/*
* tk3d.c --
*
* This module provides procedures to draw borders in
* the three-dimensional Motif style.
*
* Copyright (c) 1990-1994 The Regents of the University of California.
* Copyright (c) 1994-1997 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: tk3d.c,v 1.2 1998/09/14 18:23:02 stanton Exp $
*/
#include "tk3d.h"
/*
* Hash table to map from a border's values (color, etc.) to a
* Border structure for those values.
*/
static Tcl_HashTable borderTable;
typedef struct {
Tk_Uid colorName; /* Color for border. */
Colormap colormap; /* Colormap used for allocating border
* colors. */
Screen *screen; /* Screen on which border will be drawn. */
} BorderKey;
static int initialized = 0; /* 0 means static structures haven't
* been initialized yet. */
/*
* Forward declarations for procedures defined in this file:
*/
static void BorderInit _ANSI_ARGS_((void));
static int Intersect _ANSI_ARGS_((XPoint *a1Ptr, XPoint *a2Ptr,
XPoint *b1Ptr, XPoint *b2Ptr, XPoint *iPtr));
static void ShiftLine _ANSI_ARGS_((XPoint *p1Ptr, XPoint *p2Ptr,
int distance, XPoint *p3Ptr));
/*
*--------------------------------------------------------------
*
* Tk_Get3DBorder --
*
* Create a data structure for displaying a 3-D border.
*
* Results:
* The return value is a token for a data structure
* describing a 3-D border. This token may be passed
* to Tk_Draw3DRectangle and Tk_Free3DBorder. If an
* error prevented the border from being created then
* NULL is returned and an error message will be left
* in interp->result.
*
* Side effects:
* Data structures, graphics contexts, etc. are allocated.
* It is the caller's responsibility to eventually call
* Tk_Free3DBorder to release the resources.
*
*--------------------------------------------------------------
*/
Tk_3DBorder
Tk_Get3DBorder(interp, tkwin, colorName)
Tcl_Interp *interp; /* Place to store an error message. */
Tk_Window tkwin; /* Token for window in which border will
* be drawn. */
Tk_Uid colorName; /* String giving name of color
* for window background. */
{
BorderKey key;
Tcl_HashEntry *hashPtr;
register TkBorder *borderPtr;
int new;
XGCValues gcValues;
if (!initialized) {
BorderInit();
}
/*
* First, check to see if there's already a border that will work
* for this request.
*/
key.colorName = colorName;
key.colormap = Tk_Colormap(tkwin);
key.screen = Tk_Screen(tkwin);
hashPtr = Tcl_CreateHashEntry(&borderTable, (char *) &key, &new);
if (!new) {
borderPtr = (TkBorder *) Tcl_GetHashValue(hashPtr);
borderPtr->refCount++;
} else {
XColor *bgColorPtr;
/*
* No satisfactory border exists yet. Initialize a new one.
*/
bgColorPtr = Tk_GetColor(interp, tkwin, colorName);
if (bgColorPtr == NULL) {
Tcl_DeleteHashEntry(hashPtr);
return NULL;
}
borderPtr = TkpGetBorder();
borderPtr->screen = Tk_Screen(tkwin);
borderPtr->visual = Tk_Visual(tkwin);
borderPtr->depth = Tk_Depth(tkwin);
borderPtr->colormap = key.colormap;
borderPtr->refCount = 1;
borderPtr->bgColorPtr = bgColorPtr;
borderPtr->darkColorPtr = NULL;
borderPtr->lightColorPtr = NULL;
borderPtr->shadow = None;
borderPtr->bgGC = None;
borderPtr->darkGC = None;
borderPtr->lightGC = None;
borderPtr->hashPtr = hashPtr;
Tcl_SetHashValue(hashPtr, borderPtr);
/*
* Create the information for displaying the background color,
* but delay the allocation of shadows until they are actually
* needed for drawing.
*/
gcValues.foreground = borderPtr->bgColorPtr->pixel;
borderPtr->bgGC = Tk_GetGC(tkwin, GCForeground, &gcValues);
}
return (Tk_3DBorder) borderPtr;
}
/*
*--------------------------------------------------------------
*
* Tk_Draw3DRectangle --
*
* Draw a 3-D border at a given place in a given window.
*
* Results:
* None.
*
* Side effects:
* A 3-D border will be drawn in the indicated drawable.
* The outside edges of the border will be determined by x,
* y, width, and height. The inside edges of the border
* will be determined by the borderWidth argument.
*
*--------------------------------------------------------------
*/
void
Tk_Draw3DRectangle(tkwin, drawable, border, x, y, width, height,
borderWidth, relief)
Tk_Window tkwin; /* Window for which border was allocated. */
Drawable drawable; /* X window or pixmap in which to draw. */
Tk_3DBorder border; /* Token for border to draw. */
int x, y, width, height; /* Outside area of region in
* which border will be drawn. */
int borderWidth; /* Desired width for border, in
* pixels. */
int relief; /* Type of relief: TK_RELIEF_RAISED,
* TK_RELIEF_SUNKEN, TK_RELIEF_GROOVE, etc. */
{
if (width < 2*borderWidth) {
borderWidth = width/2;
}
if (height < 2*borderWidth) {
borderWidth = height/2;
}
Tk_3DVerticalBevel(tkwin, drawable, border, x, y, borderWidth, height,
1, relief);
Tk_3DVerticalBevel(tkwin, drawable, border, x+width-borderWidth, y,
borderWidth, height, 0, relief);
Tk_3DHorizontalBevel(tkwin, drawable, border, x, y, width, borderWidth,
1, 1, 1, relief);
Tk_3DHorizontalBevel(tkwin, drawable, border, x, y+height-borderWidth,
width, borderWidth, 0, 0, 0, relief);
}
/*
*--------------------------------------------------------------
*
* Tk_NameOf3DBorder --
*
* Given a border, return a textual string identifying the
* border's color.
*
* Results:
* The return value is the string that was used to create
* the border.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
char *
Tk_NameOf3DBorder(border)
Tk_3DBorder border; /* Token for border. */
{
TkBorder *borderPtr = (TkBorder *) border;
return ((BorderKey *) borderPtr->hashPtr->key.words)->colorName;
}
/*
*--------------------------------------------------------------------
*
* Tk_3DBorderColor --
*
* Given a 3D border, return the X color used for the "flat"
* surfaces.
*
* Results:
* Returns the color used drawing flat surfaces with the border.
*
* Side effects:
* None.
*
*--------------------------------------------------------------------
*/
XColor *
Tk_3DBorderColor(border)
Tk_3DBorder border; /* Border whose color is wanted. */
{
return(((TkBorder *) border)->bgColorPtr);
}
/*
*--------------------------------------------------------------------
*
* Tk_3DBorderGC --
*
* Given a 3D border, returns one of the graphics contexts used to
* draw the border.
*
* Results:
* Returns the graphics context given by the "which" argument.
*
* Side effects:
* None.
*
*--------------------------------------------------------------------
*/
GC
Tk_3DBorderGC(tkwin, border, which)
Tk_Window tkwin; /* Window for which border was allocated. */
Tk_3DBorder border; /* Border whose GC is wanted. */
int which; /* Selects one of the border's 3 GC's:
* TK_3D_FLAT_GC, TK_3D_LIGHT_GC, or
* TK_3D_DARK_GC. */
{
TkBorder * borderPtr = (TkBorder *) border;
if ((borderPtr->lightGC == None) && (which != TK_3D_FLAT_GC)) {
TkpGetShadows(borderPtr, tkwin);
}
if (which == TK_3D_FLAT_GC) {
return borderPtr->bgGC;
} else if (which == TK_3D_LIGHT_GC) {
return borderPtr->lightGC;
} else if (which == TK_3D_DARK_GC){
return borderPtr->darkGC;
}
panic("bogus \"which\" value in Tk_3DBorderGC");
/*
* The code below will never be executed, but it's needed to
* keep compilers happy.
*/
return (GC) None;
}
/*
*--------------------------------------------------------------
*
* Tk_Free3DBorder --
*
* This procedure is called when a 3D border is no longer
* needed. It frees the resources associated with the
* border. After this call, the caller should never again
* use the "border" token.
*
* Results:
* None.
*
* Side effects:
* Resources are freed.
*
*--------------------------------------------------------------
*/
void
Tk_Free3DBorder(border)
Tk_3DBorder border; /* Token for border to be released. */
{
register TkBorder *borderPtr = (TkBorder *) border;
Display *display = DisplayOfScreen(borderPtr->screen);
borderPtr->refCount--;
if (borderPtr->refCount == 0) {
TkpFreeBorder(borderPtr);
if (borderPtr->bgColorPtr != NULL) {
Tk_FreeColor(borderPtr->bgColorPtr);
}
if (borderPtr->darkColorPtr != NULL) {
Tk_FreeColor(borderPtr->darkColorPtr);
}
if (borderPtr->lightColorPtr != NULL) {
Tk_FreeColor(borderPtr->lightColorPtr);
}
if (borderPtr->shadow != None) {
Tk_FreeBitmap(display, borderPtr->shadow);
}
if (borderPtr->bgGC != None) {
Tk_FreeGC(display, borderPtr->bgGC);
}
if (borderPtr->darkGC != None) {
Tk_FreeGC(display, borderPtr->darkGC);
}
if (borderPtr->lightGC != None) {
Tk_FreeGC(display, borderPtr->lightGC);
}
Tcl_DeleteHashEntry(borderPtr->hashPtr);
ckfree((char *) borderPtr);
}
}
/*
*----------------------------------------------------------------------
*
* Tk_SetBackgroundFromBorder --
*
* Change the background of a window to one appropriate for a given
* 3-D border.
*
* Results:
* None.
*
* Side effects:
* Tkwin's background gets modified.
*
*----------------------------------------------------------------------
*/
void
Tk_SetBackgroundFromBorder(tkwin, border)
Tk_Window tkwin; /* Window whose background is to be set. */
Tk_3DBorder border; /* Token for border. */
{
register TkBorder *borderPtr = (TkBorder *) border;
Tk_SetWindowBackground(tkwin, borderPtr->bgColorPtr->pixel);
}
/*
*----------------------------------------------------------------------
*
* Tk_GetRelief --
*
* Parse a relief description and return the corresponding
* relief value, or an error.
*
* Results:
* A standard Tcl return value. If all goes well then
* *reliefPtr is filled in with one of the values
* TK_RELIEF_RAISED, TK_RELIEF_FLAT, or TK_RELIEF_SUNKEN.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
Tk_GetRelief(interp, name, reliefPtr)
Tcl_Interp *interp; /* For error messages. */
char *name; /* Name of a relief type. */
int *reliefPtr; /* Where to store converted relief. */
{
char c;
size_t length;
c = name[0];
length = strlen(name);
if ((c == 'f') && (strncmp(name, "flat", length) == 0)) {
*reliefPtr = TK_RELIEF_FLAT;
} else if ((c == 'g') && (strncmp(name, "groove", length) == 0)
&& (length >= 2)) {
*reliefPtr = TK_RELIEF_GROOVE;
} else if ((c == 'r') && (strncmp(name, "raised", length) == 0)
&& (length >= 2)) {
*reliefPtr = TK_RELIEF_RAISED;
} else if ((c == 'r') && (strncmp(name, "ridge", length) == 0)) {
*reliefPtr = TK_RELIEF_RIDGE;
} else if ((c == 's') && (strncmp(name, "solid", length) == 0)) {
*reliefPtr = TK_RELIEF_SOLID;
} else if ((c == 's') && (strncmp(name, "sunken", length) == 0)) {
*reliefPtr = TK_RELIEF_SUNKEN;
} else {
sprintf(interp->result, "bad relief type \"%.50s\": must be %s",
name, "flat, groove, raised, ridge, solid, or sunken");
return TCL_ERROR;
}
return TCL_OK;
}
/*
*--------------------------------------------------------------
*
* Tk_NameOfRelief --
*
* Given a relief value, produce a string describing that
* relief value.
*
* Results:
* The return value is a static string that is equivalent
* to relief.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
char *
Tk_NameOfRelief(relief)
int relief; /* One of TK_RELIEF_FLAT, TK_RELIEF_RAISED,
* or TK_RELIEF_SUNKEN. */
{
if (relief == TK_RELIEF_FLAT) {
return "flat";
} else if (relief == TK_RELIEF_SUNKEN) {
return "sunken";
} else if (relief == TK_RELIEF_RAISED) {
return "raised";
} else if (relief == TK_RELIEF_GROOVE) {
return "groove";
} else if (relief == TK_RELIEF_RIDGE) {
return "ridge";
} else if (relief == TK_RELIEF_SOLID) {
return "solid";
} else {
return "unknown relief";
}
}
/*
*--------------------------------------------------------------
*
* Tk_Draw3DPolygon --
*
* Draw a border with 3-D appearance around the edge of a
* given polygon.
*
* Results:
* None.
*
* Side effects:
* Information is drawn in "drawable" in the form of a
* 3-D border borderWidth units width wide on the left
* of the trajectory given by pointPtr and numPoints (or
* -borderWidth units wide on the right side, if borderWidth
* is negative).
*
*--------------------------------------------------------------
*/
void
Tk_Draw3DPolygon(tkwin, drawable, border, pointPtr, numPoints,
borderWidth, leftRelief)
Tk_Window tkwin; /* Window for which border was allocated. */
Drawable drawable; /* X window or pixmap in which to draw. */
Tk_3DBorder border; /* Token for border to draw. */
XPoint *pointPtr; /* Array of points describing
* polygon. All points must be
* absolute (CoordModeOrigin). */
int numPoints; /* Number of points at *pointPtr. */
int borderWidth; /* Width of border, measured in
* pixels to the left of the polygon's
* trajectory. May be negative. */
int leftRelief; /* TK_RELIEF_RAISED or
* TK_RELIEF_SUNKEN: indicates how
* stuff to left of trajectory looks
* relative to stuff on right. */
{
XPoint poly[4], b1, b2, newB1, newB2;
XPoint perp, c, shift1, shift2; /* Used for handling parallel lines. */
register XPoint *p1Ptr, *p2Ptr;
TkBorder *borderPtr = (TkBorder *) border;
GC gc;
int i, lightOnLeft, dx, dy, parallel, pointsSeen;
Display *display = Tk_Display(tkwin);
if (borderPtr->lightGC == None) {
TkpGetShadows(borderPtr, tkwin);
}
/*
* Handle grooves and ridges with recursive calls.
*/
if ((leftRelief == TK_RELIEF_GROOVE) || (leftRelief == TK_RELIEF_RIDGE)) {
int halfWidth;
halfWidth = borderWidth/2;
Tk_Draw3DPolygon(tkwin, drawable, border, pointPtr, numPoints,
halfWidth, (leftRelief == TK_RELIEF_GROOVE) ? TK_RELIEF_RAISED
: TK_RELIEF_SUNKEN);
Tk_Draw3DPolygon(tkwin, drawable, border, pointPtr, numPoints,
-halfWidth, (leftRelief == TK_RELIEF_GROOVE) ? TK_RELIEF_SUNKEN
: TK_RELIEF_RAISED);
return;
}
/*
* If the polygon is already closed, drop the last point from it
* (we'll close it automatically).
*/
p1Ptr = &pointPtr[numPoints-1];
p2Ptr = &pointPtr[0];
if ((p1Ptr->x == p2Ptr->x) && (p1Ptr->y == p2Ptr->y)) {
numPoints--;
}
/*
* The loop below is executed once for each vertex in the polgon.
* At the beginning of each iteration things look like this:
*
* poly[1] /
* * /
* | /
* b1 * poly[0] (pointPtr[i-1])
* | |
* | |
* | |
* | |
* | |
* | | *p1Ptr *p2Ptr
* b2 *--------------------*
* |
* |
* x-------------------------
*
* The job of this iteration is to do the following:
* (a) Compute x (the border corner corresponding to
* pointPtr[i]) and put it in poly[2]. As part of
* this, compute a new b1 and b2 value for the next
* side of the polygon.
* (b) Put pointPtr[i] into poly[3].
* (c) Draw the polygon given by poly[0..3].
* (d) Advance poly[0], poly[1], b1, and b2 for the
* next side of the polygon.
*/
/*
* The above situation doesn't first come into existence until
* two points have been processed; the first two points are
* used to "prime the pump", so some parts of the processing
* are ommitted for these points. The variable "pointsSeen"
* keeps track of the priming process; it has to be separate
* from i in order to be able to ignore duplicate points in the
* polygon.
*/
pointsSeen = 0;
for (i = -2, p1Ptr = &pointPtr[numPoints-2], p2Ptr = p1Ptr+1;
i < numPoints; i++, p1Ptr = p2Ptr, p2Ptr++) {
if ((i == -1) || (i == numPoints-1)) {
p2Ptr = pointPtr;
}
if ((p2Ptr->x == p1Ptr->x) && (p2Ptr->y == p1Ptr->y)) {
/*
* Ignore duplicate points (they'd cause core dumps in
* ShiftLine calls below).
*/
continue;
}
ShiftLine(p1Ptr, p2Ptr, borderWidth, &newB1);
newB2.x = newB1.x + (p2Ptr->x - p1Ptr->x);
newB2.y = newB1.y + (p2Ptr->y - p1Ptr->y);
poly[3] = *p1Ptr;
parallel = 0;
if (pointsSeen >= 1) {
parallel = Intersect(&newB1, &newB2, &b1, &b2, &poly[2]);
/*
* If two consecutive segments of the polygon are parallel,
* then things get more complex. Consider the following
* diagram:
*
* poly[1]
* *----b1-----------b2------a
* \
* \
* *---------*----------* b
* poly[0] *p2Ptr *p1Ptr /
* /
* --*--------*----c
* newB1 newB2
*
* Instead of using x and *p1Ptr for poly[2] and poly[3], as
* in the original diagram, use a and b as above. Then instead
* of using x and *p1Ptr for the new poly[0] and poly[1], use
* b and c as above.
*
* Do the computation in three stages:
* 1. Compute a point "perp" such that the line p1Ptr-perp
* is perpendicular to p1Ptr-p2Ptr.
* 2. Compute the points a and c by intersecting the lines
* b1-b2 and newB1-newB2 with p1Ptr-perp.
* 3. Compute b by shifting p1Ptr-perp to the right and
* intersecting it with p1Ptr-p2Ptr.
*/
if (parallel) {
perp.x = p1Ptr->x + (p2Ptr->y - p1Ptr->y);
perp.y = p1Ptr->y - (p2Ptr->x - p1Ptr->x);
(void) Intersect(p1Ptr, &perp, &b1, &b2, &poly[2]);
(void) Intersect(p1Ptr, &perp, &newB1, &newB2, &c);
ShiftLine(p1Ptr, &perp, borderWidth, &shift1);
shift2.x = shift1.x + (perp.x - p1Ptr->x);
shift2.y = shift1.y + (perp.y - p1Ptr->y);
(void) Intersect(p1Ptr, p2Ptr, &shift1, &shift2, &poly[3]);
}
}
if (pointsSeen >= 2) {
dx = poly[3].x - poly[0].x;
dy = poly[3].y - poly[0].y;
if (dx > 0) {
lightOnLeft = (dy <= dx);
} else {
lightOnLeft = (dy < dx);
}
if (lightOnLeft ^ (leftRelief == TK_RELIEF_RAISED)) {
gc = borderPtr->lightGC;
} else {
gc = borderPtr->darkGC;
}
XFillPolygon(display, drawable, gc, poly, 4, Convex,
CoordModeOrigin);
}
b1.x = newB1.x;
b1.y = newB1.y;
b2.x = newB2.x;
b2.y = newB2.y;
poly[0].x = poly[3].x;
poly[0].y = poly[3].y;
if (parallel) {
poly[1].x = c.x;
poly[1].y = c.y;
} else if (pointsSeen >= 1) {
poly[1].x = poly[2].x;
poly[1].y = poly[2].y;
}
pointsSeen++;
}
}
/*
*----------------------------------------------------------------------
*
* Tk_Fill3DRectangle --
*
* Fill a rectangular area, supplying a 3D border if desired.
*
* Results:
* None.
*
* Side effects:
* Information gets drawn on the screen.
*
*----------------------------------------------------------------------
*/
void
Tk_Fill3DRectangle(tkwin, drawable, border, x, y, width,
height, borderWidth, relief)
Tk_Window tkwin; /* Window for which border was allocated. */
Drawable drawable; /* X window or pixmap in which to draw. */
Tk_3DBorder border; /* Token for border to draw. */
int x, y, width, height; /* Outside area of rectangular region. */
int borderWidth; /* Desired width for border, in
* pixels. Border will be *inside* region. */
int relief; /* Indicates 3D effect: TK_RELIEF_FLAT,
* TK_RELIEF_RAISED, or TK_RELIEF_SUNKEN. */
{
register TkBorder *borderPtr = (TkBorder *) border;
int doubleBorder;
/*
* This code is slightly tricky because it only draws the background
* in areas not covered by the 3D border. This avoids flashing
* effects on the screen for the border region.
*/
if (relief == TK_RELIEF_FLAT) {
borderWidth = 0;
}
doubleBorder = 2*borderWidth;
if ((width > doubleBorder) && (height > doubleBorder)) {
XFillRectangle(Tk_Display(tkwin), drawable, borderPtr->bgGC,
x + borderWidth, y + borderWidth,
(unsigned int) (width - doubleBorder),
(unsigned int) (height - doubleBorder));
}
if (borderWidth) {
Tk_Draw3DRectangle(tkwin, drawable, border, x, y, width,
height, borderWidth, relief);
}
}
/*
*----------------------------------------------------------------------
*
* Tk_Fill3DPolygon --
*
* Fill a polygonal area, supplying a 3D border if desired.
*
* Results:
* None.
*
* Side effects:
* Information gets drawn on the screen.
*
*----------------------------------------------------------------------
*/
void
Tk_Fill3DPolygon(tkwin, drawable, border, pointPtr, numPoints,
borderWidth, leftRelief)
Tk_Window tkwin; /* Window for which border was allocated. */
Drawable drawable; /* X window or pixmap in which to draw. */
Tk_3DBorder border; /* Token for border to draw. */
XPoint *pointPtr; /* Array of points describing
* polygon. All points must be
* absolute (CoordModeOrigin). */
int numPoints; /* Number of points at *pointPtr. */
int borderWidth; /* Width of border, measured in
* pixels to the left of the polygon's
* trajectory. May be negative. */
int leftRelief; /* Indicates 3D effect of left side of
* trajectory relative to right:
* TK_RELIEF_FLAT, TK_RELIEF_RAISED,
* or TK_RELIEF_SUNKEN. */
{
register TkBorder *borderPtr = (TkBorder *) border;
XFillPolygon(Tk_Display(tkwin), drawable, borderPtr->bgGC,
pointPtr, numPoints, Complex, CoordModeOrigin);
if (leftRelief != TK_RELIEF_FLAT) {
Tk_Draw3DPolygon(tkwin, drawable, border, pointPtr, numPoints,
borderWidth, leftRelief);
}
}
/*
*--------------------------------------------------------------
*
* BorderInit --
*
* Initialize the structures used for border management.
*
* Results:
* None.
*
* Side effects:
* Read the code.
*
*-------------------------------------------------------------
*/
static void
BorderInit()
{
initialized = 1;
Tcl_InitHashTable(&borderTable, sizeof(BorderKey)/sizeof(int));
}
/*
*--------------------------------------------------------------
*
* ShiftLine --
*
* Given two points on a line, compute a point on a
* new line that is parallel to the given line and
* a given distance away from it.
*
* Results:
* None.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
static void
ShiftLine(p1Ptr, p2Ptr, distance, p3Ptr)
XPoint *p1Ptr; /* First point on line. */
XPoint *p2Ptr; /* Second point on line. */
int distance; /* New line is to be this many
* units to the left of original
* line, when looking from p1 to
* p2. May be negative. */
XPoint *p3Ptr; /* Store coords of point on new
* line here. */
{
int dx, dy, dxNeg, dyNeg;
/*
* The table below is used for a quick approximation in
* computing the new point. An index into the table
* is 128 times the slope of the original line (the slope
* must always be between 0 and 1). The value of the table
* entry is 128 times the amount to displace the new line
* in y for each unit of perpendicular distance. In other
* words, the table maps from the tangent of an angle to
* the inverse of its cosine. If the slope of the original
* line is greater than 1, then the displacement is done in
* x rather than in y.
*/
static int shiftTable[129];
/*
* Initialize the table if this is the first time it is
* used.
*/
if (shiftTable[0] == 0) {
int i;
double tangent, cosine;
for (i = 0; i <= 128; i++) {
tangent = i/128.0;
cosine = 128/cos(atan(tangent)) + .5;
shiftTable[i] = (int) cosine;
}
}
*p3Ptr = *p1Ptr;
dx = p2Ptr->x - p1Ptr->x;
dy = p2Ptr->y - p1Ptr->y;
if (dy < 0) {
dyNeg = 1;
dy = -dy;
} else {
dyNeg = 0;
}
if (dx < 0) {
dxNeg = 1;
dx = -dx;
} else {
dxNeg = 0;
}
if (dy <= dx) {
dy = ((distance * shiftTable[(dy<<7)/dx]) + 64) >> 7;
if (!dxNeg) {
dy = -dy;
}
p3Ptr->y += dy;
} else {
dx = ((distance * shiftTable[(dx<<7)/dy]) + 64) >> 7;
if (dyNeg) {
dx = -dx;
}
p3Ptr->x += dx;
}
}
/*
*--------------------------------------------------------------
*
* Intersect --
*
* Find the intersection point between two lines.
*
* Results:
* Under normal conditions 0 is returned and the point
* at *iPtr is filled in with the intersection between
* the two lines. If the two lines are parallel, then
* -1 is returned and *iPtr isn't modified.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
static int
Intersect(a1Ptr, a2Ptr, b1Ptr, b2Ptr, iPtr)
XPoint *a1Ptr; /* First point of first line. */
XPoint *a2Ptr; /* Second point of first line. */
XPoint *b1Ptr; /* First point of second line. */
XPoint *b2Ptr; /* Second point of second line. */
XPoint *iPtr; /* Filled in with intersection point. */
{
int dxadyb, dxbdya, dxadxb, dyadyb, p, q;
/*
* The code below is just a straightforward manipulation of two
* equations of the form y = (x-x1)*(y2-y1)/(x2-x1) + y1 to solve
* for the x-coordinate of intersection, then the y-coordinate.
*/
dxadyb = (a2Ptr->x - a1Ptr->x)*(b2Ptr->y - b1Ptr->y);
dxbdya = (b2Ptr->x - b1Ptr->x)*(a2Ptr->y - a1Ptr->y);
dxadxb = (a2Ptr->x - a1Ptr->x)*(b2Ptr->x - b1Ptr->x);
dyadyb = (a2Ptr->y - a1Ptr->y)*(b2Ptr->y - b1Ptr->y);
if (dxadyb == dxbdya) {
return -1;
}
p = (a1Ptr->x*dxbdya - b1Ptr->x*dxadyb + (b1Ptr->y - a1Ptr->y)*dxadxb);
q = dxbdya - dxadyb;
if (q < 0) {
p = -p;
q = -q;
}
if (p < 0) {
iPtr->x = - ((-p + q/2)/q);
} else {
iPtr->x = (p + q/2)/q;
}
p = (a1Ptr->y*dxadyb - b1Ptr->y*dxbdya + (b1Ptr->x - a1Ptr->x)*dyadyb);
q = dxadyb - dxbdya;
if (q < 0) {
p = -p;
q = -q;
}
if (p < 0) {
iPtr->y = - ((-p + q/2)/q);
} else {
iPtr->y = (p + q/2)/q;
}
return 0;
}