glfw/docs/monitor.dox

/*!

@page monitor Monitor guide

@tableofcontents

This guide introduces the monitor related functions of GLFW.  There are also
guides for the other areas of GLFW.

 - @ref intro
 - @ref window
 - @ref context
 - @ref input

To see how GLFW views your monitor setup and its available video modes, run the
`modes` test program.


@section monitor_objects Monitor objects

A monitor object represents a currently connected monitor and is represented as
a pointer to the [opaque](https://en.wikipedia.org/wiki/Opaque_data_type) type
@ref GLFWmonitor.  Monitor objects cannot be created or destroyed by the
application and retain their addresses until the monitors they represent are
disconnected or until the library is [terminated](@ref intro_init_terminate).

Each monitor has a current video mode, a list of supported video modes,
a virtual position, a human-readable name, an estimated physical size and
a gamma ramp.  One of the monitors is the primary monitor.

The virtual position of a monitor is in
[screen coordinates](@ref coordinate_systems) and, together with the current
video mode, describes the viewports that the connected monitors provide into the
virtual desktop that spans them.


@subsection monitor_monitors Retrieving monitors

The primary monitor is returned by @ref glfwGetPrimaryMonitor.  It is the user's
preferred monitor and is usually the one with global UI elements like task bar
or menu bar.

@code
GLFWmonitor* primary = glfwGetPrimaryMonitor();
@endcode

You can retrieve all currently connected monitors with @ref glfwGetMonitors.
See the reference documentation for the lifetime of the returned array.

@code
int count;
GLFWmonitor** monitors = glfwGetMonitors(&count);
@endcode

The primary monitor is always the first monitor in the returned array, but other
monitors may be moved to a different index when a monitor is connected or
disconnected.


@subsection monitor_event Monitor configuration changes

If you wish to be notified when a monitor is connected or disconnected, set
a monitor callback.

@code
glfwSetMonitorCallback(monitor_callback);
@endcode

The callback function receives the handle for the monitor that has been
connected or disconnected and a monitor action.

@code
void monitor_callback(GLFWmonitor* monitor, int event)
{
}
@endcode

The action is one of `GLFW_CONNECTED` or `GLFW_DISCONNECTED`.


@section monitor_properties Monitor properties

Each monitor has a current video mode, a list of supported video modes,
a virtual position, a human-readable name, an estimated physical size and
a gamma ramp.


@subsection monitor_modes Video modes

GLFW generally does a good job selecting a suitable video mode when you create
a full screen window, but it is sometimes useful to know exactly which video
modes are supported.

Video modes are represented as @ref GLFWvidmode structures.  You can get an
array of the video modes supported by a monitor with @ref glfwGetVideoModes.
See the reference documentation for the lifetime of the returned array.

@code
int count;
GLFWvidmode* modes = glfwGetVideoModes(monitor, &count);
@endcode

To get the current video mode of a monitor call @ref glfwGetVideoMode.  See the
reference documentation for the lifetime of the returned pointer.

@code
const GLFWvidmode* mode = glfwGetVideoMode(monitor);
@endcode

The resolution of a video mode is specified in
[screen coordinates](@ref coordinate_systems), not pixels.


@subsection monitor_size Physical size

The physical size of a monitor in millimetres, or an estimation of it, can be
retrieved with @ref glfwGetMonitorPhysicalSize.  This has no relation to its
current _resolution_, i.e. the width and height of its current
[video mode](@ref monitor_modes).

@code
int widthMM, heightMM;
glfwGetMonitorPhysicalSize(monitor, &widthMM, &heightMM);
@endcode

This can, for example, be used together with the current video mode to calculate
the DPI of a monitor. 

@code
const double dpi = mode->width / (widthMM / 25.4);
@endcode


@subsection monitor_pos Virtual position

The position of the monitor on the virtual desktop, in
[screen coordinates](@ref coordinate_systems), can be retrieved with @ref
glfwGetMonitorPos.

@code
int xpos, ypos;
glfwGetMonitorPos(monitor, &xpos, &ypos);
@endcode


@subsection monitor_name Human-readable name

The human-readable, UTF-8 encoded name of a monitor is returned by @ref
glfwGetMonitorName.  See the reference documentation for the lifetime of the
returned string.

@code
const char* name = glfwGetMonitorName(monitor);
@endcode

Monitor names are not guaranteed to be unique.  Two monitors of the same model
and make may have the same name.  Only the monitor handle is guaranteed to be
unique, and only until that monitor is disconnected.


@subsection monitor_gamma Gamma ramp

The gamma ramp of a monitor can be set with @ref glfwSetGammaRamp, which accepts
a monitor handle and a pointer to a @ref GLFWgammaramp structure.

@code
GLFWgammaramp ramp;
unsigned short red[256], green[256], blue[256];

ramp.size = 256;
ramp.red = red;
ramp.green = green;
ramp.blue = blue;

for (i = 0;  i < ramp.size;  i++)
{
    // Fill out gamma ramp arrays as desired
}

glfwSetGammaRamp(monitor, &ramp);
@endcode

The gamma ramp data is copied before the function returns, so there is no need
to keep it around once the ramp has been set.

@note It is recommended to use gamma ramps of size 256, as that is the size
supported by all graphics cards on all platforms.

The current gamma ramp for a monitor is returned by @ref glfwGetGammaRamp.  See
the reference documentation for the lifetime of the returned structure.

@code
const GLFWgammaramp* ramp = glfwGetGammaRamp(monitor);
@endcode

If you wish to set a regular gamma ramp, you can have GLFW calculate it for you
from the desired exponent with @ref glfwSetGamma, which in turn calls @ref
glfwSetGammaRamp with the resulting ramp.

@code
glfwSetGamma(monitor, 1.0);
@endcode

*/