/**************************************************************************/
/*  view_panner.cpp                                                       */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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/* Permission is hereby granted, free of charge, to any person obtaining  */
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/* included in all copies or substantial portions of the Software.        */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
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/**************************************************************************/

#include "view_panner.h"

#include "core/input/input.h"
#include "core/input/shortcut.h"
#include "core/os/keyboard.h"

bool ViewPanner::gui_input(const Ref<InputEvent> &p_event, Rect2 p_canvas_rect) {
	Ref<InputEventMouseButton> mb = p_event;
	if (mb.is_valid()) {
		Vector2 scroll_vec = Vector2((mb->get_button_index() == MouseButton::WHEEL_RIGHT) - (mb->get_button_index() == MouseButton::WHEEL_LEFT), (mb->get_button_index() == MouseButton::WHEEL_DOWN) - (mb->get_button_index() == MouseButton::WHEEL_UP));
		// Moving the scroll wheel sends two events: one with pressed as true,
		// and one with pressed as false. Make sure we only process one of them.
		if (scroll_vec != Vector2() && mb->is_pressed()) {
			if (control_scheme == SCROLL_PANS) {
				if (mb->is_ctrl_pressed()) {
					// Compute the zoom factor.
					float zoom_factor = mb->get_factor() <= 0 ? 1.0 : mb->get_factor();
					zoom_factor = ((scroll_zoom_factor - 1.0) * zoom_factor) + 1.0;
					float zoom = (scroll_vec.x + scroll_vec.y) > 0 ? 1.0 / scroll_zoom_factor : scroll_zoom_factor;
					callback_helper(zoom_callback, varray(zoom, mb->get_position(), p_event));
					return true;
				} else {
					Vector2 panning = scroll_vec * mb->get_factor();
					if (pan_axis == PAN_AXIS_HORIZONTAL) {
						panning = Vector2(panning.x + panning.y, 0);
					} else if (pan_axis == PAN_AXIS_VERTICAL) {
						panning = Vector2(0, panning.x + panning.y);
					} else if (mb->is_shift_pressed()) {
						panning = Vector2(panning.y, panning.x);
					}
					callback_helper(pan_callback, varray(-panning * scroll_speed, p_event));
					return true;
				}
			} else {
				if (mb->is_ctrl_pressed()) {
					Vector2 panning = scroll_vec * mb->get_factor();
					if (pan_axis == PAN_AXIS_HORIZONTAL) {
						panning = Vector2(panning.x + panning.y, 0);
					} else if (pan_axis == PAN_AXIS_VERTICAL) {
						panning = Vector2(0, panning.x + panning.y);
					} else if (mb->is_shift_pressed()) {
						panning = Vector2(panning.y, panning.x);
					}
					callback_helper(pan_callback, varray(-panning * scroll_speed, p_event));
					return true;
				} else if (!mb->is_shift_pressed()) {
					// Compute the zoom factor.
					float zoom_factor = mb->get_factor() <= 0 ? 1.0 : mb->get_factor();
					zoom_factor = ((scroll_zoom_factor - 1.0) * zoom_factor) + 1.0;
					float zoom = (scroll_vec.x + scroll_vec.y) > 0 ? 1.0 / scroll_zoom_factor : scroll_zoom_factor;
					callback_helper(zoom_callback, varray(zoom, mb->get_position(), p_event));
					return true;
				}
			}
		}

		// Alt is not used for button presses, so ignore it.
		if (mb->is_alt_pressed()) {
			return false;
		}

		bool is_drag_event = mb->get_button_index() == MouseButton::MIDDLE ||
				(enable_rmb && mb->get_button_index() == MouseButton::RIGHT) ||
				(!simple_panning_enabled && mb->get_button_index() == MouseButton::LEFT && is_panning()) ||
				(force_drag && mb->get_button_index() == MouseButton::LEFT);

		if (is_drag_event) {
			if (mb->is_pressed()) {
				is_dragging = true;
			} else {
				is_dragging = false;
			}
			return mb->get_button_index() != MouseButton::LEFT || mb->is_pressed(); // Don't consume LMB release events (it fixes some selection problems).
		}
	}

	Ref<InputEventMouseMotion> mm = p_event;
	if (mm.is_valid()) {
		if (is_dragging) {
			if (p_canvas_rect != Rect2()) {
				callback_helper(pan_callback, varray(Input::get_singleton()->warp_mouse_motion(mm, p_canvas_rect), p_event));
			} else {
				callback_helper(pan_callback, varray(mm->get_relative(), p_event));
			}
			return true;
		}
	}

	Ref<InputEventMagnifyGesture> magnify_gesture = p_event;
	if (magnify_gesture.is_valid()) {
		// Zoom gesture
		callback_helper(zoom_callback, varray(magnify_gesture->get_factor(), magnify_gesture->get_position(), p_event));
		return true;
	}

	Ref<InputEventPanGesture> pan_gesture = p_event;
	if (pan_gesture.is_valid()) {
		callback_helper(pan_callback, varray(-pan_gesture->get_delta() * scroll_speed, p_event));
	}

	Ref<InputEventScreenDrag> screen_drag = p_event;
	if (screen_drag.is_valid()) {
		callback_helper(pan_callback, varray(screen_drag->get_relative(), p_event));
	}

	Ref<InputEventKey> k = p_event;
	if (k.is_valid()) {
		if (pan_view_shortcut.is_valid() && pan_view_shortcut->matches_event(k)) {
			pan_key_pressed = k->is_pressed();
			if (simple_panning_enabled || Input::get_singleton()->get_mouse_button_mask().has_flag(MouseButtonMask::LEFT)) {
				is_dragging = pan_key_pressed;
			}
			return true;
		}
	}

	return false;
}

void ViewPanner::release_pan_key() {
	pan_key_pressed = false;
	is_dragging = false;
}

void ViewPanner::callback_helper(Callable p_callback, Vector<Variant> p_args) {
	const Variant **argptr = (const Variant **)alloca(sizeof(Variant *) * p_args.size());
	for (int i = 0; i < p_args.size(); i++) {
		argptr[i] = &p_args[i];
	}

	Variant result;
	Callable::CallError ce;
	p_callback.callp(argptr, p_args.size(), result, ce);
}

void ViewPanner::set_callbacks(Callable p_pan_callback, Callable p_zoom_callback) {
	pan_callback = p_pan_callback;
	zoom_callback = p_zoom_callback;
}

void ViewPanner::set_control_scheme(ControlScheme p_scheme) {
	control_scheme = p_scheme;
}

void ViewPanner::set_enable_rmb(bool p_enable) {
	enable_rmb = p_enable;
}

void ViewPanner::set_pan_shortcut(Ref<Shortcut> p_shortcut) {
	pan_view_shortcut = p_shortcut;
	pan_key_pressed = false;
}

void ViewPanner::set_simple_panning_enabled(bool p_enabled) {
	simple_panning_enabled = p_enabled;
}

void ViewPanner::set_scroll_speed(int p_scroll_speed) {
	ERR_FAIL_COND(p_scroll_speed <= 0);
	scroll_speed = p_scroll_speed;
}

void ViewPanner::set_scroll_zoom_factor(float p_scroll_zoom_factor) {
	ERR_FAIL_COND(p_scroll_zoom_factor <= 1.0);
	scroll_zoom_factor = p_scroll_zoom_factor;
}

void ViewPanner::set_pan_axis(PanAxis p_pan_axis) {
	pan_axis = p_pan_axis;
}

void ViewPanner::setup(ControlScheme p_scheme, Ref<Shortcut> p_shortcut, bool p_simple_panning) {
	set_control_scheme(p_scheme);
	set_pan_shortcut(p_shortcut);
	set_simple_panning_enabled(p_simple_panning);
}

bool ViewPanner::is_panning() const {
	return is_dragging || pan_key_pressed;
}

void ViewPanner::set_force_drag(bool p_force) {
	force_drag = p_force;
}

ViewPanner::ViewPanner() {
	Array inputs;
	inputs.append(InputEventKey::create_reference(Key::SPACE));

	pan_view_shortcut.instantiate();
	pan_view_shortcut->set_events(inputs);
}