Fix font fallback for lines with only non-visual/control characters.

Author: bruvzg

modules/text_server_adv/text_server_adv.cpp

@@ -4998,6 +4998,7 @@ bool TextServerAdvanced::_shaped_text_resize_object(const RID &p_shaped, const V
 
 		int sd_size = sd->glyphs.size();
 		int span_size = spans.size();
+		const char32_t *ch = sd->text.ptr();
 
 		for (int i = 0; i < sd_size; i++) {
 			Glyph gl = sd->glyphs[i];
@@ -5026,7 +5027,7 @@ bool TextServerAdvanced::_shaped_text_resize_object(const RID &p_shaped, const V
 					}
 					sd->upos = MAX(sd->upos, _font_get_underline_position(gl.font_rid, gl.font_size));
 					sd->uthk = MAX(sd->uthk, _font_get_underline_thickness(gl.font_rid, gl.font_size));
-				} else if (sd->preserve_invalid || (sd->preserve_control && is_control(gl.index))) {
+				} else if (sd->preserve_invalid || (sd->preserve_control && is_control(ch[gl.start - sd->start]))) {
 					// Glyph not found, replace with hex code box.
 					if (sd->orientation == ORIENTATION_HORIZONTAL) {
 						sd->ascent = MAX(sd->ascent, get_hex_code_box_size(gl.font_size, gl.index).y * 0.85);
@@ -5200,6 +5201,7 @@ bool TextServerAdvanced::_shape_substr(ShapedTextDataAdvanced *p_new_sd, const S
 
 		int sd_size = p_sd->glyphs.size();
 		const Glyph *sd_glyphs = p_sd->glyphs.ptr();
+		const char32_t *ch = p_sd->text.ptr();
 		for (int ov = 0; ov < bidi_ranges.size(); ov++) {
 			UErrorCode err = U_ZERO_ERROR;
 
@@ -5330,7 +5332,7 @@ bool TextServerAdvanced::_shape_substr(ShapedTextDataAdvanced *p_new_sd, const S
 									p_new_sd->ascent = MAX(p_new_sd->ascent, Math::round(_font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x * 0.5));
 									p_new_sd->descent = MAX(p_new_sd->descent, Math::round(_font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x * 0.5));
 								}
-							} else if (p_new_sd->preserve_invalid || (p_new_sd->preserve_control && is_control(gl.index))) {
+							} else if (p_new_sd->preserve_invalid || (p_new_sd->preserve_control && is_control(ch[gl.start - p_sd->start]))) {
 								// Glyph not found, replace with hex code box.
 								if (p_new_sd->orientation == ORIENTATION_HORIZONTAL) {
 									p_new_sd->ascent = MAX(p_new_sd->ascent, get_hex_code_box_size(gl.font_size, gl.index).y * 0.85);
@@ -6936,6 +6938,24 @@ void TextServerAdvanced::_shape_run(ShapedTextDataAdvanced *p_sd, int64_t p_star
 		p_sd->descent = MAX(p_sd->descent, _font_get_descent(f, fs) + _font_get_spacing(f, SPACING_BOTTOM));
 		p_sd->upos = MAX(p_sd->upos, _font_get_underline_position(f, fs));
 		p_sd->uthk = MAX(p_sd->uthk, _font_get_underline_thickness(f, fs));
+	} else if (p_start != p_end) {
+		if (p_fb_index >= p_fonts.size()) {
+			Glyph gl;
+			gl.start = p_start;
+			gl.end = p_end;
+			gl.span_index = p_span;
+			gl.font_rid = f;
+			gl.font_size = fs;
+			gl.flags = GRAPHEME_IS_VALID;
+			p_sd->glyphs.push_back(gl);
+
+			p_sd->ascent = MAX(p_sd->ascent, _font_get_ascent(f, fs) + _font_get_spacing(f, SPACING_TOP));
+			p_sd->descent = MAX(p_sd->descent, _font_get_descent(f, fs) + _font_get_spacing(f, SPACING_BOTTOM));
+			p_sd->upos = MAX(p_sd->upos, _font_get_underline_position(f, fs));
+			p_sd->uthk = MAX(p_sd->uthk, _font_get_underline_thickness(f, fs));
+		} else {
+			_shape_run(p_sd, p_start, p_end, p_script, p_direction, p_fonts, p_span, p_fb_index + 1, p_start, p_end, f);
+		}
 	}
 }
 

scene/gui/label.cpp

@@ -159,7 +159,7 @@ void Label::_shape() const {
 		for (const String &str : para_text) {
 			Paragraph para;
 			para.text_rid = TS->create_shaped_text();
-			para.text = str;
+			para.text = str + String::chr(0x200B);
 			para.start = start;
 			start += str.length() + ps.length();
 			paragraphs.push_back(para);