wtl for mfc programmers, part v.mht

大家知道wtl是window UI库

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      <DIV id=3Dcontentdiv><!-- Article Starts -->
      <UL class=3Ddownload>
        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/WTL4MFC5/WTL4MFC5_demo.zip">Downlo=
ad=20
        demo project - 81 KB</A> </LI></UL><!-- Add the rest of your =
HTML here -->
      <H2>Contents</H2>
      <UL>
        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#intro">Introduction =
to=20
        Part V</A>=20
        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#specialized">Speciali=
zed=20
        Owner Draw and Custom Draw Classes</A>=20
        <UL>
          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#cownerdraw">COwnerDra=
w</A>=20

          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#ccustomdraw">CCustomD=
raw</A>=20
          </LI></UL>
        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#newwtlctrls">New WTL =

        Controls</A>=20
        <UL>
          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#newcbitmapbutton">CBi=
tmapButton</A>=20

          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#cchecklist">CCheckLis=
tViewCtrl</A>=20

          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#treeex">CTreeViewCtrl=
Ex=20
          and CTreeItem</A>=20
          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#chyperlink">CHyperLin=
k</A>=20
          </LI></UL>
        <LI><A =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#uiupdctrl">UI=20
        Updating Dialog Controls</A>=20
        <LI><A =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#ddv">DDV</A>=20
        <UL>
          <LI><A=20
          =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#ddvfail">Handling=20
          DDV failures</A> </LI></UL>
        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#resizing">Resizing=20
        Dialogs</A>=20
        <LI><A =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#upnext">Up=20
        Next</A>=20
        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#references">Reference=
s</A>=20

        <LI><A=20
        =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#revisionhistory">Revi=
sion=20
        History</A> </LI></UL>
      <H2><A name=3Dintro></A>Introduction to Part V</H2>
      <P>In the last article, we saw some of WTL's features relating to =
dialogs=20
      and controls that worked like the corresponding MFC classes. In =
this one,=20
      we'll cover some new WTL classes that implement some more advanced =
UI=20
      features: Owner draw and custom draw, new WTL controls, UI =
updating, and=20
      dialog data validation (DDV).</P>
      <H2><A name=3Dspecialized></A>Specialized Owner Draw and Custom =
Draw=20
      Classes</H2>
      <P>Since owner drawn and custom drawn controls are so common in =
GUI work,=20
      WTL provides mix-in classes that handle some of the grunt work. =
We'll=20
      cover each of them next, as we start on the sequel to the last =
sample=20
      project, ControlMania2. If you are following along by creating a =
project=20
      with the AppWizard, be sure to make this dialog modeless. It has =
to be=20
      modeless in order for UI updating to work properly. I'll give more =
details=20
      on this in the <A=20
      =
href=3D"http://www.codeproject.com/wtl/wtl4mfc5.asp#uiupdctrl">section =
on UI=20
      updating</A>.</P>
      <H3><A name=3Dcownerdraw></A>COwnerDraw</H3>
      <P>Owner drawing involves handling up to four messages:=20
      <CODE>WM_MEASUREITEM</CODE>, <CODE>WM_DRAWITEM</CODE>,=20
      <CODE>WM_COMPAREITEM</CODE>, and <CODE>WM_DELETEITEM</CODE>. The=20
      <CODE>COwnerDraw</CODE> class, defined in atlframe.h, simplifies =
your code=20
      since you don't need messages handlers for all those messages. =
Instead,=20
      you chain messages to <CODE>COwnerDraw</CODE>, and it calls =
overridable=20
      functions that you implement in your class.</P>
      <P>How you chain messages depends on whether you are reflecting =
messages=20
      to the control or not. Here is the <CODE>COwnerDraw</CODE> message =
map,=20
      which will make the distinction clear:</P><PRE><SPAN =
class=3Dcpp-keyword>template</SPAN> &lt;<SPAN =
class=3Dcpp-keyword>class</SPAN> T&gt; <SPAN =
class=3Dcpp-keyword>class</SPAN> COwnerDraw
{
<SPAN class=3Dcpp-keyword>public</SPAN>:
  BEGIN_MSG_MAP(COwnerDraw&lt;T&gt;)
    MESSAGE_HANDLER(WM_DRAWITEM, OnDrawItem)
    MESSAGE_HANDLER(WM_MEASUREITEM, OnMeasureItem)
    MESSAGE_HANDLER(WM_COMPAREITEM, OnCompareItem)
    MESSAGE_HANDLER(WM_DELETEITEM, OnDeleteItem)
  ALT_MSG_MAP(<SPAN class=3Dcpp-literal>1</SPAN>)
    MESSAGE_HANDLER(OCM_DRAWITEM, OnDrawItem)
    MESSAGE_HANDLER(OCM_MEASUREITEM, OnMeasureItem)