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<H1>App Part 4: Multiple Document Interface</H1>
<P>Example: app_four</P>
<IMG SRC="images/app_four.gif" ALT="[images/app_four.gif]" ALIGN="right">
<H2>MDI Overview</H2>
First a bit of background... Every window has a <I>Client Area</I>, this is
where most programs draw images, place controls etc... the Client Area is not
seperate from the window itself, it is simply a smaller specialised region
of it. Sometimes a window can be all client area, and nothing else, sometimes
the client area is smaller to make room for menus, titles, scrollbars, etc...
<P>
In MDI terms, your main window is called the Frame, this is probably the
only window you would have in a SDI (Single Document Interface) program.
In MDI there is an additional window, called the <I>MDI Client Window</I>
which is a child of your Frame window.
Unlike the <I>Client Area</I> it is a complete and seperate window all on it's
own, it has a client area of it's own and probably a few pixels for a border.
You never directly handle messages for the MDI Client, it is done by the
pre-defined windows class <CODE>"MDICLIENT"</CODE>. You can communicate with
and manipulate the MDI Client and the windows it contains through messages.
<P>
When it comes to the windows which actually display your document or
whatever your program displays, you send a message to the MDI Client to tell it to create a new
window of the type you've specified. The new window is created as a child of
the MDI Client, not of your Frame window. This new window is an MDI Child.
The MDI Child is a child of the MDI Client, which in turn is a child of the
MDI Frame (Getting dizzy yet?). To make matters worse, the MDI Child will
probably have child windows of its own, for instance the edit control in the
example program for this section.
<P>
You are responsable for writing two (or more) Window Procedures. One, just like
always, for your main window(the Frame). And one more for the MDI Child. You may also
have more than one type of Child, in which case, you'll want a seperate window
procedure for each type.
<P>
If I've thoroughly confused you now talking about MDI Clients and things, this diagram
may clear things up a little better:
<P ALIGN="CENTER">
<IMG SRC="images/mdi_diagram.gif" ALT="[images/mdi_diagram.gif]" BORDER="1">
</P>
<H2>Getting Started with MDI</H2>
MDI requires a few subtle changes throughout a program, so please read through this section
carefully... chances are that if your MDI program doesn't work or has strange behaviour
it's because you missed one of the alterations from a regular program.
<H3>MDI Client Window</H3>
Before we create our MDI window we need to make a change to the default message processing
that goes on in our Window Procedure... since we're creating a Frame window that will
host an MDI Client, we need to change the <CODE>DefWindowProc()</CODE> call to <CODE>DefFrameProc()</CODE> which adds
specialized message handling for Frame Windows,
<PRE CLASS="SNIP">
default:
return DefFrameProc(hwnd, g_hMDIClient, msg, wParam, lParam);
</PRE>
The next step is to create the MDI Client window itself, as a child of our frame window.
We do this in <CODE>WM_CREATE</CODE> as usual...
<PRE CLASS="SNIP">
CLIENTCREATESTRUCT ccs;
ccs.hWindowMenu = GetSubMenu(GetMenu(hwnd), 2);
ccs.idFirstChild = ID_MDI_FIRSTCHILD;
g_hMDIClient = CreateWindowEx(WS_EX_CLIENTEDGE, "mdiclient", NULL,
WS_CHILD | WS_CLIPCHILDREN | WS_VSCROLL | WS_HSCROLL | WS_VISIBLE,
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
hwnd, (HMENU)IDC_MAIN_MDI, GetModuleHandle(NULL), (LPVOID)&ccs);
</PRE>
The menu handle is the handle to the popup menu that the MDI client will add items to
representing each window that is created, allowing the user to select the window they want
to activate from the menu, we'll add functionality shortly to handle this case. In this example
it's the 3rd popup (index 2) since I've added Edit and Window to the menu after File.
<P>
<CODE>ccs.idFirstChild</CODE> is a number to use as the first ID for the items
the Client adds to the Window menu... you want this to be easily
distinguishable from your own menu identifiers so you can handle your menu commands
and pass the Window menu commands to <CODE>DefFrameProc()</CODE> for processing. In the
example I specify an identifier defined as <CODE>50000</CODE>, high enough that I know none
of my menu command id's will be above it.
<P>
Now to get this menu to work properly we need to add some special handling to our
<CODE>WM_COMMAND</CODE> handler:
<PRE CLASS="SNIP">
case WM_COMMAND:
switch(LOWORD(wParam))
{
case ID_FILE_EXIT:
PostMessage(hwnd, WM_CLOSE, 0, 0);
break;
// ... handle other regular IDs ...
// Handle MDI Window commands
default:
{
if(LOWORD(wParam) >= ID_MDI_FIRSTCHILD)
{
DefFrameProc(hwnd, g_hMDIClient, msg, wParam, lParam);
}
else
{
HWND hChild = (HWND)SendMessage(g_hMDIClient, WM_MDIGETACTIVE,0,0);
if(hChild)
{
SendMessage(hChild, WM_COMMAND, wParam, lParam);
}
}
}
}
break;
</PRE>
<P>
I've added a <CODE>default:</CODE> case which will catch all commands that I didn't process
directly and do a check to see if the value is greater than or equal to <CODE>ID_MDI_FIRSTCHILD</CODE>.
If it is, then the user has clicked on one of the Window menu items and we send
the message on to <CODE>DefFrameProc()</CODE> for processing.
<P>
If it isn't one of the Window
IDs then I get the handle to the active child window and forward the message
to it for processing. This allows you to delegate responsibility to the Child
windows for performing certain actions, and allows different child windows
to handle commands in different ways if so desired. In the example I only
handle commands that are global to the program in the Frame window procedure,
and send the commands which affect a certain document or child window on to the
child window itself for processsing.
<P>
Since we're building on the last example, the code to size the MDI client is the same as
the code to resize the edit control in the last example, that takes into account the size
and position of the tool and status bars so they don't overlap the MDI client window.
<P>
We also need to modify our message loop a little...
<PRE CLASS="SNIP">
while(GetMessage(&Msg, NULL, 0, 0))
{
if (!TranslateMDISysAccel(g_hMDIClient, &Msg))
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
}
</PRE>
We've added an extra step (<CODE>TranslateMDISysAccel()</CODE>), that checks for the
pre-defined accelerator keys, Ctrl+F6 which swtiches to the next window, Ctrl+F4 which closes the Child
and so on. If you don't add in this check you will annoy your users by not
providing the standard behaviour they've gotten used to, or you'll have to
implement it manually.
<H3>Child Window Class</H3>
In addition to the main window of the program (the Frame window) we need to create new
window classes for each type of child window we want. For example you might have one
to display text, and one to display a picture or graph. In this example we'll only
be creating one child type, which will be just like the editor program in the previous
examples.
<PRE CLASS="SNIP">
BOOL SetUpMDIChildWindowClass(HINSTANCE hInstance)
{
WNDCLASSEX wc;
wc.cbSize = sizeof(WNDCLASSEX);
wc.st
基于C++的WIN32 API
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Win32API学习资料(C++)，很好.zip （45个子文件） 
tutorial 
window_click.html 9KB animation.html 9KB simple_window.html 16KB errors.html 6KB app_two.html 11KB dlgfaq.html 7KB modeless_dialogs.html 7KB resources.html 7KB transparency.html 11KB fonts.html 14KB references.html 4KB start.html 7KB resnotes.html 4KB msvc.html 3KB app_one.html 7KB dialogs.html 10KB bitmaps.html 13KB bcpp.html 6KB images 
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zerocleaner2012-11-18这是基于C的，还有些汇编。但是还能用，谢谢分享。- tyuck2012-10-15很详细，找到我需要的
