From 06d46a19aef83cbe0f960f0dc73e7bdbd77f1166 Mon Sep 17 00:00:00 2001
From: Ivan Mahonin <bh@icystar.com>
Date: Mar 05 2020 12:34:50 +0000
Subject: freetype: floating alignment


---

diff --git a/c++/freetype/src/freetypeview.cpp b/c++/freetype/src/freetypeview.cpp
index 3717311..a21067b 100644
--- a/c++/freetype/src/freetypeview.cpp
+++ b/c++/freetype/src/freetypeview.cpp
@@ -28,8 +28,7 @@ FreeTypeView::FreeTypeView():
 	params.italic = false;
 	params.size = 12;
 
-	params.hor_spacing = 2;
-	params.vert_spacing = 20;
+	params.spacing = Vector2(3, 2);
 	
 	params.hinting = false;
 	params.antialiasing = true;
@@ -47,9 +46,12 @@ FreeTypeView::FreeTypeView():
 		"sunt in culpa qui officia deserunt mollit anim id est laborum.";
 	//params.text = "1\n2\n3\n";
 	
-	params.alignment = 1;
+	params.alignment = -1;
 	params.justify = true;
 	params.wrap_width = 600;
+	params.alignment_by_origin = true;
+	
+	params.origin = Vector2(0.25, 0.8);
 	
 	Glib::signal_timeout().connect(
 		sigc::mem_fun(*this, &FreeTypeView::on_timeout),
@@ -83,20 +85,26 @@ FreeTypeView::update_surface() {
 	if (width <= 0 || height <= 0)
 		return;
 	
-	const Real hor_spacing = params.hor_spacing > real_precision ? params.hor_spacing : 1;
+	const Vector2 spacing(
+		params.spacing.x > real_precision ? params.spacing.x : 1,
+		params.spacing.y > real_precision ? params.spacing.y : 1 );
 
+	const Vector2 origin(
+		clamp(params.origin.x, 0, 1),
+		clamp(params.origin.y, 0, 1) );
+	
 	Matrix matrix = params.matrix;
 	Matrix2 glyph_matrix(
 		matrix.row_x().vec2(),
 		matrix.row_y().vec2() );
-	matrix.row_x() *= hor_spacing;
+	matrix *= Matrix().scaling(spacing);
 
 	if (fabs(glyph_matrix.det()) <= real_precision_sqr)
 		return;
 
 	
 	const Real size = params.size;
-	const Real wrap_width = params.wrap_width/hor_spacing;
+	const Real wrap_width = params.wrap_width;
 	
 	// init
 	PangoFontMap *font_map = lab_pango_font_map_new(params.hinting, params.antialiasing);
@@ -120,24 +128,17 @@ FreeTypeView::update_surface() {
 		params.alignment < 0 ? PANGO_ALIGN_LEFT :
 		params.alignment > 0 ? PANGO_ALIGN_RIGHT : PANGO_ALIGN_CENTER );
 	pango_layout_set_justify(layout, params.justify);
-	if (params.vert_spacing > real_precision)
-		pango_layout_set_spacing(layout, (int)round(params.vert_spacing*PANGO_SCALE));
 	pango_layout_set_text(layout, params.text.c_str(), (int)params.text.size());
 	
 	// move origin
 	PangoRectangle rect;
 	pango_layout_get_extents(layout, nullptr, &rect);
-	const IntVector2 offset_to_origin_int(
-		params.origin.x < 0 ? 0 : 
-		params.origin.x > 0 ? (rect.x + rect.width) : (rect.x + rect.width)/2,
-		params.origin.y < 0 ? 0 : 
-		params.origin.y > 0 ? (rect.y + rect.height) : (rect.y + rect.height)/2 );
 	const Vector2 offset_to_origin(
-		offset_to_origin_int.x/Real(PANGO_SCALE),
-		offset_to_origin_int.y/Real(PANGO_SCALE) );
+		(rect.x + rect.width)/Real(PANGO_SCALE) * origin.x,
+		(rect.y + rect.height)/Real(PANGO_SCALE) * origin.y );
 	matrix *= Matrix().translation(-offset_to_origin);
 	
-	// reneder
+	// create renderer
 	DataSurface surface(width, height);
 	LabPangoRendererParams rp;
 	rp.surface      = &surface;
@@ -147,7 +148,22 @@ FreeTypeView::update_surface() {
 	rp.hinting      = params.hinting;
 	rp.antialiasing = params.antialiasing;
 	PangoRenderer *renderer = lab_pango_renderer_new(&rp);
-	pango_renderer_draw_layout(renderer, layout, 0, 0);
+	
+	// render line by line
+	pango_renderer_activate(renderer);
+	PangoLayoutIter *iter = pango_layout_get_iter(layout);
+	do {
+		PangoRectangle line_rect;
+		pango_layout_iter_get_line_extents(iter, nullptr, &line_rect);
+		PangoLayoutLine *line = pango_layout_iter_get_line_readonly(iter);
+		int baseline = pango_layout_iter_get_baseline(iter);
+		int x = params.alignment_by_origin
+			  ? (int)round((rect.x + rect.width - line_rect.width)*origin.x)
+			  : line_rect.x;
+		pango_renderer_draw_layout_line(renderer, line, x, baseline);
+	} while(pango_layout_iter_next_line(iter));
+	pango_layout_iter_free(iter);
+	pango_renderer_deactivate(renderer);
 	
 	// free pango
 	g_object_unref(renderer);
diff --git a/c++/freetype/src/freetypeview.h b/c++/freetype/src/freetypeview.h
index bdc2c60..9caac6e 100644
--- a/c++/freetype/src/freetypeview.h
+++ b/c++/freetype/src/freetypeview.h
@@ -18,11 +18,11 @@ public:
 		int alignment;
 		bool justify;
 		Real wrap_width;
+		bool alignment_by_origin;
 		
-		Real hor_spacing;
-		Real vert_spacing;
+		Vector2 spacing;
 		
-		IntVector2 origin;
+		Vector2 origin;
 		Matrix matrix;
 		Color color;
 
@@ -37,8 +37,7 @@ public:
 			alignment(),
 			justify(),
 			wrap_width(),
-			hor_spacing(),
-			vert_spacing()
+			alignment_by_origin()
 		{ }
 	};