MFC CView Paint

CtrlColor 这个选择颜色的调色板

将要绘制时调用。

这货是个调色板，父窗口绘制控件之前会相应改消息，获取指定控件的背景颜色。

WM_CTLCOLOR afx_msg HBRUSH OnCtlColor(CDC pDC, CWnd pWnd, UINT nCtlColor);

pDC Contains a pointer to the display context for the child window. May be temporary. pWnd Contains a pointer to the control asking for the color. May be temporary. nCtlColor Contains one of the following values, specifying the type of control: CTLCOLOR_BTN Button control CTLCOLOR_DLG Dialog box CTLCOLOR_EDIT Edit control CTLCOLOR_LISTBOX List-box control CTLCOLOR_MSGBOX Message box CTLCOLOR_SCROLLBAR Scroll-bar control CTLCOLOR_STATIC Static control

在子控件将要绘制时由框架调用。 The framework calls this member function when a child control is about to be drawn.

OnCtlColor必须返回一个指向可用画刷的句柄，用于绘画控件背景。 OnCtlColor must return a handle to the brush that is to be used for painting the control background.

大多数控件处理他们的父窗口(通常是一个对话框)发送的WM_CTLCOLOR消息用于准备DC在绘制控件时使用正确的颜色。 Most controls send this message to their parent (usually a dialog box) to prepare the pDC for drawing the control using the correct colors.

OnEraseBkgnd 考虑要不要清除背景

afx_msg BOOL OnEraseBkgnd(CDC* pDC);

控件重绘背景前调用，处理需要重绘的区域。 It is called to prepare an invalidated region for painting.

返回非零则不需要清除背景，返回0需要清除背景。 Nonzero if it erases the background; otherwise 0.

MFC框架会在窗口对象背景需要重绘的情况(例如:窗口大小改变)下调用该接口。 The framework calls this member function when the CWnd object background needs erasing (for example, when resized).

OnPaint 开始画了

WM_PAINT afx_msg void OnPaint();

The framework calls this member function when Windows or an application makes a request to repaint a portion of an application's window.

The WM_PAINT message is sent when the UpdateWindow or RedrawWindow member function is called.

OnDrawItem(DrawItem) 画得更好

WM_DRAWiTEM afx_msg void OnDrawItem(int nIDCtl, LPDRAWITEMSTRUCT lpDrawItemStruct);

// Overridables (for owner draw only) virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);

The framework calls this member function for the owner of an owner-draw button control, combo-box control, list-box control, or menu when a visual aspect of the control or menu has changed.

OnDrawItem是由宿主类调用的，DrawItem是在OnDrawItem中被是控件自己(子类)调用的。

总结

WM_CTLCOLOR -> WM_ERASEBKGND -> WM_PAINT -(owner draw only)-> WM_DRAWiTEM