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* Copyright (C) 2007 Alp Toker <>
* Copyright (C) 2007 Apple Inc.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* Library General Public License for more details.
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
#ifndef PrintContext_h
#define PrintContext_h
#include "core/CoreExport.h"
#include "platform/heap/Handle.h"
#include "platform/wtf/Forward.h"
#include "platform/wtf/HashMap.h"
#include "platform/wtf/Vector.h"
#include "platform/wtf/text/WTFString.h"
namespace blink {
class Element;
class FloatSize;
class GraphicsContext;
class IntRect;
class LocalFrame;
class Node;
class CORE_EXPORT PrintContext
: public GarbageCollectedFinalized<PrintContext> {
// By shrinking to a width of 75%, we will render the correct physical
// dimensions in paged media (i.e. cm, pt,). The shrinkage used
// to be 80% to match other browsers - they have since moved on.
// Wide pages will be scaled down more than this.
// This value is the percentage inverted.
static constexpr float kPrintingMinimumShrinkFactor = 1.33333333f;
// This number determines how small we are willing to reduce the page content
// in order to accommodate the widest line. If the page would have to be
// reduced smaller to make the widest line fit, we just clip instead (this
// behavior matches MacIE and Mozilla, at least).
// TODO(rhogan): Decide if this quirk is still required.
static constexpr float kPrintingMaximumShrinkFactor = 2;
explicit PrintContext(LocalFrame*);
virtual ~PrintContext();
LocalFrame* GetFrame() const { return frame_; }
// Break up a page into rects without relayout.
// FIXME: This means that CSS page breaks won't be on page boundary if the
// size is different than what was passed to BeginPrintMode(). That's probably
// not always desirable.
virtual void ComputePageRects(const FloatSize& print_size);
// Deprecated. Page size computation is already in this class, clients
// shouldn't be copying it.
virtual void ComputePageRectsWithPageSize(
const FloatSize& page_size_in_pixels);
// These are only valid after page rects are computed.
size_t PageCount() const { return page_rects_.size(); }
const IntRect& PageRect(size_t page_number) const {
return page_rects_[page_number];
const Vector<IntRect>& PageRects() const { return page_rects_; }
// Enter print mode, updating layout for new page size.
// This function can be called multiple times to apply new print options
// without going back to screen mode.
virtual void BeginPrintMode(float width, float height = 0);
// Return to screen mode.
virtual void EndPrintMode();
// The following static methods are used by layout tests:
// Returns -1 if page isn't found.
static int PageNumberForElement(Element*,
const FloatSize& page_size_in_pixels);
static String PageProperty(LocalFrame*,
const char* property_name,
int page_number);
static bool IsPageBoxVisible(LocalFrame*, int page_number);
static String PageSizeAndMarginsInPixels(LocalFrame*,
int page_number,
int width,
int height,
int margin_top,
int margin_right,
int margin_bottom,
int margin_left);
static int NumberOfPages(LocalFrame*, const FloatSize& page_size_in_pixels);
virtual void Trace(blink::Visitor*);
friend class PrintContextTest;
void OutputLinkedDestinations(GraphicsContext&, const IntRect& page_rect);
Member<LocalFrame> frame_;
Vector<IntRect> page_rects_;
void ComputePageRectsWithPageSizeInternal(
const FloatSize& page_size_in_pixels);
void CollectLinkedDestinations(Node*);
bool IsFrameValid() const;
// Used to prevent misuses of BeginPrintMode() and EndPrintMode() (e.g., call
// EndPrintMode() without BeginPrintMode()).
bool is_printing_;
HeapHashMap<String, Member<Element>> linked_destinations_;
bool linked_destinations_valid_;
class ScopedPrintContext {
explicit ScopedPrintContext(LocalFrame*);
PrintContext* operator->() const { return context_.Get(); }
Member<PrintContext> context_;
} // namespace blink