5.3   Layouts

When you double-click a disk image, Mac OS X mounts it and opens a Finder window showing its top-level contents. Layouts let you control the appearance of this window: the window position, background picture, view options, and icon positions. Additionally, when you create a disk image with a layout, DropDMG sets it to automatically open the window when mounting the image or inserting a disc burned from the image.

Use the + button to create a new layout and the - button or the Delete key to remove one. Several commands are available in the action menu and contextual menu:

Duplicate Layout

Create a new layout that matches the selected one.

Rename Layout

Change the name of the selected layout. You can also click-and-hold on the name or press the Return or Enter key.

The middle portion of the window shows a preview of the selected layout. You can drag and drop to rearrange the icons. By default, DropDMG uses a 16×16 grid so that the icons are aligned with one another. To drag an icon to any position, unconstrained by the grid, hold down the Command key. You can also move the selected icons one pixel at a time by pressing the arrow keys.

It is common for a disk image to contain a link to the user’s Applications folder. This makes it possible to install an application by dragging its icon onto the Applications icon in the same window. To create this type of link, drag your Applications folder into the layout. The name will appear in oblique text. When you create a disk image using the layout, DropDMG will automatically add a symlink to the Applications folder.

Window position

This controls the position of the upper left corner of the window, relative to the upper left corner of the user’s main display (i.e. the Apple menu).

Background image

Set the background image by dragging an image file onto the well or by clicking the Choose… button. The background image determines the size of the layout. If you do not specify a background image, DropDMG uses a plain white background with dimensions 640×480.

Note: It is recommended that you design your background image such that it looks good if the bottom 43 pixels are hidden. This is because Mac OS X does not allow the disk image to control whether the window’s status bar (20 pixels) or path bar (23 pixels) are shown, and the bars consume space that would otherwise be available for the window’s content. DropDMG sets the window size such that, if the user has the bars turned off, the Finder will show the full background image; if both the bars are turned on, the Finder will show all but the bottom 43 pixels.

Tip: Use a background picture that’s 72×72 dpi to ensure that the icon positions in DropDMG and the Finder line up.

Text boxes

Click Add Text to create text boxes that are drawn atop the background image. Click once on a text box to resize it. Double-click to edit its contents. After selecting some text, you can use the Fonts panel to set the font, style, color, and shadow. The ruler lets save favorite styles and adjust the spacing and alignment (left, center, full, or right) of the text.

The Variables pop-down menu lets you add placeholders that DropDMG will fill in when you build the disk image, so that you don’t have to manually update the text in your layout. The supported variables are Application Name (e.g. DropDMG), Application Short Version String (the marketing version from CFBundleShortVersionString), Application Version (the build number from CFBundleVersion), and Date (YYYY-MM-DD) (e.g. the date the disk image was created).

Icon positions

To add an icon to the layout, drag and drop a file or folder or click the Add Icon… button. The files/folders that you choose here are only used for the purposes of designing the layout, i.e. specifying where each icon goes. The actual contents of the disk image are determined by which source folder you drag onto DropDMG.

Tip: This makes it possible to reuse layouts in some interesting ways. For example, you can use the same layout to create disk images with different contents. The layout can contain more icons than are present in any given source folder.

Icon size

The icons can be displayed at 16×16, 32×32, 48×48, 64×64, or 128×128.

Text size

The text size can vary from 10 to 16 point.

DropDMG automatically saves the layouts that you create. You can also create copies of the layouts outside DropDMG, as described in the Sharing Licenses and Layouts section.

Note: With the Mac OS X 10.6 Finder, Apple changed the file format that it uses to save a folder’s view options. Previous versions of Mac OS X do not know how to fully read the new format. This means that disk images created on Mac OS X 10.6 (using either the Finder or DropDMG) may not appear exactly as intended when using Mac OS X 10.4 or 10.5. To deploy a disk image for previous versions of Mac OS X, you may wish to create the disk image using DropDMG on Mac OS X 10.5. Another option is to create a read-write disk image, manually tweak its view options on Mac OS X 10.5, and then use DropDMG to convert it to a final format.

Note: There seems to be a bug in Mac OS X 10.6 that prevents background pictures from being set if you have FileVault enabled.