Atlas - SDL_nullvideo.c
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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#include "SDL_internal.h"
22
23#ifdef SDL_VIDEO_DRIVER_DUMMY
24
25/* Dummy SDL video driver implementation; this is just enough to make an
26 *  SDL-based application THINK it's got a working video driver, for
27 *  applications that call SDL_Init(SDL_INIT_VIDEO) when they don't need it,
28 *  and also for use as a collection of stubs when porting SDL to a new
29 *  platform for which you haven't yet written a valid video driver.
30 *
31 * This is also a great way to determine bottlenecks: if you think that SDL
32 *  is a performance problem for a given platform, enable this driver, and
33 *  then see if your application runs faster without video overhead.
34 *
35 * Initial work by Ryan C. Gordon ([email protected]). A good portion
36 *  of this was cut-and-pasted from Stephane Peter's work in the AAlib
37 *  SDL video driver.  Renamed to "DUMMY" by Sam Lantinga.
38 */
39
40#include "../SDL_sysvideo.h"
41#include "../SDL_pixels_c.h"
42#include "../../events/SDL_events_c.h"
43#ifdef SDL_INPUT_LINUXEV
44#include "../../core/linux/SDL_evdev.h"
45#endif
46
47#include "SDL_nullvideo.h"
48#include "SDL_nullevents_c.h"
49#include "SDL_nullframebuffer_c.h"
50
51#define DUMMYVID_DRIVER_NAME       "dummy"
52#define DUMMYVID_DRIVER_EVDEV_NAME "evdev"
53
54// Initialization/Query functions
55static bool DUMMY_VideoInit(SDL_VideoDevice *_this);
56static void DUMMY_VideoQuit(SDL_VideoDevice *_this);
57
58static bool DUMMY_SetWindowPosition(SDL_VideoDevice *_this, SDL_Window *window)
59{
60    SDL_SendWindowEvent(window, SDL_EVENT_WINDOW_MOVED, window->pending.x, window->pending.y);
61    return true;
62}
63
64static void DUMMY_SetWindowSize(SDL_VideoDevice *_this, SDL_Window *window)
65{
66    SDL_SendWindowEvent(window, SDL_EVENT_WINDOW_RESIZED, window->pending.w, window->pending.h);
67}
68
69// DUMMY driver bootstrap functions
70
71static bool DUMMY_Available(const char *drivername)
72{
73    const char *hint = SDL_GetHint(SDL_HINT_VIDEO_DRIVER);
74    if (hint && SDL_strstr(hint, drivername) != NULL) {
75        return true;
76    }
77    return false;
78}
79
80static void DUMMY_DeleteDevice(SDL_VideoDevice *device)
81{
82    SDL_free(device);
83}
84
85static SDL_VideoDevice *DUMMY_InternalCreateDevice(const char *enable_hint)
86{
87    SDL_VideoDevice *device;
88
89    if (!DUMMY_Available(enable_hint)) {
90        return NULL;
91    }
92
93    // Initialize all variables that we clean on shutdown
94    device = (SDL_VideoDevice *)SDL_calloc(1, sizeof(SDL_VideoDevice));
95    if (!device) {
96        return NULL;
97    }
98    device->is_dummy = true;
99
100    // Set the function pointers
101    device->VideoInit = DUMMY_VideoInit;
102    device->VideoQuit = DUMMY_VideoQuit;
103    device->PumpEvents = DUMMY_PumpEvents;
104    device->SetWindowSize = DUMMY_SetWindowSize;
105    device->SetWindowPosition = DUMMY_SetWindowPosition;
106    device->CreateWindowFramebuffer = SDL_DUMMY_CreateWindowFramebuffer;
107    device->UpdateWindowFramebuffer = SDL_DUMMY_UpdateWindowFramebuffer;
108    device->DestroyWindowFramebuffer = SDL_DUMMY_DestroyWindowFramebuffer;
109    device->free = DUMMY_DeleteDevice;
110
111    return device;
112}
113
114static SDL_VideoDevice *DUMMY_CreateDevice(void)
115{
116    return DUMMY_InternalCreateDevice(DUMMYVID_DRIVER_NAME);
117}
118
119VideoBootStrap DUMMY_bootstrap = {
120    DUMMYVID_DRIVER_NAME, "SDL dummy video driver",
121    DUMMY_CreateDevice,
122    NULL, // no ShowMessageBox implementation
123    false
124};
125
126#ifdef SDL_INPUT_LINUXEV
127
128static void DUMMY_EVDEV_Poll(SDL_VideoDevice *_this)
129{
130    (void)_this;
131    SDL_EVDEV_Poll();
132}
133
134static SDL_VideoDevice *DUMMY_EVDEV_CreateDevice(void)
135{
136    SDL_VideoDevice *device = DUMMY_InternalCreateDevice(DUMMYVID_DRIVER_EVDEV_NAME);
137    if (device) {
138        device->PumpEvents = DUMMY_EVDEV_Poll;
139    }
140    return device;
141}
142
143VideoBootStrap DUMMY_evdev_bootstrap = {
144    DUMMYVID_DRIVER_EVDEV_NAME, "SDL dummy video driver with evdev",
145    DUMMY_EVDEV_CreateDevice,
146    NULL, // no ShowMessageBox implementation
147    false
148};
149
150#else
151
152static bool DUMMY_SetRelativeMouseMode(bool enabled)
153{
154    return true;
155}
156
157#endif // SDL_INPUT_LINUXEV
158
159bool DUMMY_VideoInit(SDL_VideoDevice *_this)
160{
161    SDL_DisplayMode mode;
162
163    // Use a fake 32-bpp desktop mode
164    SDL_zero(mode);
165    mode.format = SDL_PIXELFORMAT_XRGB8888;
166    mode.w = 1024;
167    mode.h = 768;
168    if (SDL_AddBasicVideoDisplay(&mode) == 0) {
169        return false;
170    }
171
172#ifdef SDL_INPUT_LINUXEV
173    SDL_EVDEV_Init();
174#else
175    SDL_GetMouse()->SetRelativeMouseMode = DUMMY_SetRelativeMouseMode;
176#endif
177
178    // We're done!
179    return true;
180}
181
182void DUMMY_VideoQuit(SDL_VideoDevice *_this)
183{
184#ifdef SDL_INPUT_LINUXEV
185    SDL_EVDEV_Quit();
186#endif
187}
188
189#endif // SDL_VIDEO_DRIVER_DUMMY
190
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