screen update time with system.draw?

[aceaudio]

Hi there my first post :) ..To cut to the chase, ultimately my question is when you execute some lines of code to display lets say a bitmap image inside a rectangle with a border, will the screen have updated and displayed everything by the time it comes to execute the next line of code?.. or is the message sent to the system and not displayed until the screen next refresh's?

I ask this because I'm creating a program that will display an image to which the user has to respond with a key press. The time in which it takes them to respond will be recorded and it's important that the response time is as accurate as possible. Not being an expert with c++ I'm uncertain how an application actually handles a message like this as i don't want a timer to begin before the image is displayed, a millisecond or two error rate would be acceptable but if the message is sent to the system and not displayed until the screen refresh's while the program still continues to execute the code, a much higher and unacceptable error rate would seem possible to me, maybe there is a way to validate that the image has been displayed on the screen correctly before continuing to execute any more code?

Hope that makes sense and many thanks.


Just incase anyone needs to know the application is being made as a widows form in visual c++ 2005 and access to 2008 is also possible.