From: Alexis Laferrière <alexis.laf@xymus.net>
Date: Mon, 5 Oct 2015 14:03:38 +0000 (-0400)
Subject: lib/gamnit: intro `keys` to keep track of pressed keys
X-Git-Tag: v0.8~13^2
X-Git-Url: http://nitlanguage.org

lib/gamnit: intro `keys` to keep track of pressed keys

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
---

diff --git a/lib/gamnit/keys.nit b/lib/gamnit/keys.nit
new file mode 100644
index 0000000..85e9e1e
--- /dev/null
+++ b/lib/gamnit/keys.nit
@@ -0,0 +1,47 @@
+# This file is part of NIT (http://www.nitlanguage.org).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#	 http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Simple service keeping track of which keys are currently pressed
+#
+# This service revolves around `app.pressed_keys`, a `Set` of the names of currently pressed keys.
+# As a `Set`, `app.pressed_keys` can be iterated and queried with `has`.
+#
+# Limitations: The keys names are platform dependent.
+module keys
+
+import mnit::input
+import gamnit
+
+redef class App
+	# Currently pressed keys
+	var pressed_keys = new Set[String] is lazy
+
+	# Register `event` to update `app.pressed_keys`
+	private fun register_key_event(event: KeyEvent)
+	do
+		var key = event.name
+		if event.is_down then
+			app.pressed_keys.add key
+		else if app.pressed_keys.has(key) then
+			app.pressed_keys.remove key
+		end
+	end
+
+	redef fun accept_event(event)
+	do
+		if event isa KeyEvent then register_key_event event
+
+		return super
+	end
+end