Working with Building Blocks
|Word Developer Reference|
Building blocks in Microsoft Office Word 2007 are similar to autotext entries in previous versions. However, with building blocks, you can organize entries in a way that enables you to determine how a user uses them. A custom building block helps users insert rich content anywhere in a document by using a formatted drop-down list. When used together with content controls, building blocks can enable you to develop powerful solutions very quickly and easily.
The building blocks object model includes three new objects and four new collections. These enable you to create an organizational structure that works for your specific needs and to modify the structure for a specific solution. The new objects and collections are described in the following table.
|BuildingBlock||A specific building block entry.|
|BuildingBlocks||A collection of building block entries in a template that are of the same type and category.|
|BuildingBlockEntries||A collection of all the building blocks in a template.|
|BuildingBlockType||A building block type.|
|BuildingBlockTypes||A collection of building block types.|
|Category||A building block category.|
|Categories||A collection of building block categories.|
Understanding Building Blocks
Building blocks are organized by type and category. Building block types are composed of a limited number of WdBuildingBlockTypes constants. Although there are a limited number of these constants, that number is not small. There are 35 different WdBuildingBlockTypes constants. These types help you to define and organize your building blocks and, although you cannot create additional building block types, you can create an unlimited number of categories for each type.
Categories are composed of an unlimited number of strings that you can define to organize your custom building blocks. Building blocks are stored in templates. By default, the templates that are included with Word 2007 have building block categories like "General" and "Built-In". But you are not limited to just the categories that are included in these templates. A category can be any string that you define. Types and categories are explained in detail later in this topic.
Because you can organize building blocks into types and categories, building blocks can be incredibly flexible. For example, you can have a building block named "Title" that has a type of wdTypeBibliography and a category of "Book Titles" and another building block named "Title" that has a type of wdTypeBibliography and a category of "Movie Titles". And then you can have yet another building block named "Title" that has a type of wdTypeCustomHeaders and a category of "Book Titles". And the list goes on. The incredible flexibility that building blocks provide gives you power to create custom solutions without writing any code.
However, building block are also programmable. You can create new building blocks, delete building blocks, and manage building blocks programmatically. You can also watch for when users insert new building blocks into a document by using the BuildingBlockInsert event. Plus, you can use building blocks with content controls to give you even greater control over which building blocks users can insert into their documents. For example, you can use a building block content control to filter the types of building blocks that a user sees, which means that the user cannot insert a building block into a document that is not allowed at a specific place in the document. There are several examples in the following sections that show you how to use the building block objects to work with building blocks programmatically.
Some Simple Tasks
The following sections provide some very simple examples of how to do specific tasks using the building block objects. You can find additional code examples in the object topics and in many of the member topics.
Creating a Custom Building Block
Creating a custom building block is as simple as using the Add method for the BuildingBlockEntries collection. You can also use the Add method for the BuildingBlocks collection; however, this method may raise a run-time error if there are currently no building blocks for the specified type or category. As explained in the table of objects, the BuildingBlocks collection is a collection of building blocks for a specific type and category. The BuildingBlocksEntries collection contains all the building blocks for a template. Therefore, the preferred way to add new building blocks programmatically is to use the Add method for the BuildingBlockEntries collection.
The following example collapses the current selection, creates a range and specifies the text for the range, and then adds the selection as a custom building block to the collection of building block entries in the template attached to the current document.
Adding a New Category
As mentioned previously, you can add an unlimited number of categories. However, there is no Add method for the Categories collection. Therefore, to add a new category to the collection, you need to add a new building block. For example, in the previous code sample, if the "Book Titles" category does not exist when you run the code, Word adds it to the Categories collection.
Accessing an Existing Building Block
At some point you will want to access one of the building blocks that you have, whether that is a custom building block or one of the built-in building blocks. You could use the BuildingBlockEntries collection; however, because building blocks can share the same name, you would need to identify the type and category for the building block before knowing which one you want returned. Therefore, the best way to access existing building blocks is through the BuildingBlocks collection.
The following example accesses the building block that you added in the previous code sample.
Inserting a Building Block into a Document
After you have access to a building block, use the Insert method of the BuildingBlock object to insert it into a document. The following example expands the previous code sample by adding a line for inserting the building into the active document at the Insertion Point (or for replacing the selected text, if text is selected).
|When you insert a building block by using the Ribbon, Word automatically determines certain things about the building block, such as where to insert it; however, when you insert a buildng block through the object model, none of this built-in intelligence automatically happens. For example, when you insert a header building block by using the Ribbon, Word automatically determines to replace the existing header. When inserting the same header building block by using the object model, you need to explicitly specify where to place the building block text.|
Filtering a List of Building Blocks in a Content Control
If you combine building blocks with content controls, you can filter which building blocks a user can access. You do this using a content control and an event. When a user enters a content control, the ContentControlOnEnter event for the Document object fires. This event has a parameter for the active content control. You can determine whether the content control is a building block content control. If it is, you use the BuildingBlockType property and the BuildingBlockCategory property to identify which type and category to use to filter the list of building blocks that are available for the content control. This specifies which building blocks show up in the drop-down list in the content control header.
The following example assumes that there is at least one content control in the document. If the content control is a building block content control, the list of building blocks displayed in the building block list in the content control header includes only those added by using the AddCustomBuildingBlock subroutine shown earlier in this topic. For more information about content controls, see Working with Content Controls.