9.windows message Mechanism (iv)

1. Drawing messages

WM_PAINT-the window processing function is sent when the window needs to be drawn.

Situations where repainting is required:

(1) window from creation to first display

(2) from being obscured to re-displaying

(3) The window becomes larger (the window becomes the hour, the window itself does not need to be re-cs_hredraw, but if the registration window class is added | Cs_vredraw style, will be redrawn)

(4) Call the InvalidateRect function

Invalid window area-declared as an area that needs to be redrawn.

BOOL InvalidateRect (HWND hwnd,//Window handle

CONST rect* LpRect,//rectangle coordinates of the area

BOOL bErase); Whether to erase before re-return

In the program, if you need to draw the window, call the Function declaration window invalid area.

WPARAM-Do not use

LPARAM-Do not use

Message processing steps

(1) Start drawing processing

HDC BeginPaint (HWND hwnd,//drawing window

Lppaintstruct lppaint); Buffer for drawing parameters

Returns the drawing device handle HDC

(2) Drawing

(3) Finish drawing

BOOL EndPaint (HWND hwnd,//drawing window

CONST paintstruct *lppaint); Pointers to drawing parameters

2. Keyboard messages

Wm_keydown-generated when the key is pressed

Wm_keyup-generated when the button is released

Wm_syskeydown-generated when the system key is pressed, such as ALT, F10

Wm_syskeyup-generated when System key is released

WM_CHAR-Character message (TranslateMessage sent)

Message parameters:

Key message: WPARAM-Key Virtual key

LPARAM-key parameters, such as the number of presses

WM_CHAR message:

WPARAM-Input character (ASC character encoding)

LPARAM-Parameters related to keys

9.windows message Mechanism (iv)