From ab22733fe471821f1f9a46b1f20a2596dda28f60 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Sun, 17 Oct 2021 17:56:27 -0600
Subject: [PATCH] canvas: continuously variable Canvas::Text height if packed
 inside a layout-sensitive container

---
 libs/canvas/canvas/text.h | 10 ++++++
 libs/canvas/text.cc       | 74 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)

diff --git a/libs/canvas/canvas/text.h b/libs/canvas/canvas/text.h
index fe7cf2ab86..6ddc865d19 100644
--- a/libs/canvas/canvas/text.h
+++ b/libs/canvas/canvas/text.h
@@ -21,6 +21,8 @@
 #ifndef __ardour_canvas_text_h__
 #define __ardour_canvas_text_h__
 
+#include <map>
+
 #include <pangomm/fontdescription.h>
 #include <pangomm/layout.h>
 
@@ -38,6 +40,7 @@ public:
 
 	void render (Rect const &, Cairo::RefPtr<Cairo::Context>) const;
 	void compute_bounding_box () const;
+	void _size_allocate (Rect const&);
 
 	Gtkmm2ext::Color color () const { return _color; }
 	void set_color (Gtkmm2ext::Color);
@@ -56,6 +59,10 @@ public:
 
 	std::string text() const { return _text; }
 	double text_width() const;
+	double text_height() const;
+
+	static int font_size_for_height (Distance height, Glib::RefPtr<Pango::Context> const &);
+	typedef std::map<Distance,int> FontSizeMap;
 
 private:
 	std::string             _text;
@@ -69,8 +76,11 @@ private:
 	mutable bool            _need_redraw;
 	mutable double          _width_correction;
 	double                  _clamped_width;
+	std::string             _font_family;
 
 	void _redraw () const;
+
+	static FontSizeMap font_size_map;
 };
 
 }
diff --git a/libs/canvas/text.cc b/libs/canvas/text.cc
index 592f3e609f..6ae9daa128 100644
--- a/libs/canvas/text.cc
+++ b/libs/canvas/text.cc
@@ -24,6 +24,8 @@
 #include <gtkmm/window.h>
 #include <gtkmm/label.h>
 
+#include "pbd/i18n.h"
+
 #include "canvas/text.h"
 #include "canvas/canvas.h"
 #include "gtkmm2ext/colors.h"
@@ -31,6 +33,7 @@
 using namespace std;
 using namespace ArdourCanvas;
 
+Text::FontSizeMap Text::font_size_map;
 
 Text::Text (Canvas* c)
 	: Item (c)
@@ -326,3 +329,74 @@ Text::text_width() const
     return _width;
 }
 
+double
+Text::text_height() const
+{
+    if (_need_redraw) {
+        redraw ();
+    }
+
+    return _height;
+}
+
+void
+Text::_size_allocate (Rect const & r)
+{
+	Item::_size_allocate (r);
+
+	if (!layout_sensitive()) {
+		/* not doing this */
+		return;
+	}
+
+	int font_size = font_size_for_height (r.height(), _canvas->get_pango_context());
+
+	if (font_size) {
+		char font_name[32];
+		std::string family = "Sans"; // UIConfiguration::instance().get_ui_font_family();
+		snprintf (font_name, sizeof (font_name), "%s %d", family.c_str(), font_size);
+		Pango::FontDescription pfd (font_name);
+		set_font_description (pfd);
+	}
+}
+
+int
+Text::font_size_for_height (Distance height, Glib::RefPtr<Pango::Context> const & ctxt)
+{
+	FontSizeMap::iterator fsm = font_size_map.find (height);
+
+	if (fsm != font_size_map.end()) {
+		return fsm->second;
+	}
+
+	std::string family = "Sans"; // UIConfiguration::instance().get_ui_font_family();
+	Glib::RefPtr<Pango::Layout> l (Pango::Layout::create (ctxt));
+	int font_size = 0;
+	char font_name[32];
+
+	/* Translators: Xg is a nonsense string that should include the
+	   highest glyph and a glyph with the lowest descender
+	*/
+
+	l->set_text (_("Xg"));
+
+	for (uint32_t pt = 5; pt < 24; ++pt) {
+
+		snprintf (font_name, sizeof (font_name), "%s %d", family.c_str(), pt);
+		Pango::FontDescription pfd (font_name);
+		l->set_font_description (pfd);
+
+		int w, h;
+		l->get_pixel_size (w, h);
+		if (h > height) {
+			font_size = pt - 1;
+			break;
+		}
+	}
+
+	if (font_size) {
+		font_size_map[height] = font_size;
+	}
+
+	return font_size;
+}