touch_input.h

Go to the documentation of this file.

#ifndef YAZE_APP_GUI_CORE_TOUCH_INPUT_H
#define YAZE_APP_GUI_CORE_TOUCH_INPUT_H
 
#include <array>
#include <functional>
#include <memory>
 
#include "imgui/imgui.h"
 
namespace yaze {
namespace gui {
 
enum class TouchGesture {
  kNone,         // No gesture active
  kTap,          // Single finger tap (click)
  kDoubleTap,    // Double tap (context menu or zoom to fit)
  kLongPress,    // Long press (500ms+) for context menu
  kPan,          // Two-finger pan/scroll
  kPinchZoom,    // Two-finger pinch to zoom
  kRotate        // Two-finger rotation (optional)
};
 
enum class TouchPhase {
  kBegan,     // Gesture started
  kChanged,   // Gesture in progress with updated values
  kEnded,     // Gesture completed successfully
  kCancelled  // Gesture was cancelled
};
 
struct TouchPoint {
  int id = -1;                      // Unique identifier for this touch
  ImVec2 position = ImVec2(0, 0);   // Current position
  ImVec2 start_position = ImVec2(0, 0);  // Position when touch started
  ImVec2 previous_position = ImVec2(0, 0);  // Previous frame position
  float pressure = 1.0f;            // Touch pressure (0.0 - 1.0)
  double timestamp = 0.0;           // Time when touch started
  bool active = false;              // Whether this touch is currently active
};
 
struct GestureState {
  TouchGesture gesture = TouchGesture::kNone;
  TouchPhase phase = TouchPhase::kBegan;
 
  // Position data
  ImVec2 position = ImVec2(0, 0);       // Center position of gesture
  ImVec2 start_position = ImVec2(0, 0); // Where gesture started
  ImVec2 translation = ImVec2(0, 0);    // Pan/drag offset
  ImVec2 velocity = ImVec2(0, 0);       // Movement velocity for inertia
 
  // Scale/rotation data
  float scale = 1.0f;           // Pinch zoom scale factor
  float scale_delta = 0.0f;     // Change in scale this frame
  float rotation = 0.0f;        // Rotation angle in radians
  float rotation_delta = 0.0f;  // Change in rotation this frame
 
  // Touch count
  int touch_count = 0;
 
  // Timing
  double duration = 0.0;  // How long the gesture has been active
};
 
struct TouchConfig {
  // Timing thresholds (in seconds)
  float tap_max_duration = 0.3f;      // Max duration for a tap
  float double_tap_max_delay = 0.3f;  // Max delay between taps for double-tap
  float long_press_duration = 0.5f;   // Duration to trigger long press
 
  // Distance thresholds (in pixels)
  float tap_max_movement = 10.0f;     // Max movement for a tap
  float pan_threshold = 10.0f;        // Min movement to start pan
  float pinch_threshold = 5.0f;       // Min scale change to start pinch
  float rotation_threshold = 0.1f;    // Min rotation to start rotate (radians)
 
  // Feature toggles
  bool enable_pan_zoom = true;     // Enable two-finger pan/zoom
  bool enable_rotation = false;    // Enable two-finger rotation
  bool enable_inertia = true;      // Enable inertia scrolling after swipe
 
  // Inertia settings
  float inertia_deceleration = 0.95f;  // Velocity multiplier per frame
  float inertia_min_velocity = 0.5f;   // Minimum velocity to continue inertia
 
  // Scale limits
  float min_zoom = 0.25f;
  float max_zoom = 4.0f;
};
 
class TouchInput {
 public:
  static constexpr int kMaxTouchPoints = 10;
 
  static void Initialize();
 
  static void Shutdown();
 
  static void Update();
 
  static bool IsTouchActive();
 
  static bool IsTouchMode();
 
  static GestureState GetCurrentGesture();
 
  static TouchPoint GetTouchPoint(int index);
 
  static int GetActiveTouchCount();
 
  // === Canvas Integration ===
 
  static void SetPanZoomEnabled(bool enabled);
 
  static bool IsPanZoomEnabled();
 
  static ImVec2 GetPanOffset();
 
  static float GetZoomLevel();
 
  static float GetRotation();
 
  static ImVec2 GetZoomCenter();
 
  static void ApplyPanOffset(ImVec2 offset);
 
  static void SetZoomLevel(float zoom);
 
  static void SetPanOffset(ImVec2 offset);
 
  static void ResetCanvasState();
 
  // === Configuration ===
 
  static TouchConfig& GetConfig();
 
  static void SetGestureCallback(std::function<void(const GestureState&)> callback);
 
  // === Platform-Specific Hooks ===
 
#ifdef __EMSCRIPTEN__
  static void OnTouchEvent(int type, int id, float x, float y,
                           float pressure, double timestamp);
 
  static void OnGestureEvent(int type, int phase, float x, float y,
                             float scale, float rotation);
#endif
 
 private:
  TouchInput() = delete;  // Static-only class
 
  // Internal state management
  static void UpdateGestureRecognition();
  static void ProcessInertia();
  static void TranslateToImGuiEvents();
  static double GetCurrentTime();
 
  // Platform-specific initialization
  static void InitializePlatform();
  static void ShutdownPlatform();
};
 
}  // namespace gui
}  // namespace yaze
 
#endif  // YAZE_APP_GUI_CORE_TOUCH_INPUT_H