vxKernel/src/display/draw/dcircle.c

#include <vhex/display/draw/circle.h>
#include <vhex/display/draw/line.h>
#include <vhex/display.h>

//---
// Kernel-level API
//---

/* dcircle_render() : real drawing algorithm */
void dcircle_filled_render(
	dsurface_t *surface,
	int x, int y,
	int radius,
	int color
) {
	int px;
	int py;
	int d;

	px = 0;
	py = radius;
	d = 1 - radius;

	dhline_render(surface, y, x - py, x + py, color);
	while(py > px)
	{
		if(d < 0) {
			d += (2 * px) + 3;
		} else {
			d += (2 * (px - py)) + 5;
			py--;
			dhline_render(surface, y + py + 1, x - px, x + px, color);
			dhline_render(surface, y - py - 1, x - px, x + px, color);
		}
		px++;
		if(py >= px) {
			dhline_render(surface, y + px, x - py, x + py, color);
			dhline_render(surface, y - px, x - py, x + py, color);
		}
	}
}

//---
// Dstack-level API
//---

/* dcircle_filled_dstack() : dstack wrapper primitive */
void dcircle_filled_dstack(dsurface_t *surface, uint32_t *args)
{
	dcircle_filled_render(
		surface,
		(int)args[0],
		(int)args[1],
		(size_t)args[2],
		(int)args[3]
	);
}

//---
// User-level API
//---

/* dcircle_filled() : draw a filled circle */
void dcircle_filled(int x, int y, size_t radius, int mode, int color)
{
	if (color == C_NONE) return;

	int offset = radius & 1;

	if (mode & DCIRCLE_LEFT)   x += (radius >> 1) + offset;
	if (mode & DCIRCLE_RIGHT)  x -= (radius >> 1) + offset;
	if (mode & DCIRCLE_TOP)    y += (radius >> 1) + offset;
	if (mode & DCIRCLE_BOTTOM) y -= (radius >> 1) + offset;

	dstack_add_action(
		DSTACK_CALL(&dcircle_filled_dstack, x, y, radius, color),
		NULL,
		NULL
	);
}