chromium/src/third_party/blink/renderer/core/paint/ng/ng_text_painter.cc

// Copyright 2017 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 "third_party/blink/renderer/core/paint/ng/ng_text_painter.h"

#include "third_party/blink/renderer/core/css/css_property_names.h"
#include "third_party/blink/renderer/core/frame/settings.h"
#include "third_party/blink/renderer/core/layout/ng/ng_unpositioned_float.h"
#include "third_party/blink/renderer/core/paint/box_painter.h"
#include "third_party/blink/renderer/core/paint/paint_info.h"
#include "third_party/blink/renderer/core/paint/paint_timing_detector.h"
#include "third_party/blink/renderer/core/style/computed_style.h"
#include "third_party/blink/renderer/core/style/shadow_list.h"
#include "third_party/blink/renderer/platform/fonts/font.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_result_view.h"
#include "third_party/blink/renderer/platform/graphics/graphics_context.h"
#include "third_party/blink/renderer/platform/graphics/graphics_context_state_saver.h"
#include "third_party/blink/renderer/platform/graphics/paint/paint_controller.h"
#include "third_party/blink/renderer/platform/wtf/assertions.h"
#include "third_party/blink/renderer/platform/wtf/text/character_names.h"

namespace blink {

void NGTextPainter::Paint(unsigned start_offset,
                          unsigned end_offset,
                          unsigned length,
                          const TextPaintStyle& text_style,
                          DOMNodeId node_id,
                          ShadowMode shadow_mode) {
  GraphicsContextStateSaver state_saver(graphics_context_, false);
  UpdateGraphicsContext(graphics_context_, text_style, horizontal_, state_saver,
                        shadow_mode);
  // TODO(layout-dev): Handle combine text here or elsewhere.
  PaintInternal<kPaintText>(start_offset, end_offset, length, node_id);

  if (!emphasis_mark_.IsEmpty()) {
    if (text_style.emphasis_mark_color != text_style.fill_color)
      graphics_context_.SetFillColor(text_style.emphasis_mark_color);
    PaintInternal<kPaintEmphasisMark>(start_offset, end_offset, length,
                                      node_id);
  }
}

// This function paints text twice with different styles in order to:
// 1. Paint glyphs inside of |selection_rect| using |selection_style|, and
//    outside using |text_style|.
// 2. Paint parts of a ligature glyph.
void NGTextPainter::PaintSelectedText(unsigned start_offset,
                                      unsigned end_offset,
                                      unsigned length,
                                      const TextPaintStyle& text_style,
                                      const TextPaintStyle& selection_style,
                                      const PhysicalRect& selection_rect,
                                      DOMNodeId node_id) {
  if (!fragment_paint_info_.shape_result)
    return;

  // Use fast path if all glyphs fit in |selection_rect|. |visual_rect_| is the
  // ink bounds of all glyphs of this text fragment, including characters before
  // |start_offset| or after |end_offset|. Computing exact bounds is expensive
  // that this code only checks bounds of all glyphs.
  IntRect snapped_selection_rect(PixelSnappedIntRect(selection_rect));
  // Allowing 1px overflow is almost unnoticeable, while it can avoid two-pass
  // painting in most small text.
  snapped_selection_rect.Inflate(1);
  if (snapped_selection_rect.Contains(visual_rect_)) {
    Paint(start_offset, end_offset, length, selection_style, node_id);
    return;
  }

  // Adjust start/end offset when they are in the middle of a ligature. e.g.,
  // when |start_offset| is between a ligature of "fi", it needs to be adjusted
  // to before "f".
  fragment_paint_info_.shape_result->ExpandRangeToIncludePartialGlyphs(
      &start_offset, &end_offset);

  // Because only a part of the text glyph can be selected, we need to draw
  // the selection twice. First, draw the glyphs outside the selection area,
  // with the original style.
  FloatRect float_selection_rect(selection_rect);
  {
    GraphicsContextStateSaver state_saver(graphics_context_);
    graphics_context_.ClipOut(float_selection_rect);
    Paint(start_offset, end_offset, length, text_style, node_id,
          kTextProperOnly);
  }
  // Then draw the glyphs inside the selection area, with the selection style.
  {
    GraphicsContextStateSaver state_saver(graphics_context_);
    graphics_context_.Clip(float_selection_rect);
    Paint(start_offset, end_offset, length, selection_style, node_id);
  }
}

template <NGTextPainter::PaintInternalStep step>
void NGTextPainter::PaintInternalFragment(
    unsigned from,
    unsigned to,
    DOMNodeId node_id) {
  DCHECK(from <= fragment_paint_info_.text.length());
  DCHECK(to <= fragment_paint_info_.text.length());

  fragment_paint_info_.from = from;
  fragment_paint_info_.to = to;

  if (step == kPaintEmphasisMark) {
    graphics_context_.DrawEmphasisMarks(
        font_, fragment_paint_info_, emphasis_mark_,
        FloatPoint(text_origin_) + IntSize(0, emphasis_mark_offset_));
  } else {
    DCHECK(step == kPaintText);
    graphics_context_.DrawText(font_, fragment_paint_info_,
                               FloatPoint(text_origin_), node_id);
    // TODO(npm): Check that there are non-whitespace characters. See
    // crbug.com/788444.
    graphics_context_.GetPaintController().SetTextPainted();

    if (!font_.ShouldSkipDrawing())
      PaintTimingDetector::NotifyTextPaint(visual_rect_);
  }
}

template <NGTextPainter::PaintInternalStep Step>
void NGTextPainter::PaintInternal(unsigned start_offset,
                                  unsigned end_offset,
                                  unsigned truncation_point,
                                  DOMNodeId node_id) {
  // TODO(layout-dev): We shouldn't be creating text fragments without text.
  if (!fragment_paint_info_.shape_result)
    return;

  if (start_offset <= end_offset) {
    PaintInternalFragment<Step>(start_offset, end_offset, node_id);
  } else {
    if (end_offset > 0) {
      PaintInternalFragment<Step>(ellipsis_offset_, end_offset, node_id);
    }
    if (start_offset < truncation_point) {
      PaintInternalFragment<Step>(start_offset, truncation_point, node_id);
    }
  }
}

void NGTextPainter::ClipDecorationsStripe(float upper,
                                          float stripe_width,
                                          float dilation) {
  if (fragment_paint_info_.from >= fragment_paint_info_.to ||
      !fragment_paint_info_.shape_result)
    return;

  Vector<Font::TextIntercept> text_intercepts;
  font_.GetTextIntercepts(
      fragment_paint_info_, graphics_context_.DeviceScaleFactor(),
      graphics_context_.FillFlags(),
      std::make_tuple(upper, upper + stripe_width), text_intercepts);

  DecorationsStripeIntercepts(upper, stripe_width, dilation, text_intercepts);
}

void NGTextPainter::PaintEmphasisMarkForCombinedText() {}

}  // namespace blink