gems/terminal: support 'CHARACTER' events

This patch adds the handling of 'CHARACTER' events as emitted by the
input-filter's character generator (<chargen>). To avoid interpreting
press/release events twice (at the input filter and by the terminal's
built-in scancode tracker), the terminal's scancode tracker can be
explicitly disabled via <config> <keyboard layout="none"/> </config>.
In the future, the terminal's built-in scancode tracker will be
removed.

The use of the terminal with the input filter is illustrated by the
'terminal_echo.run' script.

Issue #2264

repos/gems/run/terminal_echo.run

@@ -1,6 +1,6 @@
 set build_components {
 	core init drivers/timer
-	server/terminal test/terminal_echo
+	server/input_filter server/terminal test/terminal_echo
 	drivers/framebuffer drivers/input
 }
 
@@ -11,6 +11,9 @@ build $build_components
 
 create_boot_directory
 
+exec cp -f [genode_dir]/repos/os/src/server/input_filter/en_us.chargen bin/
+exec cp -f [genode_dir]/repos/os/src/server/input_filter/de.chargen bin/
+
 append config {
 	<config verbose="yes">
 		<parent-provides>
@@ -36,7 +39,9 @@ append_if [have_spec sdl] config {
 			<service name="Input"/>
 			<service name="Framebuffer"/>
 		</provides>
-	</start>}
+		<config width="640" height="480"/>
+	</start>
+	<alias name="input_drv" child="fb_sdl"/>}
 
 append_platform_drv_config
 
@@ -44,27 +49,63 @@ append_if [have_spec framebuffer] config {
 	<start name="fb_drv">
 		<resource name="RAM" quantum="4M"/>
 		<provides><service name="Framebuffer"/></provides>
+		<config width="640" height="480"/>
 	</start>}
 
 append_if [have_spec ps2] config {
 	<start name="ps2_drv">
 		<resource name="RAM" quantum="1M"/>
 		<provides><service name="Input"/></provides>
-	</start> }
+	</start>
+	<alias name="input_drv" child="ps2_drv"/>}
 
 append config {
 		<start name="timer">
 			<resource name="RAM" quantum="1M"/>
 			<provides><service name="Timer"/></provides>
 		</start>
+		<start name="input_filter">
+			<resource name="RAM" quantum="1M"/>
+			<provides> <service name="Input"/> </provides>
+			<config>
+				<input label="input"/>
+				<output>
+					<chargen>
+						<input name="input"/>
+						<mod1>
+							<key name="KEY_LEFTSHIFT"/> <key name="KEY_RIGHTSHIFT"/>
+						</mod1>
+						<mod2>
+							<key name="KEY_LEFTCTRL"/> <key name="KEY_RIGHTCTRL"/>
+						</mod2>
+						<mod3>
+							<key name="KEY_RIGHTALT"/> <!-- AltGr -->
+						</mod3>
+						<repeat delay_ms="500" rate_ms="250"/>
+						<!-- <include rom="de.chargen"/> -->
+						<include rom="en_us.chargen"/>
+					</chargen>
+				</output>
+			</config>
+			<route>
+				<service name="Input"> <child name="input_drv"/> </service>
+				<any-service> <parent/> <any-child/> </any-service>
+			</route>
+		</start>
 		<start name="terminal">
 			<resource name="RAM" quantum="2M"/>
 			<provides><service name="Terminal"/></provides>
 			<config>
+				<keyboard layout="none"/>
 				<!-- supported built-in font sizes are 8, 12, and 16 -->
 				<font size="12" />
 			</config>
+			<route>
+				<service name="Input"> <child name="input_filter"/> </service>
+				<any-service> <parent/> <any-child/> </any-service>
+			</route>
 		</start>
+
 		<start name="test-terminal_echo">
 			<resource name="RAM" quantum="1M"/>
 		</start>
@@ -79,7 +120,8 @@ install_config $config
 
 # generic modules
 set boot_modules {
-	core ld.lib.so init timer terminal test-terminal_echo
+	core ld.lib.so init timer input_filter terminal test-terminal_echo
+	en_us.chargen de.chargen
 }
 
 # platform-specific modules

repos/gems/src/server/terminal/main.cc

@@ -544,7 +544,7 @@ struct Terminal::Main
 	/* create root interface for service */
 	Terminal::Root_component _root;
 
-	Terminal::Scancode_tracker _scancode_tracker;
+	Constructible<Terminal::Scancode_tracker> _scancode_tracker;
 
 	/* state needed for key-repeat handling */
 	unsigned const _repeat_delay = 250;
@@ -608,27 +608,45 @@ struct Terminal::Main
 		      font_family),
 		_scancode_tracker(keymap, shift, altgr, Terminal::control)
 	{
+		/*
+		 * Construct scancode tracker only if a key map is defined. Otherwise,
+		 * the terminal responds solely by 'CHARACTER' input events.
+		 */
+		if (keymap)
+			_scancode_tracker.construct(keymap, shift, altgr, Terminal::control);
+
 		_input.sigh(_input_handler);
 
 		/* announce service at our parent */
 		_env.parent().announce(_env.ep().manage(_root));
 	}
-
 };
 
 
 void Terminal::Main::_handle_input()
 {
 	_input.for_each_event([&] (Input::Event const &event) {
+
+	 	if (event.type() == Input::Event::CHARACTER) {
+	 		Input::Event::Utf8 const utf8 = event.utf8();
+	 		_read_buffer.add(utf8.b0);
+	 		if (utf8.b1) _read_buffer.add(utf8.b1);
+	 		if (utf8.b2) _read_buffer.add(utf8.b2);
+	 		if (utf8.b3) _read_buffer.add(utf8.b3);
+		}
+
+		if (!_scancode_tracker.constructed())
+			return;
+
 		bool press   = (event.type() == Input::Event::PRESS   ? true : false);
 		bool release = (event.type() == Input::Event::RELEASE ? true : false);
 		int  keycode =  event.code();
 
 		if (press || release)
-			_scancode_tracker.submit(keycode, press);
+			_scancode_tracker->submit(keycode, press);
 
 		if (press) {
-			_scancode_tracker.emit_current_character(_read_buffer);
+			_scancode_tracker->emit_current_character(_read_buffer);
 
 			/* setup first key repeat */
 			_repeat_next = _repeat_delay;
@@ -648,7 +666,7 @@ void Terminal::Main::_handle_key_repeat(Time_source::Microseconds)
 	if (_repeat_next) {
 
 		/* repeat current character or sequence */
-		_scancode_tracker.emit_current_character(_read_buffer);
+		_scancode_tracker->emit_current_character(_read_buffer);
 
 		_repeat_next = _repeat_rate;
 	}
@@ -723,12 +741,20 @@ void Component::construct(Genode::Env &env)
 	try {
 		if (config.xml().sub_node("keyboard")
 		                        .attribute("layout").has_value("de")) {
-
 			keymap = Terminal::german_keymap;
 			shift  = Terminal::german_shift;
 			altgr  = Terminal::german_altgr;
 		}
 	} catch (...) { }
 
+	try {
+		if (config.xml().sub_node("keyboard")
+		                        .attribute("layout").has_value("none")) {
+			keymap = nullptr;
+			shift  = nullptr;
+			altgr  = nullptr;
+		}
+	} catch (...) { }
+
 	static Terminal::Main main(env, font_family, keymap, shift, altgr, Terminal::control);
 }

repos/os/include/terminal/scancode_tracker.h

@@ -113,7 +113,7 @@ class Terminal::Scancode_tracker
 			_mod_altgr(false),
 			_last_character(0),
 			_last_sequence(0)
-		{ };
+		{ }
 
 		/**
 		 * Submit key event to state machine