scissor command

src/ugui_font.c3

@@ -1,9 +1,12 @@
 module ugui;
 
 import schrift;
+import grapheme;
 import std::collections::map;
 import std::core::mem;
 import std::io;
+import std::ascii;
+
 
 // unicode code point, different type for a different hash
 def Codepoint = uint;
@@ -161,4 +164,50 @@ fn void Font.free(&font)
 fn void! Ctx.load_font(&ctx, String name, String path, uint height, float scale = 1.0)
 {
 	return ctx.font.load(name, path, height, scale);
+}
+
+<*
+@require off != null
+*>
+fn Codepoint str_to_codepoint(char[] str, usz* off)
+{
+	Codepoint cp;
+	isz b = grapheme::decode_utf8(str, str.len, &cp);
+	if (b == 0 || b > str.len) {
+		return 0;
+	}
+	*off = b;
+	return cp;
+}
+
+fn Rect! Ctx.get_text_bounds(&ctx, String text)
+{
+	Rect text_bounds;
+	short line_height = (short)ctx.font.ascender - (short)ctx.font.descender;
+	short line_gap = (short)ctx.font.linegap;
+	text_bounds.h = line_height;
+	Glyph* gp;
+
+	// TODO: account for unicode codepoints
+	short line_len;
+	Codepoint cp;
+	usz off, x;
+	while ((cp = str_to_codepoint(text[off..], &x)) != 0) {
+		off += x;
+		bool n;
+		if (!ascii::is_cntrl((char)cp)) {
+			gp = ctx.font.get_glyph(cp)!;
+			line_len += gp.adv;
+		} else if (cp == '\n'){
+			text_bounds.h += line_height + line_gap;
+			line_len = 0;
+		} else {
+			continue;
+		}
+		if (line_len > text_bounds.w) {
+			text_bounds.w = line_len;
+		}
+	}
+
+	return text_bounds;
 }