Fix XYPlot axis major tick mark hangup

Create XYPlot.
Set width to 1530 pixels.
Set X axis range to min=3.0, max=3.0
There will be a warning about the invalid axis range, it gets adjusted
to some small range, but then the major tick mark computation gets
stuck, keeps adding tick marks for the same position until it runs out
of memory.

This update detects a stuck linear axis tick mark computation and moved
on.

app/rtplot/src/main/java/org/csstudio/javafx/rtplot/internal/LinearTicks.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2014-2017 Oak Ridge National Laboratory.
+ * Copyright (c) 2014-2024 Oak Ridge National Laboratory.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -90,7 +90,7 @@ public void compute(Double low, Double high, final Graphics2D gc, final int scre
         double newHigh = adjustedRange.getValue();
 
         if (newLow != low || newHigh != high) {
-            logger.log(Level.WARNING, "Invalid value range for a linear scale {0,number,#.###############E0} ... {1,number,#.###############E0}. Adjusting the range to {2,number,#.###############E0} ... {3,number,#.###############E0}.",
+            logger.log(Level.WARNING, "     for a linear scale {0,number,#.###############E0} ... {1,number,#.###############E0}. Adjusting the range to {2,number,#.###############E0} ... {3,number,#.###############E0}.",
                     new Object[] {low, high, newLow, newHigh });
             high = newHigh;
             low = newLow;
@@ -163,35 +163,45 @@ public void compute(Double low, Double high, final Graphics2D gc, final int scre
         {
             double start = Math.ceil(low / distance) * distance;
 
-        	// Set prev to one before the start
-        	// and loop until high + distance
-        	// to get minor marks before and after the major tick mark range
-        	double prev = start - distance;
-        	for (double value = start; value < high + distance; value += distance)
-        	{
-        	    // Compute major tick marks
-        	    if (value >= low  &&  value <= high)
-        	        major_ticks.add(new MajorTick<>(value, format(value)));
-
-        	    // Fill major tick marks with minor ticks
-        	    for (int i=1; i<minor; ++i)
-        	    {
-        	        final double min_val = prev + ((value - prev)*i)/minor;
-        	        if (min_val <= low || min_val >= high)
-        	            continue;
-        	        minor_ticks.add(new MinorTick<>(min_val));
-        	    }
-        	    prev = value;
-        	}
+            // Set prev to one before the start
+            // and loop until high + distance
+            // to get minor marks before and after the major tick mark range
+            double prev = start - distance;
+            for (double value = start; value < high + distance; value += distance)
+            {
+                if (prev == value)
+                {
+                    logger.log(Level.WARNING, "Major ticks for axis " + start + " ... " + high + " do not advance from " + value);
+                    break;
+                }
+                // Compute major tick marks
+                if (value >= low  &&  value <= high)
+                    major_ticks.add(new MajorTick<>(value, format(value)));
+
+                // Fill major tick marks with minor ticks
+                for (int i=1; i<minor; ++i)
+                {
+                    final double min_val = prev + ((value - prev)*i)/minor;
+                    if (min_val <= low || min_val >= high)
+                        continue;
+                    minor_ticks.add(new MinorTick<>(min_val));
+                }
+                prev = value;
+            }
         }
         else
         {
-        	distance = -distance;
-        	double start = Math.floor(low / distance) * distance;
+            distance = -distance;
+            double start = Math.floor(low / distance) * distance;
 
             double prev = start - distance;
             for (double value = start; value > high + distance; value += distance)
             {
+                if (prev == value)
+                {
+                    logger.log(Level.WARNING, "Major ticks for axis " + start + " ... " + high + " do not advance from " + value);
+                    break;
+                }
                 // Compute major tick marks
                 if (value <= low  &&  value >= high)
                     major_ticks.add(new MajorTick<>(value, format(value)));