package nodebox.handle;

import nodebox.node.Node;

/**

* A Handle Delegate can react to changes requested by a Handle.

*/

public interface HandleDelegate {

/**

* Set a value on the node.

* <p/>

* This callback is fired whenever we want to set a value and have an error reported back.

* This method can be called for every drag or move of the mouse, if needed.

*

* @param node The node to set the value on.

* @param parameterName The parameter this value is linked to.

* @param value The ne value.

*/

public void setValue(Node node, String parameterName, Object value);

/**

* Set a value on the node without causing an error.

* <p/>

* This callback is fired whenever we want to set a value, but ignore every error.

* For handles, this is the default, since we don't want to mess with error handling.

* This automatically does the right thing.

* <p/>

* For example, on a constrained handle where width / height need to be equal, calling this method

* will keep them in sync without raising errors that one can't be bigger than the other.

*

* @param node The node to set the value on.

* @param parameterName The parameter this value is linked to.

* @param value The ne value.

*/

public void silentSet(Node node, String parameterName, Object value);

/**

* Edits are no longer recorded until you call stopEditing. This allows you to batch edits.

*

* @param command the command name of the edit batch

*/

public void startEdits(String command);

/**

* Indicates that the user has stopped an editing operation.

* <p/>

* Use this when something significant has happened in your code, e.g. when you've drawn a line in the freehand node.

* <p/>

* This causes the undo mechanism to create a new undo "step".

*

* @param node The node we're editing.

*/

public void stopEditing(Node node);

/**

* Indicates that the handle needs to be updated.

* <p/>

* This calls the update method on the handle, then repaints it.

* <p/>

* The handle is updated every time a value is changed.

* Use this method whenever you want to update the handle state without changing a value,

* for example to redraw a handle cursor.

*

* @param node The node we're editing.

*/

public void updateHandle(Node node);

}