?
Solved

problem in drawing.

Posted on 2002-06-23
7
Medium Priority
?
234 Views
Last Modified: 2013-11-20
how to improve draw efficient?
how OnPaint()and OnDraw()do?

how to exchange data between to class?


thank you!
                     ¡ª¡ªÐ¦¿´·çÔÆ
0
Comment
Question by:ytsjiang
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
7 Comments
 
LVL 3

Expert Comment

by:Crius
ID: 7104162
Drawing is fastest done by using BitBlt. When you render an image, render it into an HBITMAP or CBitmap, and in the OnDraw, use BitBlt to quickly transfer it to the screen.

As for exchanging data between classes, that depends on the data. If it's a big chunk of data, like a state, you can create a struct or class that handles the state data (contains all the variables), and pass that to your classes.
0
 
LVL 3

Accepted Solution

by:
Melange earned 300 total points
ID: 7111279
If you're not using BitBlt, but simply standard GDI calls to the screen, then make sure you only draw what's visible.

You can use RectVisible and/or GetClipBox functions from CDC to determine whether to draw that section or not.

The fastest method (as Crius mentioned) is to draw the image in the background and then BitBlt to the screen (also making sure to only BitBlt the visible rect). But, this takes more memory overhead (as you have to manage the background bitmap) and you have to take into account resizing of your window (if necessary).

It depends on your app which is better.
0
 
LVL 3

Expert Comment

by:Crius
ID: 10870315
I recommend accepting Melange. It is a more useful, and in depth answer.
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In this article, I'll describe -- and show pictures of -- some of the significant additions that have been made available to programmers in the MFC Feature Pack for Visual C++ 2008.  These same feature are in the MFC libraries that come with Visual …
This is to be the first in a series of articles demonstrating the development of a complete windows based application using the MFC classes.  I’ll try to keep each article focused on one (or a couple) of the tasks that one may meet.   Introductio…
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…
Suggested Courses
Course of the Month10 days, 18 hours left to enroll

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question