Activity 1: Creating a Simple Script

1. Create a blank Harmony project containing only the default Drawing, Composite, Display, and Write nodes.
2. Open the Script Editor view or your favourite external editor. If you are using an external editor, link it to the Script Editor view.
3. In the Script Editor View menu, select File > New Script.
4. In the New Script dialog box, name your new script Create_Drawing_Nodes.
5. In the Script Editor script list, select your new script.
6. Create the createDrawingNodes() function, by typing:

function createDrawingNodes()
{  
    
}

7. Since the script will work based on a selection, the first information to get is the node selection using the selection class. It requires to use the following two public slots. You can read more about them in the scripting API references.
   1. numberOfNodesSelected ()
   2. selectedNode (int i)
8. Type the following code in your function to get the number of nodes selected and to loop through these nodes to access the specific parameters for each instance in the loop.

function createDrawingNodes()
{ 
var selectedNodes = selection.numberOfNodesSelected();  
for(var n = 0; n < selectedNodes; n++){ 
var currentNode = selection.selectedNode(n); 
}	
}

9. To make sure there is only one node selected, add a condition making sure selectedNodes() is equal to 1 or else return a warning message with the MessageBox class to only select one node. Later on, you can decide to also validate that the selected node is of Composite type.

function createDrawingNodes()
{  
var selectedNodes = selection.numberOfNodesSelected(); 
if(selectedNodes == 1){  
for(var n = 0; n < selectedNodes; n++){ 
var currentNode = selection.selectedNode(n);  
} 
}else{
   MessageBox.information("You must select only 1 Composite node."); 
}
}

10. Press the Script Editor view Save button.
11. Once you have access to the currently selected node, you can then use the node class to affect it or gain information from it. Using the coordX() and coordY() functions in the node class, you will get the X and Y position of the selected node in the Node view. You will be able to use this information to position your new nodes not too far from the selected Composite node.

function createDrawingNodes()
{
var selectedNodes = selection.numberOfNodesSelected(); 
if(selectedNodes == 1){ 
for(var n = 0; n < selectedNodes; n++){ 
var currentNode = selection.selectedNode(n);
var posX = node.coordX(currentNode);         var posY = node.coordY(currentNode);  
  } 
}else{  
MessageBox.information("You must select only 1 Composite node."); 
} 
}

12. Now that you have the information of your selected node, you can now create new drawing nodes and link them to your selected Composite. To add new nodes, the fasted and most efficient way to do so is by using a loop. In this loop, we will add 4 new drawing nodes. Create the loop after the coordinate information.

function createDrawingNodes()
{ 
var selectedNodes = selection.numberOfNodesSelected(); 
if(selectedNodes == 1){  
    for(var n = 0; n < selectedNodes; n++){  
        var currentNode = selection.selectedNode(n); 
        var posX = node.coordX(currentNode); 
        var posY = node.coordY(currentNode);  w
        for(var i = 0; i < 4; i++){   
        }  
     } 
}else{  
     MessageBox.information("You must select only 1 Composite node.");
} 
}

13. To add a new node, you need to use the add() function from the node class: add (String parentGroup, String name, String type, int x, int y, int z). The first argument is the group in which to add the node. For this, you will need to get the group information in which your selected Composite is. The second argument is the name to give to the node. The third argument is the type of node to add. Here, you will be adding drawing nodes. Drawing node have a particular type string. This is where you will use the *.xstage file information to find it. and finally, the last arguments are for coordinates. We will use the posX and posY values as reference. Let's start with writing the add function and inserting the arguments we know. Based on the selected Composite coordinates, you can use the looping value to increment the X value and increase the Y to be above the composite.

function createDrawingNodes()
{ 
var selectedNodes = selection.numberOfNodesSelected();  
 if(selectedNodes == 1){ 
for(var n = 0; n < selectedNodes; n++){ 
var currentNode = selection.selectedNode(n);
var posX = node.coordX(currentNode);
var posY = node.coordY(currentNode);  
for(var i = 0; i < 4; i++){ 
var newNode =  node.add("", "drawing_" + (i + 1), "", posX + (120 * i), posY + 100, 0); 
}  
   } 
}else{  
     MessageBox.information("You must select only 1 Composite node.");
} 
}

14. You can get the group information from your selected node using the parentNode() function.

function createDrawingNodes()
{  
 var selectedNodes = selection.numberOfNodesSelected(); 
if(selectedNodes == 1){ 
for(var n = 0; n < selectedNodes; n++){ 
var currentNode = selection.selectedNode(n);
var posX = node.coordX(currentNode); 
       var posY = node.coordY(currentNode); 
for(var i = 0; i < 4; i++){ 
var newNode =  node.add(node.parentNode(currentNode), "drawing_" + (i + 1), "", posX + (120 * i), posY + 100, 0);  
       } 
} 
}else{  
     MessageBox.information("You must select only 1 Composite node.");
} 
}

15. Finally, to get the last argument about the node type, you need to open the project *.xstage file and look at the module elements. You will see a type argument. Some modules are type COMPOSITE, DISPLAY, WRITE, or READ. If you add more nodes to your Node view such as effects, mode types will appear in the *.xstage file. Since the backend information doesn't always match the user interface strings, it's always important to verify it. The drawing node type is READ.

function createDrawingNodes()
{  
 var selectedNodes = selection.numberOfNodesSelected(); 
if(selectedNodes == 1){  
     for(var n = 0; n < selectedNodes; n++){  
       var currentNode = selection.selectedNode(n);
var posX = node.coordX(currentNode); 
       var posY = node.coordY(currentNode); 
for(var i = 0; i < 4; i++){ 
var newNode =  node.add(node.parentNode(currentNode), "drawing_" + (i + 1), "READ", posX + (120 * i), posY + 100, 0); 
}  
     } 
}else{ 
MessageBox.information("You must select only 1 Composite node."); 
 } 
}

16. Press the Script Editor view Save button.
17. Next, to link the new nodes to the selected Composite, you need to use the link() function: link (String srcNode, int srcPort, String dstNode, int dstPort). This function requires the source node, which port number to connect from, the destination node, and which port number to connect it in.

function createDrawingNodes()
{ 
var selectedNodes = selection.numberOfNodesSelected();  
if(selectedNodes == 1){  
   for(var n = 0; n < selectedNodes; n++){  
     var currentNode = selection.selectedNode(n); 
     var posX = node.coordX(currentNode); 
      var posY = node.coordY(currentNode);  
      for(var i = 0; i < 4; i++){  
       var newNode =  node.add(node.parentNode(currentNode), "drawing_" + (i + 1), "READ", posX + (120 * i), posY + 100, 0);
node.link(newNode, 0, currentNode, 0);
}  
   } 
}else{  
  MessageBox.information("You must select only 1 Composite node."); 
} 
}

18. At this point, the script is functional, but if you undo the action, you will have to undo the link and additional of every single node, which can be taxing. You can use the beginUndoRedoAccum() and endUndoRedoAccum() functions in the scene class to undo the entire list of operations in one action.

function createDrawingNodes()
{  
var selectedNodes = selection.numberOfNodesSelected(); 
if(selectedNodes == 1){ 
scene.beginUndoRedoAccum("Create Drawing Nodes"); 
for(var n = 0; n < selectedNodes; n++){ 
var currentNode = selection.selectedNode(n);
var posX = node.coordX(currentNode); 
      var posY = node.coordY(currentNode);  
      for(var i = 0; i < 4; i++){  
         var newNode =  node.add(node.parentNode(currentNode), "drawing_" + (i + 1), "READ", posX + (120 * i), posY + 100, 0);
node.link(newNode, 0, currentNode, 0);
}  
     }  
     scene.endUndoRedoAccum();  
 }else{  
     MessageBox.information("You must select only 1 Composite node.");
} 
}

19. Press the Script Editor view Save button.
20. You can add comments to your script to remember what the various lines of code do using // at the beginning of the line.
21. Execute your script, either by using the Run button or importing it in the Scripting toolbar.
22. Now that you are more familiar with scripting in Harmony, try to add a second condition validating if the type of the selected node is indeed a composite.