Struct gdk::GLContext[][src]

pub struct GLContext(_);
Expand description

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

Retrieves the value set using set_debug_enabled().

Returns

true if debugging is enabled

Retrieves the Display the self is created for

Returns

a Display or None

Retrieves the value set using set_forward_compatible().

Returns

true if the context should be forward compatible

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

Retrieves the GLContext that this self share data with.

Returns

a GLContext or None

This is supported on crate feature v3_22 only.

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

Returns

true if the GLContext is using an OpenGL ES profile

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

Retrieves the Window used by the self.

Returns

a Window or None

This is supported on crate feature v3_20 only.

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

Makes the self the current one.

Realizes the given GLContext.

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

Returns

true if the context is realized

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

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

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

This is supported on crate feature v3_22 only.

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

Clears the current GLContext.

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

Retrieves the current GLContext.

Returns

the current GLContext, or None

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Formats the value using the given formatter. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

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

This method tests for !=.

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

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

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

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

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

Returns the type identifier of Self.

Auto Trait Implementations

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Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

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Upcasts an object to a superclass or interface T. Read more

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Tries to downcast to a subclass or interface implementor T. Read more

Tries to downcast to a reference of its subclass or interface implementor T. Read more

Tries to cast to an object of type T. This handles upcasting, downcasting and casting between interface and interface implementors. All checks are performed at runtime, while downcast and upcast will do many checks at compile-time already. Read more

Tries to cast to reference to an object of type T. This handles upcasting, downcasting and casting between interface and interface implementors. All checks are performed at runtime, while downcast and upcast will do many checks at compile-time already. Read more

Casts to T unconditionally. Read more

Casts to &T unconditionally. Read more

Performs the conversion.

Performs the conversion.

Returns true if the object is an instance of (can be cast to) T.

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Same as connect but takes a SignalId instead of a signal name.

Same as connect_local but takes a SignalId instead of a signal name.

Same as connect_unsafe but takes a SignalId instead of a signal name.

Emit signal by signal id.

Emit signal with details by signal id.

Emit signal by it’s name.

Same as emit but takes Value for the arguments.

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The resulting type after obtaining ownership.

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The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

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