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graphics_regis.c
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graphics_regis.c
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/* $XTermId: graphics_regis.c,v 1.80 2016/05/29 16:20:42 tom Exp $ */
/*
* Copyright 2014-2015,2016 by Ross Combs
*
* All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name(s) of the above copyright
* holders shall not be used in advertising or otherwise to promote the
* sale, use or other dealings in this Software without prior written
* authorization.
*/
#include <xterm.h>
#include <stdio.h>
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#if OPT_DOUBLE_BUFFER
#include <X11/extensions/Xdbe.h>
#endif
#include <data.h>
#include <VTparse.h>
#include <ptyx.h>
#include <assert.h>
#include <graphics.h>
#include <graphics_regis.h>
/* get rid of shadowing warnings (we will not draw Bessel functions) */
#define y1 my_y1
#define y0 my_y0
#define IS_HEX_DIGIT(CH) ( \
(CH) == '0' || \
(CH) == '1' || \
(CH) == '2' || \
(CH) == '3' || \
(CH) == '4' || \
(CH) == '5' || \
(CH) == '6' || \
(CH) == '7' || \
(CH) == '8' || \
(CH) == '9' || \
(CH) == 'a' || \
(CH) == 'b' || \
(CH) == 'c' || \
(CH) == 'd' || \
(CH) == 'e' || \
(CH) == 'f' || \
(CH) == 'A' || \
(CH) == 'B' || \
(CH) == 'C' || \
(CH) == 'D' || \
(CH) == 'E' || \
(CH) == 'F' )
#define SCALE_FIXED_POINT 16U
#undef DEBUG_PARSING
#undef DEBUG_ALPHABET_LOOKUP
#undef DEBUG_ALPHABETS
#undef DEBUG_BEZIER
#undef DEBUG_SPLINE_SEGMENTS
#undef DEBUG_SPLINE_POINTS
#undef DEBUG_SPLINE_WITH_ROTATION
#undef DEBUG_SPLINE_WITH_OVERDRAW
#undef DEBUG_ARC_POINTS
#undef DEBUG_ARC_CENTER
#undef DEBUG_ARC_START
#undef DEBUG_ARC_END
#undef DEBUG_SPECIFIC_CHAR_METRICS
#define IS_DEBUG_CHAR(CH) ((CH) == 'W') /* glyphs to dump to terminal */
#undef DEBUG_COMPUTED_FONT_METRICS
#undef DEBUG_FONT_NAME
#undef DEBUG_FONT_SIZE_SEARCH
#undef DEBUG_XFT_GLYPH
#undef DEBUG_USER_GLYPH
#undef DEBUG_LOAD
/* controls for extensions over VT3x0 limitations */
#define ENABLE_RGB_COLORSPECS
#define ENABLE_FREE_ROTATION
#define ENABLE_UPLOAD_ALPHABET_FROM_FONT
#define ENABLE_UPLOAD_ALPHABET_ZERO
#define ENABLE_USER_FONT_SIZE
#define ENABLE_VARIABLE_ITALICS
#define MIN_ITERATIONS_BEFORE_REFRESH 10U
#define MIN_MS_BEFORE_REFRESH 33
/* *INDENT-OFF* */
typedef struct RegisPoint {
int x, y;
} RegisPoint;
typedef struct RegisWriteControls {
unsigned pv_multiplier;
unsigned pattern;
unsigned pattern_multiplier;
unsigned invert_pattern;
unsigned plane_mask;
unsigned write_style;
RegisterNum foreground;
unsigned shading_enabled;
char shading_character;
int shading_reference;
unsigned shading_reference_dim;
unsigned line_width;
} RegisWriteControls;
typedef struct RegisTextControls {
unsigned alphabet_num;
unsigned character_set_l; /* default: "(B" (ASCII) */
unsigned character_set_r; /* default: "-@" (Latin-1) */
unsigned character_display_w;
unsigned character_display_h;
unsigned character_unit_cell_w;
unsigned character_unit_cell_h;
int character_inc_x;
int character_inc_y;
int string_rotation;
int character_rotation;
int slant; /* for italic/oblique */
} RegisTextControls;
#define FixedCopy(dst, src, len) strncpy(dst, src, len - 1)[len - 1] = '\0'
#define CopyFontname(dst, src) FixedCopy(dst, src, REGIS_FONTNAME_LEN)
#define MAX_REGIS_PAGES 8U
#define MAX_REGIS_ALPHABETS 8U
#define REGIS_ALPHABET_NAME_LEN 11U
#define REGIS_FONTNAME_LEN 256U
/* enough for a 16x24 font (about 100KB) */
#define MAX_REGIS_ALPHABET_BYTES (256U * 16U * 24U)
#define MAX_GLYPH_PIXELS 8192U
#define MAX_GLYPHS 256U
#define INVALID_ALPHABET_NUM ~0U
typedef struct RegisAlphabet {
unsigned alphabet_num;
unsigned pixw, pixh;
char name[REGIS_ALPHABET_NAME_LEN];
char fontname[REGIS_FONTNAME_LEN];
int use_font;
int loaded[MAX_GLYPHS];
unsigned char *bytes;
} RegisAlphabet;
typedef struct RegisDataFragment {
char const *start;
unsigned pos;
unsigned len;
} RegisDataFragment;
/* *INDENT-ON* */
#define POSITION_STACK_SIZE 16U
#define DUMMY_STACK_X -32768
#define DUMMY_STACK_Y -32768
#define CURVE_POSITION_ARC_EDGE 0U
#define CURVE_POSITION_ARC_CENTER 1U
#define CURVE_POSITION_OPEN_CURVE 2U
#define CURVE_POSITION_CLOSED_CURVE 3U
#define MAX_INPUT_CURVE_POINTS 16U
#define MAX_CURVE_POINTS (MAX_INPUT_CURVE_POINTS + 4U)
#define MAX_FILL_POINTS 2048U
typedef struct RegisParseState {
RegisDataFragment input;
char *temp;
unsigned templen;
char command;
char option;
/* position stack */
int stack_x[POSITION_STACK_SIZE];
int stack_y[POSITION_STACK_SIZE];
unsigned stack_next; /* next empty position */
/* curve options */
int curve_mode;
int arclen;
int x_points[MAX_CURVE_POINTS];
int y_points[MAX_CURVE_POINTS];
unsigned num_points;
/* load options */
char load_name[REGIS_ALPHABET_NAME_LEN];
unsigned load_alphabet;
unsigned load_w, load_h;
unsigned load_index;
unsigned load_glyph;
unsigned load_row;
/* text options */
int string_rot_set; /* flag to distinguish string vs. character rotation */
} RegisParseState;
typedef struct RegisGraphicsContext {
Graphic *destination_graphic;
Graphic *display_graphic;
int terminal_id;
int x_off, y_off;
int x_div, y_div;
int width, height;
unsigned all_planes;
RegisterNum background;
char const *builtin_font;
RegisAlphabet alphabets[MAX_REGIS_ALPHABETS];
RegisWriteControls persistent_write_controls;
RegisWriteControls temporary_write_controls;
RegisTextControls persistent_text_controls;
RegisTextControls temporary_text_controls;
RegisTextControls *current_text_controls;
int multi_input_mode;
int graphics_output_cursor_x;
int graphics_output_cursor_y;
unsigned pattern_count;
unsigned pattern_bit;
int fill_mode;
RegisPoint fill_points[MAX_FILL_POINTS];
unsigned fill_point_count;
unsigned destination_page;
unsigned display_page;
int force_refresh;
} RegisGraphicsContext;
static RegisGraphicsContext persistent_context;
static RegisParseState persistent_state;
#define MAX_PATTERN_BITS 8U
#define WRITE_STYLE_OVERLAY 1U
#define WRITE_STYLE_REPLACE 2U
#define WRITE_STYLE_COMPLEMENT 3U
#define WRITE_STYLE_ERASE 4U
#define WRITE_SHADING_REF_Y 0U
#define WRITE_SHADING_REF_X 1U
#define WRITE_SHADING_REF_NONE 2U
/* keypress event example: http://iraf.net/forum/viewtopic.php?showtopic=61692 */
#define MIN2(X, Y) ( (X) < (Y) ? (X) : (Y) )
#define MIN3(X, Y, Z) ( MIN2(MIN2((X), (Y)), MIN2((Y), (Z))) )
#define MAX2(X, Y) ( (X) > (Y) ? (X) : (Y) )
#define MAX3(X, Y, Z) ( MAX2(MAX2((X), (Y)), MAX2((Y), (Z))) )
#define ROT_LEFT_N(V, N) ( (((V) << ((N) & 3U )) & 255U) | \
((V) >> (8U - ((N) & 3U))) )
#define ROT_LEFT(V) ( (((V) << 1U) & 255U) | ((V) >> 7U) )
/* convert user coordinates to absolute pixel coordinates */
#define SCALE_XCOORD(C, X, S) ( ( (X) * ((C)->width - 1) ) / ( (C)->x_div * (S) ) )
#define SCALE_YCOORD(C, Y, S) ( ( (Y) * ((C)->height - 1) ) / ( (C)->y_div * (S) ) )
#define TRANSLATE_XCOORD(C, X, S) SCALE_XCOORD((C), (X) - (C)->x_off * (S), (S) )
#define TRANSLATE_YCOORD(C, Y, S) SCALE_YCOORD((C), (Y) - (C)->y_off * (S), (S) )
#if 0
/* convert absolute pixel coordinate to user coordinates */
#define SCALE_XPIX(C, X, S) ( ( (X) * ((C)->x_div * (S) ) ) / ((C)->width - 1) )
#define SCALE_YPIX(C, Y, S) ( ( (Y) * ((C)->y_div * (S) ) ) / ((C)->height - 1) )
#define TRANSLATE_XPIX(C, X, S) ( SCALE_XPIX((C), (X), (S) ) + (C)->x_off * (S) )
#define TRANSLATE_YPIX(C, Y, S) ( SCALE_YPIX((C), (Y), (S) ) + (C)->y_off * (S) )
#endif
#define READ_PIXEL(C, X, Y) read_pixel((C)->destination_graphic, (X), (Y))
#define DRAW_PIXEL(C, X, Y, COL) draw_solid_pixel((C)->destination_graphic, (X), (Y), (COL))
#define DRAW_ALL(C, COL) \
draw_solid_rectangle((C)->destination_graphic, 0, 0, (C)->width, (C)->height, (COL))
static unsigned get_shade_character_pixel(unsigned char const *pixels,
unsigned w, unsigned h,
unsigned smaxf, unsigned scale,
int slant_dx, int px, int py);
static void get_bitmap_of_character(RegisGraphicsContext const *context,
int ch, unsigned maxw, unsigned maxh,
unsigned char *pixels,
unsigned *w, unsigned *h,
unsigned max_pixels);
static int
ifloor(double d)
{
double dl = floor(d);
return (int) dl;
}
static int
isqrt(double d)
{
double dl = sqrt(d);
return (int) dl;
}
static void
draw_regis_pixel(RegisGraphicsContext *context, int x, int y,
unsigned value)
{
unsigned color = 0;
switch (context->temporary_write_controls.write_style) {
case WRITE_STYLE_OVERLAY:
/*
* Update pixels with foreground when pattern is 1,
* don't change when pattern is 0.
*/
if (!value) {
return;
}
if (context->temporary_write_controls.invert_pattern) {
color = context->background;
} else {
color = context->temporary_write_controls.foreground;
}
break;
case WRITE_STYLE_REPLACE:
/*
* Update pixels with foreground when pattern is 1,
* set to background when pattern is 0.
*/
{
unsigned fg, bg;
if (context->temporary_write_controls.invert_pattern) {
fg = context->background;
bg = context->temporary_write_controls.foreground;
} else {
fg = context->temporary_write_controls.foreground;
bg = context->background;
}
color = value ? fg : bg;
}
break;
case WRITE_STYLE_COMPLEMENT:
/*
* Update pixels with background when pattern is 1,
* don't change when pattern is 0.
*/
if (!value) {
return;
}
color = READ_PIXEL(context, x, y);
if (color == COLOR_HOLE)
color = context->background;
color = color ^ context->all_planes;
break;
case WRITE_STYLE_ERASE:
/* Update pixels to foreground. */
if (context->temporary_write_controls.invert_pattern) {
color = context->temporary_write_controls.foreground;
} else {
color = context->background;
}
break;
}
DRAW_PIXEL(context, x, y, color);
}
static void
shade_pattern_to_pixel(RegisGraphicsContext *context, unsigned dim, int ref,
int x, int y)
{
unsigned value;
if (dim == WRITE_SHADING_REF_X) {
int delta = x > ref ? 1 : -1;
int curr_x;
context->pattern_bit = 1U << (((unsigned) y) & 7U);
for (curr_x = ref; curr_x != x + delta; curr_x += delta) {
value = context->temporary_write_controls.pattern &
context->pattern_bit;
draw_regis_pixel(context, curr_x, y, value);
}
} else if (dim == WRITE_SHADING_REF_Y) {
int delta = y > ref ? 1 : -1;
int curr_y;
for (curr_y = ref; curr_y != y + delta; curr_y += delta) {
context->pattern_bit = 1U << (((unsigned) curr_y) & 7U);
value = context->temporary_write_controls.pattern &
context->pattern_bit;
draw_regis_pixel(context, x, curr_y, value);
}
} else {
TRACE(("ERROR: shading requested, but there is no reference axis\n"));
}
}
static void
shade_char_to_pixel(RegisGraphicsContext *context, unsigned char const *pixels,
unsigned w, unsigned h, unsigned dim, int ref, int x, int y)
{
unsigned xmaxf = context->current_text_controls->character_unit_cell_w;
unsigned ymaxf = context->current_text_controls->character_unit_cell_h;
unsigned smaxf;
unsigned s;
unsigned scale;
unsigned value;
if (xmaxf > ymaxf) {
smaxf = ymaxf;
s = h;
} else {
smaxf = xmaxf;
s = w;
}
scale = (s << SCALE_FIXED_POINT) / smaxf;
if (dim == WRITE_SHADING_REF_X) {
int delta = x > ref ? 1 : -1;
int curr_x;
for (curr_x = ref; curr_x != x + delta; curr_x += delta) {
value = get_shade_character_pixel(pixels, w, h, smaxf, scale, 0,
curr_x, y);
draw_regis_pixel(context, curr_x, y, value);
}
} else if (dim == WRITE_SHADING_REF_Y) {
int delta = y > ref ? 1 : -1;
int curr_y;
for (curr_y = ref; curr_y != y + delta; curr_y += delta) {
value = get_shade_character_pixel(pixels, w, h, smaxf, scale, 0, x,
curr_y);
draw_regis_pixel(context, x, curr_y, value);
}
} else {
TRACE(("ERROR: shading requested, but there is no reference axis\n"));
}
}
static void
draw_patterned_pixel(RegisGraphicsContext *context, int x, int y)
{
if (context->pattern_count >=
context->temporary_write_controls.pattern_multiplier) {
context->pattern_count = 0U;
context->pattern_bit = ROT_LEFT(context->pattern_bit);
}
context->pattern_count++;
draw_regis_pixel(context, x, y,
context->temporary_write_controls.pattern &
context->pattern_bit);
}
static void
shade_to_pixel(RegisGraphicsContext *context, unsigned dim, int ref,
int x, int y)
{
if (context->temporary_write_controls.shading_character != '\0') {
unsigned xmaxf = context->current_text_controls->character_unit_cell_w;
unsigned ymaxf = context->current_text_controls->character_unit_cell_h;
char ch = context->temporary_write_controls.shading_character;
unsigned char pixels[MAX_GLYPH_PIXELS];
unsigned w, h;
get_bitmap_of_character(context, ch, xmaxf, ymaxf, pixels, &w, &h,
MAX_GLYPH_PIXELS);
if (w > 0 && h > 0) {
shade_char_to_pixel(context, pixels, w, h, dim, ref, x, y);
}
} else {
shade_pattern_to_pixel(context, dim, ref, x, y);
}
}
static void
draw_or_save_patterned_pixel(RegisGraphicsContext *context, int x, int y)
{
if (context->fill_mode == 1) {
if (context->fill_point_count >= MAX_FILL_POINTS) {
TRACE(("point %d,%d can not be added to filled polygon\n",
x, y));
return;
}
if (context->fill_point_count > 0U &&
context->fill_points[context->fill_point_count - 1U].x == x &&
context->fill_points[context->fill_point_count - 1U].y == y) {
return;
}
context->fill_points[context->fill_point_count].x = x;
context->fill_points[context->fill_point_count].y = y;
context->fill_point_count++;
return;
}
if (context->temporary_write_controls.shading_enabled) {
unsigned dim = context->temporary_write_controls.shading_reference_dim;
int ref = context->temporary_write_controls.shading_reference;
shade_to_pixel(context, dim, ref, x, y);
return;
}
draw_patterned_pixel(context, x, y);
}
static int
sort_points(void const *l, void const *r)
{
RegisPoint const *const lp = l;
RegisPoint const *const rp = r;
if (lp->y < rp->y)
return -1;
if (lp->y > rp->y)
return +1;
if (lp->x < rp->x)
return -1;
if (lp->x > rp->x)
return +1;
return 0;
}
static void
draw_filled_polygon(RegisGraphicsContext *context)
{
unsigned p;
int old_x, old_y;
int inside;
unsigned char pixels[MAX_GLYPH_PIXELS];
unsigned w, h;
if (context->temporary_write_controls.shading_character != '\0') {
char ch = context->temporary_write_controls.shading_character;
unsigned xmaxf = context->current_text_controls->character_unit_cell_w;
unsigned ymaxf = context->current_text_controls->character_unit_cell_h;
get_bitmap_of_character(context, ch, xmaxf, ymaxf, pixels, &w, &h,
MAX_GLYPH_PIXELS);
if (w < 1U || h < 1U) {
return;
}
}
qsort(context->fill_points, context->fill_point_count,
sizeof(context->fill_points[0]), sort_points);
old_x = DUMMY_STACK_X;
old_y = DUMMY_STACK_Y;
inside = 0;
for (p = 0U; p < context->fill_point_count; p++) {
int new_x = context->fill_points[p].x;
int new_y = context->fill_points[p].y;
#if 0
printf("got %d,%d (%d,%d) inside=%d\n", new_x, new_y, old_x, old_y, inside);
#endif
/*
* FIXME: This is using pixels to represent lines which loses
* information about exact slope and how many lines are present which
* causes misbehavior with some inputs (especially complex polygons).
* It also takes more room than remembering vertices, but I'd rather
* not have to implement line segments for arcs. Maybe store a count
* at each vertex instead (doesn't fix the slope problem).
*/
/*
* FIXME: Change this to only draw inside of polygons, and round
* points in a uniform direction to avoid overlapping drawing. As an
* option we could continue to support drawing the outline.
*/
if (new_y != old_y) {
if (inside) {
/*
* Just draw the vertical line when there is not a matching
* edge on the right side.
*/
if (context->temporary_write_controls.shading_character != '\0') {
shade_char_to_pixel(context, pixels, w, h,
WRITE_SHADING_REF_X,
old_x, old_x, old_y);
} else {
shade_pattern_to_pixel(context, WRITE_SHADING_REF_X,
old_x, old_x, old_y);
}
}
inside = 1;
} else {
if (inside) {
if (context->temporary_write_controls.shading_character != '\0') {
shade_char_to_pixel(context, pixels, w, h,
WRITE_SHADING_REF_X,
old_x, new_x, new_y);
} else {
shade_pattern_to_pixel(context, WRITE_SHADING_REF_X,
old_x, new_x, new_y);
}
}
if (new_x > old_x + 1) {
inside = !inside;
}
}
old_x = new_x;
old_y = new_y;
}
context->destination_graphic->dirty = 1;
}
static void
draw_patterned_line(RegisGraphicsContext *context, int x1, int y1,
int x2, int y2)
{
int x, y;
int dx, dy;
int dir, diff;
dx = abs(x1 - x2);
dy = abs(y1 - y2);
if (dx > dy) {
if (x1 > x2) {
int tmp;
EXCHANGE(x1, x2, tmp);
EXCHANGE(y1, y2, tmp);
}
if (y1 < y2)
dir = 1;
else if (y1 > y2)
dir = -1;
else
dir = 0;
diff = 0;
y = y1;
for (x = x1; x <= x2; x++) {
if (diff >= dx) {
diff -= dx;
y += dir;
}
diff += dy;
draw_or_save_patterned_pixel(context, x, y);
}
} else {
if (y1 > y2) {
int tmp;
EXCHANGE(y1, y2, tmp);
EXCHANGE(x1, x2, tmp);
}
if (x1 < x2)
dir = 1;
else if (x1 > x2)
dir = -1;
else
dir = 0;
diff = 0;
x = x1;
for (y = y1; y <= y2; y++) {
if (diff >= dy) {
diff -= dy;
x += dir;
}
diff += dx;
draw_or_save_patterned_pixel(context, x, y);
}
}
context->destination_graphic->dirty = 1;
}
typedef struct {
int dxx;
int dxy;
int dyx;
int dyy;
} quadmap_coords;
static void
draw_patterned_arc(RegisGraphicsContext *context,
int cx, int cy,
int ex, int ey,
int a_start, int a_length,
int *ex_final, int *ey_final)
{
const double third = hypot((double) (cx - ex), (double) (cy - ey));
const int radius = (int) third;
const int ra = radius;
const int rb = radius;
const quadmap_coords neg_quadmap[4] =
{
{-1, 0, 0, +1},
{0, -1, -1, 0},
{+1, 0, 0, -1},
{0, +1, +1, 0},
};
const quadmap_coords pos_quadmap[4] =
{
{-1, 0, 0, -1},
{0, -1, +1, 0},
{+1, 0, 0, +1},
{0, +1, -1, 0},
};
const quadmap_coords *quadmap;
int total_points;
int half_degree;
int points_start, points_stop;
int points;
unsigned iterations;
long rx, ry;
long dx, dy;
int x, y;
long e2;
long error;
TRACE(("orig a_length=%d a_start=%d\n", a_length, a_start));
if (a_length == 0)
return;
if (a_length > 0) {
quadmap = pos_quadmap;
} else {
quadmap = neg_quadmap;
if (a_start != 0)
a_start = 3600 - a_start;
a_length = abs(a_length);
}
TRACE(("positive a_length=%d a_start=%d\n", a_length, a_start));
rx = -ra;
ry = 0;
e2 = rb;
dx = (2 * rx + 1) * e2 * e2;
dy = rx * rx;
error = dx + dy;
total_points = 0;
do {
total_points += 4;
e2 = 2 * error;
if (e2 >= dx) {
rx++;
dx += 2 * rb * rb;
error += dx;
}
if (e2 <= dy) {
ry++;
dy += 2 * ra * ra;
error += dy;
}
}
while (rx <= 0);
/* FIXME: This is apparently not accurate enough because some arcs start or
* end a few pixels off. Maybe compare line slopes in the loop below
* instead?
*/
half_degree = total_points * 5;
points_start = (total_points * a_start - half_degree) / 3600;
points_stop = (total_points * a_start +
total_points * a_length + half_degree) / 3600;
TRACE(("drawing arc with %d points clockwise from %g degrees for %g degrees (from point %d to %d out of %d)\n",
total_points, a_start / 10.0, a_length / 10.0, points_start, points_stop,
total_points));
/* FIXME: The four pixels at the cardinal directions are double-drawn. */
points = 0;
for (iterations = 0U; iterations < 8U; iterations++) {
int q2 = iterations & 0x3;
rx = -ra;
ry = 0;
e2 = rb;
dx = (2 * rx + 1) * e2 * e2;
dy = rx * rx;
error = dx + dy;
do {
#ifdef DEBUG_ARC_POINTS
double rad = atan2(
(double) (quadmap[q2].dyx * rx +
quadmap[q2].dyy * ry),
(double) (quadmap[q2].dxx * rx +
quadmap[q2].dxy * ry));
double deg = (360.0 * rad / (2.0 * M_PI));
if (deg < 0.0)
deg += 360.0;
#endif
if (points >= points_start && points <= points_stop) {
x = (int) (cx +
quadmap[q2].dxx * rx +
quadmap[q2].dxy * ry);
y = (int) (cy +
quadmap[q2].dyx * rx +
quadmap[q2].dyy * ry);
#ifdef DEBUG_ARC_POINTS
TRACE(("drawing point %u at %d,%d (%.5g deg)\n",
points, x, y, deg));
#endif
draw_or_save_patterned_pixel(context, x, y);
if (ex_final)
*ex_final = x;
if (ey_final)
*ey_final = y;
} else {
#ifdef DEBUG_ARC_POINTS
x = (int) (cx + quadmap[q2].dxx * rx + quadmap[q2].dxy * ry);
y = (int) (cy + quadmap[q2].dyx * rx + quadmap[q2].dyy * ry);
TRACE(("skipping point %u at %d,%d which is outside of range (%.5g deg)\n",
points, x, y, deg));
#endif
}
points++;
e2 = 2 * error;
if (e2 >= dx) {
rx++;
dx += 2 * rb * rb;
error += dx;
}
if (e2 <= dy) {
ry++;
dy += 2 * ra * ra;
error += dy;
}
}
while (rx <= 0);
}
context->destination_graphic->dirty = 1;
}
/*
* The plot* functions are based on optimized rasterization primitves written by Zingl Alois.
* See http://members.chello.at/easyfilter/bresenham.html
*/
/*
* FIXME:
* This is a terrible temporary hack. The plot functions below can be adapted
* to work like the other rasterization functions but there's no point in doing
* that until we know we don't have to write something completely different.
*/
static RegisGraphicsContext *global_context;
static void
setPixel(int x, int y)
{
draw_or_save_patterned_pixel(global_context, x, y);
}
static void
plotLine(int x0, int y0, int x1, int y1)
{
int dx = abs(x1 - x0), sx = x0 < x1 ? 1 : -1;
int dy = -abs(y1 - y0), sy = y0 < y1 ? 1 : -1;
int err = dx + dy; /* error value e_xy */
for (;;) { /* loop */
int e2;
setPixel(x0, y0);
e2 = 2 * err;
if (e2 >= dy) { /* e_xy+e_x > 0 */
if (x0 == x1)
break;
err += dy;
x0 += sx;
}
if (e2 <= dx) { /* e_xy+e_y < 0 */
if (y0 == y1)
break;
err += dx;
y0 += sy;
}
}
}
static void
plotQuadBezierSeg(int x0, int y0, int x1, int y1, int x2, int y2)
{ /* plot a limited quadratic Bezier segment */
int sx = x2 - x1;
int sy = y2 - y1;
long xx = (x0 - x1); /* relative values for checks */
long yy = (y0 - y1);
double cur = (double) (xx * sy - yy * sx); /* curvature */
assert(xx * sx <= 0 && yy * sy <= 0); /* sign of gradient must not change */
if (sx * (long) sx + sy * (long) sy > xx * xx + yy * yy) { /* begin with longer part */
x2 = x0;
x0 = sx + x1;
y2 = y0;
y0 = sy + y1;
cur = -cur; /* swap P0 P2 */
}
if (cur != 0) { /* no straight line */
long xy;
double dx, dy, err;
xx += sx;
xx *= sx = x0 < x2 ? 1 : -1; /* x step direction */
yy += sy;
yy *= sy = y0 < y2 ? 1 : -1; /* y step direction */
xy = 2 * xx * yy;
xx *= xx;
yy *= yy; /* differences 2nd degree */
if (cur * sx * sy < 0) { /* negated curvature? */
xx = -xx;
yy = -yy;
xy = -xy;
cur = -cur;
}
/* differences 1st degree */
dx = ((4.0 * sy * cur * (x1 - x0)) + (double) xx) - (double) xy;
dy = ((4.0 * sx * cur * (y0 - y1)) + (double) yy) - (double) xy;
xx += xx;
yy += yy;
err = dx + dy + (double) xy; /* error 1st step */
do {
setPixel(x0, y0); /* plot curve */
if (x0 == x2 && y0 == y2)
return; /* last pixel -> curve finished */
y1 = (2 * err) < dx; /* save value for test of y step */
if ((2 * err) > dy) {
x0 += sx;
dx -= (double) xy;
dy += (double) yy;
err += dy;
} /* x step */
if (y1) {
y0 += sy;
dy -= (double) xy;
dx += (double) xx;
err += dx;
} /* y step */
} while (dy < 0 && dx > 0); /* gradient negates -> algorithm fails */
}
plotLine(x0, y0, x2, y2); /* plot remaining part to end */
}
#if 0
static void
plotQuadBezier(int x0, int y0, int x1, int y1, int x2, int y2)
{ /* plot any quadratic Bezier curve */
int x = x0 - x1;
int y = y0 - y1;
double t = x0 - 2 * x1 + x2;
double r;
if ((long) x * (x2 - x1) > 0) { /* horizontal cut at P4? */
if ((long) y * (y2 - y1) > 0) /* vertical cut at P6 too? */
if (fabs((y0 - 2 * y1 + y2) / t * x) > abs(y)) { /* which first? */
x0 = x2;
x2 = x + x1;
y0 = y2;
y2 = y + y1; /* swap points */
} /* now horizontal cut at P4 comes first */
t = (x0 - x1) / t;
r = (1 - t) * ((1 - t) * y0 + 2.0 * t * y1) + t * t * y2; /* By(t=P4) */
t = (x0 * x2 - x1 * x1) * t / (x0 - x1); /* gradient dP4/dx=0 */
x = ifloor(t + 0.5);
y = ifloor(r + 0.5);
r = (y1 - y0) * (t - x0) / (x1 - x0) + y0; /* intersect P3 | P0 P1 */
plotQuadBezierSeg(x0, y0, x, ifloor(r + 0.5), x, y);
r = (y1 - y2) * (t - x2) / (x1 - x2) + y2; /* intersect P4 | P1 P2 */
x0 = x1 = x;
y0 = y;
y1 = ifloor(r + 0.5); /* P0 = P4, P1 = P8 */
}
if ((long) (y0 - y1) * (y2 - y1) > 0) { /* vertical cut at P6? */
t = y0 - 2 * y1 + y2;
t = (y0 - y1) / t;
r = (1 - t) * ((1 - t) * x0 + 2.0 * t * x1) + t * t * x2; /* Bx(t=P6) */
t = (y0 * y2 - y1 * y1) * t / (y0 - y1); /* gradient dP6/dy=0 */
x = ifloor(r + 0.5);
y = ifloor(t + 0.5);
r = (x1 - x0) * (t - y0) / (y1 - y0) + x0; /* intersect P6 | P0 P1 */
plotQuadBezierSeg(x0, y0, ifloor(r + 0.5), y, x, y);
r = (x1 - x2) * (t - y2) / (y1 - y2) + x2; /* intersect P7 | P1 P2 */
x0 = x;
x1 = ifloor(r + 0.5);
y0 = y1 = y; /* P0 = P6, P1 = P7 */