Struct gdk::GLContext

#[repr(transparent)]
pub struct GLContext { /* private fields */ }

GLContext is an object representing the platform-specific OpenGL drawing context.

GdkGLContexts are created for a Window using Window::create_gl_context(), and the context will match the Visual of the window.

A GLContext is not tied to any particular normal framebuffer. For instance, it cannot draw to the Window back buffer. The GDK repaint system is in full control of the painting to that. Instead, you can create render buffers or textures and use gdk_cairo_draw_from_gl() in the draw function of your widget to draw them. Then GDK will handle the integration of your rendering with that of other widgets.

Support for GLContext is platform-specific, context creation can fail, returning None context.

A GLContext has to be made “current” in order to start using it, otherwise any OpenGL call will be ignored.

Creating a new OpenGL context

In order to create a new GLContext instance you need a Window, which you typically get during the realize call of a widget.

A GLContext is not realized until either make_current(), or until it is realized using realize(). It is possible to specify details of the GL context like the OpenGL version to be used, or whether the GL context should have extra state validation enabled after calling Window::create_gl_context() by calling realize(). If the realization fails you have the option to change the settings of the GLContext and try again.

Using a GdkGLContext

You will need to make the GLContext the current context before issuing OpenGL calls; the system sends OpenGL commands to whichever context is current. It is possible to have multiple contexts, so you always need to ensure that the one which you want to draw with is the current one before issuing commands:

⚠️ The following code is in C ⚠️

  gdk_gl_context_make_current (context);

You can now perform your drawing using OpenGL commands.

You can check which GLContext is the current one by using current(); you can also unset any GLContext that is currently set by calling clear_current().

This is an Abstract Base Class, you cannot instantiate it.

Implementations

impl GLContext

pub fn is_debug_enabled(&self) -> bool

Retrieves the value set using set_debug_enabled().

Returns

true if debugging is enabled

pub fn display(&self) -> Option<Display>

Retrieves the Display the self is created for

Returns

a Display or None

pub fn is_forward_compatible(&self) -> bool

Retrieves the value set using set_forward_compatible().

Returns

true if the context should be forward compatible

pub fn required_version(&self) -> (i32, i32)

Retrieves the major and minor version requested by calling set_required_version().

Returns

major

return location for the major version to request

minor

return location for the minor version to request

pub fn shared_context(&self) -> Option<GLContext>

Retrieves the GLContext that this self share data with.

Returns

a GLContext or None

pub fn uses_es(&self) -> bool

Checks whether the self is using an OpenGL or OpenGL ES profile.

Returns

true if the GLContext is using an OpenGL ES profile

pub fn version(&self) -> (i32, i32)

Retrieves the OpenGL version of the self.

The self must be realized prior to calling this function.

Returns

major

return location for the major version

minor

return location for the minor version

pub fn window(&self) -> Option<Window>

Retrieves the Window used by the self.

Returns

a Window or None

pub fn is_legacy(&self) -> bool

Whether the GLContext is in legacy mode or not.

The GLContext must be realized before calling this function.

When realizing a GL context, GDK will try to use the OpenGL 3.2 core profile; this profile removes all the OpenGL API that was deprecated prior to the 3.2 version of the specification. If the realization is successful, this function will return false.

If the underlying OpenGL implementation does not support core profiles, GDK will fall back to a pre-3.2 compatibility profile, and this function will return true.

You can use the value returned by this function to decide which kind of OpenGL API to use, or whether to do extension discovery, or what kind of shader programs to load.

Returns

true if the GL context is in legacy mode

pub fn make_current(&self)

Makes the self the current one.

pub fn realize(&self) -> Result<(), Error>

Realizes the given GLContext.

It is safe to call this function on a realized GLContext.

Returns

true if the context is realized

pub fn set_debug_enabled(&self, enabled: bool)

Sets whether the GLContext should perform extra validations and run time checking. This is useful during development, but has additional overhead.

The GLContext must not be realized or made current prior to calling this function.

enabled

whether to enable debugging in the context

pub fn set_forward_compatible(&self, compatible: bool)

Sets whether the GLContext should be forward compatible.

Forward compatibile contexts must not support OpenGL functionality that has been marked as deprecated in the requested version; non-forward compatible contexts, on the other hand, must support both deprecated and non deprecated functionality.

The GLContext must not be realized or made current prior to calling this function.

compatible

whether the context should be forward compatible

pub fn set_required_version(&self, major: i32, minor: i32)

Sets the major and minor version of OpenGL to request.

Setting major and minor to zero will use the default values.

The GLContext must not be realized or made current prior to calling this function.

major

the major version to request

minor

the minor version to request

pub fn set_use_es(&self, use_es: i32)

Requests that GDK create a OpenGL ES context instead of an OpenGL one, if the platform and windowing system allows it.

The self must not have been realized.

By default, GDK will attempt to automatically detect whether the underlying GL implementation is OpenGL or OpenGL ES once the self is realized.

You should check the return value of uses_es() after calling realize() to decide whether to use the OpenGL or OpenGL ES API, extensions, or shaders.

use_es

whether the context should use OpenGL ES instead of OpenGL, or -1 to allow auto-detection

pub fn clear_current()

Clears the current GLContext.

Any OpenGL call after this function returns will be ignored until make_current() is called.

pub fn current() -> Option<GLContext>

Retrieves the current GLContext.

Returns

the current GLContext, or None

Trait Implementations

impl Clone for GLContext

fn clone(&self) -> Self

Returns a copy of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for GLContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for GLContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for GLContext

fn hash<H>(&self, state: &mut H)where
    H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,

Feeds a slice of this type into the given Hasher.

impl Ord for GLContext

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

const fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

const fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

const fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: PartialOrd<Self>,

Restrict a value to a certain interval.

impl ParentClassIs for GLContext

type Parent = Object

impl<OT: ObjectType> PartialEq<OT> for GLContext

fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.

const fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<OT: ObjectType> PartialOrd<OT> for GLContext

fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

const fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

const fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

const fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

const fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StaticType for GLContext

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for GLContext