GDK (

GIMP GIMP ( ; GNU Image Manipulation Program) is a free and open-source raster graphics editor used for image manipulation (retouching) and image editing, free-form drawing, transcoding between different image file formats, and more specialized task ...

Drawing Kit) is a

library A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vir ...

that acts as a wrapper around the low-level functions provided by the underlying windowing and graphics systems. GDK lies between the

display server In computing, a windowing system (or window system) is software that manages separately different parts of display screens. It is a type of graphical user interface (GUI) which implements the WIMP (windows, icons, menus, pointer) paradigm for ...

and the

GTK GTK (formerly GIMP ToolKit and GTK+) is a free and open-source cross-platform widget toolkit for creating graphical user interfaces (GUIs). It is licensed under the terms of the GNU Lesser General Public License, allowing both free and propriet ...

library, handling basic rendering such as drawing primitives,

raster graphics upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for ...

(bitmaps),

cursor Cursor may refer to: * Cursor (user interface), an indicator used to show the current position for user interaction on a computer monitor or other display device * Cursor (databases), a control structure that enables traversal over the records in ...

font In metal typesetting, a font is a particular size, weight and style of a typeface. Each font is a matched set of type, with a piece (a "sort") for each glyph. A typeface consists of a range of such fonts that shared an overall design. In mod ...

s, as well as window events and

drag-and-drop In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, it can be used to ...

functionality. Like

GTK Scene Graph Kit GTK Scene Graph Kit (GSK) is the rendering and scene graph API for GTK introduced with version 3.90. GSK lies between the graphical control elements (widgets) and the rendering. Like GDK, GSK is part of GTK and licensed under the GNU Lesser Ge ...

(GSK), GDK is part of GTK and licensed under the

GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

(LGPL).

Software architecture

GTK is implemented on top of an abstraction layer called GDK, freeing GTK from low-level concerns like input gathering,

Drag and drop In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, it can be used to i ...

and pixel format conversion. GDK is an intermediate layer which separates GTK from the details of the windowing system. GDK is an important part of GTK's portability. Since low-level cross-platform functionality is already provided by

GLib GLib is a bundle of three (formerly five) low-level system libraries written in C and developed mainly by GNOME. GLib's code was separated from GTK, so it can be used by software other than GNOME and has been developed in parallel ever sinc ...

, all that is needed to make GTK run on other platforms is to port GDK to the underlying

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

's graphics layer. Hence, the GDK ports to the

Windows API The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems. The name Windows API collectively refers to several different platform implementations th ...

and

Quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

are what enable GTK applications to run on

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

and

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...

, respectively. Starting with GTK+ 2.8, GDK supports

Cairo Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metro ...

which should be used with GTK+ 3 instead of GDK's drawing functions. GDK is an intermediate layer which isolates

from the details of the

windowing system In computing, a windowing system (or window system) is software that manages separately different parts of display screens. It is a type of graphical user interface (GUI) which implements the WIMP (windows, icons, menus, pointer) paradigm for ...

. GDK is a thin wrapper around

Xlib Xlib (also known as libX11) is an X Window System protocol client library written in the C programming language. It contains functions for interacting with an X server. These functions allow programmers to write programs without knowing the d ...

. The X Window System comes with a low-level library called

. Almost every function in GDK is a very thin wrapper around a corresponding Xlib function; but some of the complexity (and functionality) of Xlib is hidden, to simplify programming and to make GDK easier to port to other windowing systems, such as Wayland or Microsoft Windows. The concealed Xlib functionality will rarely be of interest to application programmers; for example, many features used solely by

window manager A window manager is system software that controls the placement and appearance of windows within a windowing system in a graphical user interface. Most window managers are designed to help provide a desktop environment. They work in conjunction ...

s are not exposed in GDK. GDK lets you do low level stuff, like e.g. " blit this pixmap to the screen". GDK provides a layer that is much more portable than say the X protocol, without sacrificing any of the low-level accessibility that systems such as X provide. The true power of this abstraction is that if you choose to use it rather than say, X, your software will automatically render on the Linux Framebuffer and Windows. Having

OpenGL OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardwa ...

(or

OpenGL ES OpenGL for Embedded Systems (OpenGL ES or GLES) is a subset of the OpenGL computer graphics rendering application programming interface (API) for rendering 2D and 3D computer graphics such as those used by video games, typically hardware-accel ...

) support in GDK, facilitates a slightly better control of the

graphics pipeline In computer graphics, a computer graphics pipeline, rendering pipeline or simply graphics pipeline, is a conceptual model that describes what steps a graphics system needs to perform to Rendering (computer graphics), render a ...

; OpenGL is well suited for compositing textured data but totally unsuited for drawing.

GdkFrameClock

GdkFrameClock was added in GTK 3.8 While GTK applications remain mainloop driven (cf. Glib event loop), meaning the application is idle inside this main loop most of the time and just waits for something to happen and then calls the appropriate subroutine when it does, GdkFrameClock adds an additional mechanism, that gives a "pulse" to the application. It tells the application when to update and repaint a window. The beat rate can be synchronized with the monitor refresh rate.

GTK Scene Graph Kit

In its history GDK contained and linked with a couple of different Canvases. * https://wiki.gnome.org/Attic/ProjectRidley/CanvasOverview ** https://wiki.gnome.org/Attic/ProjectRidley/CanvasOverview/Canvases * https://wiki.gnome.org/Projects/GooCanvas Developers were also considering new directions for the library, including removing deprecated

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standa ...

components and adding an integrated scene graph (canvas) system, similar to the

Clutter Clutter and its derivations may refer to any of the following: Excessive physical disorder * Clutter, a confusing, or disorderly, state or collection, and possible symptom of compulsive hoarding * Clutter (marketing), numerous advertisements, a ...

graphics library, effectively integrating GTK with

and

Vulkan Vulkan is a low- overhead, cross-platform API, open standard for 3D graphics and computing. Vulkan targets high-performance real-time 3D graphics applications, such as video games and interactive media. Vulkan is intended to offer higher perform ...

. *

(GSK) GTK+ Scene Graph Kit (GSK) was released as part of GTK+ 3.90 in March 2017. It is the scene graph and rendering API for GTK. GSK has not been further integrated with GDK (which is also part of GTK) but is kept in its own directory.

Windowing systems

GDK contains back-ends to a couple of

s, namely to the

X11 The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wi ...

and Wayland protocols, to

and

GDI GDI may refer to: Science and technology * Gasoline direct injection, a type of fuel injection * Graphics Device Interface, a component of Microsoft Windows * Guanosine nucleotide dissociation inhibitor, a protein Organisations * Gabriel Dumont I ...

, and even to the

Hypertext Transfer Protocol The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, ...

(HTTP) engine Broadway. With the release of GNOME 3.16 in March 2015, GDK obtained an experimental back-end for the

Mir ''Mir'' (russian: Мир, ; ) was a space station that operated in low Earth orbit from 1986 to 2001, operated by the Soviet Union and later by Russia. ''Mir'' was the first modular space station and was assembled in orbit from 1986 to&n ...

display server protocol. The Mir display server protocol is a product by

Canonical The adjective canonical is applied in many contexts to mean "according to the canon" the standard, rule or primary source that is accepted as authoritative for the body of knowledge or literature in that context. In mathematics, "canonical example ...

for their

Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: ''Desktop'', ''Server'', and ''Core'' for Internet of things devices and robots. All the ...

distribution of Linux, which they intend to compete with the Wayland display server protocol; so far, it is implemented only in Ubuntu. At present, no back-end exists for KMS. To start an application and force this instance of it to use a certain windowing system, you specify the variable ''GDK_BACKEND'':
GDK_BACKEND=wayland gnome-calculator
GDK_BACKEND=wayland CLUTTER_BACKEND=wayland cheese

gdk-pixbuf

gdk-pixbuf is a toolkit for image loading and pixel buffer manipulation. The library provides image loading and saving facilities, fast scaling and compositing of pixbufs, simple animation loading (i.e. animated GIFs), and rendering the libart image buffer to a GdkDrawable instance. gdk-pixbuf has a fairly large API. The fundamental structure in the gdk-pixbuf library is GdkPixbuf, a private, opaque data structure that mirrors many of the same concepts that ArtPixBuf supports. In fact, most of GdkPixbuf's private data fields have the same names and data types as the corresponding ones in ArtPixBuf. This similarity dates back to the earlier days when gdk-pixbuf was a wrapper around

libart Libart is a free software graphics library of functions for 2D graphics supporting a superset of the PostScript imaging model. Libart was designed to be integrated with graphics, artwork, and illustration programs. It is written in optimized C an ...

. Since that time, the libart dependency has been stripped out, and gdk-pixbuf was merged into the GTK+ 2.0 code base. As such, gdk-pixbuf's days as a standalone library are limited to the

GNOME 1 GNOME 1 is the first major release of the GNOME desktop environment. Its primary goal was to provide a consistent user-friendly environment in conjunction with the X Window System. It was also a modern and free and open source software alternativ ...

release. With the release of GTK+ 2.22 on 2010-09-23, gdk-pixbuf has been turned back into a standalone library, after being shipped as part of GTK+ since gtk+ 2.0. This was done in preparation for the transition to GTK+ 3. * https://git.gnome.org/browse/gdk-pixbuf/ The first stand-alone release wa
2.22
on 2010-Sep-21, its development started wit

on 2010-06-23. The latest release of gdk-pixbuf i

from 2017-Oct-02. The development of 3.36 started wit

on 2016-04-26.

History

GDK was originally developed on the

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wit ...

for the GIMP

raster graphics editor A raster graphics editor is a computer program that allows users to create and edit images interactively on the computer screen and save them in one of many raster graphics file formats (also known as bitmap images) such as JPEG, PNG, and GI ...

.GIMP - A Brief (and Ancient) History of GIMP
/ref>

References

External links

GDK code from release GTK+ 3.19.0

The modern Gtk drawing model
– Alexander Larsson, 2013/11/04
Overview of GTK and its Libraries
- The GTK Project * https://git.gnome.org/browse/gtk-web/plain/images/architecture.svg {{DEFAULTSORT:Gdk Graphics libraries GTK