Added ImagePipe

mojo/services/gfx/images/interfaces/image_pipe.mojom

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module mojo.gfx;
+
+import "geometry/interfaces/geometry.mojom";
+import "gfx/images/interfaces/image.mojom";
+
+// The status of the last time this image was presented
+enum PresentationStatus {
+  PRESENTED = 0,
+  // Image properties are not supported by the consumer
+  NOT_PRESENTED_INVALID_PROPERTIES = 1,
+  // Producer flushed the image pool
+  NOT_PRESENTED_FLUSHED = 2,
+};
+
+// ImagePipe is a mechanism for streaming shared images between two
+// Mojo entities, one of which provides the image contents (the 'producer') and
+// one of which does something with the image contents (the 'consumer').
+// It operates conceptually on a pool of |Image| objects that the pipe knows
+// about, allows image producers to add/remove images to/from this pool, and
+// provides mechanisms for the producer and the consumer to negotiate about who
+// owns each image in the pool at a given point in time.
+interface ImagePipe {
+
+  // Add an image persistently to the pipe's image pool
+  // Adding an image that is already added, or using an ID that is already in
+  // use are both errors and will cause the connection to close.
+  AddImage(Image image, uint32 id);
+
+  // Remove an image from the pipe's pool
+  // Use of an invalid ID will cause the connection to close.
+  RemoveImage(uint32 id);
+
+  // Mark the image as available for consumption by the consumer
+  // The reply will be sent when the consumer is done using this image and
+  // is ready to release ownership back to the producer.
+  // The reply will not be sent until another Image is presented to replace it
+  // presentuing an id that is added will cause the connection to close.
+  PresentImage(uint32 id) => (PresentationStatus status);
+
+  // Ask the consumer to release all images in the pipe's pool. This will
+  // send the presentation reply with FLUSHED on all images in the pool
+  // not being used by the consumer if the consumer is presenting this image,
+  // that image may still be presented and its Present reply will reflect that.
+  FlushImages();
+
+};