1 files changed, 76 insertions, 0 deletions
diff --git a/src/main/java/org/cristalise/gui/graph/view/DefaultDirectedEdgeRenderer.java b/src/main/java/org/cristalise/gui/graph/view/DefaultDirectedEdgeRenderer.java
new file mode 100644
index 0000000..7695885
--- /dev/null
+++ b/src/main/java/org/cristalise/gui/graph/view/DefaultDirectedEdgeRenderer.java
@@ -0,0 +1,76 @@
+package org.cristalise.gui.graph.view;
+
+import java.awt.Graphics2D;
+import java.awt.Paint;
+import java.awt.Shape;
+import java.awt.geom.AffineTransform;
+import java.awt.geom.GeneralPath;
+
+import org.cristalise.kernel.graph.model.DirectedEdge;
+import org.cristalise.kernel.graph.model.GraphPoint;
+
+
+
+public class DefaultDirectedEdgeRenderer implements DirectedEdgeRenderer
+{
+    private GeneralPath mArrowTemplate = new GeneralPath();
+    private Paint       mLinePaint     = null;
+
+
+    public DefaultDirectedEdgeRenderer(Paint linePaint)
+    {
+        mLinePaint = linePaint;
+
+        mArrowTemplate.moveTo(-5, 5);
+        mArrowTemplate.lineTo( 0, 0);
+        mArrowTemplate.lineTo( 5, 5);
+    }
+
+
+    @Override
+	public void draw(Graphics2D g2d, DirectedEdge directedEdge)
+    {
+        GraphPoint      originPoint   = directedEdge.getOriginPoint();
+        GraphPoint      terminusPoint = directedEdge.getTerminusPoint();
+        GraphPoint      midPoint      = new GraphPoint();
+        AffineTransform transform     = new AffineTransform();
+        Shape           arrow         = null;
+
+        g2d.setPaint(mLinePaint);
+        g2d.drawLine(originPoint.x, originPoint.y, terminusPoint.x, terminusPoint.y);
+
+        midPoint.x = originPoint.x + (terminusPoint.x - originPoint.x)/2;
+        midPoint.y = originPoint.y + (terminusPoint.y - originPoint.y)/2;
+
+        transform.translate(midPoint.x, midPoint.y);
+        transform.rotate(calcArrowAngle(originPoint.x, originPoint.y, terminusPoint.x, terminusPoint.y));
+
+        arrow = mArrowTemplate.createTransformedShape(transform);
+
+        g2d.draw(arrow);
+    }
+
+
+    private static double calcArrowAngle(int originX, int originY, int terminusX, int terminusY) {
+        double width  = terminusX - originX;
+        double height = terminusY - originY;
+
+        if((width == 0) && (height > 0))  return Math.PI;
+
+        if((width == 0) && (height < 0))  return 0;
+
+        if((width > 0)  && (height == 0)) return Math.PI/2.0;
+
+        if((width < 0)  && (height == 0)) return -1.0 * Math.PI/2.0;
+
+        if((width > 0)  && (height > 0))  return Math.PI/2.0 + Math.atan(Math.abs(height)/Math.abs(width));
+
+        if((width > 0)  && (height < 0))  return Math.atan(Math.abs(width)/Math.abs(height));
+
+        if((width < 0)  && (height < 0))  return -1.0 * Math.atan(Math.abs(width)/Math.abs(height));
+
+        if((width < 0)  && (height > 0))  return -1.0 * (Math.PI/2.0 + Math.atan(Math.abs(height)/Math.abs(width)));
+
+        return 0.0;
+    }
+}