Hack 41 Top Screenshot Tips


These screen-capture tips provide built-in and add-on solutions to just about anything you might wish to snap.

Capturing good screenshots in Mac OS X requires some experimentation. If you simply want to capture the screen for reference later on, you can do it easily with the built-in screen-capture tool. However, if you are a professional writer or a student preparing that term paper and need great-looking screen shots, you have to spend a little more time exploring your options.

These screen capture tips provide built-in and add-on solutions to just about anything you might wish to snap.

41.1 Built-Ins

Mac OS X Jaguar comes with a built-in capability for capturing screenshots. To capture the entire screen, simply press figs/command.gif-Shift-3 and a PDF grab of your current view will appear on your desktop. Screenshots are numbered sequentially, such as Picture 1.pdf, Picture 2.pdf, and so on.

To capture a particular region of the screen, type figs/command.gif-Shift-4 and highlight ? using click-and-drag ? whatever portion of the screen you'd like, as shown in Figure 4-26.

Figure 4-26. Capturing a portion of the screen

An extension to region grabbing is snagging a picture of a particular window or dialog box. Press figs/command.gif-Shift-4, then the spacebar; any window you run your mouse over will be highlighted. Click to capture it. You can toggle back and forth between region and window modes by pressing the spacebar.

To change your mind and cancel screen capture, press the Escape (Esc) key on your keyboard.

While the built-in screen-capture tool is good enough for just about all purposes, it has a couple of drawbacks. It doesn't capture the mouse pointer in any of the screenshots ? not even optionally (see Figure 4-27). This is a bust for technical writers explaining the operation of menus, buttons, and so forth. Second, while PDF is the be-all and end-all of all things GUI under Mac OS X, I need my screenshots in PNG or TIFF. Sure, I can convert them using Preview or the like [Hack #51], but that's an extra step I simply shouldn't have to take.

Figure 4-27. The cursor is not captured using screen capture

41.2 Grab

Mac OS X bundles a little utility called Grab (Applications Utilities Grab) which supports three modes of screen capture: screen, selection (a.k.a. region), and timed screen (captures the entire screen after a specific time interval). Unlike its built-in counterpart, Grab saves to TIFF format and optionally includes mouse pointers in its captures; it even allows you to specify a preferred pointer (Grab Preferences), as shown in Figure 4-28.

Figure 4-28. Using the timed screen mode to capture action, mouse pointer included

There is one problem that I noticed with the selection capture. In order to capture an active window using the selection mode, you need to switch to Grab first. Yet doing so makes the window inactive and fall to the background. Now, when I do a selection grab, I want to capture the window in its active state.

The selection grab will also display the size of the image you are capturing at the bottom right corner of the selection region. This is useful if you need to capture images of an exact size. One gripe though: you can't create a region of a particular size and then move it about.

Oddly, while Capture Window is listed, it's grayed out and doesn't appear to be functional.

41.3 Using Snapz Pro X

The ultimate screen-capture utility is Snapz Pro X ($29, $49 with movie-capture support; 30-day demo available) from Ambrosia Software Inc. (http://www.ambrosiasw.com/utilities/snapzprox/). It sports customizability and multiple output formats, and it grabs the screen as you see it, including or excluding that pesky mouse arrow, at will.

Set up your shot and press figs/command.gif-Shift-3 (customizable) to freeze the screen and take care of the details, as shown in Figure 4-29. You can choose the entire screen, objects (windows or icons), or a region, even during Quicktime and DVD movie playback (the built-in screen capture featrure is disabled while DVD Player is active).

Figure 4-29. Taking care of SnapZ Pro X screenshot details

Selection capture, coming after you've set up your screen just the way you like it (see Figure 4-30), allows you to take your time to mark out and alter the region before double-clicking it to take the final shot.

Figure 4-30. Capturing a portion of the screen

Snapz Pro X can even capture the drop-shadows beneath a window. Simply change the Border option under Image Options to Drop Shadow. Prior to Snapz Pro X, I'd always have to switch the background to white to capture the nice shadow around the window without including a slice of my desktop image.

There's so much more to Snapz Pro X ? like recording screen activities as a QuickTime movie for purposes such as product demos ? that it's difficult to do it justice in this quick overview. Download the 30-day trial and give it a whirl yourself.

41.4 Screen Capture with Terminal

Terminal [Hack #48] comes with a command-line version of the built-in screen-capture utility, aptly named screencapture. For usage instructions, simply invoke it on the command line:

% screencapture 
screencapture: illegal usage, file required if not going to clipboard
usage: screencapture [-icmwsWx] [file] [cursor]
  -i      capture screen interactively, by selection or window
            control key - causes screen shot to go to clipboard
            space key   - toggle between mouse selection and
                          window selection modes
            escape key  - cancels interactive screen shot
  -c      force screen capture to go to the clipboard
  -m      only capture the main monitor, undefined if -i is set
  -w      only allow window selection mode
  -s      only allow mouse selection mode
  -W      start interaction in window selection mode
  -x      do not play sounds
  file    where to save the screen capture

To capture the entire screen, type screencapture ~/Desktop/image.pdf, where ~/Desktop/image.pdf is the path and filename to which you wish it saved. To capture the screen interactively in regional or window mode, use screencapture -i image.pdf, as shown in Figure 4-31.

Figure 4-31. Using screencapture on the command line

If you prefer the output to go right to the clipboard rather than an image file, use screencapture -c. Of course, you can use these various command-line options in tandem; screencapture -ic, for example, is an interactive screen-capture session, sending the result to the clipboard.

You can grab a screenshot of a remote Mac's desktop ? or even the login screen ? thanks to screencapture and some not-so-fancy remote access footwork [Hack #71]. Simply log in to the other Mac remotely, run screencapture on the command line, and copy the resulting screenshots back over to your local Mac.

?Wei-Meng Lee