Touch Screen support is built into Ignition. Turn it on through the Project Properties or scripting in the Designer.
Change the settings as desired then click OK.
Make sure Comm Read/Write is enabled in Project Properties of the Designer.
To handle touch screen logic via scripting, the general pattern is to respond to a mouse event, popup up a keyboard, and then set the component's value to whatever was entered in the keyboard. For example, for a text field, you would write a script like this:
if system.gui.isTouchscreenModeEnabled(): currentText = event.source.text newText = system.gui.showTouchscreenKeyboard(currentText)
See also: system.gui.setTouchscreenModeEnabled
You can control the size of the Touch Screen keyboard that is displayed in a Vision Client.
This setting controls both the alphanumeric keyboard and the numeric keypad.