implement frame rate display as transparent & draggable dialog

(ordered by Curt as Christmas present :-)

Nasal/gui.nas

@@ -69,10 +69,26 @@ INIT = func {
     # enable/disable menu entries
     menuEnable("fuel-and-payload", getprop("/sim/flight-model") == "yasim");
     menuEnable("autopilot", props.globals.getNode("/autopilot/KAP140/locks") == nil);
+
+    fps_loop();
 }
 settimer(INIT, 0);
 
 
+##
+# Show/hide the fps display dialog.
+#
+var show_fps = -1;
+fps_loop = func {
+	var i = getprop("/sim/rendering/fps-display");
+	if (i != show_fps) {
+		fgcommand(i ? "dialog-show" : "dialog-close",
+				props.Node.new({"dialog-name": "fps"}));
+		show_fps = i;
+	}
+	settimer(fps_loop, 1);
+}
+
 
 ##
 # How many seconds do we show the tip?

gui/dialogs/fps.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+
+<PropertyList>
+	<name>fps</name>
+	<x>-1</x>
+	<y>0</y>
+	<width>30</width>
+	<height>20</height>
+	<color>
+		<red>1</red>
+		<green>1</green>
+		<blue>1</blue>
+		<alpha>0</alpha>
+	</color>
+	<text>
+		<label>000</label>
+		<property>/sim/frame-rate</property>
+		<live>true</live>
+		<!--font>
+			<name>typewriter</name>
+			<size>16</size>
+		</font-->
+		<color>
+			<red>1</red>
+			<green>0</green>
+			<blue>0</blue>
+			<alpha>1</alpha>
+		</color>
+	</text>
+</PropertyList>

gui/dialogs/rendering.xml

@@ -18,7 +18,7 @@
     <checkbox>
       <halign>left</halign>
       <label>Show frame rate</label>
-      <property>/sim/hud/draw-fps</property>
+      <property>/sim/rendering/fps-display</property>
       <binding>
         <command>dialog-apply</command>
       </binding>

preferences.xml

@@ -56,6 +56,7 @@ Started September 2000 by David Megginson, david@megginson.com
    <shadows-ai type="bool">false</shadows-ai>
    <shadows-to type="bool">false</shadows-to>
    <shadows-debug type="bool">false</shadows-debug>
+   <fps-display type="bool">false</fps-display>
   </rendering>
   <model-hz type="int">120</model-hz>
   <navdb>