project problem

hi, i just started creating an SDI for my project with serveral dialogs. i need to visualize images each time user input some data into a certain dialog, more of like reading in the “process inputs” and visualizing the output onto the SDI main window at every stage. Problem is, i want my Onpaint() in the View class to draw only when those dialogs receive any user inputs, not at beginnging of program. how do i control that? Also, my intention is to write those drawing code in the various dialog.cpp files and then call Onpaint() in view class to show the images, is this fleasible and correct approach? will appreciate if anyone can help