sdk/fidl/fuchsia.ui.composition/screenshot.fidl

// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.ui.composition;

alias ImageId = uint64;

/// The enum of possible errors following a [`CreateImage`] call.
type CreateImageError = strict enum {
    /// One or more arguments are missing in [`CreateImageArgs`].
    MISSING_ARGS = 1;
    /// A general error occurred in [`CreateImage`].
    BAD_OPERATION = 2;
};

/// The table of arguments passed into the [`CreateImage`] call. Note that all
/// fields are necessary.
type CreateImageArgs = resource table {
    /// The image ID for the image about to be created. It must be unique, and
    /// may not be 0, which is invalid.
    1: image_id ImageId;
    /// The import token referencing a BufferCollection registered with
    /// Allocator. This function will fail unless all clients of the specified
    /// BufferCollection have set their constraints.
    2: import_token BufferCollectionImportToken;
    /// The VMO index must be valid and in the range of constraints of the specified
    /// BufferCollection.
    3: vmo_index uint32;
    /// image_width must be valid and in the range of constraints of the specified
    /// BufferCollection.
    4: image_width uint32;
    /// image_height must be valid and in the range of constraints of the specified
    /// BufferCollection.
    5: image_height uint32;
};

/// This protocol provides a low-level Screenshot API for clients to use.
/// Screenshot clients should familiarize themselves with the sysmem and
/// Allocator protocols as those are necessary to create the BufferCollections
/// and images Screenshot uses.
protocol Screenshot {
    /// Clients should first use the Allocator protocol to register a
    /// BufferCollection for screenshot use.
    ///
    /// Afterwards, clients should create the image that will eventually be
    /// rendered to using this method.
    ///
    /// Finally, clients can use their specified `ImageId` in TakeScreenshot().
    CreateImage(resource struct {
        args CreateImageArgs;
    }) -> (struct {}) error CreateImageError;
};