Adobe 38040334 Extending Dreamweaver - Page 155

canAcceptCommand

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DREAMWEAVER CS3 149 Extending Dreamweaver The key attribute defines keyboard shortcut keys that the user can type to invoke the menu item. The file attribute specifies the name of the command file that Dreamweaver executes when Dreamweaver invokes the menu item. The value of the arguments attribute defines the arguments that Dreamweaver will pass when it calls the receiveArguments() function. The following figure shows these menu items: Writing the JavaScript code When the user selects either Undo or Redo on the MyMenu menu, Dreamweaver calls the MyMenu.htm command file, which is specified by the file attribute of the menuitem tag. Create the MyMenu.htm command file in the Dreamweaver Configuration/Menus folder and add the three menu command API functions, canAcceptCommand(), receiveArguments(), and setMenuText(), to implement the logic associated with the Undo and Redo menu items. The following sections describe these functions. canAcceptCommand() Dreamweaver calls the canAcceptCommand() function for each menu item in the MyMenu menu to determine whether it should be enabled or disabled. In the MyMenu.htm file, the canAcceptCommand() function checks the value of arguments[0] to determine whether Dreamweaver is processing a Redo menu item or an Undo menu item. If the argument is "undo", the canAcceptCommand() function calls the enabler function dw.canUndo() and returns the returned value, which is either true or false. Likewise, if the argument is "redo", the canAcceptCommand() function calls the enabler function dw.canRedo() and returns its value to Dreamweaver. If the canAcceptCommand() function returns the value false, Dreamweaver dims the menu item for which it called the function. The following example shows the code for the canAcceptCommand() function: function canAcceptCommand() { var selarray; if (arguments.length != 1) return false; var bResult = false; var whatToDo = arguments[0]; if (whatToDo == "undo") { bResult = dw.canUndo(); } else if (whatToDo == "redo") { bResult = dw.canRedo(); } return bResult; }

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DREAMWEAVER CS3
Extending Dreamweaver
149
<menuitem name="MyUndo" key="Cmd+Z" file="Menus/MyMenu.htm" arguments="'undo'"
id="MyMenu_Edit_Undo" />
<menuitem name="MyRedo" key="Cmd+Y" file="Menus/MyMenu.htm" arguments="'redo'"
id="MyMenu_Edit_Redo" />
</menu>
The
key
attribute defines keyboard shortcut keys that the user can type to invoke the menu item. The
file
attribute
specifies the name of the command file that Dreamweaver executes when Dreamweaver invokes the menu item. The
value of the
arguments
attribute defines the arguments that Dreamweaver will pass when it calls the
receiveArguments()
function.
The following figure shows these menu items:
Writing the JavaScript code
When the user selects either Undo or Redo on the MyMenu menu, Dreamweaver calls the MyMenu.htm command
file, which is specified by the
file
attribute of the
menuitem
tag. Create the MyMenu.htm command file in the
Dreamweaver Configuration/Menus folder and add the three menu command API functions,
canAcceptCommand()
,
receiveArguments()
,
and
setMenuText()
, to implement the logic associated with the
Undo and Redo menu items
.
The following sections describe these functions.
canAcceptCommand()
Dreamweaver calls the
canAcceptCommand()
function for each menu item in the MyMenu menu to determine
whether it should be enabled or disabled. In the MyMenu.htm file, the
canAcceptCommand()
function checks the
value of
arguments[0]
to determine whether Dreamweaver is processing a Redo menu item or an Undo menu item.
If the argument is
"undo"
, the
canAcceptCommand()
function calls the enabler function
dw.canUndo()
and returns
the returned value, which is either
true
or
false
. Likewise, if the argument is
"redo"
, the
canAcceptCommand()
function calls the enabler function
dw.canRedo()
and returns its value to Dreamweaver. If the
canAcceptCommand()
function returns the value
false
, Dreamweaver dims the menu item for which it called the
function. The following example shows the code for the
canAcceptCommand()
function:
function canAcceptCommand()
{
var selarray;
if (arguments.length != 1) return false;
var bResult = false;
var whatToDo = arguments[0];
if (whatToDo == "undo")
{
bResult = dw.canUndo();
}
else if (whatToDo == "redo")
{
bResult = dw.canRedo();
}
return bResult;
}