// Copyright 2014 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.

// The spec for HTMLCanvasElement.getContext() defines the context
// creation attributes as type "any". In order to eliminate custom
// bindings for getContext(), we define a dictionary that contains the
// union of all of the context types' attributes. Note that it is not
// possible to use a union type for this purpose because two dictionary
// types are not distinguishable.
//
// Fortunately, there aren't any context creation attributes which are
// defined with different default values in different context
// specifications. (The "alpha" value, in particular, has a default
// value of true for both the Canvas2D and WebGL specifications.)
//
// The PermissiveDictionaryConversion extended attribute ignores
// non-object types (like 'true' and 'false') passed to getContext() for
// the attributes instead of raising TypeError, following the behavior
// of the previous custom binding.
//
// N.B.: Web IDL doesn't support multiple inheritance of dictionaries.

enum CanvasColorSpace {
    "srgb", // default
    "rec2020",
    "p3",
};

enum CanvasPixelFormat {
    "8-8-8-8", // default
    "10-10-10-2",
    "12-12-12-12",
    "float16",
};

[PermissiveDictionaryConversion]
dictionary CanvasContextCreationAttributes {
    // Canvas 2D attributes
    boolean alpha = true;  // Also used for WebGL.
    // TODO(crbug.com/637288): Do we keep "legacy-srgb" as the default?
    // Must decide before shipping.
    [RuntimeEnabled=ExperimentalCanvasFeatures] CanvasColorSpace colorSpace = "legacy-srgb";
    [RuntimeEnabled=ExperimentalCanvasFeatures] CanvasPixelFormat pixelFormat = "8-8-8-8";
    [RuntimeEnabled=ExperimentalCanvasFeatures] boolean linearPixelMath = false;

    // WebGL attributes
    boolean depth = true;
    boolean stencil = false;
    boolean antialias = true;
    boolean premultipliedAlpha = true;
    boolean preserveDrawingBuffer = false;
    boolean failIfMajorPerformanceCaveat = false;
};