Enum ScreenCaptureRequest

pub enum ScreenCaptureRequest {
    Configure {
        payload: ScreenCaptureConfig,
        responder: ScreenCaptureConfigureResponder,
    },
    GetNextFrame {
        payload: GetNextFrameArgs,
        responder: ScreenCaptureGetNextFrameResponder,
    },
    ReleaseFrame {
        buffer_id: u32,
        responder: ScreenCaptureReleaseFrameResponder,
    },
}

This protocol provides a low-level ScreenCapture API for clients to use. ScreenCapture clients should familiarize themselves with the [fuchsia.sysmem/BufferCollection] and [fuchsia.ui.composition/Allocator] protocols as those are necessary to create the BufferCollections and images ScreenCapture uses.

Variants

Configure

Clients should first use the Allocator protocol to register a BufferCollection. This function will fail with BAD_OPERATION unless all clients of the BufferCollection have set their constraints.

Afterwards, clients should create and configure the images that will eventually be rendered to using this method. All the buffers in the collection from 0 to (buffer_count-1) may be used for screen capture.

Clients are responsible for determining the rotation of the display, and applying the corrective rotation. For instance, if the display is mounted 90 degrees clockwise (the “top” is on the right, when looking at the display), then the client should specify a 270 degree rotation to account for it.

Similarly, the clients are responsible for specifying a buffer big enough for the rotated image. If the buffer is too small, a best effort attempt will be made to render the image.

Finally, clients request the server to render the current screen to the shared buffers using [GetNextFrame].

[Configure] can be called again with a new BufferCollectionImportToken if the client wishes to change any of the configuration settings. In this case all the buffers from the previous call to [Configure] will be released.

Fields

payload: ScreenCaptureConfig

responder: ScreenCaptureConfigureResponder

GetNextFrame

Following a successful call to [Configure], clients can call GetNextFrame. This will populate a buffer with the most recent frame.

Clients should wait on the zx::event they pass for successful completion of the screenshot. It is not guaranteed that the screenshot will be completed by the time this function returns.

The requested image will be in the BufferCollection that the client set up in the VMO at the index specified by buffer_id.

When ScreenCapture is used to provide a stream, the rate that the client calls GetNextFrame will drive the frame rate.

Errors: BAD_OPERATION if Configure was not called, or not called successfully MISSING_ARGS if a required argument is not present BUFFER_FULL if all buffers in the BufferCollection are in use. In this case, ReleaseFrame must be called to make a buffer available before this function can be called successfully.

Fields

payload: GetNextFrameArgs

responder: ScreenCaptureGetNextFrameResponder

ReleaseFrame

Once the client no longer needs an image, they can call ReleaseFrame on the VMO index of the buffer so that the server can reuse it in the future.

Fields

buffer_id: u32

responder: ScreenCaptureReleaseFrameResponder

Implementations

impl ScreenCaptureRequest

pub fn into_configure( self, ) -> Option<(ScreenCaptureConfig, ScreenCaptureConfigureResponder)>

pub fn into_get_next_frame( self, ) -> Option<(GetNextFrameArgs, ScreenCaptureGetNextFrameResponder)>

pub fn into_release_frame( self, ) -> Option<(u32, ScreenCaptureReleaseFrameResponder)>

pub fn method_name(&self) -> &'static str

Name of the method defined in FIDL

Trait Implementations

impl Debug for ScreenCaptureRequest

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

Formats the value using the given formatter.