Using Python in Ignition

Once you have a basic understanding of how Python works, we need to use it in Ignition. You can't write script in a vacuum, but Ignition provides many simple to use mechanisms for you to drop a simple piece of code with huge results.

Events

Event handling allows you to use scripting to respond to a wide variety of events that components fire. This lets you configure windows that are very interactive, and are an important part of project design in the Vision module. An event can be many things, like a mouse click, a key press, or simply a property changing. Whenever these events occur, a script can be called to "handle" the event. Different components can fire different types of events. For example, mouse events are very common and are fired by almost all components. The cellEdited event, on the other hand, is only fired by the Table component.

Configuring Handlers

To configure event handlers for a component, right-click on the component and choose the Scripting from the pop-up window. You can also get to this button from the toolbar ( ) or the Component menu. From the component scripting window, you can pick the appropriate event handler.

Using Components in Scripting

The majority of your scripts in Ignition need to access other components on the window. If you are filling in a form, or even clicking on something to open a details window, you'll need to access other components. Ignition provides a simple interface that allows you to select properties from another component on the window. Just click on the chain-link icon in the upper right and drill down to the property you want. You can then use these property values in whatever way you'd like.

Once selected, you'll notice that more than just the property name shows up in your code, and it always starts with "event". This can be confusing at first, but it's just a path around the window to your selected component. You can learn more about the event object and how it works here.

Moving/Resizing Components and Windows

You can use scripting to move and resize a component at runtime (in the client). The functions system.gui.transform() is used for this. It simply take a component and whatever dimension/location changes you want such as size, location, or both. Locations are always measured in pixels from the upper left point of the component's parent container. Note that if you're moving a component that is set to relative layout, your coordinates will act as if they were coordinates to the sizes of the relevant containers last time they were saved in the Designer, not the current real coordinates of the runtime. This is very helpful for creating animations. In effect what this means is that the coordinates fed into these functions "respect" the relative layout system automatically.

You can move and resize windows as well. If you have a reference to a window, you can set its size and location directly with setSize() and setLocation(). For example, if you wanted to move the floating window Popup to certain
location, you could do so with the code below. Note: the try/except is there to hide errors, it helps to test your code before adding the try/except portion of the code.

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