中级06labview结构events使用驱动编程开发用户界面焦点提高ui密集型应用程序程序性.pdf

one Develo User Interfaces with Event-driven Programming Session Focus • Improve application performance for UI-intensive applications • Modularize code making it easier to read Overview • What are effective user interfaces • Develo user interfaces • LabVIEW Event Structure • Event programming tips LabVIEW Event Structure Effective User Interfaces • Dis y information intuitively and professionally – Descriptive labels on controls NI Style Guide – Limit your VI to 3 standard fonts • Provides easy control of the user interface – Enter values – Change parameters – Drag-n-drop Elements of In ctive Interfaces • Reacting to button clicks • Entering data and reacting to it • Drag and drop • Right-click s Develo In ctive Interfaces with Polling • While loop checks the value of controls • Code executes based on the control value • Drawbacks of polling – Processor intensive • Code must process the control value each loop • Application can appear unresponsive or sluggish – Can miss user actions • Reaction of the code is dependent on data flow User Interfaces with Polling Demonstration UI Development with Event-driven Programming • reases application responsiveness • Easier to read and manager your code Event-driven Programming Demonstration What is an Event? • An event is an action that triggers a change in state – User initiated • button press • mouse click – OS initiated • timeout – Software initiated