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Implement quadratic bezier curve
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Add quadratic bezier curve support by converting quadratic spline to
cubic spline.

The conversion follows the formula:
CP1 = P0 + 2/3 * (P1 - P0)
CP2 = P2 + 2/3 * (P1 - P2)

where:
- P0, P1, P2 are quadratic control points
- CP1, CP2 are the resulting cubic control points

Ref:
https://fontforge.org/docs/techref/bezier.html#converting-truetype-to-postscript
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@ndsl7109256
ndsl7109256 committed Nov 19, 2024
1 parent c7bbcc7 commit c5dd720
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Showing 3 changed files with 107 additions and 38 deletions.
116 changes: 78 additions & 38 deletions apps/spline.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,11 @@

#define _apps_spline_pixmap(spline) ((spline)->widget.window->pixmap)

#define NPT 4

typedef struct _apps_spline {
twin_widget_t widget;
twin_point_t points[NPT];
int npt;
twin_point_t *points;
int which;
twin_fixed_t line_width;
twin_cap_t cap_style;
Expand All @@ -32,28 +32,51 @@ static void _apps_spline_paint(apps_spline_t *spline)

path = twin_path_create();
twin_path_set_cap_style(path, spline->cap_style);
twin_path_move(path, spline->points[0].x, spline->points[0].y);
twin_path_curve(path, spline->points[1].x, spline->points[1].y,
spline->points[2].x, spline->points[2].y,
spline->points[3].x, spline->points[3].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xff404040, path,
spline->line_width);
twin_path_set_cap_style(path, TwinCapButt);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xffffff00, path,
twin_int_to_fixed(2));

twin_path_empty(path);
twin_path_move(path, spline->points[0].x, spline->points[0].y);
twin_path_draw(path, spline->points[1].x, spline->points[1].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xc08000c0, path,
twin_int_to_fixed(2));
twin_path_empty(path);
twin_path_move(path, spline->points[3].x, spline->points[3].y);
twin_path_draw(path, spline->points[2].x, spline->points[2].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xc08000c0, path,
twin_int_to_fixed(2));
twin_path_empty(path);
for (i = 0; i < NPT; i++) {
if (spline->npt == 4) {
twin_path_move(path, spline->points[0].x, spline->points[0].y);
twin_path_curve(path, spline->points[1].x, spline->points[1].y,
spline->points[2].x, spline->points[2].y,
spline->points[3].x, spline->points[3].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xff404040, path,
spline->line_width);
twin_path_set_cap_style(path, TwinCapButt);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xffffff00, path,
twin_int_to_fixed(2));

twin_path_empty(path);
twin_path_move(path, spline->points[0].x, spline->points[0].y);
twin_path_draw(path, spline->points[1].x, spline->points[1].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xc08000c0, path,
twin_int_to_fixed(2));
twin_path_empty(path);
twin_path_move(path, spline->points[3].x, spline->points[3].y);
twin_path_draw(path, spline->points[2].x, spline->points[2].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xc08000c0, path,
twin_int_to_fixed(2));
twin_path_empty(path);
} else if (spline->npt == 3) {
twin_path_move(path, spline->points[0].x, spline->points[0].y);
twin_path_quadratic_curve(path, spline->points[1].x,
spline->points[1].y, spline->points[2].x,
spline->points[2].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xff404040, path,
spline->line_width);
twin_path_set_cap_style(path, TwinCapButt);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xffffff00, path,
twin_int_to_fixed(2));
twin_path_empty(path);
twin_path_move(path, spline->points[0].x, spline->points[0].y);
twin_path_draw(path, spline->points[1].x, spline->points[1].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xc08000c0, path,
twin_int_to_fixed(2));
twin_path_empty(path);
twin_path_move(path, spline->points[1].x, spline->points[1].y);
twin_path_draw(path, spline->points[2].x, spline->points[2].y);
twin_paint_stroke(_apps_spline_pixmap(spline), 0xc08000c0, path,
twin_int_to_fixed(2));
twin_path_empty(path);
}
for (i = 0; i < spline->npt; i++) {
twin_path_empty(path);
twin_path_circle(path, spline->points[i].x, spline->points[i].y,
twin_int_to_fixed(10));
Expand Down Expand Up @@ -81,7 +104,7 @@ static int _apps_spline_hit(apps_spline_t *spline,
{
int i;

for (i = 0; i < NPT; i++)
for (i = 0; i < spline->npt; i++)
if (twin_fixed_abs(x - spline->points[i].x) < spline->line_width / 2 &&
twin_fixed_abs(y - spline->points[i].y) < spline->line_width / 2)
return i;
Expand Down Expand Up @@ -123,28 +146,40 @@ static twin_dispatch_result_t _apps_spline_dispatch(twin_widget_t *widget,

static void _apps_spline_init(apps_spline_t *spline,
twin_box_t *parent,
twin_dispatch_proc_t dispatch)
twin_dispatch_proc_t dispatch,
int npt)
{
static const twin_widget_layout_t preferred = {0, 0, 1, 1};
_twin_widget_init(&spline->widget, parent, 0, preferred, dispatch);
twin_widget_set(&spline->widget, 0xffffffff);
spline->line_width = twin_int_to_fixed(100);
spline->cap_style = TwinCapRound;
spline->points[0].x = twin_int_to_fixed(100);
spline->points[0].y = twin_int_to_fixed(100);
spline->points[1].x = twin_int_to_fixed(300);
spline->points[1].y = twin_int_to_fixed(300);
spline->points[2].x = twin_int_to_fixed(100);
spline->points[2].y = twin_int_to_fixed(300);
spline->points[3].x = twin_int_to_fixed(300);
spline->points[3].y = twin_int_to_fixed(100);
spline->points = calloc(npt, sizeof(twin_point_t));
spline->npt = npt;
if (npt == 4) {
spline->points[0].x = twin_int_to_fixed(100);
spline->points[0].y = twin_int_to_fixed(100);
spline->points[1].x = twin_int_to_fixed(300);
spline->points[1].y = twin_int_to_fixed(300);
spline->points[2].x = twin_int_to_fixed(100);
spline->points[2].y = twin_int_to_fixed(300);
spline->points[3].x = twin_int_to_fixed(300);
spline->points[3].y = twin_int_to_fixed(100);
} else if (npt == 3) {
spline->points[0].x = twin_int_to_fixed(100);
spline->points[0].y = twin_int_to_fixed(100);
spline->points[1].x = twin_int_to_fixed(200);
spline->points[1].y = twin_int_to_fixed(300);
spline->points[2].x = twin_int_to_fixed(300);
spline->points[2].y = twin_int_to_fixed(100);
}
}

static apps_spline_t *apps_spline_create(twin_box_t *parent)
static apps_spline_t *apps_spline_create(twin_box_t *parent, int npt)
{
apps_spline_t *spline = malloc(sizeof(apps_spline_t));

_apps_spline_init(spline, parent, _apps_spline_dispatch);
_apps_spline_init(spline, parent, _apps_spline_dispatch, npt);
return spline;
}

Expand All @@ -157,7 +192,12 @@ void apps_spline_start(twin_screen_t *screen,
{
twin_toplevel_t *toplevel = twin_toplevel_create(
screen, TWIN_ARGB32, TwinWindowApplication, x, y, w, h, name);
apps_spline_t *spline = apps_spline_create(&toplevel->box);
(void) spline;
apps_spline_t *spline_cubic = apps_spline_create(&toplevel->box, 4);
twin_toplevel_t *toplevel2 = twin_toplevel_create(
screen, TWIN_ARGB32, TwinWindowApplication, x + 20, y + 20, w, h, name);
apps_spline_t *spline_quad = apps_spline_create(&toplevel2->box, 3);
(void) spline_cubic;
(void) spline_quad;
twin_toplevel_show(toplevel);
twin_toplevel_show(toplevel2);
}
6 changes: 6 additions & 0 deletions include/twin.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1061,6 +1061,12 @@ void twin_path_curve(twin_path_t *path,
twin_fixed_t x3,
twin_fixed_t y3);

void twin_path_quadratic_curve(twin_path_t *path,
twin_fixed_t x1,
twin_fixed_t y1,
twin_fixed_t x2,
twin_fixed_t y2);

/*
* timeout.c
*/
Expand Down
23 changes: 23 additions & 0 deletions src/spline.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -164,3 +164,26 @@ void twin_path_curve(twin_path_t *path,
_twin_matrix_x(&path->state.matrix, x3, y3),
_twin_matrix_y(&path->state.matrix, x3, y3));
}

void twin_path_quadratic_curve(twin_path_t *path,
twin_fixed_t x1,
twin_fixed_t y1,
twin_fixed_t x2,
twin_fixed_t y2)
{
twin_spoint_t p0 = _twin_path_current_spoint(path);
/* Convert quadratic to cubic control point */
/* CP1 = P0 + 2/3 * (P1 - P0) */
twin_sfixed_t dx1 = twin_fixed_to_sfixed(x1) - p0.x;
twin_sfixed_t dy1 = twin_fixed_to_sfixed(y1) - p0.y;
twin_sfixed_t cx1 = p0.x + twin_sfixed_mul(dx1, twin_int_to_sfixed(2) / 3);
twin_sfixed_t cy1 = p0.y + twin_sfixed_mul(dy1, twin_int_to_sfixed(2) / 3);
/* CP2 = P2 + 2/3 * (P1 - P2) */
twin_sfixed_t x2s = twin_fixed_to_sfixed(x2);
twin_sfixed_t y2s = twin_fixed_to_sfixed(y2);
twin_sfixed_t dx2 = twin_fixed_to_sfixed(x1) - x2s;
twin_sfixed_t dy2 = twin_fixed_to_sfixed(y1) - y2s;
twin_sfixed_t cx2 = x2s + twin_sfixed_mul(dx2, twin_int_to_sfixed(2) / 3);
twin_sfixed_t cy2 = y2s + twin_sfixed_mul(dy2, twin_int_to_sfixed(2) / 3);
_twin_path_scurve(path, cx1, cy1, cx2, cy2, x2s, y2s);
}

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