Atlas - SDL_waylandopengles.c
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1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2026 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#if defined(SDL_VIDEO_DRIVER_WAYLAND) && defined(SDL_VIDEO_OPENGL_EGL)
24
25#include "../../core/unix/SDL_poll.h"
26#include "../SDL_sysvideo.h"
27#include "../../events/SDL_windowevents_c.h"
28#include "SDL_waylandvideo.h"
29#include "SDL_waylandopengles.h"
30#include "SDL_waylandwindow.h"
31#include "SDL_waylandevents_c.h"
32
33#include "xdg-shell-client-protocol.h"
34
35// EGL implementation of SDL OpenGL ES support
36
37void Wayland_GLES_SetDefaultProfileConfig(SDL_VideoDevice *_this)
38{
39#if defined(SDL_PLATFORM_QNXNTO)
40    // QNX defaults to EGL_PLATFORM_SCREEN_QNX unless this is explicitly specified
41    _this->gl_config.egl_platform = EGL_PLATFORM_WAYLAND_EXT;
42#endif
43}
44
45bool Wayland_GLES_LoadLibrary(SDL_VideoDevice *_this, const char *path)
46{
47    bool result;
48    SDL_VideoData *data = _this->internal;
49
50    result = SDL_EGL_LoadLibrary(_this, path, (NativeDisplayType)data->display);
51
52    Wayland_PumpEvents(_this);
53    WAYLAND_wl_display_flush(data->display);
54
55    return result;
56}
57
58SDL_GLContext Wayland_GLES_CreateContext(SDL_VideoDevice *_this, SDL_Window *window)
59{
60    SDL_GLContext context;
61    context = SDL_EGL_CreateContext(_this, window->internal->egl_surface);
62    WAYLAND_wl_display_flush(_this->internal->display);
63
64    return context;
65}
66
67/* Wayland wants to tell you when to provide new frames, and if you have a non-zero
68   swap interval, Mesa will block until a callback tells it to do so. On some
69   compositors, they might decide that a minimized window _never_ gets a callback,
70   which causes apps to hang during swapping forever. So we always set the official
71   eglSwapInterval to zero to avoid blocking inside EGL, and manage this ourselves.
72   If a swap blocks for too long waiting on a callback, we just go on, under the
73   assumption the frame will be wasted, but this is better than freezing the app.
74   I frown upon platforms that dictate this sort of control inversion (the callback
75   is intended for _rendering_, not stalling until vsync), but we can work around
76   this for now.  --ryan. */
77/* Addendum: several recent APIs demand this sort of control inversion: Emscripten,
78   libretro, Wayland, probably others...it feels like we're eventually going to have
79   to give in with a future SDL API revision, since we can bend the other APIs to
80   this style, but this style is much harder to bend the other way.  :/ */
81bool Wayland_GLES_SetSwapInterval(SDL_VideoDevice *_this, int interval)
82{
83    if (!_this->egl_data) {
84        return SDL_SetError("EGL not initialized");
85    }
86
87    /* technically, this is _all_ adaptive vsync (-1), because we can't
88       actually wait for the _next_ vsync if you set 1, but things that
89       request 1 probably won't care _that_ much. I hope. No matter what
90       you do, though, you never see tearing on Wayland. */
91    if (interval > 1) {
92        interval = 1;
93    } else if (interval < -1) {
94        interval = -1;
95    }
96
97    // !!! FIXME: technically, this should be per-context, right?
98    _this->egl_data->egl_swapinterval = interval;
99    _this->egl_data->eglSwapInterval(_this->egl_data->egl_display, 0);
100    return true;
101}
102
103bool Wayland_GLES_GetSwapInterval(SDL_VideoDevice *_this, int *interval)
104{
105    if (!_this->egl_data) {
106        return SDL_SetError("EGL not initialized");
107    }
108
109    *interval =_this->egl_data->egl_swapinterval;
110    return true;
111}
112
113bool Wayland_GLES_SwapWindow(SDL_VideoDevice *_this, SDL_Window *window)
114{
115    SDL_WindowData *data = window->internal;
116    const int swap_interval = _this->egl_data->egl_swapinterval;
117
118    /* For windows that we know are hidden, skip swaps entirely, if we don't do
119     * this compositors will intentionally stall us indefinitely and there's no
120     * way for an end user to show the window, unlike other situations (i.e.
121     * the window is minimized, behind another window, etc.).
122     *
123     * FIXME: Request EGL_WAYLAND_swap_buffers_with_timeout.
124     * -flibit
125     */
126    if (data->shell_surface_status != WAYLAND_SHELL_SURFACE_STATUS_SHOWN &&
127        data->shell_surface_status != WAYLAND_SHELL_SURFACE_STATUS_WAITING_FOR_FRAME) {
128        return true;
129    }
130
131    /* By default, we wait for the Wayland frame callback and then issue the pageflip (eglSwapBuffers),
132     * but if we want low latency (double buffer scheme), we issue the pageflip and then wait
133     * immediately for the Wayland frame callback.
134     */
135    if (data->double_buffer) {
136        // Feed the frame to Wayland. This will set it so the wl_surface_frame callback can fire again.
137        if (!_this->egl_data->eglSwapBuffers(_this->egl_data->egl_display, data->egl_surface)) {
138            return SDL_EGL_SetError("unable to show color buffer in an OS-native window", "eglSwapBuffers");
139        }
140
141        WAYLAND_wl_display_flush(data->waylandData->display);
142    }
143
144    // Control swap interval ourselves. See comments on Wayland_GLES_SetSwapInterval
145    if (swap_interval != 0 && data->shell_surface_status == WAYLAND_SHELL_SURFACE_STATUS_SHOWN) {
146        SDL_VideoData *videodata = _this->internal;
147        struct wl_display *display = videodata->display;
148        // 20hz, so we'll progress even if throttled to zero.
149        const Uint64 max_wait = SDL_GetTicksNS() + (SDL_NS_PER_SECOND / 20);
150        while (SDL_GetAtomicInt(&data->swap_interval_ready) == 0) {
151            Uint64 now;
152
153            WAYLAND_wl_display_flush(display);
154
155            /* wl_display_prepare_read_queue() will return false if the event queue is not empty.
156             * If the event queue is empty, it will prepare us for our SDL_IOReady() call. */
157            if (WAYLAND_wl_display_prepare_read_queue(display, data->gles_swap_frame_event_queue) != 0) {
158                // We have some pending events. Check if the frame callback happened.
159                WAYLAND_wl_display_dispatch_queue_pending(display, data->gles_swap_frame_event_queue);
160                continue;
161            }
162
163            // Beyond this point, we must either call wl_display_cancel_read() or wl_display_read_events()
164
165            now = SDL_GetTicksNS();
166            if (now >= max_wait) {
167                // Timeout expired. Cancel the read.
168                WAYLAND_wl_display_cancel_read(display);
169                break;
170            }
171
172            if (SDL_IOReady(WAYLAND_wl_display_get_fd(display), SDL_IOR_READ, max_wait - now) <= 0) {
173                // Error or timeout expired without any events for us. Cancel the read.
174                WAYLAND_wl_display_cancel_read(display);
175                break;
176            }
177
178            // We have events. Read and dispatch them.
179            WAYLAND_wl_display_read_events(display);
180            WAYLAND_wl_display_dispatch_queue_pending(display, data->gles_swap_frame_event_queue);
181        }
182        SDL_SetAtomicInt(&data->swap_interval_ready, 0);
183    }
184
185    if (!data->double_buffer) {
186        // Feed the frame to Wayland. This will set it so the wl_surface_frame callback can fire again.
187        if (!_this->egl_data->eglSwapBuffers(_this->egl_data->egl_display, data->egl_surface)) {
188            return SDL_EGL_SetError("unable to show color buffer in an OS-native window", "eglSwapBuffers");
189        }
190
191        WAYLAND_wl_display_flush(data->waylandData->display);
192    }
193
194    return true;
195}
196
197bool Wayland_GLES_MakeCurrent(SDL_VideoDevice *_this, SDL_Window *window, SDL_GLContext context)
198{
199    bool result;
200
201    if (window && context) {
202        result = SDL_EGL_MakeCurrent(_this, window->internal->egl_surface, context);
203    } else {
204        result = SDL_EGL_MakeCurrent(_this, NULL, NULL);
205    }
206
207    WAYLAND_wl_display_flush(_this->internal->display);
208
209    _this->egl_data->eglSwapInterval(_this->egl_data->egl_display, 0); // see comments on Wayland_GLES_SetSwapInterval.
210
211    return result;
212}
213
214bool Wayland_GLES_DestroyContext(SDL_VideoDevice *_this, SDL_GLContext context)
215{
216    bool result = SDL_EGL_DestroyContext(_this, context);
217    WAYLAND_wl_display_flush(_this->internal->display);
218    return result;
219}
220
221EGLSurface Wayland_GLES_GetEGLSurface(SDL_VideoDevice *_this, SDL_Window *window)
222{
223    SDL_WindowData *windowdata = window->internal;
224
225    return windowdata->egl_surface;
226}
227
228#endif // SDL_VIDEO_DRIVER_WAYLAND && SDL_VIDEO_OPENGL_EGL
229
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