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<HTML><LINK HREF="style.css" REL="STYLESHEET" TYPE="text/css"><HEAD><TITLE>Tutorial: Using Resources</TITLE></HEAD><BODY><FONT SIZE="-1">[ <A HREF="./index.html">contents</A>| <A HREF="http://www.winprog.org/">#winprog</A>]</FONT><HR><H1>Using Resources</H1><P>You may also want to refer to the Appendices at the end of this tutorial for more information on resources with VC++ and BC++.<P>Before we get any deeper I will cover the topic of resources so that I won'thave to re-write it for each section.<B>Youdon't actually need to compile the stuff in this section, it's as example only.</B><P>Resources are pre-defined bits of data stored in binary format inside yourexecutable file. You create resources in a resources script, a file withan extension of ".rc". comercial compilers will have a visual resourceeditor which allows you to create resources without manually editing thisfile but sometimes editing it is the only way to go, especially if your compilerhas no visual editor, it sucks, or doesn't support the exact feature you need. <P>Unfortunately different compiler suites handle resources differently. I willdo the best I can to explain the common features needed to work with resourcesin general.<P>The resource editor included with MSVC++ makes it very difficult to edit the resources manually, since it enforces a proprietary format on them, and will totally mangle thefile if you save one that you had created by hand. In general you shouldn't bother withcreating .rc files from scratch, but knowing how to modify them manually can be very useful.Another annoyance is that MSVC++ will by default name the resource header file "resource.h"even if you wanted to call it something else. I will go with this for the sake of simplicityin this document, but will show you how to change this in the appendix on compilers.<P>First lets take a very simple resource script, with a single icon.<PRE CLASS="LIST">#include "resource.h"IDI_MYICON ICON "my_icon.ico"</PRE><P>That's the entire file. <CODE>IDI_MYICON</CODE> is the identifier of the resource, <CODE>ICON</CODE> is the typeand "my_icon.ico" is the name of the external file which contains it. Thisshould work on any compiler.<P>Now what about this <CODE>#include "resource.h"</CODE> ? Well your program needs a way toidentify the icon, and the best way to do that is to assign it a unique ID (<CODE>IDI_MYICON</CODE>). We can do this by creating the file "resource.h" and including it in both our resource script, and oursource file.<PRE CLASS="LIST">#define IDI_MYICON 101</PRE><P>As you can see, we've assigned <CODE>IDI_MYICON</CODE> the value of <CODE>101</CODE>. We could just forget about the identifier and use <CODE>101</CODE> wherever we needto reference the icon, but <CODE>IDI_MYICON</CODE> is a lot clearer as to what youare refering too, and easier to remember when you have large number of resources.<P>Now lets say we add a <CODE>MENU</CODE> resource:<PRE CLASS="LIST">#include "resource.h"IDI_MYICON ICON "my_icon.ico"IDR_MYMENU MENUBEGIN POPUP "&File" BEGIN MENUITEM "E&xit", ID_FILE_EXIT ENDEND</PRE>Again <CODE>IDR_MYMENU</CODE> is the name of the resource and <CODE>MENU</CODE> is the type. Now a fine point, see the <CODE>BEGIN</CODE> and <CODE>END</CODE> up there? Some resource editors or compilers use <CODE>{</CODE> in placeof <CODE>BEGIN</CODE> and <CODE>}</CODE> in place of <CODE>END</CODE>. If your compiler supports both feel free to pick which one you use. If it only supports one or the other, you will need to make the necessary replacements to get it to work.<P>We've also added a new identifier, <CODE>ID_FILE_EXIT</CODE>, so we need to add this to ourresource header file, resource.h, in order to use it in our program.<PRE CLASS="LIST">#define IDI_MYICON 101#define ID_FILE_EXIT 4001</PRE><P>Generating and keeping track of all these ids can become a real chore with large projects,that's why most people use a visual resource editor which takes care of all this for you.They still screw up from time to time, and you could end up with multiple items withthe same ID or a similar problem, and it's good to be able to go in and fix it yourself.<P>Now an example of how to use a resource in your program.<PRE CLASS="SNIP"> HICON hMyIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_MYICON));</PRE>The first parameter of <CODE>LoadIcon()</CODE> and many other resource using functions is thehandle to the current instance (which we are given in <CODE>WinMain()</CODE> and can also be retreived byusing <CODE>GetModuleHandle()</CODE> as demonstrated in previous sections). Thesecond is the identifier of the resource.<P>You're probably wondering what's up with <CODE>MAKEINTRESOURCE()</CODE> and possibly wonderingwhy <CODE>LoadIcon()</CODE> takes a parameter of type <CODE>LPCTSTR</CODE> instead of say <CODE>UINT</CODE>when we're passing it an ID. All <CODE>MAKEINTRESOURCE()</CODE> does is cast from an integer (what our ID is) to <CODE>LPCTSTR</CODE>, which <CODE>LoadIcon()</CODE> expects. This brings usto the second way of identifying resources, and that's with strings. Almost nobody does thisany more, so I won't go into details, but basically if you don't use #define to assign an integervalue to your resources then the name is interpreted as a string, and can be referenced inyour program like this:<PRE CLASS="SNIP"> HICON hMyIcon = LoadIcon(hInstance, "MYICON");</PRE><P><CODE>LoadIcon()</CODE> and other resource loading APIs can tell the difference between aninteger passed in and a pointer to a string passed in by checking the high word of the value.If it's <CODE>0</CODE> (as would be the case of any integer with a value less than or equalto 65535) then it assumes it is a resource ID. This effectively limits your resources tousing IDs below 65535, which unless you have a whole lot of resources, should not be a problem.If it's not <CODE>0</CODE> then it assumes the value is a pointer, and looks up the resourceby name. Never rely on an API to do this unless it is explicitely stated in the documentation.<P>For example, this doesn't work for menu commands like <CODE>ID_FILE_EXIT</CODE>, since they can only be integers.<HR><FONT SIZE="-1">Copyright © 1998-2003, Brook Miles (<A HREF="mailto:forger(nospam)winprog.org">theForger</A>). All rights reserved.</FONT><SCRIPT language="JavaScript"><!-- var re = /\(nospam\)/ig; var str; for(i = 0;i < document.links.length;i++) { str = "" + document.links(i).href; if(str.search(re) != -1) document.links(i).href = str.replace(re, "@"); str = "" + document.links(i).innerHTML; if(str.search(re) != -1) document.links(i).innerHTML = str.replace(re, "@"); }--></SCRIPT></BODY></HTML>?? 快捷鍵說明
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