refactor

1 files changed, 65 insertions, 0 deletions

diff --git a/drawing.ha b/drawing.ha
new file mode 100644
index 0000000..ff2aa71
--- /dev/null
+++ b/drawing.ha
@@ -0,0 +1,65 @@
+use sdl2;
+
+
+// 2d position, x and y
+type pos = (int, int);
+
+type drawing_state = struct {
+	// is the mouse button held down?
+	drawing: bool,
+	pos: pos,
+	picture: picture,
+};
+
+type picture = struct {
+	d: *[*]u32,
+	w: size,
+	h: size,
+};
+// Returns array index of the pixel at position pos.
+// Bounds check happens in here instead of using a slice type, so
+// that it's easier to remove later.
+fn pidx(pic: *picture, pos: pos) size = {
+	const (x,y) = pos;
+	const (xs,ys) = (x:size, y:size);
+	assert(0 <= x, "x position must not be less than 0");
+	assert(0 <= y, "y position must not be less than 0");
+	assert(xs < pic.w, "x position must be less than picture width");
+	assert(ys < pic.h, "y position must be less than picture height");
+
+	return xs + pic.w*ys;
+};
+fn pic_set(pic: *picture, pos: pos, val: u32) void = pic.d[pidx(pic,pos)] = val;
+fn picture_from_surface(surf: *sdl2::SDL_Surface) picture = picture {
+	w = surf.w: size,
+	h = surf.h: size,
+	d = (surf.pixels as *opaque: *[*]u32),
+};
+
+fn min(a: int, b: int) int = if (a<b) a else b;
+fn max(a: int, b: int) int = if (a<b) b else a;
+
+fn circle(dstate: *drawing_state, c: pos, r: int, color: u32) void = {
+	const (cx,cy) = c;
+	const ymin = max(0, cy-r);
+	const ymax = min(dstate.picture.h:int-1, cy+r);
+	const xmin = max(0, cx-r);
+	const xmax = min(dstate.picture.w:int-1, cx+r);
+
+	const r2 = r*r + r;
+
+	for (let y = ymin; y<=ymax; y+=1) {
+		const yd = y-cy;
+		for (let x = xmin; x<=xmax; x+=1) {
+			const xd = x-cx;
+			if (yd*yd + xd*xd <= r2) {
+				pic_set(&dstate.picture, (x,y), color);
+			};
+		};
+	};
+
+};
+
+fn do_drawing(dstate: *drawing_state) void = {
+	if (dstate.drawing) circle(dstate, dstate.pos, 20, 0xff0088);
+};