gamnit: use the same code to limit fps than mnit and fix errors

contrib/crazy_moles/src/moles.nit

@@ -318,7 +318,7 @@ redef class App
 	do
 		super
 
-		maximum_fps = 50
+		maximum_fps = 50.0
 	end
 
 	redef fun frame_core(display)

contrib/tinks/src/client/client.nit

@@ -80,7 +80,7 @@ redef class App
 	redef fun on_create
 	do
 		super
-		maximum_fps = 60
+		maximum_fps = 60.0
 		assets.assign_images_to_story context.game.story
 	end
 
@@ -127,7 +127,7 @@ redef class App
 			return new LocalServerContext
 		else
 			print "Connecting to:{address}:{port}"
-			maximum_fps = 0
+			maximum_fps = 0.0
 
 			# Args are: tinks server_address {port}
 			#var address = "riph" # args[0]

examples/mnit_ballz/src/ballz_android.nit

@@ -38,7 +38,7 @@ redef class App
 		gyroscope.enabled = true
 		light.enabled = true
 		proximity.enabled = true
-		maximum_fps = 50
+		maximum_fps = 50.0
 		sensors_support_enabled = true
 		super
 	end

examples/mnit_ballz/src/ballz_linux.nit

@@ -29,7 +29,7 @@ redef class App
 
 	redef fun run
 	do
-		maximum_fps = 50
+		maximum_fps = 50.0
 		super
 	end
 

examples/mnit_dino/src/dino.nit

@@ -39,7 +39,7 @@ redef class App
 	do
 		super
 
-		maximum_fps = 80
+		maximum_fps = 80.0
 
 		var display = display
 		assert display != null

lib/core/time.nit

@@ -32,6 +32,16 @@ redef class Sys
 	`}
 end
 
+redef class Float
+	# Sleep approximately `self` seconds
+	fun sleep `{
+		time_t s = self;
+		long ns = (self-s) * 1000000000.0;
+		const struct timespec req = {s, ns};
+		nanosleep(&req, NULL);
+	`}
+end
+
 # Time since epoch
 extern class TimeT `{time_t`}
 

lib/gamnit/limit_fps.nit

@@ -0,0 +1,78 @@
+# 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.
+
+# Frame-rate control for applications
+module limit_fps
+
+import gamnit
+private import realtime
+
+redef class App
+	# Limit the frame-rate to a given frequency
+	#
+	# This basically limits how much `frame_core` is called per second.
+	# Zero (or a negative value) means no limit.
+	#
+	# Applications can modify this value even during the main-loop.
+	var maximum_fps = 60.0 is writable
+
+	# Current frame-rate
+	#
+	# Updated each 5 seconds.
+	var current_fps = 0.0
+
+	redef fun frame_full
+	do
+		super
+		limit_fps
+	end
+
+	# The clock for limit_fps
+	private var clock = new Clock
+
+	# Number of frames since the last deadline
+	#
+	# Used to compute `current_fps`.
+	private var frame_count = 0
+
+	# Deadline used to compute `current_fps`
+	private var frame_count_deadline = 0
+
+	# Check and sleep to maintain a frame-rate bellow `maximum_fps`
+	#
+	# Also periodically update `current_fps`
+	# Is automatically called at the end of `full_frame`.
+	fun limit_fps
+	do
+		var t = clock.total.sec
+		if t >= frame_count_deadline then
+			var cfps = frame_count.to_f / 5.0
+			self.current_fps = cfps
+			frame_count = 0
+			frame_count_deadline = t + 5
+		end
+		frame_count += 1
+
+		var mfps = maximum_fps
+		if mfps <= 0.0 then return
+		var lapse = clock.lapse
+		var dt = lapse.to_f
+		var target_dt = 1.0 / mfps
+		if dt < target_dt then
+			var sleep_t = target_dt - dt
+			sleep_t.sleep
+			clock.lapse
+		end
+	end
+end

lib/mnit/mnit_fps.nit

@@ -24,7 +24,7 @@ redef class App
 	# Zero (or a negative value) means no limit.
 	#
 	# Applications can modify this value even during the main-loop.
-	var maximum_fps = 60 is writable
+	var maximum_fps = 60.0 is writable
 
 	# Current frame-rate
 	# Updated each 5 seconds.
@@ -53,23 +53,22 @@ redef class App
 	do
 		var t = clock.total.sec
 		if t >= frame_count_deadline then
-			var cfps = frame_count_deadline.to_f / 5.0
+			var cfps = frame_count.to_f / 5.0
 			self.current_fps = cfps
 			frame_count = 0
 			frame_count_deadline = t + 5
 		end
 		frame_count += 1
 
 		var mfps = maximum_fps
-		if mfps <= 0 then return
-		var dt = clock.lapse
-		var target_dt = 1000000000 / mfps
-		var sec = dt.sec
-		var nanosec = dt.nanosec
-		if sec == 0 and nanosec < target_dt then
-			var sleep_t = target_dt - nanosec
-			sys.nanosleep(0, sleep_t)
-			dt = clock.lapse
+		if mfps <= 0.0 then return
+		var lapse = clock.lapse
+		var dt = lapse.to_f
+		var target_dt = 1.0 / mfps
+		if dt < target_dt then
+			var sleep_t = target_dt - dt
+			sleep_t.sleep
+			clock.lapse
 		end
 	end
 end