spek

commit 5ef71cbb9bcd9f4dff30b33ec7a3e348b01f29e2
parent f625d32a6e5393de4757ed930caf5ff802fb2008
Author: Alexander Kojevnikov <alexander@kojevnikov.com>
Date:   Sun, 16 May 2010 19:30:53 +1000

Auto-fitting duration ticks

Diffstat:
M
src/spek-spectrogram.vala
 | 
44
+++++++++++++++++++++++++++++++++++++-------

1 file changed, 37 insertions(+), 7 deletions(-)
diff --git a/src/spek-spectrogram.vala b/src/spek-spectrogram.vala
@@ -116,21 +116,46 @@ namespace Spek {
 				cr.paint ();
 				cr.identity_matrix ();
 
-				// Time ruler.
-				int64[] time_points = {0, source.duration};
+				// Prepare to draw the time ruler.
 				cr.set_source_rgb (1, 1, 1);
 				cr.set_line_width (1);
 				cr.set_antialias (Antialias.NONE);
 				cr.select_font_face ("sans-serif", FontSlant.NORMAL, FontWeight.NORMAL);
 				cr.set_font_size (10.0);
+
+				// Mesure the label text.
 				TextExtents ext;
 				cr.text_extents ("00:00", out ext);
-				double tick_width = ext.width;
-				foreach (var pt in time_points) {
-					var seconds = (int) (pt / 1000000000);
-					var label = "%d:%02d".printf (seconds / 60, seconds % 60);
-					var pos = PADDING + (w - 2 * PADDING) * pt / source.duration;
+				double label_width = ext.width;
+
+				// Select the factor to use, we want some space between the labels.
+				int duration_seconds = (int) (source.duration / 1000000000);
+				int[] time_factors = {1, 2, 5, 10, 20, 30, 1*60, 2*60, 5*60, 10*60, 20*60, 30*60};
+				int time_factor = 0;
+				foreach (var factor in time_factors) {
+					if (time_to_px (factor, w, duration_seconds) >= 1.5 * label_width) {
+						time_factor = factor;
+						break;
+					}
+				}
+
+				// Add the ticks.
+				int[] ticks = { 0, duration_seconds };
+				if (time_factor > 0) {
+					for (var tick = time_factor; tick < duration_seconds; tick += time_factor) {
+						ticks += tick;
+					}
+					// The last item should be skipped, it's too close to the end tick.
+					// TODO: `ticks = ticks[0:-1]` crashes, file a bug.
+					ticks = ticks[0:ticks.length - 1];
+				}
+
+				// Draw the ticks.
+				foreach (var tick in ticks) {
+					var label = "%d:%02d".printf (tick / 60, tick % 60);
+					var pos = PADDING + time_to_px (tick, w, duration_seconds);
 					cr.text_extents (label, out ext);
+					// TODO: use font measurements instead ext.height
 					cr.move_to (pos - ext.width / 2, h - PADDING + GAP + ext.height);
 					cr.show_text (label);
 					cr.move_to (pos, h - PADDING);
@@ -154,6 +179,11 @@ namespace Spek {
 			cr.identity_matrix ();
 		}
 
+		// TODO: factor out the ruler logic and pass this as an anonymous method.
+		private double time_to_px (int time, double w, int duration_seconds) {
+			return (w - 2 * PADDING) * time / duration_seconds;
+		}
+
 		private void put_pixel (ImageSurface surface, int x, int y, uint32 color) {
 			var i = y * surface.get_stride () + x * 4;
 			unowned uchar[] data = surface.get_data ();