homeassistant_espscreen/components/smart_display/cyd_ui.h

#pragma once
#include <algorithm>
#include <cmath>
#include <cstdint>
#include <string>

namespace cyd {
// The n-th quoted item of a JSON list such as ["auto","low","high"]; empty when absent.
inline std::string list_item(const std::string &json, unsigned index) {
  size_t pos = 0; unsigned n = 0;
  while ((pos = json.find('"', pos)) != std::string::npos) {
    size_t end = json.find('"', pos + 1);
    if (end == std::string::npos) return {};
    if (n++ == index) return json.substr(pos + 1, end - pos - 1);
    pos = end + 1;
  }
  return {};
}
// Work in tenths of a degree and always clamp AFTER rounding.
inline int quantize_temperature(int value, int minimum, int maximum, int step) {
  step = std::max(1, step);
  value = std::clamp(value, minimum, maximum);
  const int snapped = minimum + static_cast<int>(std::lround(
      static_cast<double>(value - minimum) / step)) * step;
  return std::clamp(snapped, minimum, maximum);
}

class TouchGuard {
 public:
  enum Reject { NONE, MOVED, TOO_SHORT, USED, BOUNCE };
  // Board tuning, set from the profile on boot: how far the finger may drift (pixels) before
  // a tap is dropped, 0 for no limit at all (LVGL then decides: releasing inside the tile is a
  // tap, leaving it is not), and the shortest contact that counts. A resistive panel (CYD)
  // bounces on landing and lift-off and needs both; a capacitive one (Guition) needs neither.
  void configure(int move_limit_px, uint32_t min_press_ms) {
    move_limit_ = move_limit_px;
    min_press_ = min_press_ms;
  }
  int move_limit() const { return move_limit_; }
  uint32_t min_press() const { return min_press_; }
  void begin(uint32_t now, int x = 0, int y = 0, int contact = 0) {
    started_ = now;
    accepted_ = false;
    moved_ = false;
    contact_ = contact;
    samples_ = 1;
    sum_x_ = anchor_x_ = x;
    sum_y_ = anchor_y_ = y;
    distance_ = 0;
    reject_ = NONE;
  }
  int contact() const { return contact_; }
  // Follows only the contact that started this touch: a second finger elsewhere is no movement.
  // The reference point settles over the first samples, because a finger flattens as it lands;
  // a tap is dropped once the finger is farther than the limit from that point.
  void update(int x, int y, int contact = 0) {
    if (contact != contact_) return;
    if (samples_ < SETTLE_SAMPLES) {
      ++samples_;
      sum_x_ += x;
      sum_y_ += y;
      anchor_x_ = sum_x_ / samples_;
      anchor_y_ = sum_y_ / samples_;
    }
    const long dx = x - anchor_x_, dy = y - anchor_y_;
    const int distance = static_cast<int>(std::lround(std::sqrt(static_cast<double>(dx * dx + dy * dy))));
    distance_ = std::max(distance_, distance);
    if (move_limit_ > 0 && distance > move_limit_) moved_ = true;
  }
  int distance() const { return distance_; }
  void consume() { accepted_ = true; moved_ = true; }
  bool accept(uint32_t now, int tile) {
    if (moved_) { reject_ = MOVED; return false; }
    return accept_slider(now, tile);
  }
  // For -/+ keys: every clean tap counts, even the third within a second, so a
  // setpoint moves several steps in one go. Only bounce (same key within `gap`) is dropped.
  bool accept_repeat(uint32_t now, int tile, uint32_t gap = 150) {
    if (moved_) { reject_ = MOVED; return false; }
    if (accepted_) { reject_ = USED; return false; }
    if (!long_enough(now, std::min<uint32_t>(min_press_, 40))) return false;
    if (has_previous_ && tile == previous_tile_ && now - previous_ < gap) { reject_ = BOUNCE; return false; }
    remember(now, tile);
    return true;
  }
  // Only for a slider which captured this contact and did not lose the press.
  // Consume the gesture so its parent can never also turn it into a tile tap.
  bool accept_slider(uint32_t now, int tile) {
    if (accepted_) { reject_ = USED; return false; }
    if (!long_enough(now, min_press_)) return false;
    if (has_previous_ && tile == previous_tile_ && now - previous_ < 600) { reject_ = BOUNCE; return false; }
    remember(now, tile);
    return true;
  }
  // Why the last accept() refused, for the touch log; empty after a success.
  std::string reason() const {
    switch (reject_) {
      case MOVED: return "moved " + std::to_string(distance_) + " px (limit " + std::to_string(move_limit_) + ")";
      case TOO_SHORT: return "too short (" + std::to_string(duration_) + " ms, minimum " + std::to_string(min_press_) + ")";
      case USED: return "already handled in this contact";
      case BOUNCE: return "same button within the debounce window";
      default: return "";
    }
  }
 private:
  static constexpr int SETTLE_SAMPLES = 4;
  bool long_enough(uint32_t now, uint32_t minimum) {
    duration_ = now - started_;
    if (duration_ < minimum) { reject_ = TOO_SHORT; return false; }
    return true;
  }
  void remember(uint32_t now, int tile) {
    accepted_ = true;
    has_previous_ = true;
    previous_tile_ = tile;
    previous_ = now;
    reject_ = NONE;
  }
  int move_limit_{18};
  uint32_t min_press_{60};
  uint32_t started_{0}, previous_{0}, duration_{0};
  int previous_tile_{-1};
  int contact_{0}, samples_{1};
  long sum_x_{0}, sum_y_{0};
  int anchor_x_{0}, anchor_y_{0}, distance_{0};
  bool moved_{false};
  bool accepted_{false}, has_previous_{false};
  Reject reject_{NONE};
};
inline TouchGuard touch_guard;

// Page navigation by swiping in from a side edge (Guition, firmware 0.2.24+). Fed from
// ESPHome's touchscreen triggers: on_touch begins, on_update updates, on_release ends.
// LVGL 9.5 does not send PRESSING to the input device, so the native touch points are
// used and rotated here the way ESPHome's LVGL component rotates its pointer. A touch that
// starts within `band` pixels of the left or right edge of the screen as the user sees it
// and travels `travel` pixels inward, more sideways than up or down, flips one page: from
// the right edge leftwards is "next", from the left edge rightwards "previous". No speed
// requirement; a touch that starts in the middle never counts, so tapping and dragging on
// tiles cannot change the page by accident.
class EdgeSwipe {
 public:
  void configure(int width, int height, int band, int travel) {
    width_ = width; height_ = height; band_ = band; travel_ = travel;
  }
  // Native touch coordinates plus the LVGL rotation in degrees (0, 90, 180, 270).
  void begin(int x, int y, int rotation = 0) {
    rotation_ = rotation;
    rotate(x, y);
    start_x_ = x; start_y_ = y;
    const int width = (rotation == 90 || rotation == 270) ? height_ : width_;
    from_ = x < band_ ? 1 : x >= width - band_ ? -1 : 0;  // 1: left edge, -1: right edge
    done_ = false;
    inward_ = sideways_ = 0;
  }
  bool armed() const { return from_ != 0 && !done_; }
  // +1 next page, -1 previous page, 0 nothing; fires at most once per touch.
  int update(int x, int y) {
    if (!armed()) return 0;
    rotate(x, y);
    const int dx = x - start_x_, dy = y - start_y_;
    const int inward = from_ == 1 ? dx : -dx;
    inward_ = std::max(inward_, inward);
    sideways_ = std::max(sideways_, std::abs(dy));
    if (inward < travel_ || std::abs(dx) < std::abs(dy)) return 0;
    done_ = true;
    return from_ == 1 ? -1 : 1;
  }
  // The finger left the glass: a stale armed state must never fire on the next touch
  // (ESPHome runs on_update before on_touch in the first cycle of a new touch).
  void end() { done_ = true; }
  // How far the finger got, for the log when an edge touch ends without a page flip.
  int inward() const { return inward_; }
  int sideways() const { return sideways_; }
 private:
  void rotate(int &x, int &y) const {
    if (rotation_ == 90) { const int tmp = y; y = width_ - x - 1; x = tmp; }
    else if (rotation_ == 180) { x = width_ - x - 1; y = height_ - y - 1; }
    else if (rotation_ == 270) { const int tmp = x; x = height_ - y - 1; y = tmp; }
  }
  int width_{480}, height_{480}, band_{32}, travel_{40}, rotation_{0};
  int start_x_{0}, start_y_{0}, from_{0}, inward_{0}, sideways_{0};
  bool done_{true};
};
inline EdgeSwipe edge_swipe;

// The GT911 (Guition) now and then reports a contact at exactly (0, 0), mostly as the last
// sample before the finger lifts. LVGL takes the last pressed sample as the finger's position
// on release, so a slider jumped to its end and sent that value (a colour turning red). The
// corner pixel is never a real touch: such a sample repeats the read before it instead.
struct PointerRead {
  bool pressed;
  int x, y;
};
class GhostTouch {
 public:
  // `ghost_x`, `ghost_y`: where the native (0, 0) lands after the display rotation.
  PointerRead filter(PointerRead read, int ghost_x, int ghost_y) {
    if (read.pressed && read.x == ghost_x && read.y == ghost_y) {
      ++dropped_;
      return last_;
    }
    last_ = read;
    return read;
  }
  unsigned dropped() const { return dropped_; }
 private:
  PointerRead last_{false, 0, 0};
  unsigned dropped_{0};
};
inline GhostTouch ghost_touch;

// A dragged slider that LVGL moved to one of its ends on release, far from where the finger held
// it: the touch panel reported a stray point. Worth a log line, the finger was never there.
inline bool release_jump(int held, int released, int minimum, int maximum) {
  const bool at_end = released <= minimum || released >= maximum;
  return at_end && std::abs(released - held) * 4 > maximum - minimum;
}
}  // namespace cyd