gecko/dom/canvas/WebGLTexture.cpp

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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/. */

#include "WebGLTexture.h"

#include <algorithm>
#include "GLContext.h"
#include "mozilla/dom/WebGLRenderingContextBinding.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/Scoped.h"
#include "ScopedGLHelpers.h"
#include "WebGLContext.h"
#include "WebGLContextUtils.h"
#include "WebGLTexelConversions.h"

namespace mozilla {

JSObject*
WebGLTexture::WrapObject(JSContext* cx) {
    return dom::WebGLTextureBinding::Wrap(cx, this);
}

WebGLTexture::WebGLTexture(WebGLContext* webgl, GLuint tex)
    : WebGLBindableName<TexTarget>(tex)
    , WebGLContextBoundObject(webgl)
    , mMinFilter(LOCAL_GL_NEAREST_MIPMAP_LINEAR)
    , mMagFilter(LOCAL_GL_LINEAR)
    , mWrapS(LOCAL_GL_REPEAT)
    , mWrapT(LOCAL_GL_REPEAT)
    , mFacesCount(0)
    , mMaxLevelWithCustomImages(0)
    , mHaveGeneratedMipmap(false)
    , mImmutable(false)
    , mBaseMipmapLevel(0)
    , mMaxMipmapLevel(1000)
    , mFakeBlackStatus(WebGLTextureFakeBlackStatus::IncompleteTexture)
{
    mContext->mTextures.insertBack(this);
}

void
WebGLTexture::Delete()
{
    mImageInfos.Clear();
    mContext->MakeContextCurrent();
    mContext->gl->fDeleteTextures(1, &mGLName);
    LinkedListElement<WebGLTexture>::removeFrom(mContext->mTextures);
}

size_t
WebGLTexture::ImageInfo::MemoryUsage() const
{
    if (mImageDataStatus == WebGLImageDataStatus::NoImageData)
        return 0;

    size_t bitsPerTexel = GetBitsPerTexel(mEffectiveInternalFormat);
    return size_t(mWidth) * size_t(mHeight) * size_t(mDepth) * bitsPerTexel / 8;
}

size_t
WebGLTexture::MemoryUsage() const
{
    if (IsDeleted())
        return 0;

    size_t result = 0;
    for(size_t face = 0; face < mFacesCount; face++) {
        for(size_t level = 0; level <= mMaxLevelWithCustomImages; level++) {
            result += ImageInfoAtFace(face, level).MemoryUsage();
        }
    }
    return result;
}

static inline size_t
MipmapLevelsForSize(const WebGLTexture::ImageInfo& info)
{
    GLsizei size = std::max(std::max(info.Width(), info.Height()), info.Depth());

    // Find floor(log2(size)). (ES 3.0.4, 3.8 - Mipmapping).
    return mozilla::FloorLog2(size);
}

bool
WebGLTexture::DoesMipmapHaveAllLevelsConsistentlyDefined(TexImageTarget texImageTarget) const
{
    // We could not have generated a mipmap if the base image wasn't defined.
    if (mHaveGeneratedMipmap)
        return true;

    if (!IsMipmapRangeValid())
        return false;

    // We want a copy here so we can modify it temporarily.
    ImageInfo expected = ImageInfoAt(texImageTarget,
                                     EffectiveBaseMipmapLevel());
    if (!expected.IsPositive())
        return false;

    // If Level{max} is > mMaxLevelWithCustomImages, then check if we are
    // missing any image levels.
    if (mMaxMipmapLevel > mMaxLevelWithCustomImages) {
        if (MipmapLevelsForSize(expected) > mMaxLevelWithCustomImages)
            return false;
    }

    // Checks if custom images are all defined up to the highest level and
    // have the expected dimensions.
    for (size_t level = EffectiveBaseMipmapLevel();
         level <= EffectiveMaxMipmapLevel(); ++level)
    {
        const ImageInfo& actual = ImageInfoAt(texImageTarget, level);
        if (actual != expected)
            return false;

        expected.mWidth = std::max(1, expected.mWidth / 2);
        expected.mHeight = std::max(1, expected.mHeight / 2);
        expected.mDepth = std::max(1, expected.mDepth / 2);

        // If the current level has size 1x1, we can stop here: The spec doesn't
        // seem to forbid the existence of extra useless levels.
        if (actual.mWidth == 1 &&
            actual.mHeight == 1 &&
            actual.mDepth == 1)
        {
            return true;
        }
    }

    return true;
}

void
WebGLTexture::Bind(TexTarget texTarget)
{
    // This function should only be called by bindTexture(). It assumes that the
    // GL context is already current.

    bool firstTimeThisTextureIsBound = !HasEverBeenBound();

    if (firstTimeThisTextureIsBound) {
        BindTo(texTarget);
    } else if (texTarget != Target()) {
        mContext->ErrorInvalidOperation("bindTexture: This texture has already"
                                        " been bound to a different target.");
        // Very important to return here before modifying texture state! This
        // was the place when I lost a whole day figuring very strange "invalid
        // write" crashes.
        return;
    }

    GLuint name = GLName();

    mContext->gl->fBindTexture(texTarget.get(), name);

    if (firstTimeThisTextureIsBound) {
        mFacesCount = (texTarget == LOCAL_GL_TEXTURE_CUBE_MAP) ? 6 : 1;
        EnsureMaxLevelWithCustomImagesAtLeast(0);
        SetFakeBlackStatus(WebGLTextureFakeBlackStatus::Unknown);

        // Thanks to the WebKit people for finding this out: GL_TEXTURE_WRAP_R
        // is not present in GLES 2, but is present in GL and it seems as if for
        // cube maps we need to set it to GL_CLAMP_TO_EDGE to get the expected
        // GLES behavior.
        if (mTarget == LOCAL_GL_TEXTURE_CUBE_MAP && !mContext->gl->IsGLES()) {
            mContext->gl->fTexParameteri(texTarget.get(),
                                         LOCAL_GL_TEXTURE_WRAP_R,
                                         LOCAL_GL_CLAMP_TO_EDGE);
        }
    }
}

void
WebGLTexture::SetImageInfo(TexImageTarget texImageTarget, GLint level,
                           GLsizei width, GLsizei height, GLsizei depth,
                           TexInternalFormat effectiveInternalFormat,
                           WebGLImageDataStatus status)
{
    MOZ_ASSERT(depth == 1 || texImageTarget == LOCAL_GL_TEXTURE_3D);
    MOZ_ASSERT(TexImageTargetToTexTarget(texImageTarget) == mTarget);

    EnsureMaxLevelWithCustomImagesAtLeast(level);

    ImageInfoAt(texImageTarget, level) = ImageInfo(width, height, depth,
                                                   effectiveInternalFormat,
                                                   status);

    if (level > 0)
        SetCustomMipmap();

    // Invalidate framebuffer status cache.
    NotifyFBsStatusChanged();

    SetFakeBlackStatus(WebGLTextureFakeBlackStatus::Unknown);
}

void
WebGLTexture::SetGeneratedMipmap()
{
    if (!mHaveGeneratedMipmap) {
        mHaveGeneratedMipmap = true;
        SetFakeBlackStatus(WebGLTextureFakeBlackStatus::Unknown);
    }
}

void
WebGLTexture::SetCustomMipmap()
{
    if (mHaveGeneratedMipmap) {
        if (!IsMipmapRangeValid())
            return;

        // If we were in GeneratedMipmap mode and are now switching to
        // CustomMipmap mode, we now need to compute all the mipmap image info.
        ImageInfo imageInfo = ImageInfoAtFace(0, EffectiveBaseMipmapLevel());
        MOZ_ASSERT(mContext->IsWebGL2() || imageInfo.IsPowerOfTwo(),
                   "This texture is NPOT, so how could GenerateMipmap() ever"
                   " accept it?");

        size_t maxRelativeLevel = MipmapLevelsForSize(imageInfo);
        size_t maxLevel = EffectiveBaseMipmapLevel() + maxRelativeLevel;
        EnsureMaxLevelWithCustomImagesAtLeast(maxLevel);

        for (size_t level = EffectiveBaseMipmapLevel() + 1;
             level <= EffectiveMaxMipmapLevel(); ++level)
        {
            imageInfo.mWidth = std::max(imageInfo.mWidth / 2, 1);
            imageInfo.mHeight = std::max(imageInfo.mHeight / 2, 1);
            imageInfo.mDepth = std::max(imageInfo.mDepth / 2, 1);
            for(size_t face = 0; face < mFacesCount; ++face) {
                ImageInfoAtFace(face, level) = imageInfo;
            }
        }
    }
    mHaveGeneratedMipmap = false;
}

bool
WebGLTexture::AreAllLevel0ImageInfosEqual() const
{
    for (size_t face = 1; face < mFacesCount; ++face) {
        if (ImageInfoAtFace(face, 0) != ImageInfoAtFace(0, 0))
            return false;
    }
    return true;
}

bool
WebGLTexture::IsMipmapComplete() const
{
    MOZ_ASSERT(mTarget == LOCAL_GL_TEXTURE_2D ||
               mTarget == LOCAL_GL_TEXTURE_3D);
    return DoesMipmapHaveAllLevelsConsistentlyDefined(LOCAL_GL_TEXTURE_2D);
}

bool
WebGLTexture::IsCubeComplete() const
{
    MOZ_ASSERT(mTarget == LOCAL_GL_TEXTURE_CUBE_MAP);

    const ImageInfo& first = ImageInfoAt(LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_X,
                                         0);
    if (!first.IsPositive() || !first.IsSquare())
        return false;

    return AreAllLevel0ImageInfosEqual();
}

bool
WebGLTexture::IsMipmapCubeComplete() const
{
    // In particular, this checks that this is a cube map:
    if (!IsCubeComplete())
        return false;

    for (int i = 0; i < 6; i++) {
        const TexImageTarget face = TexImageTargetForTargetAndFace(LOCAL_GL_TEXTURE_CUBE_MAP,
                                                                   i);
        if (!DoesMipmapHaveAllLevelsConsistentlyDefined(face))
            return false;
    }
    return true;
}

bool
WebGLTexture::IsMipmapRangeValid() const
{
    // In ES3, if a texture is immutable, the mipmap levels are clamped.
    if (IsImmutable())
        return true;
    if (mBaseMipmapLevel > std::min(mMaxLevelWithCustomImages, mMaxMipmapLevel))
        return false;
    return true;
}

WebGLTextureFakeBlackStatus
WebGLTexture::ResolvedFakeBlackStatus()
{
    if (MOZ_LIKELY(mFakeBlackStatus != WebGLTextureFakeBlackStatus::Unknown))
        return mFakeBlackStatus;

    // Determine if the texture needs to be faked as a black texture.
    // See 3.8.2 Shader Execution in the OpenGL ES 2.0.24 spec, and 3.8.13 in
    // the OpenGL ES 3.0.4 spec.
    if (!IsMipmapRangeValid()) {
        mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
        return mFakeBlackStatus;
    }

    for (size_t face = 0; face < mFacesCount; ++face) {
        WebGLImageDataStatus status = ImageInfoAtFace(face, EffectiveBaseMipmapLevel()).mImageDataStatus;
        if (status == WebGLImageDataStatus::NoImageData) {
            // In case of undefined texture image, we don't print any message
            // because this is a very common and often legitimate case
            // (asynchronous texture loading).
            mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            return mFakeBlackStatus;
        }
    }

    const char preamble[] = "A texture is going to be rendered as if it were"
                            " black, as per the OpenGL ES 2.0.24 spec section"
                            " 3.8.2, because it";

    if (mTarget == LOCAL_GL_TEXTURE_2D ||
        mTarget == LOCAL_GL_TEXTURE_3D)
    {
        int dim = mTarget == LOCAL_GL_TEXTURE_2D ? 2 : 3;
        if (DoesMinFilterRequireMipmap()) {
            if (!IsMipmapComplete()) {
                mContext->GenerateWarning("%s is a %dD texture, with a"
                                          " minification filter requiring a"
                                          " mipmap, and is not mipmap complete"
                                          " (as defined in section 3.7.10).",
                                          preamble, dim);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            } else if (!mContext->IsWebGL2() &&
                       !ImageInfoBase().IsPowerOfTwo())
            {
                mContext->GenerateWarning("%s is a %dD texture, with a"
                                          " minification filter requiring a"
                                          " mipmap, and either its width or"
                                          " height is not a power of two.",
                                          preamble, dim);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            }
        } else {
            // No mipmap required here.
            if (!ImageInfoBase().IsPositive()) {
                mContext->GenerateWarning("%s is a %dD texture and its width or"
                                          " height is equal to zero.",
                                          preamble, dim);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            } else if (!AreBothWrapModesClampToEdge() &&
                       !mContext->IsWebGL2() &&
                       !ImageInfoBase().IsPowerOfTwo())
            {
                mContext->GenerateWarning("%s is a %dD texture, with a"
                                          " minification filter not requiring a"
                                          " mipmap, with its width or height"
                                          " not a power of two, and with a wrap"
                                          " mode different from CLAMP_TO_EDGE.",
                                          preamble, dim);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            }
        }
    } else  {
        // Cube map
        bool legalImageSize = true;
        if (!mContext->IsWebGL2()) {
            for (size_t face = 0; face < mFacesCount; ++face)
                legalImageSize &= ImageInfoAtFace(face, 0).IsPowerOfTwo();
        }

        if (DoesMinFilterRequireMipmap()) {
            if (!IsMipmapCubeComplete()) {
                mContext->GenerateWarning("%s is a cube map texture, with a"
                                          " minification filter requiring a"
                                          " mipmap, and is not mipmap cube"
                                          " complete (as defined in section"
                                          " 3.7.10).", preamble);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            } else if (!legalImageSize) {
                mContext->GenerateWarning("%s is a cube map texture, with a"
                                          " minification filter requiring a"
                                          " mipmap, and either the width or the"
                                          " height of some level 0 image is not"
                                          " a power of two.", preamble);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            }
        }
        else // no mipmap required
        {
            if (!IsCubeComplete()) {
                mContext->GenerateWarning("%s is a cube map texture, with a"
                                          " minification filter not requiring a"
                                          " mipmap, and is not cube complete"
                                          " (as defined in section 3.7.10).",
                                          preamble);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            } else if (!AreBothWrapModesClampToEdge() && !legalImageSize) {
                mContext->GenerateWarning("%s is a cube map texture, with a"
                                          " minification filter not requiring a"
                                          " mipmap, with some level 0 image"
                                          " having width or height not a power"
                                          " of two, and with a wrap mode"
                                          " different from CLAMP_TO_EDGE.",
                                          preamble);
                mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
            }
        }
    }

    TexType type = TypeFromInternalFormat(ImageInfoBase().mEffectiveInternalFormat);

    const char* badFormatText = nullptr;
    const char* extText = nullptr;

    if (type == LOCAL_GL_FLOAT &&
        !Context()->IsExtensionEnabled(WebGLExtensionID::OES_texture_float_linear))
    {
        badFormatText = "FLOAT";
        extText = "OES_texture_float_linear";
    } else if (type == LOCAL_GL_HALF_FLOAT &&
               !Context()->IsExtensionEnabled(WebGLExtensionID::OES_texture_half_float_linear))
    {
        badFormatText = "HALF_FLOAT";
        extText = "OES_texture_half_float_linear";
    }

    const char* badFilterText = nullptr;
    if (badFormatText) {
        if (mMinFilter == LOCAL_GL_LINEAR ||
            mMinFilter == LOCAL_GL_LINEAR_MIPMAP_LINEAR ||
            mMinFilter == LOCAL_GL_LINEAR_MIPMAP_NEAREST ||
            mMinFilter == LOCAL_GL_NEAREST_MIPMAP_LINEAR)
        {
            badFilterText = "minification";
        } else if (mMagFilter == LOCAL_GL_LINEAR) {
            badFilterText = "magnification";
        }
    }

    if (badFilterText) {
        mContext->GenerateWarning("%s is a texture with a linear %s filter,"
                                  " which is not compatible with format %s by"
                                  " default. Try enabling the %s extension, if"
                                  " supported.", preamble, badFilterText,
                                  badFormatText, extText);
        mFakeBlackStatus = WebGLTextureFakeBlackStatus::IncompleteTexture;
    }

    // We have exhausted all cases of incomplete textures, where we would need opaque black.
    // We may still need transparent black in case of uninitialized image data.
    bool hasUninitializedImageData = false;
    for (size_t level = 0; level <= mMaxLevelWithCustomImages; ++level) {
        for (size_t face = 0; face < mFacesCount; ++face) {
            bool cur = (ImageInfoAtFace(face, level).mImageDataStatus == WebGLImageDataStatus::UninitializedImageData);
            hasUninitializedImageData |= cur;
        }
    }

    if (hasUninitializedImageData) {
        bool hasAnyInitializedImageData = false;
        for (size_t level = 0; level <= mMaxLevelWithCustomImages; ++level) {
            for (size_t face = 0; face < mFacesCount; ++face) {
                if (ImageInfoAtFace(face, level).mImageDataStatus == WebGLImageDataStatus::InitializedImageData) {
                    hasAnyInitializedImageData = true;
                    break;
                }
            }
            if (hasAnyInitializedImageData) {
                break;
            }
        }

        if (hasAnyInitializedImageData) {
            /* The texture contains some initialized image data, and some
             * uninitialized image data. In this case, we have no choice but to
             * initialize all image data now. Fortunately, in this case we know
             * that we can't be dealing with a depth texture per
             * WEBGL_depth_texture and ANGLE_depth_texture (which allow only one
             * image per texture) so we can assume that glTexImage2D is able to
             * upload data to images.
             */
            for (size_t level = 0; level <= mMaxLevelWithCustomImages; ++level)
            {
                for (size_t face = 0; face < mFacesCount; ++face) {
                    TexImageTarget imageTarget = TexImageTargetForTargetAndFace(mTarget,
                                                                                face);
                    const ImageInfo& imageInfo = ImageInfoAt(imageTarget, level);
                    if (imageInfo.mImageDataStatus == WebGLImageDataStatus::UninitializedImageData)
                    {
                        EnsureNoUninitializedImageData(imageTarget, level);
                    }
                }
            }
            mFakeBlackStatus = WebGLTextureFakeBlackStatus::NotNeeded;
        } else {
            // The texture only contains uninitialized image data. In this case,
            // we can use a black texture for it.
            mFakeBlackStatus = WebGLTextureFakeBlackStatus::UninitializedImageData;
        }
    }

    // we have exhausted all cases where we do need fakeblack, so if the status is still unknown,
    // that means that we do NOT need it.
    if (mFakeBlackStatus == WebGLTextureFakeBlackStatus::Unknown) {
        mFakeBlackStatus = WebGLTextureFakeBlackStatus::NotNeeded;
    }

    MOZ_ASSERT(mFakeBlackStatus != WebGLTextureFakeBlackStatus::Unknown);
    return mFakeBlackStatus;
}

static bool
ClearByMask(WebGLContext* webgl, GLbitfield mask)
{
    gl::GLContext* gl = webgl->GL();
    MOZ_ASSERT(gl->IsCurrent());

    GLenum status = gl->fCheckFramebufferStatus(LOCAL_GL_FRAMEBUFFER);
    if (status != LOCAL_GL_FRAMEBUFFER_COMPLETE)
        return false;

    bool colorAttachmentsMask[WebGLContext::kMaxColorAttachments] = {false};
    if (mask & LOCAL_GL_COLOR_BUFFER_BIT) {
        colorAttachmentsMask[0] = true;
    }

    webgl->ForceClearFramebufferWithDefaultValues(mask, colorAttachmentsMask);
    return true;
}

// `mask` from glClear.
static bool
ClearWithTempFB(WebGLContext* webgl, GLuint tex,
                TexImageTarget texImageTarget, GLint level,
                TexInternalFormat baseInternalFormat,
                GLsizei width, GLsizei height)
{
    MOZ_ASSERT(texImageTarget == LOCAL_GL_TEXTURE_2D);

    gl::GLContext* gl = webgl->GL();
    MOZ_ASSERT(gl->IsCurrent());

    gl::ScopedFramebuffer fb(gl);
    gl::ScopedBindFramebuffer autoFB(gl, fb.FB());
    GLbitfield mask = 0;

    switch (baseInternalFormat.get()) {
    case LOCAL_GL_LUMINANCE:
    case LOCAL_GL_LUMINANCE_ALPHA:
    case LOCAL_GL_ALPHA:
    case LOCAL_GL_RGB:
    case LOCAL_GL_RGBA:
    case LOCAL_GL_BGR:
    case LOCAL_GL_BGRA:
        mask = LOCAL_GL_COLOR_BUFFER_BIT;
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_COLOR_ATTACHMENT0,
                                  texImageTarget.get(), tex, level);
        break;
    case LOCAL_GL_DEPTH_COMPONENT32_OES:
    case LOCAL_GL_DEPTH_COMPONENT24_OES:
    case LOCAL_GL_DEPTH_COMPONENT16:
    case LOCAL_GL_DEPTH_COMPONENT:
        mask = LOCAL_GL_DEPTH_BUFFER_BIT;
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_DEPTH_ATTACHMENT,
                                  texImageTarget.get(), tex, level);
        break;

    case LOCAL_GL_DEPTH24_STENCIL8:
    case LOCAL_GL_DEPTH_STENCIL:
        mask = LOCAL_GL_DEPTH_BUFFER_BIT |
               LOCAL_GL_STENCIL_BUFFER_BIT;
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_DEPTH_ATTACHMENT,
                                  texImageTarget.get(), tex, level);
        gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_STENCIL_ATTACHMENT,
                                  texImageTarget.get(), tex, level);
        break;

    default:
        return false;
    }
    MOZ_ASSERT(mask);

    if (ClearByMask(webgl, mask))
        return true;

    // Failed to simply build an FB from the tex, but maybe it needs a
    // color buffer to be complete.

    if (mask & LOCAL_GL_COLOR_BUFFER_BIT) {
        // Nope, it already had one.
        return false;
    }

    gl::ScopedRenderbuffer rb(gl);
    {
        gl::ScopedBindRenderbuffer(gl, rb.RB());
        gl->fRenderbufferStorage(LOCAL_GL_RENDERBUFFER,
                                 LOCAL_GL_RGBA4,
                                 width, height);
    }

    gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_COLOR_ATTACHMENT0,
                                 LOCAL_GL_RENDERBUFFER, rb.RB());
    mask |= LOCAL_GL_COLOR_BUFFER_BIT;

    // Last chance!
    return ClearByMask(webgl, mask);
}


void
WebGLTexture::EnsureNoUninitializedImageData(TexImageTarget imageTarget,
                                             GLint level)
{
    const ImageInfo& imageInfo = ImageInfoAt(imageTarget, level);
    if (!imageInfo.HasUninitializedImageData())
        return;

    mContext->MakeContextCurrent();

    // Try to clear with glClear.
    if (imageTarget == LOCAL_GL_TEXTURE_2D) {
        bool cleared = ClearWithTempFB(mContext, GLName(), imageTarget, level,
                                       imageInfo.mEffectiveInternalFormat,
                                       imageInfo.mHeight, imageInfo.mWidth);
        if (cleared) {
            SetImageDataStatus(imageTarget, level,
                               WebGLImageDataStatus::InitializedImageData);
            return;
        }
    }

    // That didn't work. Try uploading zeros then.
    gl::ScopedBindTexture autoBindTex(mContext->gl, GLName(), mTarget.get());

    size_t bitspertexel = GetBitsPerTexel(imageInfo.mEffectiveInternalFormat);
    MOZ_ASSERT((bitspertexel % 8) == 0); // That would only happen for
                                         // compressed images, which cannot use
                                         // deferred initialization.
    size_t bytespertexel = bitspertexel / 8;
    CheckedUint32 checked_byteLength
        = WebGLContext::GetImageSize(
                        imageInfo.mHeight,
                        imageInfo.mWidth,
                        imageInfo.mDepth,
                        bytespertexel,
                        mContext->mPixelStoreUnpackAlignment);
    MOZ_ASSERT(checked_byteLength.isValid()); // Should have been checked
                                              // earlier.

     // Infallible for now.
    UniquePtr<uint8_t> zeros((uint8_t*)moz_xcalloc(1,
                                                   checked_byteLength.value()));

    gl::GLContext* gl = mContext->gl;
    GLenum driverInternalFormat = LOCAL_GL_NONE;
    GLenum driverFormat = LOCAL_GL_NONE;
    GLenum driverType = LOCAL_GL_NONE;
    DriverFormatsFromEffectiveInternalFormat(gl,
                                             imageInfo.mEffectiveInternalFormat,
                                             &driverInternalFormat,
                                             &driverFormat, &driverType);

    mContext->GetAndFlushUnderlyingGLErrors();
    if (imageTarget == LOCAL_GL_TEXTURE_3D) {
        MOZ_ASSERT(mImmutable,
                   "Shouldn't be possible to have non-immutable-format 3D"
                   " textures in WebGL");
        gl->fTexSubImage3D(imageTarget.get(), level, 0, 0, 0, imageInfo.mWidth,
                           imageInfo.mHeight, imageInfo.mDepth, driverFormat,
                           driverType, zeros.get());
    } else {
        if (mImmutable) {
            gl->fTexSubImage2D(imageTarget.get(), level, 0, 0, imageInfo.mWidth,
                               imageInfo.mHeight, driverFormat, driverType,
                               zeros.get());
        } else {
            gl->fTexImage2D(imageTarget.get(), level, driverInternalFormat,
                            imageInfo.mWidth, imageInfo.mHeight, 0,
                            driverFormat, driverType, zeros.get());
        }
    }
    GLenum error = mContext->GetAndFlushUnderlyingGLErrors();
    if (error) {
        // Should only be OUT_OF_MEMORY. Anyway, there's no good way to recover
        // from this here.
        printf_stderr("Error: 0x%4x\n", error);
        MOZ_CRASH(); // Errors on texture upload have been related to video
                     // memory exposure in the past.
    }

    SetImageDataStatus(imageTarget, level, WebGLImageDataStatus::InitializedImageData);
}

void
WebGLTexture::SetFakeBlackStatus(WebGLTextureFakeBlackStatus x)
{
    mFakeBlackStatus = x;
    mContext->SetFakeBlackStatus(WebGLContextFakeBlackStatus::Unknown);
}

NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(WebGLTexture)

NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(WebGLTexture, AddRef)
NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(WebGLTexture, Release)

} // namespace mozilla