Implements PrintBrowser mode.

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 72 matching lines @@
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/layout/svg/LayoutSVGRoot.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/FocusController.h"
 #include "core/page/FrameTree.h"
 #include "core/page/Page.h"
+#include "core/page/PrintContext.h"
 #include "core/page/scrolling/RootScrollerUtil.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/page/scrolling/TopDocumentRootScrollerController.h"
 #include "core/paint/FramePainter.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/PaintTiming.h"
 #include "core/paint/PrePaintTreeWalk.h"
 #include "core/plugins/PluginView.h"
 #include "core/style/ComputedStyle.h"
 #include "core/svg/SVGDocumentExtensions.h"
@@ skipping 124 matching lines @@
   visitor->trace(m_fragmentAnchor);
   visitor->trace(m_scrollableAreas);
   visitor->trace(m_animatingScrollableAreas);
   visitor->trace(m_autoSizeInfo);
   visitor->trace(m_children);
   visitor->trace(m_viewportScrollableArea);
   visitor->trace(m_visibilityObserver);
   visitor->trace(m_scrollAnchor);
   visitor->trace(m_anchoringAdjustmentQueue);
   visitor->trace(m_scrollbarManager);
+  visitor->trace(m_printContext);
   Widget::trace(visitor);
   ScrollableArea::trace(visitor);
 }
 
 void FrameView::reset() {
   // The compositor throttles the main frame using deferred commits, we can't
   // throttle it here or it seems the root compositor doesn't get setup
   // properly.
   if (RuntimeEnabledFeatures::
           renderingPipelineThrottlingLoadingIframesEnabled())
@@ skipping 2632 matching lines @@
         SourceLocation::capture(m_frame->document()), nullptr);
     m_frame->document()->dispatchErrorEvent(error, NotSharableCrossOrigin);
     // Ensure notifications will get delivered in next cycle.
     if (FrameView* frameView = m_frame->view())
       frameView->scheduleAnimation();
   }
 
   DCHECK(!layoutView()->needsLayout());
 }
 
+void FrameView::dispatchEventsForPrintingOnAllFrames() {
+  DCHECK(m_frame->isMainFrame());
+  for (Frame* currentFrame = m_frame; currentFrame;
+       currentFrame = currentFrame->tree().traverseNext(m_frame)) {
+    if (currentFrame->isLocalFrame())
+      toLocalFrame(currentFrame)->document()->dispatchEventsForPrinting();
+  }
+}
+
 // TODO(leviw): We don't assert lifecycle information from documents in child
 // PluginViews.
 void FrameView::updateLifecyclePhasesInternal(
     DocumentLifecycle::LifecycleState targetState) {
   if (m_currentUpdateLifecyclePhasesTargetState !=
       DocumentLifecycle::Uninitialized) {
     NOTREACHED() << "FrameView::updateLifecyclePhasesInternal() reentrance";
     return;
   }
 
@@ skipping 12 matching lines @@
 
   AutoReset<DocumentLifecycle::LifecycleState> targetStateScope(
       &m_currentUpdateLifecyclePhasesTargetState, targetState);
 
   if (shouldThrottleRendering()) {
     updateViewportIntersectionsForSubtree(
         std::min(targetState, DocumentLifecycle::CompositingClean));
     return;
   }
 
+  if (RuntimeEnabledFeatures::printBrowserEnabled()) {
+    if (!m_frame->document()->printing()) {

[pdr., 2017/02/08 04:28:05]

Can you split this logic out into a helper? I think that will help keep
updateLifecyclePhasesInternal simple.

[gozzard, 2017/02/08 05:40:20]

Done.

+      if (!m_printContext)
+        m_printContext = new PrintContext(m_frame);
+      if (m_frame->settings())
+        m_frame->settings()->setShouldPrintBackgrounds(true);
+      int pageWidth = 595, pageHeight = 842;  // A4 Portrait

[pdr., 2017/02/08 04:28:05]

Nit: can you break these into constants?
Maybe "const int kA4PortraitPageWidth = 595;"

[gozzard, 2017/02/08 05:40:20]

Done.

+      FloatRect pageRect(0, 0, pageWidth, pageHeight);
+      m_printContext->begin(pageRect.width(), pageRect.height());
+      float height;

[pdr., 2017/02/08 04:28:05]

Do we need to do this print context and page rect computations and event
dispatching on every call to updateLifecyclePhasesInternal?

[gozzard, 2017/02/08 05:40:20]

m_printContext->begin() indirectly sets m_frame->document()->printing() to be
true. As such this setup code will only runs as necessary.

+      m_printContext->computePageRects(pageRect, 0, 0, 1.0, height);
+      dispatchEventsForPrintingOnAllFrames();
+    }
+  } else if (m_printContext) {
+    m_printContext->end();
+    m_printContext.clear();
+  }
+
   updateStyleAndLayoutIfNeededRecursive();
   DCHECK(lifecycle().state() >= DocumentLifecycle::LayoutClean);
 
   if (targetState == DocumentLifecycle::LayoutClean) {
     updateViewportIntersectionsForSubtree(targetState);
     return;
   }
 
   forAllNonThrottledFrameViews([](FrameView& frameView) {
     frameView.performScrollAnchoringAdjustments();
@@ skipping 52 matching lines @@
       // TODO(pdr): prePaint should be under the "Paint" devtools timeline step
       // for slimming paint v2.
       if (targetState >= DocumentLifecycle::PrePaintClean)
         prePaint();
     }
 
     if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
       DocumentAnimations::updateAnimations(layoutView()->document());
 
     if (targetState == DocumentLifecycle::PaintClean) {
-      if (!m_frame->document()->printing())
+      if (!m_frame->document()->printing() ||
+          RuntimeEnabledFeatures::printBrowserEnabled())
         paintTree();
 
       if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
         pushPaintArtifactToCompositor();
 
       DCHECK(!view.hasPendingSelection());
       DCHECK((m_frame->document()->printing() &&
               lifecycle().state() == DocumentLifecycle::PrePaintClean) ||
              lifecycle().state() == DocumentLifecycle::PaintClean);
     }
@@ skipping 71 matching lines @@
 
   LayoutViewItem view = layoutViewItem();
   ASSERT(!view.isNull());
   forAllNonThrottledFrameViews([](FrameView& frameView) {
     frameView.lifecycle().advanceTo(DocumentLifecycle::InPaint);
   });
 
   if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     if (layoutView()->layer()->needsRepaint()) {
       GraphicsContext graphicsContext(*m_paintController);
+      if (RuntimeEnabledFeatures::printBrowserEnabled())

[pdr., 2017/02/08 04:28:05]

WDYT about implementing this for both spv2 (as you've done here) and the spv1
codepaths? I think it should be pretty easy to do and will make sure this
feature isn't tied to spv2's timeline.

If you do this, please add a layouttest that covers both codepaths. The virtual
test infrastructure lets you write tests that run with a flag. It's a little
confusing so please ask if you need help with this.

[gozzard, 2017/02/08 05:40:20]

I had a look into this and found that it would require significantly more
boilerplate to implement support for SPV1. Therefore we made the design decision
to (at least initially) only support SPV2. This may no longer be the case after
changing to RuntimeEnabledFeatures::printBrowserEnabled(). I will look into it,
but I think this is best done as a separate CL, especially as I probably don't
have the time left in my internship to do this.
I just finished setting this up with a virtual test environment and an example
test anyway, actually.

+        graphicsContext.setPrinting(true);
       paint(graphicsContext, CullRect(LayoutRect::infiniteIntRect()));
       m_paintController->commitNewDisplayItems(LayoutSize());
       notifyPaint(*m_paintController);
     }
   } else {
     // A null graphics layer can occur for painting of SVG images that are not
     // parented into the main frame tree, or when the FrameView is the main
     // frame view of a page overlay. The page overlay is in the layer tree of
     // the host page and will be painted during painting of the host page.
     if (GraphicsLayer* rootGraphicsLayer =
@@ skipping 2000 matching lines @@
     std::unique_ptr<CompositorAnimationTimeline> timeline) {
   m_animationTimeline = std::move(timeline);
 }
 
 void FrameView::setAnimationHost(
     std::unique_ptr<CompositorAnimationHost> host) {
   m_animationHost = std::move(host);
 }
 
 }  // namespace blink