| Certain applications that support the creation of multilayered documentssuch as Microsoft Visio, Autodesk AutoCAD, Microsoft Project, Adobe InDesign CS, and Adobe Illustrator CScan convert to PDF with layers intact. Layers are useful in many ways. You might view a drawing of a house plan where you want to show or hide a dimension grid, wiring diagrams, furniture, subwalls, or other data contained on separate layers. You might view a brochure or advertisement designed for multilingual purposes where the layout and design remain static as you turn on and off different layers of text created for different languages. You can view and print PDFs with some layers hidden and other layers visible. You'll know that a document contains layers if the Layers tab automatically appears in the Navigation pane when you open the file in Adobe Reader. For more information on using tabs in the Navigation pane, see Chapter 5, "Navigating PDF Documents." | To view a PDF with Adobe PDF Layers, use the oahuBrochure.pdf file, which you can download from www.peachpit.com/adobereader7. |
To view different layers in a PDF document containing Adobe PDF Layers: 1. | Open a file containing Adobe PDF Layers. Click the Layers tab to open the Layers pane if it's not currently open. | 2. | Layers may be collapsed in the Layers pane so that the individual layers are hidden. To expand layers and make them visible, click the icon adjacent to the filename in the Layers pane. In Windows, the icon appears as a + (plus) symbol. On the Macintosh, the icon appears as a right arrow. Click the icon, and the layer names appear in the pane. | 3. | To hide a layer, click the Eye icon for that layer in the Layers pane. If an Eye icon does not appear next to a layer name, the layer is hidden in the Document pane. | 4. | To show a layer, click inside the square next to that layer name. After clicking, an Eye icon appears inside the square (Figure 4.25). Figure 4.25. Click a square next to a layer name to toggle that layer on and off in the Document pane.
| 5. | Open the Options menu by clicking the down arrow in the Layers pane. Additional menu options offer choices for listing all layers according to document or viewed page, applying overrides that result in temporarily locking the layers, and accessing information related to the layer properties. In Adobe Reader you can only view layer properties, not change them. | 6. | To return to initial layer visibility, open the Options menu and select Reset to Initial Visibility (Figure 4.26). Selecting this menu command returns you to the layer visibility that was saved with the original file. Figure 4.26. Select Reset to Initial Visibility to return to the default layer view.
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How are layers helpful? There are many uses for creating PDF documents with Adobe PDF Layers. You can show and hide help information, access alternative views for a proposed design or plan, isolate sections of a document for easier viewing, and more. Rather than creating multiple documents to contain the various views, which may become unwieldy, PDF authors can create a single file with information supporting different alternatives. In Figure 4.25 you see an example of a multilingual brochure. The original design included image and design elements that were used as a background common for all language versions. The text in the file appears in four languages. Clicking on the respective language in the Layers tab while hiding the other language layers shows you how a single document can be used for multiple audiences. Be aware that PDF authors creating layered PDF files intend to have those documents viewed in Adobe Reader version 6 and later. Users of Adobe Reader prior to version 6 will see all layers flattened and quite often won't be able to clearly read the documentespecially when one text layer is stacked on top of each previous layer. |
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