use libgrapheme to interpret utf8 encoded strings

src/ugui_cmd.c3

@@ -1,13 +1,15 @@
 module ugui;
 
+import std::ascii;
+
 // FIXME: is this really the best solution?
 // "rect" is the bounding box of the element, which includes the border and the padding (so not just the content)
 fn void! Ctx.push_rect(&ctx, Rect rect, Color color, bool do_border = false, bool do_padding = false, bool do_radius = false)
 {
-    // FIXME: this should be culled higher up, maybe
-    if (rect.w <= 0 || rect.h <= 0) {
-        return;
-    }
+	// FIXME: this should be culled higher up, maybe
+	if (rect.w <= 0 || rect.h <= 0) {
+		return;
+	}
 
 	Rect border = ctx.style.border;
 	Rect padding = ctx.style.padding;
@@ -48,3 +50,50 @@ fn void! Ctx.push_sprite(&ctx, Rect bounds, Rect texture)
 	};
 	ctx.cmd_queue.enqueue(&cmd)!;
 }
+
+fn void! Ctx.push_string(&ctx, Rect bounds, String text)
+{
+	if (text.len == 0) {
+		return;
+	}
+	
+	short baseline = (short)ctx.font.ascender;
+	short line_height = (short)ctx.font.ascender - (short)ctx.font.descender;
+	short line_gap = (short)ctx.font.linegap;
+	Point orig = {
+		.x = bounds.x,
+		.y = bounds.y,
+	};
+
+	short line_len;
+	Codepoint cp;
+	usz off, x;
+	while ((cp = str_to_codepoint(text[off..], &x)) != 0) {
+		off += x;
+		Glyph* gp;
+		if (!ascii::is_cntrl((char)cp)) {
+			gp = ctx.font.get_glyph(cp)!;
+			Rect gb = {
+    			.x = orig.x + line_len + gp.ox,
+    			.y = orig.y + gp.oy + baseline,
+    			.w = gp.w,
+    			.h = gp.h,
+			};
+			Rect gt = {
+    			.x = gp.u,
+    			.y = gp.v,
+    			.w = gp.w,
+    			.h = gp.h,
+			};
+			if (rect_collision(gb, bounds)) {
+				ctx.push_sprite(gb, gt)!;
+			}
+			line_len += gp.adv;
+		} else if (cp == '\n'){
+			orig.y += line_height + line_gap;
+			line_len = 0;
+		} else {
+			continue;
+		}
+	}
+}