flutter_flutter/sky/engine/core/text/Paragraph.cpp

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "sky/engine/core/text/ParagraphBuilder.h"

#include "base/location.h"
#include "sky/engine/core/painting/Rect.h"
#include "sky/engine/core/rendering/PaintInfo.h"
#include "sky/engine/core/rendering/RenderText.h"
#include "sky/engine/core/rendering/style/RenderStyle.h"
#include "sky/engine/platform/fonts/FontCache.h"
#include "sky/engine/platform/graphics/GraphicsContext.h"
#include "sky/engine/public/platform/Platform.h"
#include "sky/engine/tonic/dart_args.h"
#include "sky/engine/tonic/dart_binding_macros.h"
#include "sky/engine/tonic/dart_converter.h"
#include "sky/engine/tonic/dart_library_natives.h"

namespace blink {

IMPLEMENT_WRAPPERTYPEINFO(ui, Paragraph);

#define FOR_EACH_BINDING(V) \
  V(Paragraph, width) \
  V(Paragraph, height) \
  V(Paragraph, minIntrinsicWidth) \
  V(Paragraph, maxIntrinsicWidth) \
  V(Paragraph, alphabeticBaseline) \
  V(Paragraph, ideographicBaseline) \
  V(Paragraph, layout) \
  V(Paragraph, getRectsForRange) \
  V(Paragraph, getPositionForOffset)

DART_BIND_ALL(Paragraph, FOR_EACH_BINDING)

Paragraph::Paragraph(PassOwnPtr<RenderView> renderView)
    : m_renderView(renderView)
{
}

Paragraph::~Paragraph()
{
    base::SingleThreadTaskRunner* runner = Platform::current()->GetUITaskRunner();
    runner->DeleteSoon(FROM_HERE, m_renderView.leakPtr());
}

double Paragraph::width()
{
    return firstChildBox()->width();
}

double Paragraph::height()
{
    return firstChildBox()->height();
}

double Paragraph::minIntrinsicWidth()
{
    return firstChildBox()->minPreferredLogicalWidth();
}

double Paragraph::maxIntrinsicWidth()
{
    return firstChildBox()->maxPreferredLogicalWidth();
}

double Paragraph::alphabeticBaseline()
{
    return firstChildBox()->firstLineBoxBaseline(FontBaselineOrAuto(AlphabeticBaseline));
}

double Paragraph::ideographicBaseline()
{
    return firstChildBox()->firstLineBoxBaseline(FontBaselineOrAuto(IdeographicBaseline));
}

void Paragraph::layout(double width)
{
    FontCachePurgePreventer fontCachePurgePreventer;

    int maxWidth = LayoutUnit(width); // Handles infinity properly.
    m_renderView->setFrameViewSize(IntSize(maxWidth, intMaxForLayoutUnit));
    m_renderView->layout();
}

void Paragraph::paint(Canvas* canvas, double x, double y)
{
    FontCachePurgePreventer fontCachePurgePreventer;

    // Very simplified painting to allow painting an arbitrary (layer-less) subtree.
    RenderBox* box = firstChildBox();
    SkCanvas* skCanvas = canvas->skCanvas();
    skCanvas->translate(x, y);

    GraphicsContext context(skCanvas);
    Vector<RenderBox*> layers;
    LayoutRect bounds = box->absoluteBoundingBoxRect();
    DCHECK(bounds.x() == 0 && bounds.y() == 0);
    PaintInfo paintInfo(&context, enclosingIntRect(bounds), box);
    box->paint(paintInfo, LayoutPoint(), layers);
    // Note we're ignoring any layers encountered.
    // TODO(abarth): Remove the concept of RenderLayers.

    skCanvas->translate(-x, -y);
}

std::vector<TextBox> Paragraph::getRectsForRange(unsigned start, unsigned end) {
  if (end <= start || start == end)
    return std::vector<TextBox>();

  unsigned offset = 0;
  std::vector<TextBox> boxes;
  for (RenderObject* object = m_renderView.get(); object; object = object->nextInPreOrder()) {
    if (!object->isText())
      continue;
    RenderText* text = toRenderText(object);
    unsigned length = text->textLength();
    if (offset + length > start) {
      unsigned startOffset = offset > start ? 0 : start - offset;
      unsigned endOffset = end - offset;
      text->appendAbsoluteTextBoxesForRange(boxes, startOffset, endOffset);
    }
    offset += length;
    if (offset >= end)
      break;
  }

  return boxes;
}

int Paragraph::absoluteOffsetForPosition(const PositionWithAffinity& position) {
  DCHECK(position.renderer());
  unsigned offset = 0;
  for (RenderObject* object = m_renderView.get(); object; object = object->nextInPreOrder()) {
    if (object == position.renderer())
      return offset + position.offset();
    if (object->isText()) {
      RenderText* text = toRenderText(object);
      offset += text->textLength();
    }
  }
  DCHECK(false);
  return 0;
}

Dart_Handle Paragraph::getPositionForOffset(const Offset& offset) {
  LayoutPoint point(offset.sk_size.width(), offset.sk_size.height());
  PositionWithAffinity position = m_renderView->positionForPoint(point);
  Dart_Handle result = Dart_NewList(2);
  Dart_ListSetAt(result, 0, ToDart(absoluteOffsetForPosition(position)));
  Dart_ListSetAt(result, 1, ToDart(static_cast<int>(position.affinity())));
  return result;
}

} // namespace blink