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WindowsCE.[Essential Windows CE Application Programming].Jon Wiley & Son.zip

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<B>Essential Windows CE Application Programming</B>
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<I>(Publisher: John Wiley & Sons, Inc.)</I>
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Author(s): Robert Burdick
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ISBN: 0471327476
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Publication Date: 03/01/99
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<P><BR></P>
<P>The general syntax of a menu resource is shown below. Items in uppercase are required keywords. Items in italics are supplied by the application programmer. Items in square brackets are optional values.
</P>
<!-- CODE //-->
<PRE>
  MenuName MENU [DISCARDABLE]
  BEGIN
    POPUP SubMenu1Name [, options]
     BEGIN
      MENUITEM MenuItemName, id [, options]
      ... //More MENUITEMs
     END
    POPUP SubMenu2Name [, options]
     BEGIN
      MENUITEM MenuItemName, id [, options]
      ...
     END
  END
</PRE>
<!-- END CODE //-->
<P><I>MenuName</I> is the name of the menu. Generally this is a resource identifier, but it can be a string menu name.</P>
<P>The optional DISCARDABLE keyword tells Windows CE that the menu resource can be discarded from memory automatically when no longer needed.</P>
<P>The POPUP keyword indicates that a new submenu is being defined. These POPUP definitions define the individual submenus. <I>SubMenu1Name</I>, <I>SubMenu2Name</I>, etc. are the names of the submenus. In the example in Figure 4.1, these would be &#147;&#38;File&#148; and &#147;&#38;Options&#148;.</P>
<P>Cascading menus can be defined by nesting submenus within other submenus.</P>
<P>The MENUITEM keyword inserts a new item in the submenu. The <I>MenuItemName</I> values represent the individual pull-down menu choices.</P>
<P><I>id</I> is the <I>command identifier</I> for the particular menu item. The use of this identifier is described in the next section, where we describe how applications respond to menu item selections.</P>
<P>The menu resource identifier and menu item command identifiers are typically defined in the application&#146;s RESOURCE.H file.</P>
<P>Various options can be specified for submenus and for menu items. More than one of these options can be specified by bitwise-ORing them together. For submenus, these option include:</P>
<DL>
<DD><B>GRAYED.</B> The text is grayed; the menu is inactive, and does not generate WM_COMMAND messages.
<DD><B>INACTIVE.</B> The text is displayed normally, but the menu is still inactive. No WM_COMMAND messages are generated.
<DD><B>MENUBREAK.</B> This option is supported, but has no effect in the context of menus in command bars.
<DD><B>HELP.</B> This option is supported, but has no effect in the context of menus in command bars.
</DL>
<P>Menu item options include the following:
</P>
<DL>
<DD><B>CHECKED.</B> Places a check mark to the left of the menu item text.
<DD><B>GRAYED.</B> Same meaning as for submenus; see the list above.
<DD><B>INACTIVE.</B> Same meaning as for submenus; see the list above.
<DD><B>MENUBREAK.</B> The menu item and all items that follow appear in a new column in the menu.
<DD><B>MENUBARBREAK.</B> Same as MENUBREAK, except that a vertical line separates the menu columns.
</DL>
<P>As an example, here is the menu resource definition for the cascading menu shown in Figure 4.2:
</P>
<!-- CODE //-->
<PRE>
  IDR_MENU MENU DISCARDABLE
  BEGIN
    POPUP "&#38;File"
     BEGIN
      MENUITEM "&#38;Exit",  IDC_EXIT
    END
    POPUP "&#38;Options"
     BEGIN
      MENUITEM "&#38;Empty Combo Box",  IDC_EMPTY
      MENUITEM "&#38;Fill Combo Box"   IDC_FILL
       POPUP "&#38;Cascade"
        BEGIN
         MENUITEM "Cascade Menu Item 1", IDC_SUBITEM1
         MENUITEM SEPARATOR
         MENUITEM "Cascade Menu Item 2", IDC_SUBITEM2
        END
     END
  END
</PRE>
<!-- END CODE //-->
<P><FONT SIZE="+1"><B>Responding to Menu Items</B></FONT></P>
<P>The usefulness of menus comes from the ability to map the various menu items in a menu to actions. This is done by assigning a command identifier to each of the menu items that an application is meant to respond to. The previous section described how a command identifier is assigned to a menu item.
</P>
<P>This command identifier performs the same role as control identifiers for Windows CE controls. Specifically, whenever a menu item is selected, Windows CE sends a WM_COMMAND message to the parent of the command bar control. The low word of the <I>wParam</I> parameter contains the menu item identifier. The WM_COMMAND message notification code is zero, indicating that the message is sent as a result of a menu item selection.</P>
<H3><A NAME="Heading5"></A><FONT COLOR="#000077">Creating a Command Bar</FONT></H3>
<P>Creating a command bar control is a little different from creating other Windows CE controls. Instead of using <I>CreateWindow</I> or <I>CreateWindowEx</I> as when creating child and common controls, Windows CE provides a separate API for creating and working with command bar controls.</P>
<P>To create a command bar control, an application calls <I>CommandBar_Create</I>:</P>
<!-- CODE SNIP //-->
<PRE>
  CommandBar_Create(hInst, hwndParent, idCmdbar);
</PRE>
<!-- END CODE SNIP //-->
<P>This function is a wrapper for the <I>CreateWindow</I> call that ultimately creates the actual command bar window. <I>hInst</I> is the application instance of the application in which the control is being created. <I>hwndParent</I> is the command bar&#146;s parent window. <I>idCmdBar</I> is the control identifier of the command bar.</P>
<P>If <I>CommandBar_Create</I> is successful, it returns the HWND of the newly created command bar control. Otherwise the function returns NULL. Thus creating a command bar is semantically similar to creating any other Windows CE window or control.</P>
<P>Creating the command bar control is only the beginning. The command bar in Figure 4.1 contains a menu and various child controls. After calling <I>CommandBar_Create</I>, your application is left with nothing more than the HWND of an empty command bar control.</P>
<P>Adding useful things like menus and buttons to a command bar control requires using the various <I>CommandBar_Insert</I> functions.</P><P><BR></P>
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