Quick Look


Quick Look is a quick preview feature developed by Apple Inc. which was introduced in its operating system Mac OS X 10.5 Leopard. The feature was announced at the Worldwide Developers Conference on Jun. 11, 2007.
While OS X's Finder has always had icon previews, Quick Look allows users to look at the contents of a file in the Finder at full or near-full size, depending on the size of the document relative to the screen resolution. It can preview files such as PDFs, HTML, QuickTime readable media, plain text and RTF text documents, iWork documents, ODF documents, Microsoft Office files, and RAW camera images.
Quick Look can also be opened in full screen and launched from the command line. Additionally, multi-page documents like PowerPoint slide shows can be navigated using the slide previews at the side of the preview window.
Quick Look technology is implemented throughout the Apple suite of software starting with Mac OS X 10.5, including iChat Theater, Time Machine, and Finder's Cover Flow.
Quick Look APIs are available to developers via the Quick Look framework on iOS and as part of the Quartz framework on the Mac.

Supported file types by default

Since its debut, Quick Look has included a number of generators for common file types.
FormatVersion introducedNotes
AAC10.5Cover art in icon view and can play back audio in full preview.
Adobe Photoshop10.5
AIFF10.5
Apple Icon Image format10.5
AVI10.5
BMP10.5
COLLADA's DAE10.6
Cinema 4D's.c4dDisplays the 2D Preview Image embedded in the file.
GIF10.5Did not animate animated GIFS without additional plugins until OS X 10.7.
HTML10.5Does not load remote resources or execute scripts.
iChat transcripts10.5
JPEG10.5
JPEG 200010.5
Microsoft Excel10.5
Microsoft PowerPoint10.5
Microsoft Word10.5
MIDI10.5MIDI files support has been dropped in OS X 10.8.
MP310.5Cover art in icon view and can play back audio in full preview.
MPEG410.5
MPO
PDF10.5
PictureClipping10.6
PICT10.5
PNG10.5
QuickTime movies10.5Additional stream formats require the appropriate QuickTime extension to be installed.
RTF10.5
SVG10.6
TEXT10.5
TextClipping10.6
TIFF10.5
WAV10.5

Plug-ins

can be added to Quick Look to allow previewing the content of other file formats. Plug-ins can also be used to add additional functionality to Quick Look such as syntax highlighting for source code files.
To add a plug-in to Quick Look it needs to be placed in the folder /Library/QuickLook/. To activate that plug-in, either the computer needs to be restarted or Quick Look needs to be reset with the command qlmanage -r

Usage

There are multiple ways to invoke Quick Look.
Keyboard shortcuts:
Command line:
qlmanage -p file
Menu:
Quick Look can be exploited when conducting a forensic examination of a computer's contents. A thumbnail cache is created for each user in a random subfolder of /var/folders called com.apple.QuickLook.thumbnailcache. The cache contains two files;
Quick Look thumbnails are stored for documents on internal disks and also for documents located on removable disks, including those that have been encrypted and can pose a significant security hole. A document may well have a number of thumbnails, each having different dimensions that can range from very large to very small.
The cache can be reset by invoking the qlmanage -r cache command via a Terminal window.