Add variable observer

Author: Instagram Story Size. Pixels

src/main/java/org/pybee/cassowary/Variable.java

@@ -11,6 +11,7 @@ public class Variable extends AbstractVariable
 
  private Object _attachedObject;
 
+ private VariableObserver _observer;
 
  public Variable(String name, double value)
  {
@@ -99,6 +100,9 @@ public final void set_value(double value)
  public void change_value(double value)
  {
  _value = value;
+ if (_observer != null) {
+ _observer.onVariableChanged(this);
+ }
  }
 
  public void setAttachedObject(Object o)
@@ -136,4 +140,12 @@ public Expression plus(double val)
  {
  return new Expression(this).plus(new Expression(val));
  }
+
+ public VariableObserver getObserver() {
+ return _observer;
+ }
+
+ public void setObserver(VariableObserver variableObserver) {
+ this._observer = variableObserver;
+ }
 }

src/main/java/org/pybee/cassowary/VariableObserver.java

@@ -0,0 +1,8 @@
+package org.pybee.cassowary;
+
+/**
+ * Created by alex on 03/07/15.
+ */
+public interface VariableObserver {
+ void onVariableChanged(Variable variable);
+}