Creating Custom Context Menus in Flash MX 2004

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Macromedia Flash MX 2004 ActionScript: Training from the Source

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The context menu is the menu that appears when you right-click (Control-click on a Macintosh) on a Flash movie.

There are three different types of Flash context menus:

1. The one that appears when you right-click on the anything in a Flash movie except a text field. This is called the standard menu.

2. The one that appears when you right click on a text field that is editable or selectable. This is called the edit menu.

3. The one that appears when a Flash movie fails to load within a web page and you right click in the empty area. This is called the error menu.

Both the standard and edit menus are customizable. The error menu cannot be changed. The context menus can be customized to display new items or remove the built-in default items. All built-in context menu items can be removed except for the Settings item and the Debugger item.

Figure 1 There are two classes built-in to the Flash player which there to assist you in creating a customized context menu:

• The ContextMenu class. This class allows you to create a brand new context menu, hide built-in menu items (Zoom In, Zoom Out, 100%, Play, Stop, etc.), and keep track of customized items.

• The ContextMenuItem class. Each item in a context menu is an instance of this class. The ContextMenu class has a property (array) called customItems. Each element in that array is an instance of the ContextMenuItem class.

The ContextMenu class and the ContextMenuItem class are used together to build custom context menus.

Figure 2 When creating a new instance of the ContextMenu class you can specify a function to be called when that ContextMenu is displayed.

var myContextMenu:ContextMenu = new ContextMenu(menuHandler);

Just before the context menu appears the menuHandler() function is executed. As a result of the function executing before the menu actually appears, script within the function can be used to evaluate certain conditions within the application, and items on a context menu can be dynamically added, removed, enabled, or disabled. For example, a "Save" item may be disabled if nothing has changed since the last time the user saved.

You can dynamically change the function a context menu calls before it appears, by redefining its onSelect event handler. For example:

myContextMenu.onSelect = anotherFunction;

As a result of this script, myContextMenu will now call anotherFunction() when it is selected (before it appears) instead of menuHandler(), as was defined when the ContextMenu object was initially created.

When creating custom context menus, you may wish to remove the default items that appear. To hide the built-in items in a context menu you must call the hideBuitInItems() method:

myContextMenu.hideBuiltInItems();

All built-in items will be hidden from the context menu except the Settings and Debugger items. Also, in editable text fields, the standard items such as Cut, Copy, Paste, Delete, and Select All are not removable.

Instances of the ContextMenu class have only one property, customItems. This is an array that stores the custom ContextMenuItem objects that form the custom items that appear on the menu. To add a custom item to a ContextMenu object, you must add it to the customItems array for that object:

myContextMenu.customItems.push(new ContextMenuItem("Next Page",
 nextPageHandler));

This adds a new ContextMenuItem object to the customItems array of the myContextMenu object. The first parameter is the text that will be displayed in the menu. The second parameter is the callback function for that item. When the item is selected from the context menu, the callback function (nextPageHandler()) is called.

Figure 3 Custom menu items in a context menu can be referenced like this:

myContextMenu.customItems[0] // first custom menu item
myContextMenu.customItems[1] // second custom menu item
myContextMenu.customItems[2] // third custom menu item

Knowing this, you can enable and disable menu items dynamically:

myContextMenu.customItems[1].enabled = false;
myContextMenu.customItems[3].enabled = false;

Disabled menu items will still appear on the custom context menu, but they will appear grayed-out and will not function when clicked. Menu items are enabled by default.

You can dynamically change the function a context menu item calls when it is selected, by redefining its onSelect event handler. For example:

myContextMenu.customItems[0].onSelect = differentCallbackFunction;

To use a custom context menu, it has to be assigned to a particular movie clip, button, or text field instance. Doing so will cause that custom menu to appear when the instance is right-clicked. Here's the syntax:

myClip_mc.menu = myContextMenu;

When the mouse is right-clicked while above the myClip_mc movie clip instance, the myContextMenu context menu will be displayed.

When using custom context menus, it's important to be aware that the timeline with the highest depth always captures the right-click mouse event, which causes its custom menu to be displayed. For example, if two movie clips are overlapping and each has a custom context menu associated with it, then the one that is at a higher depth is the one whose menu will be shown when the mouse is right-clicked above it. This goes for the main timeline too. If the mouse is not over a movie clip that has a custom menu but the main timeline (_root) does, then its menu will be displayed.

In this exercise you will create a custom context menu with several custom item used to print and manage the contents of an editable text field.

1) Open ContextMenu1.fla.

This file has three layers, Background, Text Field, and Actions.. The Background layer contains the graphics for the project. The Text Field layer contains an input text field instance with a name of entry_txt. Frame 1 of the Actions layer is where you will add the ActionScript for this project.

When complete, you will be able to add text to the editable text field, and then right-click to either print, delete or reformat the text.

2) Select frame 1 in the Actions layer, open the Actions panel, and add this line of ActionScript to create a new instance of the ContextMenu class

var myContextMenu:ContextMenu = new ContextMenu(menuHandler);

This code creates a new instance of the ContextMenu class named myContextMenu. This custom context menu will eventually be associated with the entry_txt text field, so that when the mouse is right-clicked over that field, this menu (and the menu items we will eventually add to it) will appear. We are going to add three custom items to this menu that will enable the user to:

• Print what's in entry_txt field

• Delete any text in the entry_txt field

• Reformat any text in the entry_txt field so that it's red in color and consists of all uppercase characters.

In the constructor , a reference to a function called menuHandler() is passed in. This function will be called whenever this menu is opened (the user right-clicks on the entry_txt text field). Let's create that function next.

3) Add the menuHandler() function definition below the current script:

function menuHandler() {
 var numberOfItems = myContextMenu.customItems.length;
 if (entry_txt.text.length > 0) {
   for(var i = 0; i < numberOfItems; ++i){
    myContextMenu.customItems[i].enabled = true;
   }
 } else {
   for(var i = 0; i < numberOfItems; ++i){
    myContextMenu.customItems[i].enabled = false;
   }
 }
}

This function will be called just before the myContextMenu menu appears. The purpose of this function is to enable and disable custom items on that menu on-the-fly, depending whether there is currently any text in the entry_txt text field. In other words, if there is text in that field, custom items on our context menu will be enabled, otherwise, if it contains no text, items will be disabled.

The first thing the function does is creates a variable named numberOfItems. The value of this variable is based on the number of custom menu items that have been added to the myContextMenu instance. In the case of this project, that instance will eventually have three items added to it, thus the value of numberOfItems will be 3. The value of this variable will be used in a moment.

Next, a conditional statement is used to evaluate whether the user has entered any text into the entry_txt text field. If the field does contain text, the first part of the statement uses a loop to quickly enable all the custom items on the myContextMenu instance. If no text is found, then all the items are disabled.

Figure 4 After this function has executed, the menu will appear. Let's next add some custom items to the myContextMenu instance:

4) Add this line of script, just below the menuHandler() function:

myContextMenu.customItems.push(new ContextMenuItem("Print Fridge Note",
 printHandler));

This line of script adds a new ContextMenuItem instance to the customItems array of the myContextMenu instance. This defines the first item that will appear when the menu is opened.

The first parameter of the ContextMenuItem constructor method contains the text that we want to appear in the menu representing this item. The second parameter is the callback function that should be executed when the item is selected. This function will be created next.

5) Add this script to define the printHandler() callback function:

function printHandler() {
 var myPrintJob:PrintJob = new PrintJob();
 var result:Boolean = myPrintJob.start();
 if (result) {
   myPrintJob.addPage("entry_txt");
   myPrintJob.send();
 }
 delete myPrintJob;
}

This function is called when Print Fridge Note is selected from the context menu. The first line creates a new instance of the PrintJob class. The second line attempts to initialize the printer. It captures the result of printer initialization. If the printer does not exist or if the user cancels the print request, then the result variable has a value of false. If the user proceeds with the print request then the result variable is set to true.

If result is true, then we use the addPage() method of the PrintJob class to add the entry_txt text field to be printed. The remaining default parameters for the addPage() method are acceptable, so we do not need to set them.

Next, the page is sent to the printer and then the myPrintJob instance is deleted.

Let's add the remaining two items to our custom context menu.

6) Add this script to the end of the current script:

myContextMenu.customItems.push(new ContextMenuItem("Clear Fridge Note", 
clearHandler));
function clearHandler() {
 entry_txt.text = ""
}

This adds another custom item to the customItems array of the myContextMenu instance. Clear Fridge Note will appear as the text for this item, and the clearHandler() function is called when this item is selected. That function is created with the three remaining lines of script. Its only task is to remove any text from the entry_txt text field.

7) Add this script below the current script:

myContextMenu.customItems.push(new ContextMenuItem("Urgent Fridge 
Note", urgentHandler));
function urgentHandler() {
 entry_txt.textColor = 0x990000;
 entry_txt.text = entry_txt.text.toUpperCase();
}

This adds one more custom item to the myContextMenu instance. As you can see, the text for this item is, Urgent Fridge Note, and the function called when this item is selected is named urgentHandler(). This function takes the text entered into the entry_txt field, colors it red, and converts it to all uppercase characters.

8) Add this final line of script:

entry_txt.menu = myContextMenu;

This associates the myContextMenu instance with the entry_txt text field. If the mouse is right-clicked on anything but this text field, then the custom context menu will not be shown. If the mouse is click on the text field, then the custom menu will be displayed.

9) Select Control > Test Movie to test your work. Type into the text field. Bring up the custom context menu and select a custom menu option.

Figure 5 You'll notice that if the text field is blank that the custom menu items are not enabled in the context menu. They are still there, but are not selectable. If the text contains at least character of text, then the menu items become available. This is the result of the menuHandler() function created in Step 3.

10) Close the Test Movie and save your work as ContextMenu2.fla.

This completes the exercise.

As you have learned, custom context menus open up an entirely new way for users to easily interact with your application, without having to manually search for a particular button or control. Be aware that most users are not familiar with this new feature of Flash, so if you do use it, be sure to make them aware of it.