[OSM-dev] [RFC] Scale bar

[Jan-Benedict Glaw]

Hi!

I'm quite new to OSM, signed up just some days ago. I'm /not/ a Java
hacker (but I'm quite used to C) and thus I tried to address a problem
I faces with the online editing applet: the missing scale bar
disturbed me a lot. That's also a bug in the trac'ker.

Not being really familiar with the Java stuff, I implemented a
statically sized status bar and a text that points out the bar's
length in meters. (-> So this is basically always a floating value and
not something "nice.")

Index: src/org/openstreetmap/processing/OsmApplet.java
===================================================================
--- src/org/openstreetmap/processing/OsmApplet.java	(revision 1015)
+++ src/org/openstreetmap/processing/OsmApplet.java	(working copy)
@@ -384,6 +385,31 @@
 		return Integer.parseInt(param(paramName));
 	}
 
+	private void draw_scale_bar() {
+		int dist_bottom = 70;
+		int dist_right = 20;
+		int bar_length = getWidth() / 5;
+		int ending_bar_length = getHeight() / 30;
+
+		pushMatrix();
+		/* Horizonthal bar */
+		line(getWidth() - bar_length - dist_right, getHeight() - dist_bottom,
+		     getWidth() - dist_right, getHeight() - dist_bottom);
+		/* Left ending bar */
+		line(getWidth() - bar_length - dist_right, getHeight() - dist_bottom + ending_bar_length / 2,
+		     getWidth() - bar_length - dist_right, getHeight() - dist_bottom - ending_bar_length / 2);
+		/* Right ending bar */
+		line(getWidth() - dist_right, getHeight() - dist_bottom + ending_bar_length / 2,
+		     getWidth() - dist_right, getHeight() - dist_bottom - ending_bar_length / 2);
+
+		String meters = String.format ("%10.5f m", tiles.kilometersPerPixel()
+							   * bar_length * 1000.0f);
+		translate(getWidth() - dist_right - bar_length + (bar_length - textWidth(meters))/2,
+			  getHeight() - dist_bottom + 5);
+		text(meters);
+		popMatrix();
+	}
+
 	public void draw() {
 		tiles.draw();
 		try {
@@ -604,6 +630,9 @@
 				text("uploading...");
 				popMatrix();
 			}
+
+			// finally draw a scale bar
+			draw_scale_bar();
 		} catch (NullPointerException npe) {
 			npe.printStackTrace();
 		}

Comments?

MfG, JBG

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Jan-Benedict Glaw       jbglaw at lug-owl.de    . +49-172-7608481             _ O _
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