[TextServer] Improvements for line breaking, "Fill" alignment, overrun, and interaction between these modes.

Fix "Fill" alignment processing wrong side of the text if overrun trim was applied.
Improve "Fill" alignment to avoid adding excessive subsequent spaces or elongations.
Add font detection to the overrun, to correctly add ellipsis (was using last glyph font, which doesn't necessary have dot character).
Improve line breaking to avoid adding excessive subsequent soft break points for languages without word separator.
Port missing overrun/justification code to the Fallback text server.
Fix inferred text direction detection by controls.
Add tests for "Fill" alignment and line breaking glyph flags.

2 files changed, 94 insertions, 24 deletions

diff --git a/modules/text_server_fb/text_server_fb.cpp b/modules/text_server_fb/text_server_fb.cpp
index f28d174c5c..c7a7c4aa70 100644
--- a/modules/text_server_fb/text_server_fb.cpp
+++ b/modules/text_server_fb/text_server_fb.cpp
@@ -2128,6 +2128,10 @@ TextServer::Direction TextServerFallback::shaped_text_get_direction(RID p_shaped
 	return TextServer::DIRECTION_LTR;
 }
 
+TextServer::Direction TextServerFallback::shaped_text_get_inferred_direction(RID p_shaped) const {
+	return TextServer::DIRECTION_LTR;
+}
+
 void TextServerFallback::shaped_text_set_custom_punctuation(RID p_shaped, const String &p_punct) {
 	_THREAD_SAFE_METHOD_
 	ShapedTextData *sd = shaped_owner.get_or_null(p_shaped);
@@ -2631,17 +2635,38 @@ float TextServerFallback::shaped_text_fit_to_width(RID p_shaped, float p_width,
 		}
 	}
 
+	float justification_width;
+	if ((p_jst_flags & JUSTIFICATION_CONSTRAIN_ELLIPSIS) == JUSTIFICATION_CONSTRAIN_ELLIPSIS) {
+		if (sd->overrun_trim_data.trim_pos >= 0) {
+			end_pos = sd->overrun_trim_data.trim_pos;
+			justification_width = sd->width_trimmed;
+		} else {
+			return sd->width;
+		}
+	} else {
+		justification_width = sd->width;
+	}
+
 	if ((p_jst_flags & JUSTIFICATION_TRIM_EDGE_SPACES) == JUSTIFICATION_TRIM_EDGE_SPACES) {
+		// Trim spaces.
 		while ((start_pos < end_pos) && ((sd->glyphs[start_pos].flags & GRAPHEME_IS_SPACE) == GRAPHEME_IS_SPACE || (sd->glyphs[start_pos].flags & GRAPHEME_IS_BREAK_HARD) == GRAPHEME_IS_BREAK_HARD || (sd->glyphs[start_pos].flags & GRAPHEME_IS_BREAK_SOFT) == GRAPHEME_IS_BREAK_SOFT)) {
-			sd->width -= sd->glyphs[start_pos].advance * sd->glyphs[start_pos].repeat;
+			justification_width -= sd->glyphs[start_pos].advance * sd->glyphs[start_pos].repeat;
 			sd->glyphs.write[start_pos].advance = 0;
 			start_pos += sd->glyphs[start_pos].count;
 		}
 		while ((start_pos < end_pos) && ((sd->glyphs[end_pos].flags & GRAPHEME_IS_SPACE) == GRAPHEME_IS_SPACE || (sd->glyphs[end_pos].flags & GRAPHEME_IS_BREAK_HARD) == GRAPHEME_IS_BREAK_HARD || (sd->glyphs[end_pos].flags & GRAPHEME_IS_BREAK_SOFT) == GRAPHEME_IS_BREAK_SOFT)) {
-			sd->width -= sd->glyphs[end_pos].advance * sd->glyphs[end_pos].repeat;
+			justification_width -= sd->glyphs[end_pos].advance * sd->glyphs[end_pos].repeat;
 			sd->glyphs.write[end_pos].advance = 0;
 			end_pos -= sd->glyphs[end_pos].count;
 		}
+	} else {
+		// Skip breaks, but do not reset size.
+		while ((start_pos < end_pos) && ((sd->glyphs[start_pos].flags & GRAPHEME_IS_BREAK_HARD) == GRAPHEME_IS_BREAK_HARD)) {
+			start_pos += sd->glyphs[start_pos].count;
+		}
+		while ((start_pos < end_pos) && ((sd->glyphs[end_pos].flags & GRAPHEME_IS_BREAK_HARD) == GRAPHEME_IS_BREAK_HARD)) {
+			end_pos -= sd->glyphs[end_pos].count;
+		}
 	}
 
 	int space_count = 0;
@@ -2655,20 +2680,28 @@ float TextServerFallback::shaped_text_fit_to_width(RID p_shaped, float p_width,
 	}
 
 	if ((space_count > 0) && ((p_jst_flags & JUSTIFICATION_WORD_BOUND) == JUSTIFICATION_WORD_BOUND)) {
-		float delta_width_per_space = (p_width - sd->width) / space_count;
+		float delta_width_per_space = (p_width - justification_width) / space_count;
 		for (int i = start_pos; i <= end_pos; i++) {
 			Glyph &gl = sd->glyphs.write[i];
 			if (gl.count > 0) {
 				if ((gl.flags & GRAPHEME_IS_SPACE) == GRAPHEME_IS_SPACE) {
 					float old_adv = gl.advance;
 					gl.advance = MAX(gl.advance + delta_width_per_space, Math::round(0.1 * gl.font_size));
-					sd->width += (gl.advance - old_adv);
+					justification_width += (gl.advance - old_adv);
 				}
 			}
 		}
 	}
 
-	return sd->width;
+	if (Math::floor(p_width) < Math::floor(justification_width)) {
+		sd->fit_width_minimum_reached = true;
+	}
+
+	if ((p_jst_flags & JUSTIFICATION_CONSTRAIN_ELLIPSIS) != JUSTIFICATION_CONSTRAIN_ELLIPSIS) {
+		sd->width = justification_width;
+	}
+
+	return justification_width;
 }
 
 float TextServerFallback::shaped_text_tab_align(RID p_shaped, const PackedFloat32Array &p_tab_stops) {
@@ -2769,6 +2802,7 @@ bool TextServerFallback::shaped_text_update_breaks(RID p_shaped) {
 				sd_glyphs[i].flags |= GRAPHEME_IS_BREAK_SOFT;
 			}
 			if (is_linebreak(c)) {
+				sd_glyphs[i].flags |= GRAPHEME_IS_SPACE;
 				sd_glyphs[i].flags |= GRAPHEME_IS_BREAK_HARD;
 			}
 			if (c == 0x0009 || c == 0x000b) {
@@ -2827,17 +2861,50 @@ void TextServerFallback::shaped_text_overrun_trim_to_width(RID p_shaped_line, fl
 		return;
 	}
 
+	Vector<ShapedTextData::Span> &spans = sd->spans;
+	if (sd->parent != RID()) {
+		ShapedTextData *parent_sd = shaped_owner.get_or_null(sd->parent);
+		ERR_FAIL_COND(!parent_sd->valid);
+		spans = parent_sd->spans;
+	}
+
+	if (spans.size() == 0) {
+		return;
+	}
+
 	int sd_size = sd->glyphs.size();
-	RID last_gl_font_rid = sd_glyphs[sd_size - 1].font_rid;
 	int last_gl_font_size = sd_glyphs[sd_size - 1].font_size;
-	int32_t dot_gl_idx = font_get_glyph_index(last_gl_font_rid, '.', 0);
-	Vector2 dot_adv = font_get_glyph_advance(last_gl_font_rid, last_gl_font_size, dot_gl_idx);
-	int32_t whitespace_gl_idx = font_get_glyph_index(last_gl_font_rid, ' ', 0);
-	Vector2 whitespace_adv = font_get_glyph_advance(last_gl_font_rid, last_gl_font_size, whitespace_gl_idx);
+
+	// Find usable fonts, if fonts from the last glyph do not have required chars.
+	RID dot_gl_font_rid = sd_glyphs[sd_size - 1].font_rid;
+	if (!font_has_char(dot_gl_font_rid, '.')) {
+		const Vector<RID> &fonts = spans[spans.size() - 1].fonts;
+		for (const RID &font : fonts) {
+			if (font_has_char(font, '.')) {
+				dot_gl_font_rid = font;
+				break;
+			}
+		}
+	}
+	RID whitespace_gl_font_rid = sd_glyphs[sd_size - 1].font_rid;
+	if (!font_has_char(whitespace_gl_font_rid, '.')) {
+		const Vector<RID> &fonts = spans[spans.size() - 1].fonts;
+		for (const RID &font : fonts) {
+			if (font_has_char(font, ' ')) {
+				whitespace_gl_font_rid = font;
+				break;
+			}
+		}
+	}
+
+	int32_t dot_gl_idx = dot_gl_font_rid.is_valid() ? font_get_glyph_index(dot_gl_font_rid, last_gl_font_size, '.') : -10;
+	Vector2 dot_adv = dot_gl_font_rid.is_valid() ? font_get_glyph_advance(dot_gl_font_rid, last_gl_font_size, dot_gl_idx) : Vector2();
+	int32_t whitespace_gl_idx = whitespace_gl_font_rid.is_valid() ? font_get_glyph_index(whitespace_gl_font_rid, last_gl_font_size, ' ') : -10;
+	Vector2 whitespace_adv = whitespace_gl_font_rid.is_valid() ? font_get_glyph_advance(whitespace_gl_font_rid, last_gl_font_size, whitespace_gl_idx) : Vector2();
 
 	int ellipsis_width = 0;
-	if (add_ellipsis) {
-		ellipsis_width = 3 * dot_adv.x + font_get_spacing(last_gl_font_rid, last_gl_font_size, TextServer::SPACING_GLYPH) + (cut_per_word ? whitespace_adv.x : 0);
+	if (add_ellipsis && whitespace_gl_font_rid.is_valid()) {
+		ellipsis_width = 3 * dot_adv.x + font_get_spacing(whitespace_gl_font_rid, last_gl_font_size, SPACING_GLYPH) + (cut_per_word ? whitespace_adv.x : 0);
 	}
 
 	int ell_min_characters = 6;
@@ -2891,23 +2958,25 @@ void TextServerFallback::shaped_text_overrun_trim_to_width(RID p_shaped_line, fl
 				gl.count = 1;
 				gl.advance = whitespace_adv.x;
 				gl.index = whitespace_gl_idx;
-				gl.font_rid = last_gl_font_rid;
+				gl.font_rid = whitespace_gl_font_rid;
 				gl.font_size = last_gl_font_size;
 				gl.flags = GRAPHEME_IS_SPACE | GRAPHEME_IS_BREAK_SOFT | GRAPHEME_IS_VIRTUAL;
 
 				sd->overrun_trim_data.ellipsis_glyph_buf.append(gl);
 			}
 			// Add ellipsis dots.
-			Glyph gl;
-			gl.count = 1;
-			gl.repeat = 3;
-			gl.advance = dot_adv.x;
-			gl.index = dot_gl_idx;
-			gl.font_rid = last_gl_font_rid;
-			gl.font_size = last_gl_font_size;
-			gl.flags = GRAPHEME_IS_PUNCTUATION | GRAPHEME_IS_VIRTUAL;
+			if (dot_gl_idx != 0) {
+				Glyph gl;
+				gl.count = 1;
+				gl.repeat = 3;
+				gl.advance = dot_adv.x;
+				gl.index = dot_gl_idx;
+				gl.font_rid = dot_gl_font_rid;
+				gl.font_size = last_gl_font_size;
+				gl.flags = GRAPHEME_IS_PUNCTUATION | GRAPHEME_IS_VIRTUAL;
 
-			sd->overrun_trim_data.ellipsis_glyph_buf.append(gl);
+				sd->overrun_trim_data.ellipsis_glyph_buf.append(gl);
+			}
 		}
 
 		sd->text_trimmed = true;
@@ -3023,13 +3092,13 @@ bool TextServerFallback::shaped_text_shape(RID p_shaped) {
 				if (gl.font_rid.is_valid()) {
 					if (sd->text[j - sd->start] != 0 && !is_linebreak(sd->text[j - sd->start])) {
 						if (sd->orientation == ORIENTATION_HORIZONTAL) {
-							gl.advance = font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x;
+							gl.advance = Math::round(font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x);
 							gl.x_off = 0;
 							gl.y_off = 0;
 							sd->ascent = MAX(sd->ascent, font_get_ascent(gl.font_rid, gl.font_size));
 							sd->descent = MAX(sd->descent, font_get_descent(gl.font_rid, gl.font_size));
 						} else {
-							gl.advance = font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).y;
+							gl.advance = Math::round(font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).y);
 							gl.x_off = -Math::round(font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x * 0.5);
 							gl.y_off = font_get_ascent(gl.font_rid, gl.font_size);
 							sd->ascent = MAX(sd->ascent, Math::round(font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x * 0.5));
diff --git a/modules/text_server_fb/text_server_fb.h b/modules/text_server_fb/text_server_fb.h
index 9d1be50b04..e8619e0825 100644
--- a/modules/text_server_fb/text_server_fb.h
+++ b/modules/text_server_fb/text_server_fb.h
@@ -375,6 +375,7 @@ public:
 
 	virtual void shaped_text_set_direction(RID p_shaped, Direction p_direction = DIRECTION_AUTO) override;
 	virtual Direction shaped_text_get_direction(RID p_shaped) const override;
+	virtual Direction shaped_text_get_inferred_direction(RID p_shaped) const override;
 
 	virtual void shaped_text_set_bidi_override(RID p_shaped, const Array &p_override) override;