altosui/telegps: Reduce CPU time needed for flight displays

Don't update displays which aren't shown; track hierarchy changes to
trigger display from most recent state data.

Don't update values which haven't changed; remember previous values
and compare with new before updating widget contents.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/altosuilib/AltosInfoTable.java b/altosuilib/AltosInfoTable.java
index 24a895eb..8ded1bea 100644
--- a/altosuilib/AltosInfoTable.java
+++ b/altosuilib/AltosInfoTable.java
@@ -18,16 +18,20 @@
 package org.altusmetrum.altosuilib_2;
 
 import java.awt.*;
+import java.awt.event.*;
 import javax.swing.*;
 import javax.swing.table.*;
 import org.altusmetrum.altoslib_4.*;
 
-public class AltosInfoTable extends JTable implements AltosFlightDisplay {
+public class AltosInfoTable extends JTable implements AltosFlightDisplay, HierarchyListener {
 	private AltosFlightInfoTableModel model;
 
 	static final int info_columns = 3;
 	static final int info_rows = 17;
 
+	private AltosState		last_state;
+	private AltosListenerState	last_listener_state;
+
 	int desired_row_height() {
 		FontMetrics	infoValueMetrics = getFontMetrics(AltosUILib.table_value_font);
 		return (infoValueMetrics.getHeight() + infoValueMetrics.getLeading()) * 18 / 10;
@@ -56,6 +60,7 @@ public class AltosInfoTable extends JTable implements AltosFlightDisplay {
 		super(new AltosFlightInfoTableModel(info_rows, info_columns));
 		model = (AltosFlightInfoTableModel) getModel();
 		setFont(AltosUILib.table_value_font);
+		addHierarchyListener(this);
 		setAutoResizeMode(AUTO_RESIZE_ALL_COLUMNS);
 		setShowGrid(true);
 		set_layout();
@@ -71,6 +76,17 @@ public class AltosInfoTable extends JTable implements AltosFlightDisplay {
 	public void units_changed(boolean imperial_units) {
 	}
 
+	public void hierarchyChanged(HierarchyEvent e) {
+		if (last_state != null && isShowing()) {
+			AltosState		state = last_state;
+			AltosListenerState	listener_state = last_listener_state;
+
+			last_state = null;
+			last_listener_state = null;
+			show(state, listener_state);
+		}
+	}
+
 	public Dimension getPreferredScrollableViewportSize() {
 		return getPreferredSize();
 	}
@@ -108,6 +124,13 @@ public class AltosInfoTable extends JTable implements AltosFlightDisplay {
 	}
 
 	public void show(AltosState state, AltosListenerState listener_state) {
+
+		if (!isShowing()) {
+			last_state = state;
+			last_listener_state = listener_state;
+			return;
+		}
+
 		reset();
 		if (state != null) {
 			if (state.device_type != AltosLib.MISSING)