Atlas - SDL_touch.h
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1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2025 Sam Lantinga <[email protected]>
4
5  This software is provided 'as-is', without any express or implied
6  warranty.  In no event will the authors be held liable for any damages
7  arising from the use of this software.
8
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12
13  1. The origin of this software must not be misrepresented; you must not
14     claim that you wrote the original software. If you use this software
15     in a product, an acknowledgment in the product documentation would be
16     appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18     misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20*/
21
22/**
23 * # CategoryTouch
24 *
25 * SDL offers touch input, on platforms that support it. It can manage
26 * multiple touch devices and track multiple fingers on those devices.
27 *
28 * Touches are mostly dealt with through the event system, in the
29 * SDL_EVENT_FINGER_DOWN, SDL_EVENT_FINGER_MOTION, and SDL_EVENT_FINGER_UP
30 * events, but there are also functions to query for hardware details, etc.
31 *
32 * The touch system, by default, will also send virtual mouse events; this can
33 * be useful for making a some desktop apps work on a phone without
34 * significant changes. For apps that care about mouse and touch input
35 * separately, they should ignore mouse events that have a `which` field of
36 * SDL_TOUCH_MOUSEID.
37 */
38
39#ifndef SDL_touch_h_
40#define SDL_touch_h_
41
42#include <SDL3/SDL_stdinc.h>
43#include <SDL3/SDL_error.h>
44#include <SDL3/SDL_mouse.h>
45
46#include <SDL3/SDL_begin_code.h>
47/* Set up for C function definitions, even when using C++ */
48#ifdef __cplusplus
49extern "C" {
50#endif
51
52/**
53 * A unique ID for a touch device.
54 *
55 * This ID is valid for the time the device is connected to the system, and is
56 * never reused for the lifetime of the application.
57 *
58 * The value 0 is an invalid ID.
59 *
60 * \since This datatype is available since SDL 3.2.0.
61 */
62typedef Uint64 SDL_TouchID;
63
64/**
65 * A unique ID for a single finger on a touch device.
66 *
67 * This ID is valid for the time the finger (stylus, etc) is touching and will
68 * be unique for all fingers currently in contact, so this ID tracks the
69 * lifetime of a single continuous touch. This value may represent an index, a
70 * pointer, or some other unique ID, depending on the platform.
71 *
72 * The value 0 is an invalid ID.
73 *
74 * \since This datatype is available since SDL 3.2.0.
75 */
76typedef Uint64 SDL_FingerID;
77
78/**
79 * An enum that describes the type of a touch device.
80 *
81 * \since This enum is available since SDL 3.2.0.
82 */
83typedef enum SDL_TouchDeviceType
84{
85    SDL_TOUCH_DEVICE_INVALID = -1,
86    SDL_TOUCH_DEVICE_DIRECT,            /**< touch screen with window-relative coordinates */
87    SDL_TOUCH_DEVICE_INDIRECT_ABSOLUTE, /**< trackpad with absolute device coordinates */
88    SDL_TOUCH_DEVICE_INDIRECT_RELATIVE  /**< trackpad with screen cursor-relative coordinates */
89} SDL_TouchDeviceType;
90
91/**
92 * Data about a single finger in a multitouch event.
93 *
94 * Each touch event is a collection of fingers that are simultaneously in
95 * contact with the touch device (so a "touch" can be a "multitouch," in
96 * reality), and this struct reports details of the specific fingers.
97 *
98 * \since This struct is available since SDL 3.2.0.
99 *
100 * \sa SDL_GetTouchFingers
101 */
102typedef struct SDL_Finger
103{
104    SDL_FingerID id;  /**< the finger ID */
105    float x;  /**< the x-axis location of the touch event, normalized (0...1) */
106    float y;  /**< the y-axis location of the touch event, normalized (0...1) */
107    float pressure; /**< the quantity of pressure applied, normalized (0...1) */
108} SDL_Finger;
109
110/**
111 * The SDL_MouseID for mouse events simulated with touch input.
112 *
113 * \since This macro is available since SDL 3.2.0.
114 */
115#define SDL_TOUCH_MOUSEID ((SDL_MouseID)-1)
116
117/**
118 * The SDL_TouchID for touch events simulated with mouse input.
119 *
120 * \since This macro is available since SDL 3.2.0.
121 */
122#define SDL_MOUSE_TOUCHID ((SDL_TouchID)-1)
123
124
125/**
126 * Get a list of registered touch devices.
127 *
128 * On some platforms SDL first sees the touch device if it was actually used.
129 * Therefore the returned list might be empty, although devices are available.
130 * After using all devices at least once the number will be correct.
131 *
132 * \param count a pointer filled in with the number of devices returned, may
133 *              be NULL.
134 * \returns a 0 terminated array of touch device IDs or NULL on failure; call
135 *          SDL_GetError() for more information. This should be freed with
136 *          SDL_free() when it is no longer needed.
137 *
138 * \since This function is available since SDL 3.2.0.
139 */
140extern SDL_DECLSPEC SDL_TouchID * SDLCALL SDL_GetTouchDevices(int *count);
141
142/**
143 * Get the touch device name as reported from the driver.
144 *
145 * \param touchID the touch device instance ID.
146 * \returns touch device name, or NULL on failure; call SDL_GetError() for
147 *          more information.
148 *
149 * \since This function is available since SDL 3.2.0.
150 */
151extern SDL_DECLSPEC const char * SDLCALL SDL_GetTouchDeviceName(SDL_TouchID touchID);
152
153/**
154 * Get the type of the given touch device.
155 *
156 * \param touchID the ID of a touch device.
157 * \returns touch device type.
158 *
159 * \since This function is available since SDL 3.2.0.
160 */
161extern SDL_DECLSPEC SDL_TouchDeviceType SDLCALL SDL_GetTouchDeviceType(SDL_TouchID touchID);
162
163/**
164 * Get a list of active fingers for a given touch device.
165 *
166 * \param touchID the ID of a touch device.
167 * \param count a pointer filled in with the number of fingers returned, can
168 *              be NULL.
169 * \returns a NULL terminated array of SDL_Finger pointers or NULL on failure;
170 *          call SDL_GetError() for more information. This is a single
171 *          allocation that should be freed with SDL_free() when it is no
172 *          longer needed.
173 *
174 * \since This function is available since SDL 3.2.0.
175 */
176extern SDL_DECLSPEC SDL_Finger ** SDLCALL SDL_GetTouchFingers(SDL_TouchID touchID, int *count);
177
178/* Ends C function definitions when using C++ */
179#ifdef __cplusplus
180}
181#endif
182#include <SDL3/SDL_close_code.h>
183
184#endif /* SDL_touch_h_ */
185
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