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gimp/plug-ins/gfig/gfig-grid.c

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/*
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* This is a plug-in for the GIMP.
*
* Generates images containing vector type drawings.
*
* Copyright (C) 1997 Andy Thomas alt@picnic.demon.co.uk
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <gtk/gtk.h>
#include <libgimp/gimp.h>
#include "gfig.h"
#include "gfig-grid.h"
#include "libgimp/stdplugins-intl.h"
/* For the isometric grid */
#define SQRT3 1.73205080756887729353 /* Square root of 3 */
#define SIN_1o6PI_RAD 0.5 /* Sine 1/6 Pi Radians */
#define COS_1o6PI_RAD SQRT3 / 2 /* Cosine 1/6 Pi Radians */
#define TAN_1o6PI_RAD 1 / SQRT3 /* Tangent 1/6 Pi Radians == SIN / COS */
#define RECIP_TAN_1o6PI_RAD SQRT3 /* Reciprocal of Tangent 1/6 Pi Radians */
static GdkGC *grid_hightlight_drawgc;
gint grid_gc_type = GTK_STATE_NORMAL;
static GdkGC *gfig_get_grid_gc (GtkWidget *widget,
gint gctype);
static gint get_num_radials (void);
/* find_grid_pos - Given an x, y point return the grid position of it */
/* return the new position in the passed point */
void
gfig_grid_colours (GtkWidget *widget)
{
GdkColormap *colormap;
GdkGCValues values;
GdkColor col1;
GdkColor col2;
guchar stipple[8] =
{
0xAA, /* ####---- */
0x55, /* ###----# */
0xAA, /* ##----## */
0x55, /* #----### */
0xAA, /* ----#### */
0x55, /* ---####- */
0xAA, /* --####-- */
0x55, /* -####--- */
};
colormap = gdk_screen_get_rgb_colormap (gtk_widget_get_screen (widget));
gdk_color_parse ("gray50", &col1);
gdk_colormap_alloc_color (colormap, &col1, FALSE, TRUE);
gdk_color_parse ("gray80", &col2);
gdk_colormap_alloc_color (colormap, &col2, FALSE, TRUE);
values.background.pixel = col1.pixel;
values.foreground.pixel = col2.pixel;
values.fill = GDK_OPAQUE_STIPPLED;
values.stipple = gdk_bitmap_create_from_data (widget->window,
(gchar *) stipple, 4, 4);
grid_hightlight_drawgc = gdk_gc_new_with_values (widget->window,
&values,
GDK_GC_FOREGROUND |
GDK_GC_BACKGROUND |
GDK_GC_FILL |
GDK_GC_STIPPLE);
}
void
find_grid_pos (GdkPoint *p,
GdkPoint *gp,
guint is_butt3)
{
gint16 x = p->x;
gint16 y = p->y;
static GdkPoint cons_pnt;
static gdouble cons_radius;
static gdouble cons_ang;
static gboolean cons_center;
if (selvals.opts.gridtype == RECT_GRID)
{
if (p->x % selvals.opts.gridspacing > selvals.opts.gridspacing/2)
x += selvals.opts.gridspacing;
if (p->y % selvals.opts.gridspacing > selvals.opts.gridspacing/2)
y += selvals.opts.gridspacing;
gp->x = (x/selvals.opts.gridspacing)*selvals.opts.gridspacing;
gp->y = (y/selvals.opts.gridspacing)*selvals.opts.gridspacing;
if (is_butt3)
{
if (abs (gp->x - cons_pnt.x) < abs (gp->y - cons_pnt.y))
gp->x = cons_pnt.x;
else
gp->y = cons_pnt.y;
}
else
{
/* Store the point since might be used later */
cons_pnt = *gp; /* Structure copy */
}
}
else if (selvals.opts.gridtype == POLAR_GRID)
{
gdouble ang_grid;
gdouble ang_radius;
gdouble real_radius;
gdouble real_angle;
gdouble rounded_angle;
gint rounded_radius;
gint16 shift_x = x - preview_width/2;
gint16 shift_y = -y + preview_height/2;
real_radius = ang_radius = sqrt ((shift_y*shift_y) + (shift_x*shift_x));
/* round radius */
rounded_radius = (gint)(RINT (ang_radius/selvals.opts.gridspacing))*selvals.opts.gridspacing;
if (rounded_radius <= 0 || real_radius <=0)
{
/* DEAD CENTER */
gp->x = preview_width/2;
gp->y = preview_height/2;
if (!is_butt3) cons_center = TRUE;
#ifdef DEBUG
printf ("Dead center\n");
#endif /* DEBUG */
return;
}
ang_grid = 2*G_PI/get_num_radials ();
real_angle = atan2 (shift_y, shift_x);
if (real_angle < 0)
real_angle += 2*G_PI;
rounded_angle = (RINT ((real_angle/ang_grid)))*ang_grid;
#ifdef DEBUG
printf ("real_ang = %f ang_gid = %f rounded_angle = %f rounded radius = %d\n",
real_angle, ang_grid, rounded_angle, rounded_radius);
printf ("preview_width = %d preview_height = %d\n", preview_width, preview_height);
#endif /* DEBUG */
gp->x = (gint)RINT ((rounded_radius*cos (rounded_angle))) + preview_width/2;
gp->y = -(gint)RINT ((rounded_radius*sin (rounded_angle))) + preview_height/2;
if (is_butt3)
{
if (!cons_center)
{
if (fabs (rounded_angle - cons_ang) > ang_grid/2)
{
gp->x = (gint)RINT ((cons_radius*cos (rounded_angle))) + preview_width/2;
gp->y = -(gint)RINT ((cons_radius*sin (rounded_angle))) + preview_height/2;
}
else
{
gp->x = (gint)RINT ((rounded_radius*cos (cons_ang))) + preview_width/2;
gp->y = -(gint)RINT ((rounded_radius*sin (cons_ang))) + preview_height/2;
}
}
}
else
{
cons_radius = rounded_radius;
cons_ang = rounded_angle;
cons_center = FALSE;
}
}
else if (selvals.opts.gridtype == ISO_GRID)
{
/*
* This really needs a picture to show the math...
*
* Consider an isometric grid with one of the sets of lines parallel to the
* y axis (vertical alignment). Further define that the origin of a Cartesian
* grid is at a isometric vertex. For simplicity consider the first quadrant only.
*
* - Let one line segment between vertices be r
* - Define the value of r as the grid spacing
* - Assign an integer n identifier to each vertical grid line along the x axis.
* with n=0 being the y axis. n can be any integer
* - Let m to be any integer
* - Let h be the spacing between vertical grid lines measured along the x axis.
* It follows from the isometric grid that h has a value of r * COS(1/6 Pi Rad)
*
* Consider a Vertex V at the Cartesian location [Xv, Yv]
*
* It follows that vertices belong to the set...
* V[Xv, Yv] = [ [ n * h ] ,
* [ m * r + ( 0.5 * r (n % 2) ) ] ]
* for all integers n and m
*
* Who cares? Me. It's useful in solving this problem:
* Consider an arbitrary point P[Xp,Yp], find the closest vertex in the set V.
*
* Restated this problem is "find values for m and n that are drive V closest to P"
*
* A Solution method (there may be a better one?):
*
* Step 1) bound n to the two closest values for Xp
* n_lo = (int) (Xp / h)
* n_hi = n_lo + 1
*
* Step 2) Consider the two closes vertices for each n_lo and n_hi. The further of
* the vertices in each pair can readily be discarded.
* m_lo_n_lo = (int) ( (Yp / r) - 0.5 (n_lo % 2) )
* m_hi_n_lo = m_lo_n_lo + 1
*
* m_lo_n_hi = (int) ( (Yp / r) - 0.5 (n_hi % 2) )
* m_hi_n_hi = m_hi_n_hi
*
* Step 3) compute the distance from P to V1 and V2. Snap to the closer point.
*/
gint n_lo;
gint n_hi;
gint m_lo_n_lo;
gint m_hi_n_lo;
gint m_lo_n_hi;
gint m_hi_n_hi;
gint m_n_lo;
gint m_n_hi;
gdouble r;
gdouble h;
gint x1;
gint x2;
gint y1;
gint y2;
r = selvals.opts.gridspacing;
h = COS_1o6PI_RAD * r;
n_lo = (gint) x / h;
n_hi = n_lo + 1;
/* evaluate m candidates for n_lo */
m_lo_n_lo = (gint) ( (y / r) - 0.5 * (n_lo % 2) );
m_hi_n_lo = m_lo_n_lo + 1;
/* figure out which is the better candidate */
if (abs((m_lo_n_lo * r + (0.5 * r * (n_lo % 2))) - y) <
abs((m_hi_n_lo * r + (0.5 * r * (n_lo % 2))) - y)) {
m_n_lo = m_lo_n_lo;
}
else {
m_n_lo = m_hi_n_lo;
}
/* evaluate m candidates for n_hi */
m_lo_n_hi = (gint) ( (y / r) - 0.5 * (n_hi % 2) );
m_hi_n_hi = m_lo_n_hi + 1;
/* figure out which is the better candidate */
if (abs((m_lo_n_hi * r + (0.5 * r * (n_hi % 2))) - y) <
abs((m_hi_n_hi * r + (0.5 * r * (n_hi % 2))) - y)) {
m_n_hi = m_lo_n_hi;
}
else {
m_n_hi = m_hi_n_hi;
}
/* Now, which is closer to [x,y]? we can use a somewhat abbreviated form of the
* distance formula since we only care about relative values. */
x1 = (gint) (n_lo * h);
y1 = (gint) (m_n_lo * r + (0.5 * r * (n_lo % 2)));
x2 = (gint) (n_hi * h);
y2 = (gint) (m_n_hi * r + (0.5 * r * (n_hi % 2)));
if (((x - x1) * (x - x1) + (y - y1) * (y - y1)) <
((x - x2) * (x - x2) + (y - y2) * (y - y2))) {
gp->x = x1;
gp->y = y1;
}
else {
gp->x = x2;
gp->y = y2;
}
}
}
static void
draw_grid_polar (GdkGC *drawgc)
{
gint step;
gint loop;
gint radius;
gint max_rad;
gdouble ang_grid;
gdouble ang_loop;
gdouble ang_radius;
/* Pick center and draw concentric circles */
gint grid_x_center = preview_width/2;
gint grid_y_center = preview_height/2;
step = selvals.opts.gridspacing;
max_rad = sqrt (preview_width * preview_width +
preview_height * preview_height) / 2;
for (loop = 0; loop < max_rad; loop += step)
{
radius = loop;
gdk_draw_arc (gfig_context->preview->window,
drawgc,
0,
grid_x_center - radius,
grid_y_center - radius,
radius*2,
radius*2,
0,
360 * 64);
}
/* Lines */
ang_grid = 2 * G_PI / get_num_radials ();
ang_radius = sqrt ((preview_width * preview_width) +
(preview_height * preview_height)) / 2;
for (loop = 0; loop <= get_num_radials (); loop++)
{
gint lx, ly;
ang_loop = loop * ang_grid;
lx = RINT (ang_radius * cos (ang_loop));
ly = RINT (ang_radius * sin (ang_loop));
gdk_draw_line (gfig_context->preview->window,
drawgc,
lx + (preview_width) / 2,
- ly + (preview_height) / 2,
(preview_width) / 2,
(preview_height) / 2);
}
}
static void
draw_grid_sq (GdkGC *drawgc)
{
gint step;
gint loop;
/* Draw the horizontal lines */
step = selvals.opts.gridspacing;
for (loop = 0 ; loop < preview_height ; loop += step)
{
gdk_draw_line (gfig_context->preview->window,
drawgc,
0,
loop,
preview_width,
loop);
}
/* Draw the vertical lines */
for (loop = 0 ; loop < preview_width ; loop += step)
{
gdk_draw_line (gfig_context->preview->window,
drawgc,
loop,
0,
loop,
preview_height);
}
}
static void
draw_grid_iso (GdkGC *drawgc)
{
/* vstep is an int since it's defined from grid size */
gint vstep;
gdouble loop;
gdouble hstep;
gdouble diagonal_start;
gdouble diagonal_end;
gdouble diagonal_width;
gdouble diagonal_height;
vstep = selvals.opts.gridspacing;
hstep = selvals.opts.gridspacing * COS_1o6PI_RAD;
/* Draw the vertical lines - These are easy */
for (loop = 0 ; loop < preview_width ; loop += hstep){
gdk_draw_line (gfig_context->preview->window,
drawgc,
(gint)loop,
(gint)0,
(gint)loop,
(gint)preview_height);
}
/* draw diag lines at a Theta of +/- 1/6 Pi Rad */
diagonal_start = -(((int)preview_width * TAN_1o6PI_RAD) - (((int)(preview_width * TAN_1o6PI_RAD)) % vstep));
diagonal_end = preview_height + (preview_width * TAN_1o6PI_RAD);
diagonal_end -= ((int)diagonal_end) % vstep;
diagonal_width = preview_width;
diagonal_height = preview_width * TAN_1o6PI_RAD;
/* Draw diag lines */
for (loop = diagonal_start ; loop < diagonal_end ; loop += vstep)
{
gdk_draw_line (gfig_context->preview->window,
drawgc,
(gint)0,
(gint)loop,
(gint)diagonal_width,
(gint)loop + diagonal_height);
gdk_draw_line (gfig_context->preview->window,
drawgc,
(gint)0,
(gint)loop,
(gint)diagonal_width,
(gint)loop - diagonal_height);
}
}
static GdkGC *
gfig_get_grid_gc (GtkWidget *w, gint gctype)
{
switch (gctype)
{
case GFIG_BLACK_GC:
return (w->style->black_gc);
case GFIG_WHITE_GC:
return (w->style->white_gc);
case GFIG_GREY_GC:
return (grid_hightlight_drawgc);
case GTK_STATE_NORMAL:
return (w->style->bg_gc[GTK_STATE_NORMAL]);
case GTK_STATE_ACTIVE:
return (w->style->bg_gc[GTK_STATE_ACTIVE]);
case GTK_STATE_PRELIGHT:
return (w->style->bg_gc[GTK_STATE_PRELIGHT]);
case GTK_STATE_SELECTED:
return (w->style->bg_gc[GTK_STATE_SELECTED]);
case GTK_STATE_INSENSITIVE:
return (w->style->bg_gc[GTK_STATE_INSENSITIVE]);
default:
g_warning ("Unknown type for grid colouring\n");
return (w->style->bg_gc[GTK_STATE_PRELIGHT]);
}
}
void
draw_grid (void)
{
GdkGC *drawgc;
/* Get the size of the preview and calc where the lines go */
/* Draw in prelight to start with... */
/* Always start in the upper left corner for rect.
*/
if ((preview_width < selvals.opts.gridspacing &&
preview_height < selvals.opts.gridspacing))
{
/* Don't draw if they don't fit */
return;
}
if (selvals.opts.drawgrid)
drawgc = gfig_get_grid_gc (gfig_context->preview, grid_gc_type);
else
return;
if (selvals.opts.gridtype == RECT_GRID)
draw_grid_sq (drawgc);
else if (selvals.opts.gridtype == POLAR_GRID)
draw_grid_polar (drawgc);
else if (selvals.opts.gridtype == ISO_GRID)
draw_grid_iso (drawgc);
}
static gint
get_num_radials (void)
{
gint gridsp = MAX_GRID + MIN_GRID;
/* select number of radials to draw */
/* Either have 16 32 or 48 */
/* correspond to GRID_MAX, midway and GRID_MIN */
return gridsp - selvals.opts.gridspacing;
}
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