Quick Look is a quick preview feature developed by

Apple Inc. Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Comput ...

which was introduced in its

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

Mac OS X 10.5 Leopard. The feature was announced at the

Worldwide Developers Conference The Worldwide Developers Conference (WWDC) is an information technology conference held annually by Apple Inc. The conference is currently held at Apple Park in California. The event is used to showcase new software and technologies in the macO ...

on Jun. 11, 2007. While macOS's Finder has always had smaller previews in Get Info windows or column view, Quick Look allows users to look at the contents of a file at full or near-full size in the Finder, depending on the size of the document relative to the screen resolution. It can preview files such as

PDF Portable document format (PDF), standardized as ISO 32000, is a file format developed by Adobe Inc., Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, computer hardware, ...

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

, QuickTime readable media,

plain text In computing, plain text is a loose term for data (e.g. file contents) that represent only characters of readable material but not its graphical representation nor other objects ( floating-point numbers, images, etc.). It may also include a lim ...

and RTF text documents,

iWork iWork is an office suite of applications created by Apple Inc., Apple for its macOS, iPadOS, and iOS operating systems, and also available cross-platform through the iCloud website. iWork includes the presentation program, presentation applicat ...

( Keynote, Pages, and

Numbers A number is a mathematical object used to count, measure, and label. The most basic examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers can ...

) documents, ODF documents,

Microsoft Office Microsoft Office, MS Office, or simply Office, is an office suite and family of client software, server software, and services developed by Microsoft. The first version of the Office suite, announced by Bill Gates on August 1, 1988, at CO ...

(

Word A word is a basic element of language that carries semantics, meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consensus among linguist ...

, Excel, and PowerPoint) files (including OOXML), and RAW camera images. In addition, Quick Look supports viewing multiple files simultaneously by selecting them and using a split view to compare contents side by side, a feature particularly useful for examining differences between documents or 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. Starting with macOS Mojave, Quick Look has been enhanced with markup tools, allowing users to annotate PDFs and images directly within the Quick Look interface without opening a separate application. 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. The integration with Time Machine allows users to preview versions of files within the backup system, making it easier to find specific versions before restoring them. Quick Look APIs are available to developers via the Quick Look framework on iOS and as part of the Quartz framework on the Mac. Developers can customize Quick Look to support additional file types in their applications, expanding the utility of this feature across various software ecosystems.

Supported file types by default

Since its debut, Quick Look has included a number of generators for common file types.

Plug-ins

Plug-ins can be added to Quick Look to allow previewing the content of other

file formats A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, pr ...

. Plug-ins can also be used to add additional functionality to Quick Look such as

syntax highlighting Syntax highlighting is a feature of text editors that is used for programming language, programming, scripting language, scripting, or markup language, markup languages, such as HTML. The feature displays text, especially source code, in differe ...

for

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

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 In computing, a keyboard shortcut (also hotkey/hot key or key binding) is a software-based assignment of an action to one or more keys on a computer keyboard. Most Operating system, operating systems and Application software, applications come ...

: * - * * - (open in full screen) * hold to zoom an image to actual size (Quick Look must already be open) Command line: qlmanage -p file Menu: * File — Quick Look ''file name''; * Context menu (right-click or -mouse click), then Quick Look ''file name''.

Caching and Forensics

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; * index.sqlite which is a SQLite database containing two tables - files and thumbnails. ::files contains the name, path, file-identifier, and volume-identifier of each file in the database. ::thumbnails contains metadata about each thumbnail, including the file linked-to in the files table and the offset of its data contained in thumbnails.data. * thumbnails.data contains the raw

bitmap In computing, a bitmap (also called raster) graphic is an image formed from rows of different colored pixels. A GIF is an example of a graphics image file that uses a bitmap. As a noun, the term "bitmap" is very often used to refer to a partic ...

s of the cached thumbnails. 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.

References

External links

A Quick Look Plugins list for Mac OS X

Gloobus
a

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...