chart freezing bug fix

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/Axis.java

@@ -299,7 +299,7 @@ public class Axis implements ChartPart {
       // System.out.println("sampleLabel: " + sampleLabel);
 
       // get the height of the label including rotation
-      TextLayout textLayout = new TextLayout(sampleLabel, getChartPainter().getStyleManager().getAxisTickLabelsFont(), new FontRenderContext(null, true, false));
+      TextLayout textLayout = new TextLayout(sampleLabel.length() == 0 ? " " : sampleLabel, getChartPainter().getStyleManager().getAxisTickLabelsFont(), new FontRenderContext(null, true, false));
       AffineTransform rot = getChartPainter().getStyleManager().getXAxisLabelRotation() == 0 ? null : AffineTransform.getRotateInstance(-1 * Math.toRadians(getChartPainter().getStyleManager()
           .getXAxisLabelRotation()));
       Shape shape = textLayout.getOutline(rot);
@@ -337,7 +337,7 @@ public class Axis implements ChartPart {
       }
 
       // get the height of the label including rotation
-      TextLayout textLayout = new TextLayout(sampleLabel, getChartPainter().getStyleManager().getAxisTickLabelsFont(), new FontRenderContext(null, true, false));
+      TextLayout textLayout = new TextLayout(sampleLabel.length() == 0 ? " " : sampleLabel, getChartPainter().getStyleManager().getAxisTickLabelsFont(), new FontRenderContext(null, true, false));
       Rectangle2D rectangle = textLayout.getBounds();
 
       axisTickLabelsHeight = rectangle.getWidth() + getChartPainter().getStyleManager().getAxisTickPadding() + getChartPainter().getStyleManager().getAxisTickMarkLength();

xchart/src/main/java/com/xeiam/xchart/internal/chartpart/AxisTickDateCalculator.java

@@ -49,15 +49,18 @@ public class AxisTickDateCalculator extends AxisTickCalculator {
     // tick space - a percentage of the working space available for ticks
     double tickSpace = styleManager.getAxisTickSpacePercentage() * workingSpace; // in plot space
 
+    // this prevents an infinite loop when the plot gets sized really small.
+    if (tickSpace < 10) {
+      return;
+    }
+
     // where the tick should begin in the working space in pixels
     double margin = Utils.getTickStartOffset(workingSpace, tickSpace); // in plot space double gridStep = getGridStepForDecimal(tickSpace);
 
     // the span of the data
     long span = (long) Math.abs(maxValue - minValue); // in data space
 
-    // Can tickSpacingHint be intelligently calculated by looking at the label data?
-    // YES. Generate the labels first, see if they "look" OK and reiterate with an increased tickSpacingHint
-    // TODO apply this to other Axis types including bar charts
+    // Generate the labels first, see if they "look" OK and reiterate with an increased tickSpacingHint
     int tickSpacingHint = styleManager.getXAxisTickMarkSpacingHint() - 5;
     do {