, drawable, scalePtr->value,
scalePtr->horizValueY);
}
/*
* Display the trough and the slider.
*/
y = scalePtr->horizTroughY;
Tk_Draw3DRectangle(tkwin, drawable,
scalePtr->bgBorder, scalePtr->inset, y,
Tk_Width(tkwin) - 2*scalePtr->inset,
scalePtr->width + 2*scalePtr->borderWidth,
scalePtr->borderWidth, TK_RELIEF_SUNKEN);
XFillRectangle(scalePtr->display, drawable, scalePtr->troughGC,
scalePtr->inset + scalePtr->borderWidth,
y + scalePtr->borderWidth,
(unsigned) (Tk_Width(tkwin) - 2*scalePtr->inset
- 2*scalePtr->borderWidth),
(unsigned) scalePtr->width);
if (scalePtr->state == tkActiveUid) {
sliderBorder = scalePtr->activeBorder;
} else {
sliderBorder = scalePtr->bgBorder;
}
width = scalePtr->sliderLength/2;
height = scalePtr->width;
x = TkpValueToPixel(scalePtr, scalePtr->value) - width;
y += scalePtr->borderWidth;
shadowWidth = scalePtr->borderWidth/2;
if (shadowWidth == 0) {
shadowWidth = 1;
}
Tk_Draw3DRectangle(tkwin, drawable, sliderBorder,
x, y, 2*width, height, shadowWidth, scalePtr->sliderRelief);
x += shadowWidth;
y += shadowWidth;
width -= shadowWidth;
height -= 2*shadowWidth;
Tk_Fill3DRectangle(tkwin, drawable, sliderBorder, x, y, width, height,
shadowWidth, scalePtr->sliderRelief);
Tk_Fill3DRectangle(tkwin, drawable, sliderBorder, x+width, y,
width, height, shadowWidth, scalePtr->sliderRelief);
/*
* Draw the label at the top of the scale.
*/
if ((scalePtr->flags & REDRAW_OTHER) && (scalePtr->labelLength != 0)) {
Tk_FontMetrics fm;
Tk_GetFontMetrics(scalePtr->tkfont, &fm);
Tk_DrawChars(scalePtr->display, drawable, scalePtr->textGC,
scalePtr->tkfont, scalePtr->label, scalePtr->labelLength,
scalePtr->inset + fm.ascent/2, scalePtr->horizLabelY + fm.ascent);
}
}
/*
*----------------------------------------------------------------------
*
* DisplayHorizontalValue --
*
* This procedure is called to display values (scale readings)
* for horizontally-oriented scales.
*
* Results:
* None.
*
* Side effects:
* The numerical value corresponding to value is displayed with
* its bottom edge at "bottom", and at a horizontal position in
* the scale that corresponds to "value".
*
*----------------------------------------------------------------------
*/
static void
DisplayHorizontalValue(scalePtr, drawable, value, top)
register TkScale *scalePtr; /* Information about widget in which to
* display value. */
Drawable drawable; /* Pixmap or window in which to draw
* the value. */
double value; /* X-coordinate of number to display,
* specified in application coords, not
* in pixels (we'll compute pixels). */
int top; /* Y-coordinate of top edge of text,
* specified in pixels. */
{
register Tk_Window tkwin = scalePtr->tkwin;
int x, y, length, width;
char valueString[PRINT_CHARS];
Tk_FontMetrics fm;
x = TkpValueToPixel(scalePtr, value);
Tk_GetFontMetrics(scalePtr->tkfont, &fm);
y = top + fm.ascent;
sprintf(valueString, scalePtr->format, value);
length = strlen(valueString);
width = Tk_TextWidth(scalePtr->tkfont, valueString, length);
/*
* Adjust the x-coordinate if necessary to keep the text entirely
* inside the window.
*/
x -= (width)/2;
if (x < (scalePtr->inset + SPACING)) {
x = scalePtr->inset + SPACING;
}
if (x > (Tk_Width(tkwin) - scalePtr->inset)) {
x = Tk_Width(tkwin) - scalePtr->inset - SPACING - width;
}
Tk_DrawChars(scalePtr->display, drawable, scalePtr->textGC,
scalePtr->tkfont, valueString, length, x, y);
}
/*
*----------------------------------------------------------------------
*
* TkpDisplayScale --
*
* This procedure is invoked as an idle handler to redisplay
* the contents of a scale widget.
*
* Results:
* None.
*
* Side effects:
* The scale gets redisplayed.
*
*----------------------------------------------------------------------
*/
void
TkpDisplayScale(clientData)
ClientData clientData; /* Widget record for scale. */
{
TkScale *scalePtr = (TkScale *) clientData;
Tk_Window tkwin = scalePtr->tkwin;
Tcl_Interp *interp = scalePtr->interp;
Pixmap pixmap;
int result;
char string[PRINT_CHARS];
XRectangle drawnArea;
if ((scalePtr->tkwin == NULL) || !Tk_IsMapped(scalePtr->tkwin)) {
goto done;
}
/*
* Invoke the scale's command if needed.
*/
Tcl_Preserve((ClientData) scalePtr);
Tcl_Preserve((ClientData) interp);
if ((scalePtr->flags & INVOKE_COMMAND) && (scalePtr->command != NULL)) {
sprintf(string, scalePtr->format, scalePtr->value);
result = Tcl_VarEval(interp, scalePtr->command, " ", string,
(char *) NULL);
if (result != TCL_OK) {
Tcl_AddErrorInfo(interp, "\n (command executed by scale)");
Tcl_BackgroundError(interp);
}
}
Tcl_Release((ClientData) interp);
scalePtr->flags &= ~INVOKE_COMMAND;
if (scalePtr->tkwin == NULL) {
Tcl_Release((ClientData) scalePtr);
return;
}
Tcl_Release((ClientData) scalePtr);
/*
* In order to avoid screen flashes, this procedure redraws
* the scale in a pixmap, then copies the pixmap to the
* screen in a single operation. This means that there's no
* point in time where the on-sreen image has been cleared.
*/
pixmap = Tk_GetPixmap(scalePtr->display, Tk_WindowId(tkwin),
Tk_Width(tkwin), Tk_Height(tkwin), Tk_Depth(tkwin));
drawnArea.x = 0;
drawnArea.y = 0;
drawnArea.width = Tk_Width(tkwin);
drawnArea.height = Tk_Height(tkwin);
/*
* Much of the redisplay is done totally differently for
* horizontal and vertical scales. Handle the part that's
* different.
*/
if (scalePtr->vertical) {
DisplayVerticalScale(scalePtr, pixmap, &drawnArea);
} else {
DisplayHorizontalScale(scalePtr, pixmap, &drawnArea);
}
/*
* Now handle the part of redisplay that is the same for
* horizontal and vertical scales: border and traversal
* highlight.
*/
if (scalePtr->flags & REDRAW_OTHER) {
if (scalePtr->relief != TK_RELIEF_FLAT) {
Tk_Draw3DRectangle(tkwin, pixmap, scalePtr->bgBorder,
scalePtr->highlightWidth, scalePtr->highlightWidth,
Tk_Width(tkwin) - 2*scalePtr->highlightWidth,
Tk_Height(tkwin) - 2*scalePtr->highlightWidth,
scalePtr->borderWidth, scalePtr->relief);
}
if (scalePtr->highlightWidth != 0) {
GC gc;
if (scalePtr->flags & GOT_FOCUS) {
gc = Tk_GCForColor(scalePtr->highlightColorPtr, pixmap);
} else {
gc = Tk_GCForColor(scalePtr->highlightBgColorPtr, pixmap);
}
Tk_DrawFocusHighlight(tkwin, gc, scalePtr->highlightWidth, pixmap);
}
}
/*
* Copy the information from the off-screen pixmap onto the screen,
* then delete the pixmap.
*/
XCopyArea(scalePtr->display, pixmap, Tk_WindowId(tkwin),
scalePtr->copyGC, drawnArea.x, drawnArea.y, drawnArea.width,
drawnArea.height, drawnArea.x, drawnArea.y);
Tk_FreePixmap(scalePtr->display, pixmap);
done:
scalePtr->flags &= ~REDRAW_ALL;
}
/*
*----------------------------------------------------------------------
*
* TkpScaleElement --
*
* Determine which part of a scale widget lies under a given
* point.
*
* Results:
* The return value is either TROUGH1, SLIDER, TROUGH2, or
* OTHER, depending on which of the scale's active elements
* (if any) is under the point at (x,y).
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
TkpScaleElement(scalePtr, x, y)
TkScale *scalePtr; /* Widget record for scale. */
int x, y; /* Coordinates within scalePtr's window. */
{
int sliderFirst;
if (scalePtr->vertical) {
if ((x < scalePtr->vertTroughX)
|| (x >= (scalePtr->vertTroughX + 2*scalePtr->borderWidth +
scalePtr->width))) {
return OTHER;
}
if ((y < scalePtr->inset)
|| (y >= (Tk_Height(scalePtr->tkwin) - scalePtr->inset))) {
return OTHER;
}
sliderFirst = TkpValueToPixel(scalePtr, scalePtr->value)
- scalePtr->sliderLength/2;
if (y < sliderFirst) {
return TROUGH1;
}
if (y < (sliderFirst+scalePtr->sliderLength)) {
return SLIDER;
}
return TROUGH2;
}
if ((y < scalePtr->horizTroughY)
|| (y >= (scalePtr->horizTroughY + 2*scalePtr->borderWidth +
scalePtr->width))) {
return OTHER;
}
if ((x < scalePtr->inset)
|| (x >= (Tk_Width(scalePtr->tkwin) - scalePtr->inset))) {
return OTHER;
}
sliderFirst = TkpValueToPixel(scalePtr, scalePtr->value)
- scalePtr->sliderLength/2;
if (x < sliderFirst) {
return TROUGH1;
}
if (x < (sliderFirst+scalePtr->sliderLength)) {
return SLIDER;
}
return TROUGH2;
}
/*
*--------------------------------------------------------------
*
* TkpSetScaleValue --
*
* This procedure changes the value of a scale and invokes
* a Tcl command to reflect the current position of a scale
*
* Results:
* None.
*
* Side effects:
* A Tcl command is invoked, and an additional error-processing
* command may also be invoked. The scale's slider is redrawn.
*
*--------------------------------------------------------------
*/
void
TkpSetScaleValue(scalePtr, value, setVar, invokeCommand)
register TkScale *scalePtr; /* Info about widget. */
double value; /* New value for scale. Gets adjusted
* if it's off the scale. */
int setVar; /* Non-zero means reflect new value through
* to associated variable, if any. */
int invokeCommand; /* Non-zero means invoked -command option
* to notify of new value, 0 means don't. */
{
char string[PRINT_CHARS];
value = TkRoundToResolution(scalePtr, value);
if ((value < scalePtr->fromValue)
^ (scalePtr->toValue < scalePtr->fromValue)) {
value = scalePtr->fromValue;
}
if ((value > scalePtr->toValue)
^ (scalePtr->toValue < scalePtr->fromValue)) {
value = scalePtr->toValue;
}
if (scalePtr->flags & NEVER_SET) {
scalePtr->flags &= ~NEVER_SET;
} else if (scalePtr->value == value) {
return;
}
scalePtr->value = value;
if (invokeCommand) {
scalePtr->flags |= INVOKE_COMMAND;
}
TkEventuallyRedrawScale(scalePtr, REDRAW_SLIDER);
if (setVar && (scalePtr->varName != NULL)) {
sprintf(string, scalePtr->format, scalePtr->value);
scalePtr->flags |= SETTING_VAR;
#ifdef STk_CODE
STk_tcl_setvar(scalePtr->varName, string, 0, scalePtr->env);
#else
Tcl_SetVar(scalePtr->interp, scalePtr->varName, string,
TCL_GLOBAL_ONLY);
#endif
scalePtr->flags &= ~SETTING_VAR;
}
}
/*
*----------------------------------------------------------------------
*
* TkpPixelToValue --
*
* Given a pixel within a scale window, return the scale
* reading corresponding to that pixel.
*
* Results:
* A double-precision scale reading. If the value is outside
* the legal range for the scale then it's rounded to the nearest
* end of the scale.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
double
TkpPixelToValue(scalePtr, x, y)
register TkScale *scalePtr; /* Information about widget. */
int x, y; /* Coordinates of point within
* window. */
{
double value, pixelRange;
if (scalePtr->vertical) {
pixelRange = Tk_Height(scalePtr->tkwin) - scalePtr->sliderLength
- 2*scalePtr->inset - 2*scalePtr->borderWidth;
value = y;
} else {
pixelRange = Tk_Width(scalePtr->tkwin) - scalePtr->sliderLength
- 2*scalePtr->inset - 2*scalePtr->borderWidth;
value = x;
}
if (pixelRange <= 0) {
/*
* Not enough room for the slider to actually slide: just return
* the scale's current value.
*/
return scalePtr->value;
}
value -= scalePtr->sliderLength/2 + scalePtr->inset
+ scalePtr->borderWidth;
value /= pixelRange;
if (value < 0) {
value = 0;
}
if (value > 1) {
value = 1;
}
value = scalePtr->fromValue +
value * (scalePtr->toValue - scalePtr->fromValue);
return TkRoundToResolution(scalePtr, value);
}
/*
*----------------------------------------------------------------------
*
* TkpValueToPixel --
*
* Given a reading of the scale, return the x-coordinate or
* y-coordinate corresponding to that reading, depending on
* whether the scale is vertical or horizontal, respectively.
*
* Results:
* An integer value giving the pixel location corresponding
* to reading. The value is restricted to lie within the
* defined range for the scale.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
TkpValueToPixel(scalePtr, value)
register TkScale *scalePtr; /* Information about widget. */
double value; /* Reading of the widget. */
{
int y, pixelRange;
double valueRange;
valueRange = scalePtr->toValue - scalePtr->fromValue;
pixelRange = (scalePtr->vertical ? Tk_Height(scalePtr->tkwin)
: Tk_Width(scalePtr->tkwin)) - scalePtr->sliderLength
- 2*scalePtr->inset - 2*scalePtr->borderWidth;
if (valueRange == 0) {
y = 0;
} else {
y = (int) ((value - scalePtr->fromValue) * pixelRange
/ valueRange + 0.5);
if (y < 0) {
y = 0;
} else if (y > pixelRange) {
y = pixelRange;
}
}
y += scalePtr->sliderLength/2 + scalePtr->inset + scalePtr->borderWidth;
return y;
}