Chapter 14Drawing in a Window
- The coordinate systems you use to draw in a window
- How to use a device context to draw shapes
- How and when your program draws in a window
- How to define handlers for mouse messages
- How to define your own shape classes
- How to program the mouse to draw shapes
- How to capture the mouse
You can find the wrox.com code downloads for this chapter on the Download Code tab at www.wrox.com/go/beginningvisualc. The code is in the Chapter 14 download and individually named according to the names throughout the chapter.
BASICS OF DRAWING IN A WINDOW
When you draw in the client area of a window, you must obey the rules. You must redraw the client area whenever a WM_PAINT message is sent to your application. This is because there are many external events that require that your application window is redrawn — the user resizing the window for example or moving another window to expose part of your window that was hidden. Windows sends information along with the WM_PAINT message that enables you to determine which part of the client area needs to be re-created. This means that you don’t have to draw all the client area in response to a WM_PAINT message, just the area identified as the update region. In an MFC application, the MFC intercepts the WM_PAINT message and redirects it to a function in one of your classes. I’ll explain how you handle this message later in this chapter.
The ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access