Struct components::platform::core::Onscreen

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pub struct Onscreen {
    pub window: Option<Window>,
    /* private fields */
}

Fields

window: Option<Window>

Implementations

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impl Onscreen

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pub fn new() -> Onscreen

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pub fn init(&mut self, event_loop: &EventLoop<()>, width: u32, height: u32)

Initialize an “allocated” Onscreen framebuffer that may be configured before later being allocated, either implicitly when it is first used or explicitly via Framebuffer::allocate.

Returns

A newly instantiated Onscreen framebuffer

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pub fn add_dirty_callback(&self, callback: P) -> Option<OnscreenDirtyClosure> where
P: 'static + Fn(&Onscreen, &OnscreenDirtyInfo),

Installs a callback fn that will be called whenever the window system has lost the contents of a region of the onscreen buffer and the application should redraw it to repair the buffer. For example this may happen in a window system without a compositor if a window that was previously covering up the onscreen window has been moved causing a region of the onscreen to be exposed.

The callback will be passed a OnscreenDirtyInfo struct which decribes a rectangle containing the newly dirtied region. Note that this may be called multiple times to describe a non-rectangular region composed of multiple smaller rectangles.

The dirty events are separate from FrameEvent::Sync events so the application should also listen for this event before rendering the dirty region to ensure that the framebuffer is actually ready for rendering.

`callback`

A callback fn to call for dirty events

`user_data`

A private pointer to be passed to callback

Returns

a OnscreenDirtyClosure pointer that can be used to remove the callback and associated user_data later.

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pub fn add_frame_callback(&self, callback: P) -> Option<FrameClosure> where
P: 'static + Fn(&Onscreen, &FrameEvent, &FrameInfo),

Installs a callback fn that will be called for significant events relating to the given self framebuffer.

The callback will be used to notify when the system compositor is ready for this application to render a new frame. In this case FrameEvent::Sync will be passed as the event argument to the given callback in addition to the FrameInfo corresponding to the frame beeing acknowledged by the compositor.

The callback will also be called to notify when the frame has ended. In this case FrameEvent::Complete will be passed as the event argument to the given callback in addition to the FrameInfo corresponding to the newly presented frame. The meaning of “ended” here simply means that no more timing information will be collected within the corresponding FrameInfo and so this is a good opportunity to analyse the given info. It does not necessarily mean that the GPU has finished rendering the corresponding frame.

We highly recommend throttling your application according to FrameEvent::Sync events so that your application can avoid wasting resources, drawing more frames than your system compositor can display.

`callback`

A callback fn to call for frame events

`user_data`

A private pointer to be passed to callback

Returns

a FrameClosure pointer that can be used to remove the callback and associated user_data later.

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pub fn add_resize_callback(
 &self,
 callback: P
) -> Option<OnscreenResizeClosure> where
 P: 'static + Fn(&Onscreen, i32, i32),

Registers a callback with self that will be called whenever the self framebuffer changes size.

The callback can be removed using Onscreen::remove_resize_callback passing the returned closure pointer.

Since automatically updates the viewport of an self framebuffer that is resized, a resize callback can also be used to track when the viewport has been changed automatically by in case your application needs more specialized control over the viewport.

A resize callback will only ever be called while dispatching events from the system mainloop; so for example during poll_renderer_dispatch. This is so that callbacks shouldn’t occur while an application might have arbitrary locks held for example.

`callback`

A OnscreenResizeCallback to call when the self changes size.

`user_data`

Private data to be passed to callback.

`destroy`

Returns

a OnscreenResizeClosure pointer that can be used to remove the callback and associated user_data later.

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pub fn buffer_age(&self) -> i32

Gets the current age of the buffer contents.

This fn allows applications to query the age of the current back buffer contents for a Onscreen as the number of frames elapsed since the contents were most recently defined.

These age values exposes enough information to applications about how internally manages back buffers to allow applications to re-use the contents of old frames and minimize how much must be redrawn for the next frame.

The back buffer contents can either be reported as invalid (has an age of 0) or it may be reported to be the same contents as from n frames prior to the current frame.

The queried value remains valid until the next buffer swap.

One caveat is that under X11 the buffer age does not reflect changes to buffer contents caused by the window systems. X11 applications must track Expose events to determine what buffer regions need to additionally be repaired each frame.

The recommended way to take advantage of this buffer age api is to build up a circular buffer of length 3 for tracking damage regions over the last 3 frames and when starting a new frame look at the age of the buffer and combine the damage regions for the current frame with the damage regions of previous age frames so you know everything that must be redrawn to update the old contents for the new frame.

If the system doesn’t not support being able to track the age of back buffers then this fn will always return 0 which implies that the contents are undefined.

The FeatureID::OglFeatureIdBufferAge feature can optionally be explicitly checked to determine if is currently tracking the age of Onscreen back buffer contents. If this feature is missing then this fn will always return 0.

Returns

The age of the buffer contents or 0 when the buffer contents are undefined.

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pub fn frame_counter(&self) -> i64

Gets the value of the framebuffers frame counter. This is a counter that increases by one each time Onscreen::swap_buffers or Onscreen::swap_region is called.

Returns

the current frame counter value

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pub fn resizable(&self) -> bool

Lets you query whether self has been marked as resizable via the Onscreen::set_resizable api.

By default, if possible, a self will be created by as non resizable, but it is not guaranteed that this is always possible for all window systems.

If onscreen_set_resizable(self, true) has been previously called then this fn will return true, but it’s possible that the current windowing system being used does not support window resizing (consider fullscreen windows on a phone or a TV). This fn is not aware of whether resizing is truly meaningful with your window system, only whether the self has been marked as resizable.

Returns

Returns whether self has been marked as resizable or not.

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pub fn hide(&self)

This requests to make self invisible to the user.

Actually the precise semantics of this fn depend on the window system currently in use, and if you don’t have a multi-windowining system this fn may in-fact do nothing.

This fn does not implicitly allocate the given self framebuffer before hiding it.

Since doesn’t explicitly track the visibility status of onscreen framebuffers it wont try to avoid redundant window system requests e.g. to show an already visible window. This also means that it’s acceptable to alternatively use native APIs to show and hide windows without confusing .

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pub fn remove_dirty_callback(&self, closure: &mut OnscreenDirtyClosure)

Removes a callback and associated user data that were previously registered using Onscreen::add_dirty_callback.

If a destroy callback was passed to Onscreen::add_dirty_callback to destroy the user data then this will also get called.

`closure`

A OnscreenDirtyClosure returned from Onscreen::add_dirty_callback

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pub fn remove_frame_callback(&self, closure: &mut FrameClosure)

Removes a callback and associated user data that were previously registered using Onscreen::add_frame_callback.

If a destroy callback was passed to Onscreen::add_frame_callback to destroy the user data then this will get called.

`closure`

A FrameClosure returned from Onscreen::add_frame_callback

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pub fn remove_resize_callback(&self, closure: &mut OnscreenResizeClosure)

Removes a resize callback and user_data pair that were previously associated with self via Onscreen::add_resize_callback.

`closure`

An identifier returned from Onscreen::add_resize_callback

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pub fn set_resizable(&self, resizable: bool)

Lets you request to mark an self framebuffer as resizable or not.

By default, if possible, a self will be created by as non resizable, but it is not guaranteed that this is always possible for all window systems.

does not know whether marking the self framebuffer is truly meaningful for your current window system (consider applications being run fullscreen on a phone or TV) so this fn may not have any useful effect. If you are running on a multi windowing system such as X11 or Win32 or OSX then will request to the window system that users be allowed to resize the self, although it’s still possible that some other window management policy will block this possibility.

Whenever an self framebuffer is resized the viewport will be automatically updated to match the new size of the framebuffer with an origin of (0,0). If your application needs more specialized control of the viewport it will need to register a resize handler using Onscreen::add_resize_callback so that it can track when the viewport has been changed automatically.

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pub fn set_swap_throttled(&self, throttled: bool)

Requests that the given self framebuffer should have swap buffer requests (made using Onscreen::swap_buffers) throttled either by a displays vblank period or perhaps some other mechanism in a composited environment.

`throttled`

Whether swap throttling is wanted or not.

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pub fn show(&self)

This requests to make self visible to the user.

Actually the precise semantics of this fn depend on the window system currently in use, and if you don’t have a multi-windowining system this fn may in-fact do nothing.

This fn will implicitly allocate the given self framebuffer before showing it if it hasn’t already been allocated.

When using the Wayland winsys calling this will set the surface to a toplevel type which will make it appear. If the application wants to set a different type for the surface, it can avoid calling Onscreen::show and set its own type directly with the Wayland client API via wayland_onscreen_get_surface.

Since doesn’t explicitly track the visibility status of onscreen framebuffers it wont try to avoid redundant window system requests e.g. to show an already visible window. This also means that it’s acceptable to alternatively use native APIs to show and hide windows without confusing .

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pub fn swap_buffers(&self)

Swaps the current back buffer being rendered too, to the front for display.

This fn also implicitly discards the contents of the color, depth and stencil buffers as if Framebuffer::discard_buffers were used. The significance of the discard is that you should not expect to be able to start a new frame that incrementally builds on the contents of the previous frame.

It is highly recommended that applications use Onscreen::swap_buffers_with_damage instead whenever possible and also use the Onscreen::get_buffer_age api so they can perform incremental updates to older buffers instead of having to render a full buffer for every frame.

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pub fn swap_buffers_with_damage(&self, rectangles: &[i32 ], n_rectangles: i32)

Swaps the current back buffer being rendered too, to the front for display and provides information to any system compositor about what regions of the buffer have changed (damage) with respect to the last swapped buffer.

This fn has the same semantics as framebuffer_swap_buffers except that it additionally allows applications to pass a list of damaged rectangles which may be passed on to a compositor so that it can minimize how much of the screen is redrawn in response to this applications newly swapped front buffer.

For example if your application is only animating a small object in the corner of the screen and everything else is remaining static then it can help the compositor to know that only the bottom right corner of your newly swapped buffer has really changed with respect to your previously swapped front buffer.

If n_rectangles is 0 then the whole buffer will implicitly be reported as damaged as if Onscreen::swap_buffers had been called.

This fn also implicitly discards the contents of the color, depth and stencil buffers as if Framebuffer::discard_buffers were used. The significance of the discard is that you should not expect to be able to start a new frame that incrementally builds on the contents of the previous frame. If you want to perform incremental updates to older back buffers then please refer to the Onscreen::get_buffer_age api.

Whenever possible it is recommended that applications use this fn instead of Onscreen::swap_buffers to improve performance when running under a compositor.

It is highly recommended to use this API in conjunction with the Onscreen::get_buffer_age api so that your application can perform incremental rendering based on old back buffers.

`rectangles`

An array of integer 4-tuples representing damaged rectangles as (x, y, width, height) tuples.

`n_rectangles`

The number of 4-tuples to be read from rectangles

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pub fn swap_region(&self, rectangles: &[i32 ], n_rectangles: i32)

Swaps a region of the back buffer being rendered too, to the front for display. rectangles represents the region as array of n_rectangles each defined by 4 sequential (x, y, width, height) integers.

This fn also implicitly discards the contents of the color, depth and stencil buffers as if Framebuffer::discard_buffers were used. The significance of the discard is that you should not expect to be able to start a new frame that incrementally builds on the contents of the previous frame.