src/text/text_selection_controller.cpp

#include "rive/text/text_selection_controller.hpp"
#ifdef WITH_RIVE_TEXT
#include "rive/artboard.hpp"
#include "rive/nested_artboard.hpp"
#include "rive/artboard_component_list.hpp"
#include "rive/factory.hpp"
#include "rive/file.hpp"
#include "rive/text/text.hpp"
#include "rive/text/text_selection_path.hpp"
#include "rive/text/utf.hpp"
#include <algorithm>
#include <cmath>
#include <limits>

using namespace rive;

struct TextSelectionController::Participant
{
  Text* text;
  uint32_t id = 0;
  std::string separatorBefore;
  std::vector<Unichar> source;
  GlyphLookup lookup;
  Cursor cursor = Cursor::zero();
  std::vector<AABB> rects;
  TextSelectionPath path;
  rcp<RenderPaint> paint;
  bool lookupDirty = true;
  bool geometryDirty = true;
  float radius = -1;
#ifdef TESTING
  size_t lookupBuilds = 0;
#endif

  Participant(Text* text, std::string separator)
      : text(text)
      , separatorBefore(std::move(separator))
  {}
};

// rootTransform includes every nested host and its artboard's self transform.
// Sampling the affine basis also covers Dart-mounted artboard callbacks.
static Mat2D shapeToRoot(Text* text)
{
  auto* artboard = text->artboard();
  auto origin = artboard->rootTransform(Vec2D(0, 0));
  auto x = artboard->rootTransform(Vec2D(1, 0)) - origin;
  auto y = artboard->rootTransform(Vec2D(0, 1)) - origin;
  return Mat2D(x.x, x.y, y.x, y.y, origin.x, origin.y) *
         text->shapeWorldTransform();
}

static bool finite(Vec2D position)
{
  return std::isfinite(position.x) && std::isfinite(position.y);
}

static AABB lineBounds(const OrderedLine& line)
{
  float x = line.startX();
  auto bounds = AABB::forExpansion();
  for (auto glyph : line)
  {
    auto* run = std::get<0>(glyph);
    auto index = std::get<1>(glyph);
    AABB::expandTo(bounds, Vec2D(x, line.y() + run->font->ascent(run->size)));
    x += run->advances[index];
    AABB::expandTo(bounds, Vec2D(x, line.y() + run->font->descent(run->size)));
  }
  return bounds;
}

TextSelectionController::TextSelectionController() = default;

TextSelectionController::~TextSelectionController()
{
  for (auto& participant : m_participants)
  {
    participant->text->m_selectionController = nullptr;
  }
}

TextSelectionController::Participant* TextSelectionController::find(
    Text* text) const
{
  for (auto& participant : m_participants)
  {
    if (participant->text == text)
    {
      return participant.get();
    }
  }
  return nullptr;
}

bool TextSelectionController::add(Text* text, std::string separatorBefore)
{
  if (text == nullptr || text->artboard() == nullptr ||
      text->m_selectionController != nullptr || text->haveModifiers() ||
      text->overflow() == TextOverflow::ellipsis)
  {
    return false;
  }
  clear();
  auto participant = std::make_unique<Participant>(
      text,
      std::move(separatorBefore));
  participant->source = text->m_styledText.unichars();
  participant->id = m_nextTargetId++;
  text->m_selectionController = this;
  m_participants.push_back(std::move(participant));
  return true;
}

void TextSelectionController::remove(Text* text)
{
  auto it = std::find_if(
      m_participants.begin(),
      m_participants.end(),
      [text](const std::unique_ptr<Participant>& p) {
        return p->text == text;
      });
  if (it == m_participants.end())
  {
    return;
  }
  clear();
  text->m_selectionController = nullptr;
  m_participants.erase(it);
}

bool TextSelectionController::eligible(const Participant& participant) const
{
  auto* text = participant.text;
  return !text->isHidden() && text->renderOpacity() > 0 &&
         !text->haveModifiers() && text->overflow() != TextOverflow::ellipsis &&
         !text->m_orderedLines.empty() && !participant.source.empty();
}

static void collectSelectable(Artboard* artboard, std::vector<Text*>& result)
{
  if (artboard == nullptr)
    return;
  // Every Text is a Drawable, and drawables() keeps their relative object
  // order while skipping the vertices, paints and other non-drawables that
  // make up most of objects(). Hosts synchronize on every pointer move.
  for (auto* drawable : artboard->drawables())
  {
    if (drawable->is<Text>() && drawable->isSelectable())
      result.push_back(drawable->as<Text>());
  }
  for (auto* nested : artboard->nestedArtboards())
    collectSelectable(nested->artboardInstance(), result);
  for (auto* list : artboard->artboardComponentLists())
    for (size_t i = 0; i < list->artboardCount(); ++i)
      collectSelectable(list->artboardInstance((int)i), result);
}

void TextSelectionController::synchronize(Artboard* root)
{
  m_styleFile = root != nullptr && root->isInstance()
                    ? static_cast<ArtboardInstance*>(root)->file()
                    : nullptr;
  std::vector<Text*> texts;
  collectSelectable(root, texts);
  std::vector<Text*> removed;
  for (const auto& p : m_participants)
    if (std::find(texts.begin(), texts.end(), p->text) == texts.end())
      removed.push_back(p->text);
  for (auto* text : removed)
    remove(text);
  for (auto* text : texts)
    if (find(text) == nullptr)
      add(text);
}

std::vector<uint32_t> TextSelectionController::targetIds() const
{
  std::vector<uint32_t> ids;
  for (const auto& p : m_participants)
    ids.push_back(p->id);
  return ids;
}

Text* TextSelectionController::target(uint32_t id) const
{
  for (const auto& p : m_participants)
    if (p->id == id)
      return p->text;
  return nullptr;
}

bool TextSelectionController::isEligible(Text* text) const
{
  auto* p = find(text);
  return p != nullptr && eligible(*p);
}

std::string TextSelectionController::sourceText(Text* text) const
{
  auto* p = find(text);
  std::string result;
  if (p == nullptr)
    return result;
  for (auto ch : p->source)
  {
    uint8_t bytes[4];
    auto count = UTF::Encode(bytes, ch);
    result.append(reinterpret_cast<char*>(bytes), count);
  }
  return result;
}

AABB TextSelectionController::rootBounds(Text* text) const
{
  auto* p = find(text);
  AABB result = AABB::forExpansion();
  if (p == nullptr || !eligible(*p))
    return result;
  auto transform = shapeToRoot(text);
  for (const auto& line : text->m_orderedLines)
  {
    auto b = lineBounds(line);
    if (b.isEmptyOrNaN())
      continue;
    AABB::expandTo(result, transform * Vec2D(b.minX, b.minY));
    AABB::expandTo(result, transform * Vec2D(b.maxX, b.minY));
    AABB::expandTo(result, transform * Vec2D(b.minX, b.maxY));
    AABB::expandTo(result, transform * Vec2D(b.maxX, b.maxY));
  }
  return result;
}

bool TextSelectionController::hitTest(
    Text* text,
    Vec2D point,
    bool nearest,
    uint32_t& offset,
    float& distanceSquared)
{
  auto* p = find(text);
  if (p == nullptr || !eligible(*p) || !finite(point))
    return false;
  auto transform = shapeToRoot(text);
  Mat2D inverse;
  if (!transform.invert(&inverse))
    return false;
  auto local = inverse * point;
  if (!finite(local))
    return false;
  if (!nearest)
  {
    auto artboardPoint = text->shapeWorldTransform() * local;
    if (!text->hitTestPoint(artboardPoint, false, true))
      return false;
    if (text->overflow() == TextOverflow::clipped)
    {
      Mat2D inverseWorld;
      if (!text->worldTransform().invert(&inverseWorld) ||
          !text->localBounds().contains(inverseWorld * artboardPoint))
        return false;
    }
  }
  bool found = false;
  distanceSquared = std::numeric_limits<float>::infinity();
  uint32_t index = 0;
  for (const auto& line : text->m_orderedLines)
  {
    auto b = lineBounds(line);
    if (!b.isEmptyOrNaN() && (nearest || b.contains(local)))
    {
      Vec2D closest(
          std::max(b.minX, std::min(local.x, b.maxX)),
          std::max(b.minY, std::min(local.y, b.maxY)));
      auto delta = transform * closest - point;
      auto distance = delta.x * delta.x + delta.y * delta.y;
      if (distance < distanceSquared)
      {
        distanceSquared = distance;
        offset = CursorPosition::fromLineX(index, local.x, layout(*p))
                     .codePointIndex();
        found = true;
      }
    }
    ++index;
  }
  return found;
}

void TextSelectionController::setRange(Text* text, uint32_t start, uint32_t end)
{
  auto* p = find(text);
  if (p == nullptr)
    return;
  if (!m_externalRanges)
    clear();
  m_externalRanges = true;
  auto length = (uint32_t)p->source.size();
  start = std::min(start, length);
  end = std::min(end, length);
  if (p->cursor.first().codePointIndex() == std::min(start, end) &&
      p->cursor.last().codePointIndex() == std::max(start, end))
    return;
  p->cursor = Cursor(CursorPosition(start), CursorPosition(end));
  p->geometryDirty = true;
}

TextLayoutView TextSelectionController::layout(Participant& participant)
{
  auto* text = participant.text;
  if (participant.lookupDirty)
  {
    participant.lookup.compute(text->m_styledText.unichars(), text->m_shape);
    participant.lookupDirty = false;
#ifdef TESTING
    participant.lookupBuilds++;
#endif
  }
  return TextLayoutView(
      text->m_shape,
      text->m_lines,
      text->m_orderedLines,
      participant.lookup,
      (uint32_t)participant.source.size());
}

void TextSelectionController::textUpdated(Text* text, bool shapeChanged)
{
  auto* participant = find(text);
  if (participant == nullptr)
  {
    return;
  }
  if (shapeChanged)
  {
    const auto& source = text->m_styledText.unichars();
    if (participant->source != source)
    {
      clear();
      participant->source = source;
    }
    participant->lookupDirty = true;
  }
  participant->geometryDirty = true;
  if (m_anchor.participant != nullptr && !validSelection())
  {
    clear();
  }
}

#ifdef TESTING
size_t TextSelectionController::lookupBuildCount(Text* text) const
{
  auto* participant = find(text);
  return participant == nullptr ? 0 : participant->lookupBuilds;
}
#endif

bool TextSelectionController::validSelection() const
{
  if (m_externalRanges)
  {
    for (auto& participant : m_participants)
    {
      if (participant->cursor.hasSelection() && !eligible(*participant))
        return false;
    }
    return true;
  }
  if (m_anchor.participant == nullptr || m_extent.participant == nullptr ||
      !eligible(*m_anchor.participant) || !eligible(*m_extent.participant))
  {
    return false;
  }
  for (auto& participant : m_participants)
  {
    if (participant->cursor.first().codePointIndex() !=
            participant->cursor.last().codePointIndex() &&
        !eligible(*participant))
    {
      return false;
    }
  }
  return true;
}

void TextSelectionController::clear()
{
  m_anchor = {};
  m_extent = {};
  m_dragging = false;
  m_externalRanges = false;
  for (auto& participant : m_participants)
  {
    participant->cursor = Cursor::zero();
    participant->geometryDirty = true;
  }
}

bool TextSelectionController::endpointAt(
    Participant& participant,
    Vec2D rootPosition,
    Endpoint& out)
{
  Mat2D inverse;
  if (!eligible(participant) || !finite(rootPosition) ||
      !shapeToRoot(participant.text).invert(&inverse))
  {
    return false;
  }
  auto local = inverse * rootPosition;
  if (!finite(local))
  {
    return false;
  }
  out = {
      &participant,
      CursorPosition::fromTranslation(local, layout(participant))};
  return true;
}

bool TextSelectionController::pointerDown(
    Text* hitText,
    Vec2D rootPosition,
    int pointerId,
    bool extend)
{
  // A second pointer must not replace the anchor or take over capture.
  if (m_dragging)
  {
    return false;
  }
  auto* participant = find(hitText);
  Endpoint endpoint;
  if (participant == nullptr ||
      !endpointAt(*participant, rootPosition, endpoint))
  {
    clear();
    return false;
  }
  if (!extend || m_externalRanges || !validSelection())
  {
    m_anchor = endpoint;
  }
  m_externalRanges = false;
  m_extent = endpoint;
  m_pointerId = pointerId;
  m_dragging = true;
  updateRanges();
  return true;
}

bool TextSelectionController::nearestEndpoint(Vec2D rootPosition, Endpoint& out)
{
  if (!finite(rootPosition))
  {
    return false;
  }
  float bestDistance = std::numeric_limits<float>::infinity();
  bool found = false;
  for (auto& participant : m_participants)
  {
    Mat2D inverse;
    auto transform = shapeToRoot(participant->text);
    if (!eligible(*participant) || !transform.invert(&inverse))
    {
      continue;
    }
    auto local = inverse * rootPosition;
    if (!finite(local))
    {
      continue;
    }
    uint32_t lineIndex = 0;
    for (const auto& line : participant->text->m_orderedLines)
    {
      auto bounds = lineBounds(line);
      if (!bounds.isEmptyOrNaN())
      {
        Vec2D closest(
            std::max(bounds.minX, std::min(local.x, bounds.maxX)),
            std::max(bounds.minY, std::min(local.y, bounds.maxY)));
        auto delta = transform * closest - rootPosition;
        float distance = delta.x * delta.x + delta.y * delta.y;
        if (distance < bestDistance)
        {
          bestDistance = distance;
          out = {
              participant.get(),
              CursorPosition::fromLineX(
                  lineIndex,
                  local.x,
                  layout(*participant))};
          found = true;
        }
      }
      lineIndex++;
    }
  }
  return found;
}

bool TextSelectionController::pointerMove(Vec2D rootPosition, int pointerId)
{
  if (!m_dragging || pointerId != m_pointerId)
  {
    return false;
  }
  if (!validSelection())
  {
    clear();
    return false;
  }
  Endpoint endpoint;
  if (nearestEndpoint(rootPosition, endpoint))
  {
    m_extent = endpoint;
    updateRanges();
  }
  return true;
}

bool TextSelectionController::pointerUp(Vec2D rootPosition, int pointerId)
{
  if (!pointerMove(rootPosition, pointerId))
  {
    return false;
  }
  m_dragging = false;
  return true;
}

bool TextSelectionController::pointerCancel(int pointerId)
{
  if (!m_dragging || pointerId != m_pointerId)
  {
    return false;
  }
  clear();
  return true;
}

bool TextSelectionController::select(
    Text* anchorText,
    uint32_t anchorOffset,
    Text* extentText,
    uint32_t extentOffset)
{
  auto* anchor = find(anchorText);
  auto* extent = find(extentText);
  if (anchor == nullptr || extent == nullptr || !eligible(*anchor) ||
      !eligible(*extent))
  {
    return false;
  }
  m_dragging = false;
  m_anchor = {anchor, CursorPosition::atIndex(anchorOffset, layout(*anchor))};
  m_externalRanges = false;
  m_extent = {extent, CursorPosition::atIndex(extentOffset, layout(*extent))};
  updateRanges();
  return true;
}

void TextSelectionController::selectAll()
{
  Participant* first = nullptr;
  Participant* last = nullptr;
  for (auto& participant : m_participants)
  {
    if (eligible(*participant))
    {
      if (first == nullptr)
      {
        first = participant.get();
      }
      last = participant.get();
    }
  }
  if (first != nullptr)
  {
    select(first->text, 0, last->text, (uint32_t)last->source.size());
  }
  else
  {
    clear();
  }
}

void TextSelectionController::updateRanges()
{
  auto first = m_anchor;
  auto last = m_extent;
  size_t anchorIndex = 0, extentIndex = 0;
  for (size_t i = 0; i < m_participants.size(); i++)
  {
    if (m_participants[i].get() == first.participant)
      anchorIndex = i;
    if (m_participants[i].get() == last.participant)
      extentIndex = i;
  }
  if (anchorIndex > extentIndex ||
      (anchorIndex == extentIndex && first.position > last.position))
  {
    std::swap(first, last);
    std::swap(anchorIndex, extentIndex);
  }
  for (size_t i = 0; i < m_participants.size(); i++)
  {
    auto& participant = *m_participants[i];
    uint32_t start = 0, end = 0;
    if (i >= anchorIndex && i <= extentIndex && eligible(participant))
    {
      start = i == anchorIndex ? first.position.codePointIndex() : 0;
      end = i == extentIndex ? last.position.codePointIndex()
                             : (uint32_t)participant.source.size();
    }
    participant.cursor = Cursor(CursorPosition(start), CursorPosition(end));
    participant.geometryDirty = true;
  }
}

bool TextSelectionController::hasSelection() const
{
  if (!validSelection())
  {
    return false;
  }
  if (m_externalRanges)
  {
    for (const auto& p : m_participants)
      if (p->cursor.hasSelection())
        return true;
    return false;
  }
  return m_anchor.participant != m_extent.participant ||
         m_anchor.position.codePointIndex() !=
             m_extent.position.codePointIndex();
}

Cursor TextSelectionController::selection(Text* text) const
{
  auto* participant = find(text);
  return validSelection() && participant != nullptr ? participant->cursor
                                                    : Cursor::zero();
}

std::string TextSelectionController::selectedText() const
{
  std::string result;
  if (!hasSelection())
  {
    return result;
  }
  if (m_externalRanges)
  {
    for (const auto& p : m_participants)
    {
      if (!p->cursor.hasSelection())
        continue;
      if (!result.empty())
        result += p->separatorBefore;
      for (auto i = p->cursor.first().codePointIndex();
           i < p->cursor.last().codePointIndex();
           ++i)
      {
        uint8_t bytes[4];
        auto count = UTF::Encode(bytes, p->source[i]);
        result.append(reinterpret_cast<char*>(bytes), count);
      }
    }
    return result;
  }
  bool started = false;
  bool inRange = false;
  uint32_t endpointsSeen = 0;
  // Include object boundaries even when an endpoint contributes zero
  // characters (end of A -> start of B still selects the separator).
  for (auto& participant : m_participants)
  {
    bool endpoint = participant.get() == m_anchor.participant ||
                    participant.get() == m_extent.participant;
    if (endpoint && !inRange)
    {
      inRange = true;
    }
    if (inRange && eligible(*participant))
    {
      if (started)
      {
        result += participant->separatorBefore;
      }
      started = true;
      auto first = participant->cursor.first().codePointIndex();
      auto last = participant->cursor.last().codePointIndex();
      for (auto i = first; i < last; i++)
      {
        uint8_t bytes[4];
        auto count = UTF::Encode(bytes, participant->source[i]);
        result.append(reinterpret_cast<char*>(bytes), count);
      }
    }
    if (endpoint)
    {
      endpointsSeen++;
      if (m_anchor.participant == m_extent.participant || endpointsSeen == 2)
      {
        break;
      }
    }
  }
  return result;
}

Span<const AABB> TextSelectionController::selectionRects(Text* text)
{
  auto* participant = find(text);
  if (participant == nullptr || !participant->cursor.hasSelection() ||
      !validSelection())
  {
    return {};
  }
  float radius = std::max(0.0f, style().cornerRadius());
  if (participant->geometryDirty || participant->radius != radius)
  {
    participant->rects.clear();
    auto view = layout(*participant);
    if (!view.orderedLines().empty())
    {
      // Range endpoints are source offsets. Walk every drawn line, so
      // hidden/trimmed lines do not confuse logical and visible indices.
      auto cursor = Cursor(
          CursorPosition(0, participant->cursor.first().codePointIndex()),
          CursorPosition(
              (uint32_t)view.orderedLines().size() - 1,
              participant->cursor.last().codePointIndex()));
      cursor.selectionRects(participant->rects, view);
    }
    participant->path.update(participant->rects, radius);
    participant->radius = radius;
    participant->geometryDirty = false;
  }
  return participant->rects;
}

void TextSelectionController::draw(Text* text, Renderer* renderer)
{
  if (m_anchor.participant != nullptr && !validSelection())
  {
    clear();
  }
  if (selectionRects(text).empty())
  {
    return;
  }
  auto* participant = find(text);
  auto* factory = text->artboard()->factory();
  if (participant->paint == nullptr)
  {
    participant->paint = factory->makeRenderPaint();
    participant->paint->style(RenderPaintStyle::fill);
  }
  participant->paint->color(
      colorModulateOpacity(style().highlightColor(), text->renderOpacity()));
  renderer->save();
  renderer->transform(text->shapeWorldTransform());
  renderer->drawPath(
      participant->path.renderPath(factory),
      participant->paint.get());
  renderer->restore();
}

const SelectionStyle& TextSelectionController::style() const
{
  static const SelectionStyle defaults;
  const auto* fileStyle = m_styleFile == nullptr
                              ? nullptr
                              : m_styleFile->selectionStyle();
  return m_style != nullptr     ? *m_style
         : fileStyle != nullptr ? *fileStyle
                                : defaults;
}

bool TextSelectionController::keyInput(
    Key key,
    KeyModifiers modifiers,
    bool isPressed)
{
  if (!isPressed || !validSelection())
  {
    return false;
  }
  if (key == Key::escape)
  {
    clear();
    return true;
  }
  if (key == Key::a && (modifiers & (KeyModifiers::ctrl |
                                     KeyModifiers::meta)) != KeyModifiers::none)
  {
    selectAll();
    return true;
  }
  return false;
}
#endif