gecko-dev/dom/canvas/WebGLTypes.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef WEBGLTYPES_H_
#define WEBGLTYPES_H_

#include <limits>
#include <type_traits>
#include <unordered_map>
#include <vector>

// Most WebIDL typedefs are identical to their OpenGL counterparts.
#include "GLDefs.h"
#include "mozilla/Casting.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/Range.h"
#include "mozilla/RefCounted.h"
#include "mozilla/gfx/Point.h"
#include "gfxTypes.h"

#include "nsTArray.h"
#include "nsString.h"
#include "mozilla/dom/WebGLRenderingContextBinding.h"
#include "mozilla/ipc/SharedMemoryBasic.h"
//#include "WebGLStrongTypes.h"

// Manual reflection of WebIDL typedefs that are different from their
// OpenGL counterparts.
typedef int64_t WebGLsizeiptr;
typedef int64_t WebGLintptr;
typedef bool WebGLboolean;

// -

namespace mozilla {
namespace gl {
class GLContext;  // This is going to be needed a lot.
}  // namespace gl

// -
// Prevent implicit conversions into calloc and malloc. (mozilla namespace
// only!)

template <typename DestT>
class ForbidNarrowing final {
  DestT mVal;

 public:
  template <typename SrcT>
  MOZ_IMPLICIT ForbidNarrowing(SrcT val) : mVal(val) {
    static_assert(
        std::numeric_limits<SrcT>::min() >= std::numeric_limits<DestT>::min(),
        "SrcT must be narrower than DestT.");
    static_assert(
        std::numeric_limits<SrcT>::max() <= std::numeric_limits<DestT>::max(),
        "SrcT must be narrower than DestT.");
  }

  explicit operator DestT() const { return mVal; }
};

inline void* malloc(const ForbidNarrowing<size_t> s) {
  return ::malloc(size_t(s));
}

inline void* calloc(const ForbidNarrowing<size_t> n,
                    const ForbidNarrowing<size_t> size) {
  return ::calloc(size_t(n), size_t(size));
}

// -

namespace detail {

template <typename From>
class AutoAssertCastT final {
  const From mVal;

 public:
  explicit AutoAssertCastT(const From val) : mVal(val) {}

  template <typename To>
  operator To() const {
    return AssertedCast<To>(mVal);
  }
};

}  // namespace detail

template <typename From>
inline auto AutoAssertCast(const From val) {
  return detail::AutoAssertCastT<From>(val);
}

namespace webgl {
template <typename T>
struct QueueParamTraits;
class TexUnpackBytes;
class TexUnpackImage;
class TexUnpackSurface;
}  // namespace webgl

class ClientWebGLContext;
struct WebGLTexPboOffset;
class WebGLTexture;
class WebGLBuffer;
class WebGLFramebuffer;
class WebGLProgram;
class WebGLQuery;
class WebGLRenderbuffer;
class WebGLSampler;
class WebGLShader;
class WebGLSync;
class WebGLTexture;
class WebGLTransformFeedback;
class WebGLVertexArray;

// -

class VRefCounted : public RefCounted<VRefCounted> {
 public:
  virtual ~VRefCounted() = default;

#ifdef MOZ_REFCOUNTED_LEAK_CHECKING
  virtual const char* typeName() const = 0;
  virtual size_t typeSize() const = 0;
#endif
};

// -

/*
 * Implementing WebGL (or OpenGL ES 2.0) on top of desktop OpenGL requires
 * emulating the vertex attrib 0 array when it's not enabled. Indeed,
 * OpenGL ES 2.0 allows drawing without vertex attrib 0 array enabled, but
 * desktop OpenGL does not allow that.
 */
enum class WebGLVertexAttrib0Status : uint8_t {
  Default,                     // default status - no emulation needed
  EmulatedUninitializedArray,  // need an artificial attrib 0 array, but
                               // contents may be left uninitialized
  EmulatedInitializedArray  // need an artificial attrib 0 array, and contents
                            // must be initialized
};

/*
 * The formats that may participate, either as source or destination formats,
 * in WebGL texture conversions. This includes:
 *  - all the formats accepted by WebGL.texImage2D, e.g. RGBA4444
 *  - additional formats provided by extensions, e.g. RGB32F
 *  - additional source formats, depending on browser details, used when
 * uploading textures from DOM elements. See gfxImageSurface::Format().
 */
enum class WebGLTexelFormat : uint8_t {
  // returned by SurfaceFromElementResultToImageSurface to indicate absence of
  // image data
  None,
  // common value for formats for which format conversions are not supported
  FormatNotSupportingAnyConversion,
  // dummy pseudo-format meaning "use the other format".
  // For example, if SrcFormat=Auto and DstFormat=RGB8, then the source
  // is implicitly treated as being RGB8 itself.
  Auto,
  // 1-channel formats
  A8,
  A16F,  // OES_texture_half_float
  A32F,  // OES_texture_float
  R8,
  R16F,  // OES_texture_half_float
  R32F,  // OES_texture_float
  // 2-channel formats
  RA8,
  RA16F,  // OES_texture_half_float
  RA32F,  // OES_texture_float
  RG8,
  RG16F,
  RG32F,
  // 3-channel formats
  RGB8,
  RGB565,
  RGB11F11F10F,
  RGB16F,  // OES_texture_half_float
  RGB32F,  // OES_texture_float
  // 4-channel formats
  RGBA8,
  RGBA5551,
  RGBA4444,
  RGBA16F,  // OES_texture_half_float
  RGBA32F,  // OES_texture_float
  // DOM element source only formats.
  RGBX8,
  BGRX8,
  BGRA8
};

enum class WebGLTexImageFunc : uint8_t {
  TexImage,
  TexSubImage,
  CopyTexImage,
  CopyTexSubImage,
  CompTexImage,
  CompTexSubImage,
};

enum class WebGLTexDimensions : uint8_t { Tex2D, Tex3D };

// Please keep extensions in alphabetic order.
enum class WebGLExtensionID : uint8_t {
  ANGLE_instanced_arrays,
  EXT_blend_minmax,
  EXT_color_buffer_float,
  EXT_color_buffer_half_float,
  EXT_disjoint_timer_query,
  EXT_float_blend,
  EXT_frag_depth,
  EXT_shader_texture_lod,
  EXT_sRGB,
  EXT_texture_compression_bptc,
  EXT_texture_compression_rgtc,
  EXT_texture_filter_anisotropic,
  MOZ_debug,
  OES_element_index_uint,
  OES_fbo_render_mipmap,
  OES_standard_derivatives,
  OES_texture_float,
  OES_texture_float_linear,
  OES_texture_half_float,
  OES_texture_half_float_linear,
  OES_vertex_array_object,
  OVR_multiview2,
  WEBGL_color_buffer_float,
  WEBGL_compressed_texture_astc,
  WEBGL_compressed_texture_etc,
  WEBGL_compressed_texture_etc1,
  WEBGL_compressed_texture_pvrtc,
  WEBGL_compressed_texture_s3tc,
  WEBGL_compressed_texture_s3tc_srgb,
  WEBGL_debug_renderer_info,
  WEBGL_debug_shaders,
  WEBGL_depth_texture,
  WEBGL_draw_buffers,
  WEBGL_explicit_present,
  WEBGL_lose_context,
  Max
};

template <typename T>
inline constexpr auto EnumValue(const T v) {
  return static_cast<typename std::underlying_type<T>::type>(v);
}

class UniqueBuffer {
  // Like UniquePtr<>, but for void* and malloc/calloc/free.
  void* mBuffer;

 public:
  UniqueBuffer() : mBuffer(nullptr) {}

  MOZ_IMPLICIT UniqueBuffer(void* buffer) : mBuffer(buffer) {}

  ~UniqueBuffer() { free(mBuffer); }

  UniqueBuffer(UniqueBuffer&& other) {
    this->mBuffer = other.mBuffer;
    other.mBuffer = nullptr;
  }

  UniqueBuffer& operator=(UniqueBuffer&& other) {
    free(this->mBuffer);
    this->mBuffer = other.mBuffer;
    other.mBuffer = nullptr;
    return *this;
  }

  UniqueBuffer& operator=(void* newBuffer) {
    free(this->mBuffer);
    this->mBuffer = newBuffer;
    return *this;
  }

  explicit operator bool() const { return bool(mBuffer); }

  void* get() const { return mBuffer; }

  UniqueBuffer(const UniqueBuffer& other) =
      delete;  // construct using std::move()!
  void operator=(const UniqueBuffer& other) =
      delete;  // assign using std::move()!
};

namespace webgl {
struct FormatUsageInfo;

struct SampleableInfo final {
  const char* incompleteReason = nullptr;
  uint32_t levels = 0;
  const webgl::FormatUsageInfo* usage = nullptr;
  bool isDepthTexCompare = false;

  bool IsComplete() const { return bool(levels); }
};

enum class AttribBaseType : uint8_t {
  Boolean,  // Can convert from anything.
  Float,    // Also includes NormU?Int
  Int,
  Uint,
};
webgl::AttribBaseType ToAttribBaseType(GLenum);
const char* ToString(AttribBaseType);

enum class UniformBaseType : uint8_t {
  Float,
  Int,
  Uint,
};
const char* ToString(UniformBaseType);

typedef uint64_t ObjectId;

enum class BufferKind : uint8_t {
  Undefined,
  Index,
  NonIndex,
};

}  // namespace webgl

// -

struct FloatOrInt final  // For TexParameter[fi] and friends.
{
  const bool isFloat;
  const GLfloat f;
  const GLint i;

  explicit FloatOrInt(GLint x = 0) : isFloat(false), f(x), i(x) {}

  explicit FloatOrInt(GLfloat x) : isFloat(true), f(x), i(roundf(x)) {}

  FloatOrInt& operator=(const FloatOrInt& x) {
    memcpy(this, &x, sizeof(x));
    return *this;
  }
};

struct WebGLPixelStore final {
  uint32_t mUnpackImageHeight = 0;
  uint32_t mUnpackSkipImages = 0;
  uint32_t mUnpackRowLength = 0;
  uint32_t mUnpackSkipRows = 0;
  uint32_t mUnpackSkipPixels = 0;
  uint32_t mUnpackAlignment = 0;
  GLenum mColorspaceConversion = 0;
  bool mFlipY = false;
  bool mPremultiplyAlpha = false;
  bool mRequireFastPath = false;
};

using WebGLTexUnpackVariant =
    Variant<UniquePtr<webgl::TexUnpackBytes>,
            UniquePtr<webgl::TexUnpackSurface>,
            UniquePtr<webgl::TexUnpackImage>, WebGLTexPboOffset>;

using MaybeWebGLTexUnpackVariant = Maybe<WebGLTexUnpackVariant>;

struct WebGLContextOptions {
  bool alpha = true;
  bool depth = true;
  bool stencil = false;
  bool premultipliedAlpha = true;
  bool antialias = true;
  bool preserveDrawingBuffer = false;
  bool failIfMajorPerformanceCaveat = false;
  bool xrCompatible = false;
  dom::WebGLPowerPreference powerPreference =
      dom::WebGLPowerPreference::Default;
  bool shouldResistFingerprinting = true;
  bool enableDebugRendererInfo = false;

  WebGLContextOptions();
  WebGLContextOptions(const WebGLContextOptions&) = default;

  bool operator==(const WebGLContextOptions&) const;
  bool operator!=(const WebGLContextOptions& rhs) const {
    return !(*this == rhs);
  }
};

// -

template <typename T>
struct avec2 {
  T x = T();
  T y = T();

  template <typename U, typename V>
  static Maybe<avec2> From(const U _x, const V _y) {
    const auto x = CheckedInt<T>(_x);
    const auto y = CheckedInt<T>(_y);
    if (!x.isValid() || !y.isValid()) return {};
    return Some(avec2(x.value(), y.value()));
  }

  template <typename U>
  static auto From(const U& val) {
    return From(val.x, val.y);
  }
  template <typename U>
  static auto FromSize(const U& val) {
    return From(val.width, val.height);
  }

  avec2() = default;
  avec2(const T _x, const T _y) : x(_x), y(_y) {}

  bool operator==(const avec2& rhs) const { return x == rhs.x && y == rhs.y; }
  bool operator!=(const avec2& rhs) const { return !(*this == rhs); }
};

template <typename T>
struct avec3 {
  T x = T();
  T y = T();
  T z = T();

  template <typename U, typename V>
  static Maybe<avec3> From(const U _x, const V _y, const V _z) {
    const auto x = CheckedInt<T>(_x);
    const auto y = CheckedInt<T>(_y);
    const auto z = CheckedInt<T>(_z);
    if (!x.isValid() || !y.isValid() || !z.isValid()) return {};
    return Some(avec3(x.value(), y.value(), z.value()));
  }

  template <typename U>
  static auto From(const U& val) {
    return From(val.x, val.y, val.z);
  }

  avec3() = default;
  avec3(const T _x, const T _y, const T _z) : x(_x), y(_y), z(_z) {}

  bool operator==(const avec3& rhs) const {
    return x == rhs.x && y == rhs.y && z == rhs.z;
  }
  bool operator!=(const avec3& rhs) const { return !(*this == rhs); }
};

typedef avec2<int32_t> ivec2;
typedef avec3<int32_t> ivec3;
typedef avec2<uint32_t> uvec2;
typedef avec3<uint32_t> uvec3;

// -

namespace webgl {

struct PackingInfo final {
  GLenum format = 0;
  GLenum type = 0;

  bool operator<(const PackingInfo& x) const {
    if (format != x.format) return format < x.format;

    return type < x.type;
  }

  bool operator==(const PackingInfo& x) const {
    return (format == x.format && type == x.type);
  }
};

struct DriverUnpackInfo final {
  GLenum internalFormat = 0;
  GLenum unpackFormat = 0;
  GLenum unpackType = 0;

  PackingInfo ToPacking() const { return {unpackFormat, unpackType}; }
};

struct PixelPackState final {
  uint32_t alignment = 4;
  uint32_t rowLength = 0;
  uint32_t skipRows = 0;
  uint32_t skipPixels = 0;
};

struct ReadPixelsDesc final {
  ivec2 srcOffset;
  uvec2 size;
  PackingInfo pi = {LOCAL_GL_RGBA, LOCAL_GL_UNSIGNED_BYTE};
  PixelPackState packState;
};

class ExtensionBits final {
  uint64_t mBits = 0;

  struct BitRef final {
    ExtensionBits& bits;
    const uint64_t mask;

    explicit operator bool() const { return bits.mBits & mask; }

    auto& operator=(const bool val) {
      if (val) {
        bits.mBits |= mask;
      } else {
        bits.mBits &= ~mask;
      }
      return *this;
    }
  };

  uint64_t Mask(const WebGLExtensionID i) const {
    return uint64_t{1} << static_cast<uint64_t>(i);
  }

 public:
  BitRef operator[](const WebGLExtensionID i) { return {*this, Mask(i)}; }
  bool operator[](const WebGLExtensionID i) const { return mBits & Mask(i); }
};

// -

enum class ContextLossReason : uint8_t {
  None,
  Manual,
  Guilty,
};

inline bool ReadContextLossReason(const uint8_t val,
                                  ContextLossReason* const out) {
  if (val > static_cast<uint8_t>(ContextLossReason::Guilty)) {
    return false;
  }
  *out = static_cast<ContextLossReason>(val);
  return true;
}

// -

struct InitContextDesc final {
  bool isWebgl2 = false;
  bool resistFingerprinting = false;
  uvec2 size = {};
  WebGLContextOptions options;
  uint32_t principalKey = 0;
};

struct Limits final {
  ExtensionBits supportedExtensions;

  // WebGL 1
  uint32_t maxTexUnits = 0;
  uint32_t maxTex2dSize = 0;
  uint32_t maxTexCubeSize = 0;
  uint32_t maxVertexAttribs = 0;
  std::array<uint32_t, 2> maxViewportDims = {};
  std::array<float, 2> pointSizeRange = {{1, 1}};
  std::array<float, 2> lineWidthRange = {{1, 1}};

  // WebGL 2
  uint32_t maxTexArrayLayers = 0;
  uint32_t maxTex3dSize = 0;
  uint32_t maxTransformFeedbackSeparateAttribs = 0;
  uint32_t maxUniformBufferBindings = 0;
  uint32_t uniformBufferOffsetAlignment = 0;

  // Exts
  bool astcHdr = false;
  uint32_t maxColorDrawBuffers = 1;
  uint64_t queryCounterBitsTimeElapsed = 0;
  uint64_t queryCounterBitsTimestamp = 0;
  uint32_t maxMultiviewLayers = 0;
};

struct InitContextResult final {
  std::string error;
  WebGLContextOptions options;
  webgl::Limits limits;
};

// -

struct ErrorInfo final {
  GLenum type;
  std::string info;
};

struct ShaderPrecisionFormat final {
  GLint rangeMin = 0;
  GLint rangeMax = 0;
  GLint precision = 0;
};

// -

enum class LossStatus {
  Ready,

  Lost,
  LostForever,
  LostManually,
};

// -

struct CompileResult final {
  bool pending = true;
  std::string log;
  std::string translatedSource;
  bool success = false;
};

// -

struct OpaqueFramebufferOptions {
  bool depthStencil = true;
  bool antialias = true;
  uint32_t width = 0;
  uint32_t height = 0;

  OpaqueFramebufferOptions() = default;
  OpaqueFramebufferOptions(const OpaqueFramebufferOptions&) = default;
};

// -

struct ActiveInfo {
  GLenum elemType = 0;     // `type`
  uint32_t elemCount = 0;  // `size`
  std::string name;
};

struct ActiveAttribInfo final : public ActiveInfo {
  int32_t location = -1;
  AttribBaseType baseType = AttribBaseType::Float;
};

struct ActiveUniformInfo final : public ActiveInfo {
  std::unordered_map<uint32_t, uint32_t>
      locByIndex;  // Uniform array locations are sparse.
  int32_t block_index = -1;
  int32_t block_offset = -1;  // In block, offset.
  int32_t block_arrayStride = -1;
  int32_t block_matrixStride = -1;
  bool block_isRowMajor = false;
};

struct ActiveUniformBlockInfo final {
  std::string name;
  // BLOCK_BINDING is dynamic state
  uint32_t dataSize = 0;
  std::vector<uint32_t> activeUniformIndices;
  bool referencedByVertexShader = false;
  bool referencedByFragmentShader = false;
};

struct LinkActiveInfo final {
  std::vector<ActiveAttribInfo> activeAttribs;
  std::vector<ActiveUniformInfo> activeUniforms;
  std::vector<ActiveUniformBlockInfo> activeUniformBlocks;
  std::vector<ActiveInfo> activeTfVaryings;
};

struct LinkResult final {
  bool pending = true;
  std::string log;
  bool success = false;
  LinkActiveInfo active;
  GLenum tfBufferMode = 0;
};

// -

/// 4x32-bit primitives, with a type tag.
struct TypedQuad final {
  alignas(alignof(float)) uint8_t data[4 * sizeof(float)] = {};
  webgl::AttribBaseType type = webgl::AttribBaseType::Float;
};

/// [1-16]x32-bit primitives, with a type tag.
struct GetUniformData final {
  alignas(alignof(float)) uint8_t data[4 * 4 * sizeof(float)] = {};
  GLenum type = 0;
};

struct VertAttribPointerDesc final {
  bool intFunc = false;
  uint8_t channels = 4;
  bool normalized = false;
  uint8_t byteStrideOrZero = 0;
  GLenum type = LOCAL_GL_FLOAT;
  uint64_t byteOffset = 0;
};

struct VertAttribPointerCalculated final {
  uint8_t byteSize = 4 * 4;
  uint8_t byteStride = 4 * 4;  // at-most 255
  webgl::AttribBaseType baseType = webgl::AttribBaseType::Float;
};

}  // namespace webgl

// return value for the InitializeCanvasRenderer message
struct ICRData {
  gfx::IntSize size;
  bool hasAlpha;
  bool isPremultAlpha;
};

/**
 * Represents a block of memory that it may or may not own.  The
 * inner data type must be trivially copyable by memcpy.  A RawBuffer
 * may be backed by local memory or shared memory.
 */
template <typename T = uint8_t, typename nonCV = std::remove_cv_t<T>,
          std::enable_if_t<std::is_trivially_assignable<nonCV&, nonCV>::value,
                           int> = 0>
class RawBuffer {
  // The SharedMemoryBasic that owns mData, if any.
  RefPtr<mozilla::ipc::SharedMemoryBasic> mSmem;
  // Pointer to the raw memory block
  T* mData = nullptr;
  // Length is the number of elements of size T in the array
  size_t mLength = 0;
  // true if we should delete[] the mData on destruction
  bool mOwnsData = false;

  friend struct mozilla::webgl::QueueParamTraits<RawBuffer<T>>;

 public:
  using ElementType = T;

  /**
   * If aTakeData is true, RawBuffer will delete[] the memory when destroyed.
   */
  RawBuffer(size_t len, T* data, bool aTakeData = false)
      : mData(data), mLength(len), mOwnsData(aTakeData) {}

  RawBuffer(size_t len, RefPtr<mozilla::ipc::SharedMemoryBasic>& aSmem)
      : mSmem(aSmem), mData(aSmem->memory()), mLength(len), mOwnsData(false) {
    MOZ_ASSERT(mData && mLength);
  }

  ~RawBuffer() {
    // If we have a SharedMemoryBasic then it must own mData.
    MOZ_ASSERT((!mSmem) || (!mOwnsData));
    if (mOwnsData) {
      delete[] mData;
    }
    if (mSmem) {
      mSmem->CloseHandle();
    }
  }

  auto Length() const { return mLength; }

  T* Data() { return mData; }
  const T* Data() const { return mData; }

  T& operator[](size_t idx) {
    MOZ_ASSERT(mData && (idx < mLength));
    return mData[idx];
  }
  const T& operator[](size_t idx) const {
    MOZ_ASSERT(mData && (idx < mLength));
    return mData[idx];
  }

  RawBuffer() = default;
  RawBuffer(const RawBuffer&) = delete;
  RawBuffer& operator=(const RawBuffer&) = delete;

  RawBuffer(RawBuffer&& o)
      : mSmem(o.mSmem),
        mData(o.mData),
        mLength(o.mLength),
        mOwnsData(o.mOwnsData) {
    o.mSmem = nullptr;
    o.mData = nullptr;
    o.mLength = 0;
    o.mOwnsData = false;
  }

  RawBuffer& operator=(RawBuffer&& o) {
    mSmem = o.mSmem;
    mData = o.mData;
    mLength = o.mLength;
    mOwnsData = o.mOwnsData;
    o.mSmem = nullptr;
    o.mData = nullptr;
    o.mLength = 0;
    o.mOwnsData = false;
    return *this;
  }
};

// -

// clang-format off

#define FOREACH_ID(X) \
  X(FuncScopeIdError) \
  X(compressedTexImage2D) \
  X(compressedTexImage3D) \
  X(compressedTexSubImage2D) \
  X(compressedTexSubImage3D) \
  X(copyTexSubImage2D) \
  X(copyTexSubImage3D) \
  X(drawArrays) \
  X(drawArraysInstanced) \
  X(drawElements) \
  X(drawElementsInstanced) \
  X(drawRangeElements) \
  X(renderbufferStorage) \
  X(renderbufferStorageMultisample) \
  X(texImage2D) \
  X(texImage3D) \
  X(TexStorage2D) \
  X(TexStorage3D) \
  X(texSubImage2D) \
  X(texSubImage3D) \
  X(vertexAttrib1f) \
  X(vertexAttrib1fv) \
  X(vertexAttrib2f) \
  X(vertexAttrib2fv) \
  X(vertexAttrib3f) \
  X(vertexAttrib3fv) \
  X(vertexAttrib4f) \
  X(vertexAttrib4fv) \
  X(vertexAttribI4i) \
  X(vertexAttribI4iv) \
  X(vertexAttribI4ui) \
  X(vertexAttribI4uiv) \
  X(vertexAttribIPointer) \
  X(vertexAttribPointer)

// clang-format on

enum class FuncScopeId {
#define _(X) X,
  FOREACH_ID(_)
#undef _
};

static constexpr const char* const FUNCSCOPE_NAME_BY_ID[] = {
#define _(X) #X,
    FOREACH_ID(_)
#undef _
};

#undef FOREACH_ID

inline auto GetFuncScopeName(const FuncScopeId id) {
  return FUNCSCOPE_NAME_BY_ID[static_cast<size_t>(id)];
}

// -

template <typename C, typename K>
inline auto MaybeFind(C& container, const K& key)
    -> decltype(&(container.find(key)->second)) {
  const auto itr = container.find(key);
  if (itr == container.end()) return nullptr;
  return &(itr->second);
}

template <typename C, typename K>
inline typename C::mapped_type Find(
    const C& container, const K& key,
    const typename C::mapped_type notFound = {}) {
  const auto itr = container.find(key);
  if (itr == container.end()) return notFound;
  return itr->second;
}

// -

template <typename T, typename U>
inline Maybe<T> MaybeAs(const U val) {
  const auto checked = CheckedInt<T>(val);
  if (!checked.isValid()) return {};
  return Some(checked.value());
}

// -

inline GLenum ImageToTexTarget(const GLenum imageTarget) {
  switch (imageTarget) {
    case LOCAL_GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
    case LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_X:
    case LOCAL_GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
    case LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
    case LOCAL_GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
    case LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
      return LOCAL_GL_TEXTURE_CUBE_MAP;
    default:
      return imageTarget;
  }
}

// -

namespace dom {
class Element;
class ImageBitmap;
class ImageData;
}  // namespace dom

struct TexImageSource {
  const dom::ArrayBufferView* mView = nullptr;
  GLuint mViewElemOffset = 0;
  GLuint mViewElemLengthOverride = 0;

  const WebGLintptr* mPboOffset = nullptr;

  const dom::ImageBitmap* mImageBitmap = nullptr;
  const dom::ImageData* mImageData = nullptr;

  const dom::Element* mDomElem = nullptr;
  ErrorResult* mOut_error = nullptr;
};

// ---------------------------------------
// MakeRange

template <typename T, size_t N>
inline Range<const T> MakeRange(T (&arr)[N]) {
  return {arr, N};
}

template <typename T>
inline Range<const T> MakeRange(const dom::Sequence<T>& seq) {
  return {seq.Elements(), seq.Length()};
}

template <typename T>
inline Range<const T> MakeRange(const RawBuffer<T>& from) {
  return {from.Data(), from.Length()};
}

template <typename T>
inline Range<T> MakeRange(RawBuffer<T>& from) {
  return {from.Data(), from.Length()};
}

// abv = ArrayBufferView
template <typename T>
inline auto MakeRangeAbv(const T& abv)
    -> Range<const typename T::element_type> {
  abv.ComputeState();
  return {abv.Data(), abv.Length()};
}

Maybe<Range<const uint8_t>> GetRangeFromView(const dom::ArrayBufferView& view,
                                             GLuint elemOffset,
                                             GLuint elemCountOverride);

// -

template <typename T>
RawBuffer<T> RawBufferView(const Range<T>& range) {
  return {range.length(), range.begin().get()};
}

// -

Maybe<webgl::ErrorInfo> CheckBindBufferRange(
    const GLenum target, const GLuint index, const bool isBuffer,
    const uint64_t offset, const uint64_t size, const webgl::Limits& limits);

Maybe<webgl::ErrorInfo> CheckFramebufferAttach(const GLenum bindImageTarget,
                                               const GLenum curTexTarget,
                                               const uint32_t mipLevel,
                                               const uint32_t zLayerBase,
                                               const uint32_t zLayerCount,
                                               const webgl::Limits& limits);

Result<webgl::VertAttribPointerCalculated, webgl::ErrorInfo>
CheckVertexAttribPointer(bool isWebgl2, const webgl::VertAttribPointerDesc&);

uint8_t ElemTypeComponents(GLenum elemType);

inline std::string ToString(const nsACString& text) {
  return {text.BeginReading(), text.Length()};
}

// -

}  // namespace mozilla

#endif