JSctypes: Difference between revisions

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Revision as of 07:45, 22 October 2009

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Updated the link to the devmo page

Kirschkern

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+{{Note|This article is outdated. See the devmo pages for the current version.https://developer.mozilla.org/en/JavaScript_code_modules/ctypes.jsm}}
 == Overview ==
@@ Line 16: / Line 18: @@
 <pre>
-const nsINativeTypes = Components.interfaces.nsINativeTypes;
+/* Load JS Ctypes Javascript module */
-const MB_OK = 3;
+Components.utils.import("resource://gre/modules/ctypes.jsm");
-function messageBox() {
+/* Load windows api dll */
-  // create the XPCOM js-ctypes instance
+var lib = ctypes.open("C:\\WINDOWS\\system32\\user32.dll");
-  var library = Components.classes["@developer.mozilla.org/js-ctypes;1"]
-                          .createInstance(nsINativeTypes);
+/* Declare the signature of the function we are going to call */
+var msgBox = lib.declare("MessageBoxW",
+                         ctypes.stdcall_abi,
+                         ctypes.int32_t,
+                         ctypes.int32_t,
+                         ctypes.ustring,
+                         ctypes.ustring,
+                         ctypes.int32_t);
+var MB_OK = 3;
+/* Do it! */
+var ret = msgBox(0, "Hello world", "title", MB_OK);
+/* Display the returned value */
+alert("MessageBox result : "+ret);
+lib.close();
+</pre>
-  // load the native shared library
+Instead of defining the whole path, you may also just give the file name.
-  library.open("user32.dll");
-  // declare the native method
+<pre>
-  var msgBox = library.declare("MessageBoxW",           /* function name */
+var lib = ctypes.open("user32.dll");
-                               nsINativeTypes.STDCALL,  /* call type */
+</pre>
-                               nsINativeTypes.INT32,    /* return type */
-                               nsINativeTypes.INT32,    /* arg 1 */
-                               nsINativeTypes.WSTRING,  /* arg 2 */
-                               nsINativeTypes.WSTRING,  /* arg 3 */
-                               nsINativeTypes.INT32);   /* arg 4 */
-  // call the native method
+Or even without the extension.
-  var ret = msgBox(0, "This is the coolest message", "My Title", MB_OK);
-  // test the return value
+<pre>
-  alert(ret);
+var lib = ctypes.open("user32");
-}
 </pre>
+If the full path is not given, Windows uses the following search order to locate the DLL:
+#The current directory of the task that is using the DLL.
+#The \WINNT directory.
+#The \WINNT\SYSTEM directory.
+#The \WINNT\SYSTEM32 directory.
+#The directory of the executable for the task that is using the DLL.
+#A directory listed in the PATH environment variable.
+(taken from http://support.microsoft.com/kb/164501/)
 {{Note|This functionality cannot be accessed from JavaScript used in web content. Only JavaScript that runs with chrome privileges (extensions and Firefox UI for example) can use js-ctypes.}}