Factor out log from Patchage class

Towards saner dependencies.

14 files changed, 271 insertions, 126 deletions

diff --git a/src/AlsaDriver.cpp b/src/AlsaDriver.cpp
index fc8fd34..a78c6ee 100644
--- a/src/AlsaDriver.cpp
+++ b/src/AlsaDriver.cpp
@@ -30,8 +30,9 @@ PATCHAGE_RESTORE_WARNINGS
 #include <string>
 #include <utility>
 
-AlsaDriver::AlsaDriver(Patchage* app)
+AlsaDriver::AlsaDriver(Patchage* app, ILog& log)
     : _app(app)
+    , _log(log)
     , _seq(nullptr)
     , _refresh_thread{}
 {}
@@ -47,10 +48,10 @@ AlsaDriver::attach(bool /*launch_daemon*/)
 {
 	int ret = snd_seq_open(&_seq, "default", SND_SEQ_OPEN_DUPLEX, 0);
 	if (ret) {
-		_app->error_msg("Alsa: Unable to attach.");
+		_log.error_msg("Alsa: Unable to attach.");
 		_seq = nullptr;
 	} else {
-		_app->info_msg("Alsa: Attached.");
+		_log.info_msg("Alsa: Attached.");
 
 		snd_seq_set_client_name(_seq, "Patchage");
 
@@ -61,7 +62,7 @@ AlsaDriver::attach(bool /*launch_daemon*/)
 		ret = pthread_create(
 		    &_refresh_thread, &attr, &AlsaDriver::refresh_main, this);
 		if (ret) {
-			_app->error_msg("Alsa: Failed to start refresh thread.");
+			_log.error_msg("Alsa: Failed to start refresh thread.");
 		}
 
 		signal_attached.emit();
@@ -77,7 +78,7 @@ AlsaDriver::detach()
 		snd_seq_close(_seq);
 		_seq = nullptr;
 		signal_detached.emit();
-		_app->info_msg("Alsa: Detached.");
+		_log.info_msg("Alsa: Detached.");
 	}
 }
 
@@ -395,7 +396,7 @@ AlsaDriver::connect(PatchagePort* src_port, PatchagePort* dst_port)
 	PortAddrs::const_iterator d = _port_addrs.find(dst_port);
 
 	if (s == _port_addrs.end() || d == _port_addrs.end()) {
-		_app->error_msg("Alsa: Attempt to connect port with no address.");
+		_log.error_msg("Alsa: Attempt to connect port with no address.");
 		return false;
 	}
 
@@ -404,7 +405,7 @@ AlsaDriver::connect(PatchagePort* src_port, PatchagePort* dst_port)
 
 	if (src.id.alsa_addr.client == dst.id.alsa_addr.client &&
 	    src.id.alsa_addr.port == dst.id.alsa_addr.port) {
-		_app->warning_msg("Alsa: Refusing to connect port to itself.");
+		_log.warning_msg("Alsa: Refusing to connect port to itself.");
 		return false;
 	}
 
@@ -420,23 +421,23 @@ AlsaDriver::connect(PatchagePort* src_port, PatchagePort* dst_port)
 
 	// Already connected (shouldn't happen)
 	if (!snd_seq_get_port_subscription(_seq, subs)) {
-		_app->error_msg("Alsa: Attempt to double subscribe ports.");
+		_log.error_msg("Alsa: Attempt to double subscribe ports.");
 		result = false;
 	}
 
 	int ret = snd_seq_subscribe_port(_seq, subs);
 	if (ret < 0) {
-		_app->error_msg(
+		_log.error_msg(
 		    fmt::format("Alsa: Subscription failed ({}).", snd_strerror(ret)));
 		result = false;
 	}
 
 	if (result) {
-		_app->info_msg(std::string("Alsa: Connected ") + src_port->full_name() +
-		               " => " + dst_port->full_name());
+		_log.info_msg(std::string("Alsa: Connected ") + src_port->full_name() +
+		              " => " + dst_port->full_name());
 	} else {
-		_app->error_msg(std::string("Alsa: Unable to connect ") +
-		                src_port->full_name() + " => " + dst_port->full_name());
+		_log.error_msg(std::string("Alsa: Unable to connect ") +
+		               src_port->full_name() + " => " + dst_port->full_name());
 	}
 
 	return (!result);
@@ -453,7 +454,7 @@ AlsaDriver::disconnect(PatchagePort* src_port, PatchagePort* dst_port)
 	PortAddrs::const_iterator d = _port_addrs.find(dst_port);
 
 	if (s == _port_addrs.end() || d == _port_addrs.end()) {
-		_app->error_msg("Alsa: Attempt to connect port with no address");
+		_log.error_msg("Alsa: Attempt to connect port with no address");
 		return false;
 	}
 
@@ -470,21 +471,21 @@ AlsaDriver::disconnect(PatchagePort* src_port, PatchagePort* dst_port)
 
 	// Not connected (shouldn't happen)
 	if (snd_seq_get_port_subscription(_seq, subs) != 0) {
-		_app->error_msg(
+		_log.error_msg(
 		    "Alsa: Attempt to unsubscribe ports that are not subscribed.");
 		return false;
 	}
 
 	int ret = snd_seq_unsubscribe_port(_seq, subs);
 	if (ret < 0) {
-		_app->error_msg(std::string("Alsa: Unable to disconnect ") +
-		                src_port->full_name() + " => " + dst_port->full_name() +
-		                "(" + snd_strerror(ret) + ")");
+		_log.error_msg(std::string("Alsa: Unable to disconnect ") +
+		               src_port->full_name() + " => " + dst_port->full_name() +
+		               "(" + snd_strerror(ret) + ")");
 		return false;
 	}
 
-	_app->info_msg(std::string("Alsa: Disconnected ") + src_port->full_name() +
-	               " => " + dst_port->full_name());
+	_log.info_msg(std::string("Alsa: Disconnected ") + src_port->full_name() +
+	              " => " + dst_port->full_name());
 
 	return true;
 }
@@ -503,7 +504,7 @@ AlsaDriver::create_refresh_port()
 
 	int ret = snd_seq_create_port(_seq, port_info);
 	if (ret) {
-		_app->error_msg(
+		_log.error_msg(
 		    fmt::format("Alsa: Error creating port ({})", snd_strerror(ret)));
 		return false;
 	}
@@ -514,7 +515,7 @@ AlsaDriver::create_refresh_port()
 	                           SND_SEQ_CLIENT_SYSTEM,
 	                           SND_SEQ_PORT_SYSTEM_ANNOUNCE);
 	if (ret) {
-		_app->error_msg(
+		_log.error_msg(
 		    fmt::format("Alsa: Failed to connect to system announce port ({})",
 		                snd_strerror(ret)));
 		return false;
@@ -535,7 +536,7 @@ void
 AlsaDriver::_refresh_main()
 {
 	if (!create_refresh_port()) {
-		_app->error_msg(
+		_log.error_msg(
 		    "Alsa: Could not create listen port, auto-refresh disabled.");
 		return;
 	}
diff --git a/src/AlsaDriver.hpp b/src/AlsaDriver.hpp
index 2af3553..a953b7b 100644
--- a/src/AlsaDriver.hpp
+++ b/src/AlsaDriver.hpp
@@ -29,6 +29,7 @@
 #include <set>
 #include <string>
 
+class ILog;
 class Patchage;
 class PatchagePort;
 
@@ -37,7 +38,7 @@ class PatchagePort;
 class AlsaDriver : public Driver
 {
 public:
-	explicit AlsaDriver(Patchage* app);
+	explicit AlsaDriver(Patchage* app, ILog& log);
 
 	AlsaDriver(const AlsaDriver&) = delete;
 	AlsaDriver& operator=(const AlsaDriver&) = delete;
@@ -88,6 +89,7 @@ private:
 	                          snd_seq_addr_t     addr);
 
 	Patchage*  _app;
+	ILog&      _log;
 	snd_seq_t* _seq;
 	pthread_t  _refresh_thread;
 
diff --git a/src/ILog.hpp b/src/ILog.hpp
new file mode 100644
index 0000000..a71fda2
--- /dev/null
+++ b/src/ILog.hpp
@@ -0,0 +1,41 @@
+/* This file is part of Patchage.
+ * Copyright 2007-2020 David Robillard <d@drobilla.net>
+ *
+ * Patchage is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * Patchage is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Patchage.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef PATCHAGE_ILOG_HPP
+#define PATCHAGE_ILOG_HPP
+
+#include <string>
+
+/// Interface for writing log messages
+class ILog
+{
+public:
+	ILog() = default;
+
+	ILog(const ILog&) = default;
+	ILog& operator=(const ILog&) = default;
+
+	ILog(ILog&&)  = default;
+	ILog& operator=(ILog&&) = default;
+
+	virtual ~ILog() = default;
+
+	virtual void info_msg(const std::string& msg)    = 0;
+	virtual void warning_msg(const std::string& msg) = 0;
+	virtual void error_msg(const std::string& msg)   = 0;
+};
+
+#endif // PATCHAGE_ILOG_HPP
diff --git a/src/JackDbusDriver.cpp b/src/JackDbusDriver.cpp
index 7f9221b..8098410 100644
--- a/src/JackDbusDriver.cpp
+++ b/src/JackDbusDriver.cpp
@@ -54,8 +54,9 @@ PATCHAGE_RESTORE_WARNINGS
 
 //#define USE_FULL_REFRESH
 
-JackDriver::JackDriver(Patchage* app)
+JackDriver::JackDriver(Patchage* app, ILog& log)
     : _app(app)
+    , _log(log)
     , _dbus_error()
     , _dbus_connection(nullptr)
     , _max_dsp_load(0.0f)
@@ -1190,11 +1191,11 @@ JackDriver::create_port_view(Patchage*, const PortID&)
 void
 JackDriver::error_msg(const std::string& msg) const
 {
-	_app->error_msg(std::string{"Jack: "} + msg);
+	_log.error_msg(std::string{"Jack: "} + msg);
 }
 
 void
 JackDriver::info_msg(const std::string& msg) const
 {
-	_app->info_msg(std::string{"Jack: "} + msg);
+	_log.info_msg(std::string{"Jack: "} + msg);
 }
diff --git a/src/JackDbusDriver.hpp b/src/JackDbusDriver.hpp
index aac7cd7..00c2a83 100644
--- a/src/JackDbusDriver.hpp
+++ b/src/JackDbusDriver.hpp
@@ -29,14 +29,15 @@
 
 #include <string>
 
-class PatchageEvent;
+class ILog;
 class PatchageCanvas;
+class PatchageEvent;
 class PatchagePort;
 
 class JackDriver : public Driver
 {
 public:
-	explicit JackDriver(Patchage* app);
+	explicit JackDriver(Patchage* app, ILog& log);
 
 	JackDriver(const JackDriver&) = delete;
 	JackDriver& operator=(const JackDriver&) = delete;
@@ -143,6 +144,7 @@ private:
 	void on_jack_disappeared();
 
 	Patchage*       _app;
+	ILog&           _log;
 	DBusError       _dbus_error;
 	DBusConnection* _dbus_connection;
 	float           _max_dsp_load;
diff --git a/src/JackDriver.cpp b/src/JackDriver.cpp
index 29fedd8..8a44d93 100644
--- a/src/JackDriver.cpp
+++ b/src/JackDriver.cpp
@@ -16,6 +16,7 @@
 
 #include "JackDriver.hpp"
 
+#include "ILog.hpp"
 #include "Patchage.hpp"
 #include "PatchageCanvas.hpp"
 #include "PatchageEvent.hpp"
@@ -40,8 +41,9 @@ PATCHAGE_RESTORE_WARNINGS
 #include <set>
 #include <string>
 
-JackDriver::JackDriver(Patchage* app)
+JackDriver::JackDriver(Patchage* app, ILog& log)
     : _app(app)
+    , _log(log)
     , _client(nullptr)
     , _events(128)
     , _last_pos{}
@@ -73,7 +75,7 @@ JackDriver::attach(bool launch_daemon)
 	    (!launch_daemon) ? JackNoStartServer : JackNullOption;
 	_client = jack_client_open("Patchage", options, nullptr);
 	if (_client == nullptr) {
-		_app->error_msg("Jack: Unable to create client.");
+		_log.error_msg("Jack: Unable to create client.");
 		_is_activated = false;
 	} else {
 		jack_client_t* const client = _client;
@@ -92,9 +94,9 @@ JackDriver::attach(bool launch_daemon)
 			_is_activated = true;
 			signal_attached.emit();
 			std::stringstream ss;
-			_app->info_msg("Jack: Attached.");
+			_log.info_msg("Jack: Attached.");
 		} else {
-			_app->error_msg("Jack: Client activation failed.");
+			_log.error_msg("Jack: Client activation failed.");
 			_is_activated = false;
 		}
 	}
@@ -112,7 +114,7 @@ JackDriver::detach()
 	}
 	_is_activated = false;
 	signal_detached.emit();
-	_app->info_msg("Jack: Detached.");
+	_log.info_msg("Jack: Detached.");
 }
 
 static bool
@@ -141,8 +143,8 @@ JackDriver::create_port_view(Patchage* patchage, const PortID& id)
 
 	jack_port_t* jack_port = jack_port_by_id(_client, id.id.jack_id);
 	if (!jack_port) {
-		_app->error_msg(fmt::format("Jack: Failed to find port with ID `{}'.",
-		                            id.id.jack_id));
+		_log.error_msg(fmt::format("Jack: Failed to find port with ID `{}'.",
+		                           id.id.jack_id));
 		return nullptr;
 	}
 
@@ -170,9 +172,9 @@ JackDriver::create_port_view(Patchage* patchage, const PortID& id)
 	}
 
 	if (parent->get_port(port_name)) {
-		_app->error_msg(fmt::format("Jack: Module `{}' already has port `{}'.",
-		                            module_name,
-		                            port_name));
+		_log.error_msg(fmt::format("Jack: Module `{}' already has port `{}'.",
+		                           module_name,
+		                           port_name));
 		return nullptr;
 	}
 
@@ -243,9 +245,9 @@ JackDriver::create_port(PatchageModule& parent,
 		}
 #endif
 	} else {
-		_app->warning_msg(fmt::format("Jack: Port `{}' has unknown type `{}'.",
-		                              jack_port_name(port),
-		                              type_str));
+		_log.warning_msg(fmt::format("Jack: Port `{}' has unknown type `{}'.",
+		                             jack_port_name(port),
+		                             type_str));
 		return nullptr;
 	}
 
@@ -436,11 +438,11 @@ JackDriver::connect(PatchagePort* src_port, PatchagePort* dst_port)
 	    _client, src_port->full_name().c_str(), dst_port->full_name().c_str());
 
 	if (result == 0) {
-		_app->info_msg(std::string("Jack: Connected ") + src_port->full_name() +
-		               " => " + dst_port->full_name());
+		_log.info_msg(std::string("Jack: Connected ") + src_port->full_name() +
+		              " => " + dst_port->full_name());
 	} else {
-		_app->error_msg(std::string("Jack: Unable to connect ") +
-		                src_port->full_name() + " => " + dst_port->full_name());
+		_log.error_msg(std::string("Jack: Unable to connect ") +
+		               src_port->full_name() + " => " + dst_port->full_name());
 	}
 
 	return (!result);
@@ -462,11 +464,11 @@ JackDriver::disconnect(PatchagePort* const src_port,
 	    _client, src_port->full_name().c_str(), dst_port->full_name().c_str());
 
 	if (result == 0) {
-		_app->info_msg(std::string("Jack: Disconnected ") +
-		               src_port->full_name() + " => " + dst_port->full_name());
+		_log.info_msg(std::string("Jack: Disconnected ") +
+		              src_port->full_name() + " => " + dst_port->full_name());
 	} else {
-		_app->error_msg(std::string("Jack: Unable to disconnect ") +
-		                src_port->full_name() + " => " + dst_port->full_name());
+		_log.error_msg(std::string("Jack: Unable to disconnect ") +
+		               src_port->full_name() + " => " + dst_port->full_name());
 	}
 
 	return (!result);
@@ -543,7 +545,7 @@ JackDriver::jack_shutdown_cb(void* jack_driver)
 {
 	assert(jack_driver);
 	auto* me = static_cast<JackDriver*>(jack_driver);
-	me->_app->info_msg("Jack: Shutdown.");
+	me->_log.info_msg("Jack: Shutdown.");
 
 	std::lock_guard<std::mutex> lock{me->_shutdown_mutex};
 
@@ -610,7 +612,7 @@ JackDriver::set_buffer_size(jack_nframes_t size)
 	}
 
 	if (jack_set_buffer_size(_client, size)) {
-		_app->error_msg("[JACK] Unable to set buffer size");
+		_log.error_msg("[JACK] Unable to set buffer size");
 		return false;
 	}
 
diff --git a/src/JackDriver.hpp b/src/JackDriver.hpp
index 442ce74..0875703 100644
--- a/src/JackDriver.hpp
+++ b/src/JackDriver.hpp
@@ -26,11 +26,12 @@
 #include <mutex>
 #include <string>
 
+class ILog;
 class Patchage;
-class PatchageEvent;
 class PatchageCanvas;
-class PatchagePort;
+class PatchageEvent;
 class PatchageModule;
+class PatchagePort;
 
 /** Handles all externally driven functionality, registering ports etc.
  *
@@ -40,7 +41,7 @@ class PatchageModule;
 class JackDriver : public Driver
 {
 public:
-	explicit JackDriver(Patchage* app);
+	explicit JackDriver(Patchage* app, ILog& log);
 
 	JackDriver(const JackDriver&) = delete;
 	JackDriver& operator=(const JackDriver&) = delete;
@@ -108,6 +109,7 @@ private:
 	static void jack_shutdown_cb(void* jack_driver);
 
 	Patchage*      _app;
+	ILog&          _log;
 	jack_client_t* _client;
 
 	Queue<PatchageEvent> _events;
diff --git a/src/Patchage.cpp b/src/Patchage.cpp
index 6a40c20..7fbc434 100644
--- a/src/Patchage.cpp
+++ b/src/Patchage.cpp
@@ -167,6 +167,7 @@ Patchage::Patchage(int argc, char** argv)
     , INIT_WIDGET(_log_scrolledwindow)
     , INIT_WIDGET(_status_text)
     , _legend(nullptr)
+    , _log(_status_text)
     , _pane_initialized(false)
     , _attach(true)
     , _driver_detached(false)
@@ -302,21 +303,6 @@ Patchage::Patchage(int argc, char** argv)
 		_menu_view_sprung_layout->set_sensitive(false);
 	}
 
-	for (int s = Gtk::STATE_NORMAL; s <= Gtk::STATE_INSENSITIVE; ++s) {
-		_status_text->modify_base(static_cast<Gtk::StateType>(s),
-		                          Gdk::Color("#000000"));
-		_status_text->modify_text(static_cast<Gtk::StateType>(s),
-		                          Gdk::Color("#FFFFFF"));
-	}
-
-	_error_tag                        = Gtk::TextTag::create();
-	_error_tag->property_foreground() = "#CC0000";
-	_status_text->get_buffer()->get_tag_table()->add(_error_tag);
-
-	_warning_tag                        = Gtk::TextTag::create();
-	_warning_tag->property_foreground() = "#C4A000";
-	_status_text->get_buffer()->get_tag_table()->add(_warning_tag);
-
 	_canvas->widget().show();
 	_main_win->present();
 
@@ -346,12 +332,12 @@ Patchage::Patchage(int argc, char** argv)
 		_about_win->set_logo(Gdk::Pixbuf::create_from_file(
 		    bundle_location() + "/Resources/Patchage.icns"));
 	} catch (const Glib::Exception& e) {
-		error_msg(fmt::format("failed to set logo ({})", e.what()));
+		_log.error_msg(fmt::format("failed to set logo ({})", e.what()));
 	}
 #endif
 
 #if defined(PATCHAGE_LIBJACK) || defined(HAVE_JACK_DBUS)
-	_jack_driver = new JackDriver(this);
+	_jack_driver = new JackDriver(this, _log);
 	_jack_driver->signal_detached.connect(
 	    sigc::mem_fun(this, &Patchage::driver_detached));
 
@@ -362,7 +348,7 @@ Patchage::Patchage(int argc, char** argv)
 #endif
 
 #ifdef HAVE_ALSA
-	_alsa_driver = new AlsaDriver(this);
+	_alsa_driver = new AlsaDriver(this, _log);
 #endif
 
 	connect_widgets();
@@ -370,10 +356,6 @@ Patchage::Patchage(int argc, char** argv)
 	_menu_view_toolbar->set_active(_conf->get_show_toolbar());
 	_menu_view_sprung_layout->set_active(_conf->get_sprung_layout());
 	_menu_view_sort_ports->set_active(_conf->get_sort_ports());
-	_status_text->set_pixels_inside_wrap(2);
-	_status_text->set_left_margin(4);
-	_status_text->set_right_margin(4);
-	_status_text->set_pixels_below_lines(2);
 
 	g_signal_connect(
 	    _main_win->gobj(), "configure-event", G_CALLBACK(configure_cb), this);
@@ -594,32 +576,6 @@ Patchage::clear_load()
 #endif
 }
 
-void
-Patchage::error_msg(const std::string& msg)
-{
-	Glib::RefPtr<Gtk::TextBuffer> buffer = _status_text->get_buffer();
-	buffer->insert_with_tag(buffer->end(), std::string("\n") + msg, _error_tag);
-	_status_text->scroll_to_mark(buffer->get_insert(), 0);
-	_menu_view_messages->set_active(true);
-}
-
-void
-Patchage::info_msg(const std::string& msg)
-{
-	Glib::RefPtr<Gtk::TextBuffer> buffer = _status_text->get_buffer();
-	buffer->insert(buffer->end(), std::string("\n") + msg);
-	_status_text->scroll_to_mark(buffer->get_insert(), 0);
-}
-
-void
-Patchage::warning_msg(const std::string& msg)
-{
-	Glib::RefPtr<Gtk::TextBuffer> buffer = _status_text->get_buffer();
-	buffer->insert_with_tag(
-	    buffer->end(), std::string("\n") + msg, _warning_tag);
-	_status_text->scroll_to_mark(buffer->get_insert(), 0);
-}
-
 static void
 load_module_location(GanvNode* node, void*)
 {
@@ -698,14 +654,14 @@ Patchage::show_open_session_dialog()
 
 	const std::string dir = dialog.get_filename();
 	if (g_chdir(dir.c_str())) {
-		error_msg("Failed to switch to session directory " + dir);
+		_log.error_msg("Failed to switch to session directory " + dir);
 		return;
 	}
 
 	if (system("./jack-session") < 0) {
-		error_msg("Error executing `./jack-session' in " + dir);
+		_log.error_msg("Error executing `./jack-session' in " + dir);
 	} else {
-		info_msg("Loaded session " + dir);
+		_log.info_msg("Loaded session " + dir);
 	}
 }
 
@@ -743,7 +699,7 @@ Patchage::save_session(bool close)
 
 	std::string path = dialog.get_filename();
 	if (g_mkdir_with_parents(path.c_str(), 0740)) {
-		error_msg("Failed to create session directory " + path);
+		_log.error_msg("Failed to create session directory " + path);
 		return;
 	}
 
@@ -1056,13 +1012,8 @@ Patchage::on_view_messages()
 	if (_menu_view_messages->get_active()) {
 		Glib::RefPtr<Gtk::TextBuffer> buffer = _status_text->get_buffer();
 		if (!_pane_initialized) {
-			int y           = 0;
-			int line_height = 0;
-			_status_text->get_line_yrange(buffer->begin(), y, line_height);
-
-			const int pad         = _status_text->get_pixels_inside_wrap();
+			const int min_height  = _log.min_height();
 			const int max_pos     = _main_paned->get_allocation().get_height();
-			const int min_height  = (line_height + 2 * pad);
 			const int conf_height = _conf->get_messages_height();
 			_main_paned->set_position(max_pos -
 			                          std::max(conf_height, min_height));
diff --git a/src/Patchage.hpp b/src/Patchage.hpp
index 98537a1..e453b68 100644
--- a/src/Patchage.hpp
+++ b/src/Patchage.hpp
@@ -38,7 +38,9 @@
 #include <gtkmm/viewport.h>
 #include <gtkmm/window.h>
 
+#include "ILog.hpp"
 #include "Legend.hpp"
+#include "TextViewLog.hpp"
 #include "Widget.hpp"
 #include "patchage_config.h"
 
@@ -70,6 +72,7 @@ public:
 	const std::shared_ptr<PatchageCanvas>& canvas() const { return _canvas; }
 
 	Gtk::Window* window() { return _main_win.get(); }
+	ILog&        log() { return _log; }
 
 	Configuration* conf() const { return _conf; }
 	JackDriver*    jack_driver() const { return _jack_driver; }
@@ -92,10 +95,6 @@ public:
 	inline void queue_refresh() { _refresh = true; }
 	inline void driver_detached() { _driver_detached = true; }
 
-	void info_msg(const std::string& msg);
-	void error_msg(const std::string& msg);
-	void warning_msg(const std::string& msg);
-
 	void update_state();
 	void store_window_location();
 
@@ -210,6 +209,7 @@ protected:
 	Widget<Gtk::ScrolledWindow> _log_scrolledwindow;
 	Widget<Gtk::TextView>       _status_text;
 	Legend*                     _legend;
+	TextViewLog                 _log;
 
 	Glib::RefPtr<Gtk::TextTag> _error_tag;
 	Glib::RefPtr<Gtk::TextTag> _warning_tag;
diff --git a/src/PatchageCanvas.cpp b/src/PatchageCanvas.cpp
index b6a592f..13eb0f4 100644
--- a/src/PatchageCanvas.cpp
+++ b/src/PatchageCanvas.cpp
@@ -246,7 +246,8 @@ PatchageCanvas::connect(Ganv::Node* port1, Ganv::Node* port2)
 		_app->alsa_driver()->connect(p1, p2);
 #endif
 	} else {
-		_app->warning_msg("Cannot make connection, incompatible port types.");
+		_app->log().warning_msg(
+		    "Cannot make connection, incompatible port types.");
 	}
 }
 
@@ -267,7 +268,8 @@ PatchageCanvas::disconnect(Ganv::Node* port1, Ganv::Node* port2)
 	}
 
 	if (!input || !output || input->is_output() || output->is_input()) {
-		_app->error_msg("Attempt to disconnect mismatched/unknown ports.");
+		_app->log().error_msg(
+		    "Attempt to disconnect mismatched/unknown ports.");
 		return;
 	}
 
@@ -283,7 +285,8 @@ PatchageCanvas::disconnect(Ganv::Node* port1, Ganv::Node* port2)
 		_app->alsa_driver()->disconnect(output, input);
 #endif
 	} else {
-		_app->error_msg("Attempt to disconnect ports with strange types.");
+		_app->log().error_msg(
+		    "Attempt to disconnect ports with strange types.");
 	}
 }
 
diff --git a/src/PatchageEvent.cpp b/src/PatchageEvent.cpp
index 4df2924..0f5645a 100644
--- a/src/PatchageEvent.cpp
+++ b/src/PatchageEvent.cpp
@@ -69,11 +69,11 @@ PatchageEvent::execute(Patchage* patchage)
 		if (driver) {
 			PatchagePort* port = driver->create_port_view(patchage, _port_1);
 			if (!port) {
-				patchage->error_msg(fmt::format(
+				patchage->log().error_msg(fmt::format(
 				    "Unable to create view for port `{}'", _port_1));
 			}
 		} else {
-			patchage->error_msg(
+			patchage->log().error_msg(
 			    fmt::format("Unknown type for port `{}'", _port_1));
 		}
 
@@ -87,10 +87,10 @@ PatchageEvent::execute(Patchage* patchage)
 		PatchagePort* port_2 = patchage->canvas()->find_port(_port_2);
 
 		if (!port_1) {
-			patchage->error_msg(
+			patchage->log().error_msg(
 			    fmt::format("Unable to find port `{}' to connect", _port_1));
 		} else if (!port_2) {
-			patchage->error_msg(
+			patchage->log().error_msg(
 			    fmt::format("Unable to find port `{}' to connect", _port_2));
 		} else {
 			patchage->canvas()->make_connection(port_1, port_2);
@@ -102,10 +102,10 @@ PatchageEvent::execute(Patchage* patchage)
 		PatchagePort* port_2 = patchage->canvas()->find_port(_port_2);
 
 		if (!port_1) {
-			patchage->error_msg(
+			patchage->log().error_msg(
 			    fmt::format("Unable to find port `{}' to disconnect", _port_1));
 		} else if (!port_2) {
-			patchage->error_msg(
+			patchage->log().error_msg(
 			    fmt::format("Unable to find port `{}' to disconnect", _port_2));
 		} else {
 			patchage->canvas()->remove_edge_between(port_1, port_2);
diff --git a/src/TextViewLog.cpp b/src/TextViewLog.cpp
new file mode 100644
index 0000000..b5e7a59
--- /dev/null
+++ b/src/TextViewLog.cpp
@@ -0,0 +1,83 @@
+/* This file is part of Patchage.
+ * Copyright 2007-2020 David Robillard <d@drobilla.net>
+ *
+ * Patchage is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * Patchage is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Patchage.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "TextViewLog.hpp"
+
+#include <glibmm/refptr.h>
+#include <gtkmm/textview.h>
+
+#include <string>
+
+TextViewLog::TextViewLog(Widget<Gtk::TextView>& text_view)
+    : _error_tag{Gtk::TextTag::create()}
+    , _warning_tag{Gtk::TextTag::create()}
+    , _text_view{text_view}
+{
+	for (int s = Gtk::STATE_NORMAL; s <= Gtk::STATE_INSENSITIVE; ++s) {
+		_text_view->modify_base(static_cast<Gtk::StateType>(s),
+		                        Gdk::Color("#000000"));
+		_text_view->modify_text(static_cast<Gtk::StateType>(s),
+		                        Gdk::Color("#FFFFFF"));
+	}
+
+	_error_tag->property_foreground() = "#CC0000";
+	_text_view->get_buffer()->get_tag_table()->add(_error_tag);
+
+	_warning_tag->property_foreground() = "#C4A000";
+	_text_view->get_buffer()->get_tag_table()->add(_warning_tag);
+
+	_text_view->set_pixels_inside_wrap(2);
+	_text_view->set_left_margin(4);
+	_text_view->set_right_margin(4);
+	_text_view->set_pixels_below_lines(2);
+}
+
+void
+TextViewLog::info_msg(const std::string& msg)
+{
+	Glib::RefPtr<Gtk::TextBuffer> buffer = _text_view->get_buffer();
+	buffer->insert(buffer->end(), std::string("\n") + msg);
+	_text_view->scroll_to_mark(buffer->get_insert(), 0);
+}
+
+void
+TextViewLog::warning_msg(const std::string& msg)
+{
+	Glib::RefPtr<Gtk::TextBuffer> buffer = _text_view->get_buffer();
+	buffer->insert_with_tag(
+	    buffer->end(), std::string("\n") + msg, _warning_tag);
+	_text_view->scroll_to_mark(buffer->get_insert(), 0);
+}
+
+void
+TextViewLog::error_msg(const std::string& msg)
+{
+	Glib::RefPtr<Gtk::TextBuffer> buffer = _text_view->get_buffer();
+	buffer->insert_with_tag(buffer->end(), std::string("\n") + msg, _error_tag);
+	_text_view->scroll_to_mark(buffer->get_insert(), 0);
+}
+
+int
+TextViewLog::min_height() const
+{
+	Glib::RefPtr<Gtk::TextBuffer> buffer = _text_view->get_buffer();
+
+	int y           = 0;
+	int line_height = 0;
+	_text_view->get_line_yrange(buffer->begin(), y, line_height);
+
+	return line_height + 2 * _text_view->get_pixels_inside_wrap();
+}
diff --git a/src/TextViewLog.hpp b/src/TextViewLog.hpp
new file mode 100644
index 0000000..eb44407
--- /dev/null
+++ b/src/TextViewLog.hpp
@@ -0,0 +1,56 @@
+/* This file is part of Patchage.
+ * Copyright 2007-2020 David Robillard <d@drobilla.net>
+ *
+ * Patchage is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * Patchage is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Patchage.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef PATCHAGE_TEXTVIEWLOG_HPP
+#define PATCHAGE_TEXTVIEWLOG_HPP
+
+#include "ILog.hpp"
+#include "Widget.hpp"
+
+#include <glibmm/refptr.h>
+#include <gtkmm/texttag.h>
+#include <gtkmm/textview.h>
+
+/// Log that writes colored messages to a Gtk TextView
+class TextViewLog : public ILog
+{
+public:
+	explicit TextViewLog(Widget<Gtk::TextView>& text_view);
+
+	TextViewLog(const TextViewLog&) = delete;
+	TextViewLog& operator=(const TextViewLog&) = delete;
+
+	TextViewLog(TextViewLog&&) = delete;
+	TextViewLog& operator=(TextViewLog&&) = delete;
+
+	~TextViewLog() override = default;
+
+	void info_msg(const std::string& msg) override;
+	void error_msg(const std::string& msg) override;
+	void warning_msg(const std::string& msg) override;
+
+	int min_height() const;
+
+	const Widget<Gtk::TextView>& text_view() const { return _text_view; }
+	Widget<Gtk::TextView>&       text_view() { return _text_view; }
+
+private:
+	Glib::RefPtr<Gtk::TextTag> _error_tag;
+	Glib::RefPtr<Gtk::TextTag> _warning_tag;
+	Widget<Gtk::TextView>&     _text_view;
+};
+
+#endif // PATCHAGE_TEXTVIEWLOG_HPP
diff --git a/wscript b/wscript
index cf876ac..2d80c4e 100644
--- a/wscript
+++ b/wscript
@@ -244,6 +244,7 @@ def build(bld):
             src/PatchageCanvas.cpp
             src/PatchageEvent.cpp
             src/PatchageModule.cpp
+            src/TextViewLog.cpp
             src/main.cpp
     '''
     if bld.is_defined('HAVE_JACK_DBUS'):