Atlas - SDL_emscriptenframebuffer.c
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[FILE BEGIN]
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#ifdef SDL_VIDEO_DRIVER_EMSCRIPTEN
24
25#include "SDL_emscriptenvideo.h"
26#include "SDL_emscriptenframebuffer.h"
27
28#include <emscripten/threading.h>
29
30bool Emscripten_CreateWindowFramebuffer(SDL_VideoDevice *_this, SDL_Window *window, SDL_PixelFormat *format, void **pixels, int *pitch)
31{
32    SDL_Surface *surface;
33    const SDL_PixelFormat surface_format = SDL_PIXELFORMAT_RGBA32;
34    int w, h;
35
36    // Free the old framebuffer surface
37    SDL_WindowData *data = window->internal;
38    surface = data->surface;
39    SDL_DestroySurface(surface);
40
41    // Create a new one
42    SDL_GetWindowSizeInPixels(window, &w, &h);
43
44    surface = SDL_CreateSurface(w, h, surface_format);
45    if (!surface) {
46        return false;
47    }
48
49    // Save the info and return!
50    data->surface = surface;
51    *format = surface_format;
52    *pixels = surface->pixels;
53    *pitch = surface->pitch;
54    return true;
55}
56
57bool Emscripten_UpdateWindowFramebuffer(SDL_VideoDevice *_this, SDL_Window *window, const SDL_Rect *rects, int numrects)
58{
59    SDL_Surface *surface;
60
61    SDL_WindowData *data = window->internal;
62    surface = data->surface;
63    if (!surface) {
64        return SDL_SetError("Couldn't find framebuffer surface for window");
65    }
66
67    // Send the data to the display
68
69    /* *INDENT-OFF* */ // clang-format off
70    int updated = MAIN_THREAD_EM_ASM_INT({
71        var w = $0;
72        var h = $1;
73        var pixels = $2;
74        var canvasId = UTF8ToString($3);
75        var canvas = document.querySelector(canvasId);
76
77        //TODO: this should store a context per canvas
78        var SDL3 = Module['SDL3'];
79        if (SDL3.ctxCanvas !== canvas) {
80            SDL3.ctx = Browser.createContext(canvas, false, true);
81            if (!SDL3.ctx) {
82                return false;
83            }
84            SDL3.ctxCanvas = canvas;
85        }
86        if (SDL3.w !== w || SDL3.h !== h || SDL3.imageCtx !== SDL3.ctx) {
87            SDL3.image = SDL3.ctx.createImageData(w, h);
88            SDL3.w = w;
89            SDL3.h = h;
90            SDL3.imageCtx = SDL3.ctx;
91        }
92        var data = SDL3.image.data;
93        var src = pixels / 4;
94
95        if (SDL3.data32Data !== data) {
96            SDL3.data32 = new Int32Array(data.buffer);
97            SDL3.data32Data = data;
98        }
99        var data32 = SDL3.data32;
100        data32.set(HEAP32.subarray(src, src + data32.length));
101
102        SDL3.ctx.putImageData(SDL3.image, 0, 0);
103        return true;
104    }, surface->w, surface->h, surface->pixels, data->canvas_id);
105    /* *INDENT-ON* */ // clang-format on
106
107    if (!updated) {
108        return SDL_SetError("Couldn't create context for canvas update");
109    }
110
111    if (emscripten_has_asyncify() && SDL_GetHintBoolean(SDL_HINT_EMSCRIPTEN_ASYNCIFY, true)) {
112        // give back control to browser for screen refresh
113        emscripten_sleep(0);
114    }
115
116    return true;
117}
118
119void Emscripten_DestroyWindowFramebuffer(SDL_VideoDevice *_this, SDL_Window *window)
120{
121    SDL_WindowData *data = window->internal;
122
123    SDL_DestroySurface(data->surface);
124    data->surface = NULL;
125}
126
127#endif // SDL_VIDEO_DRIVER_EMSCRIPTEN
128
[FILE END]
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