// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.ui.input;

// Descriptors are used to describe the capabilities of an input device.
//
// Devices can have multiple descriptors of multiple kinds, for example:
// |KeyboardDescriptor|, |MouseDescriptor|, |StylusDescriptor|,
// |TouchscreenDescriptor| and |SensorDescriptor|
//
// An input device will generate |InputReport| corresponding to the
// capabilities of that device listed in its descriptor.
// For instance a input device with a |KeyboardDescriptor| will generate
// |KeyboardReport| when a key is pressed on the keyboard.

// Describe a |Range| of values
struct Range {
    int32 min;
    int32 max;
};

struct RangeF {
    float32 min;
    float32 max;
};

enum AxisScale {
    LINEAR = 0;
    LOGARITHMIC = 1;
};

// An |Axis| is defined as a |range| and |resolution|.
struct Axis {
    Range range;
    int32 resolution = 1;
    AxisScale scale = LINEAR;
};

struct AxisF {
    RangeF range;
    float32 resolution = 1.0;
    AxisScale scale = LINEAR;
};

// |ButtonsDescriptor| describes the buttons.
struct ButtonsDescriptor {
    // The list of buttons available.
    uint32 buttons;
};

// Keyboards

// |KeyboardDescriptor| describes the capabilities of a keyboard.
struct KeyboardDescriptor {
    // The list of HID keyboard usages that this keyboard can generate.
    vector<uint32> keys;
};

// |KeyboardReport| lists the keys currently pressed down.
struct KeyboardReport {
    // |pressed_keys| is the list of HID usage that are currently pressed down on
    // the keyboard.
    vector<uint32> pressed_keys;
};

// Mouse

// |MouseDescriptor| describes the capabilities of a mouse.
struct MouseDescriptor {
    // The range of relative X and Y movement which can be described by a mouse
    // report.
    Axis rel_x;
    Axis rel_y;

    // The range of relative vertical and horizontal scroll which can be
    // described by a mouse report.
    Axis? vscroll;
    Axis? hscroll;

    // The list of HID mouse usages that this mouse can generate.
    uint32 buttons;
};

// |MouseReport| gives the relative mouvement of the mouse and currently
// pressed buttons.
struct MouseReport {
    // Relative X and Y positional displacement.
    int32 rel_x;
    int32 rel_y;

    // Relative horizontal and vertical scrolling displacement.
    int32 rel_hscroll;
    int32 rel_vscroll;

    // buttons currently down
    uint32 pressed_buttons;
};

// Stylus

// |Stylus| describes the capabilities of a stylus.
struct StylusDescriptor {
    // Ranges for the |x| and |y| axis of the stylus.
    Axis x;
    Axis y;

    // Range for the pressure of the tip
    Axis? pressure;

    bool is_invertible = false;

    // The list of HID button usages that this stylus can generate.
    uint32 buttons;
};

// |StylusReport| describes the current state of the stylus.
struct StylusReport {
    // Current position of the stylus within the range described in
    // |StylusDescriptor|
    int32 x;
    int32 y;

    // Pressure applied on the stylus tip
    uint32 pressure;

    // Whether the stylus has made contact with the surface.
    bool is_in_contact;

    // Whether the stylus is within range. If |is_in_contact| is false, then the stylus
    // is hovering.
    bool in_range;

    // Whether the stylus is thought to be inverted.
    bool is_inverted;

    // List of buttons currently pressed down.
    uint32 pressed_buttons;
};

// Touchscreen

// |TouchscreenDescriptor| describes the capabilities of a touchscreen.
struct TouchscreenDescriptor {
    // Ranges of the |x| and |y| axis.
    Axis x;
    Axis y;
    uint32 max_finger_id;
};

// |Touch| describes one touch on a touchscreen, which should correspond to
// one finger.
struct Touch {
    // Identifier for a finger that is down.
    // Note: |finger_id| might not be sequential and will range from 0 to
    // |max_finger_id|
    uint32 finger_id;

    // Location within the axis defined in |TouchscreenDescriptor|
    int32 x;
    int32 y;

    // Area pressed.
    uint32 width;
    uint32 height;
};

// |TouchscreenReport| describes the current touches recorded by the touchscreen
// and holds a |Touch| per finger down.
struct TouchscreenReport {
    vector<Touch> touches;
};

// Motion Sensors

// Descriptive categories for sensor devices.
// We assume that each (SensorType,SensorLocation) pair is unique to the system.

enum SensorType {
    ACCELEROMETER = 0;
    GYROSCOPE = 1;
    MAGNETOMETER = 2;
    LIGHTMETER = 3;
};

enum SensorLocation {
    UNKNOWN = 0;
    BASE = 1;
    LID = 2;
};

// |SensorDescriptor| describes the capabilities of a sensor device.  It does
// not capture properties that can be changed after initialization, such as the
// current sampling frequency.
struct SensorDescriptor {
    SensorType type;
    SensorLocation loc;

    // Min and max sampling frequencies for a sensor.
    uint32 min_sampling_freq;
    uint32 max_sampling_freq;
    // Max number of sensor events that could be in hardware FIFO.
    uint32 fifo_max_event_count;

    // Physical range of a specific sensor.
    // Accelerometer ranges are given in Gs.
    // Gyroscope ranges are given in deg/s.
    // Magnetometer ranges are given in multiples of 1/16 uT.
    // Light meter ranges can be given in Lux or units not specified.
    int32 phys_min;
    int32 phys_max;
};

// |SensorReport| describes the sensor event delivered from the event stream.
union SensorReport {
    array<int16>:3 vector;
    uint16 scalar;
};

// |ButtonsReport| describes the buttons event delivered from the event stream.
union ButtonsReport {
    // Volume changes +1/-1 for volume up/down, this is a relative value.
    int8 volume;
    bool mic_mute;
};

// Device and Report

struct DeviceInfo {
    uint32 vendor_id;
    uint32 product_id;
    uint32 version;
    string name;
};

// |DeviceDescriptor| describes one input device.
struct DeviceDescriptor {
    DeviceInfo? device_info;
    KeyboardDescriptor? keyboard;
    ButtonsDescriptor? buttons;
    MouseDescriptor? mouse;
    StylusDescriptor? stylus;
    TouchscreenDescriptor? touchscreen;
    SensorDescriptor? sensor;
};

// |InputReport| is an input |report| triggered by an input device.
struct InputReport {
    // |event_time| is in nanoseconds when the event was recorded.
    uint64 event_time;

    KeyboardReport? keyboard;
    ButtonsReport? buttons;
    MouseReport? mouse;
    StylusReport? stylus;
    TouchscreenReport? touchscreen;
    SensorReport? sensor;
};