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// Copyright 2017 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.
import 'package:flutter/foundation.dart';
import 'box.dart';
import 'layer.dart';
import 'object.dart';
/// A rectangle upon which a backend texture is mapped.
/// Backend textures are images that can be applied (mapped) to an area of the
/// Flutter view. They are created, managed, and updated using a
/// platform-specific texture registry. This is typically done by a plugin
/// that integrates with host platform video player, camera, or OpenGL APIs,
/// or similar image sources.
/// A texture box refers to its backend texture using an integer ID. Texture
/// IDs are obtained from the texture registry and are scoped to the Flutter
/// view. Texture IDs may be reused after deregistration, at the discretion
/// of the registry. The use of texture IDs currently unknown to the registry
/// will silently result in a blank rectangle.
/// Texture boxes are repainted autonomously as dictated by the backend (e.g. on
/// arrival of a video frame). Such repainting generally does not involve
/// executing Dart code.
/// The size of the rectangle is determined by the parent, and the texture is
/// automatically scaled to fit.
/// See also:
/// * <>
/// for how to create and manage backend textures on Android.
/// * <>
/// for how to create and manage backend textures on iOS.
class TextureBox extends RenderBox {
/// Creates a box backed by the texture identified by [textureId].
TextureBox({ @required int textureId })
: assert(textureId != null),
_textureId = textureId;
/// The identity of the backend texture.
int get textureId => _textureId;
int _textureId;
set textureId(int value) {
assert(value != null);
if (value != _textureId) {
_textureId = value;
bool get sizedByParent => true;
bool get alwaysNeedsCompositing => true;
bool get isRepaintBoundary => true;
void performResize() {
size = constraints.biggest;
bool hitTestSelf(Offset position) {
return true;
void paint(PaintingContext context, Offset offset) {
if (_textureId == null)
rect: Rect.fromLTWH(offset.dx, offset.dy, size.width, size.height),
textureId: _textureId,