bool DrawingBuffer::prepareMailbox(blink::WebExternalTextureMailbox* outMailbox, blink::WebExternalBitmap* bitmap)
{
if (!m_context || !m_contentsChanged)
return false;
m_context->makeContextCurrent();
// Resolve the multisampled buffer into m_colorBuffer texture.
if (m_multisampleMode != None)
commit();
if (bitmap) {
bitmap->setSize(size());
unsigned char* pixels = bitmap->pixels();
bool needPremultiply = m_attributes.alpha && !m_attributes.premultipliedAlpha;
WebGLImageConversion::AlphaOp op = needPremultiply ? WebGLImageConversion::AlphaDoPremultiply : WebGLImageConversion::AlphaDoNothing;
if (pixels)
readBackFramebuffer(pixels, size().width(), size().height(), ReadbackSkia, op);
}
// We must restore the texture binding since creating new textures,
// consuming and producing mailboxes changes it.
ScopedTextureUnit0BindingRestorer restorer(m_context, m_activeTextureUnit, m_texture2DBinding);
// First try to recycle an old buffer.
RefPtr<MailboxInfo> frontColorBufferMailbox = recycledMailbox();
// No buffer available to recycle, create a new one.
if (!frontColorBufferMailbox) {
unsigned newColorBuffer = createColorTexture(m_size);
// Bad things happened, abandon ship.
if (!newColorBuffer)
return false;
frontColorBufferMailbox = createNewMailbox(newColorBuffer);
}
if (m_preserveDrawingBuffer == Discard) {
swap(frontColorBufferMailbox->textureId, m_colorBuffer);
// It appears safe to overwrite the context's framebuffer binding in the Discard case since there will always be a
// WebGLRenderingContext::clearIfComposited() call made before the next draw call which restores the framebuffer binding.
// If this stops being true at some point, we should track the current framebuffer binding in the DrawingBuffer and restore
// it after attaching the new back buffer here.
m_context->bindFramebuffer(GL_FRAMEBUFFER, m_fbo);
if (m_multisampleMode == ImplicitResolve)
m_context->framebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer, 0, m_sampleCount);
else
m_context->framebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer, 0);
} else {
m_context->copyTextureCHROMIUM(GL_TEXTURE_2D, m_colorBuffer, frontColorBufferMailbox->textureId, 0, GL_RGBA, GL_UNSIGNED_BYTE);
}
if (m_multisampleMode != None && !m_framebufferBinding)
bind();
else
restoreFramebufferBinding();
m_contentsChanged = false;
m_context->bindTexture(GL_TEXTURE_2D, frontColorBufferMailbox->textureId);
m_context->produceTextureCHROMIUM(GL_TEXTURE_2D, frontColorBufferMailbox->mailbox.name);
m_context->flush();
frontColorBufferMailbox->mailbox.syncPoint = m_context->insertSyncPoint();
markLayerComposited();
*outMailbox = frontColorBufferMailbox->mailbox;
m_frontColorBuffer = frontColorBufferMailbox->textureId;
return true;
}
void WebGPUSwapChain::present()
{
markLayerComposited();
}
