Atlas - SDL_emscriptenmouse.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_EMSCRIPTEN
24
25#include <emscripten/emscripten.h>
26#include <emscripten/html5.h>
27#include <emscripten/threading.h>
28
29#include "SDL_emscriptenmouse.h"
30#include "SDL_emscriptenvideo.h"
31
32#include "../SDL_video_c.h"
33#include "../../events/SDL_mouse_c.h"
34
35// older Emscriptens don't have this, but we need to for wasm64 compatibility.
36#ifndef MAIN_THREAD_EM_ASM_PTR
37    #ifdef __wasm64__
38        #error You need to upgrade your Emscripten compiler to support wasm64
39    #else
40        #define MAIN_THREAD_EM_ASM_PTR MAIN_THREAD_EM_ASM_INT
41    #endif
42#endif
43
44static SDL_Cursor *Emscripten_CreateCursorFromString(const char *cursor_str, bool is_custom)
45{
46    SDL_CursorData *curdata;
47    SDL_Cursor *cursor = SDL_calloc(1, sizeof(SDL_Cursor));
48    if (cursor) {
49        curdata = (SDL_CursorData *)SDL_calloc(1, sizeof(*curdata));
50        if (!curdata) {
51            SDL_free(cursor);
52            return NULL;
53        }
54
55        curdata->system_cursor = cursor_str;
56        curdata->is_custom = is_custom;
57        cursor->internal = curdata;
58    }
59
60    return cursor;
61}
62
63static SDL_Cursor *Emscripten_CreateDefaultCursor(void)
64{
65    SDL_SystemCursor id = SDL_GetDefaultSystemCursor();
66    const char *cursor_name = SDL_GetCSSCursorName(id, NULL);
67    return Emscripten_CreateCursorFromString(cursor_name, false);
68}
69
70EM_JS_DEPS(sdlmouse, "$stringToUTF8,$UTF8ToString");
71
72static SDL_Cursor *Emscripten_CreateCursor(SDL_Surface *surface, int hot_x, int hot_y)
73{
74    const char *cursor_url = NULL;
75    SDL_Surface *conv_surf;
76
77    conv_surf = SDL_ConvertSurface(surface, SDL_PIXELFORMAT_RGBA32);
78
79    if (!conv_surf) {
80        return NULL;
81    }
82
83    /* *INDENT-OFF* */ // clang-format off
84    cursor_url = (const char *)MAIN_THREAD_EM_ASM_PTR({
85        var w = $0;
86        var h = $1;
87        var hot_x = $2;
88        var hot_y = $3;
89        var pixels = $4;
90
91        var canvas = document.createElement("canvas");
92        canvas.width = w;
93        canvas.height = h;
94
95        var ctx = canvas.getContext("2d");
96
97        var image = ctx.createImageData(w, h);
98        var data = image.data;
99        var src = pixels / 4;
100
101        var data32 = new Int32Array(data.buffer);
102        data32.set(HEAP32.subarray(src, src + data32.length));
103
104        ctx.putImageData(image, 0, 0);
105        var url = hot_x === 0 && hot_y === 0
106            ? "url(" + canvas.toDataURL() + "), auto"
107            : "url(" + canvas.toDataURL() + ") " + hot_x + " " + hot_y + ", auto";
108
109        var urlBuf = _SDL_malloc(url.length + 1);
110        stringToUTF8(url, urlBuf, url.length + 1);
111
112        return urlBuf;
113    }, surface->w, surface->h, hot_x, hot_y, conv_surf->pixels);
114    /* *INDENT-ON* */ // clang-format on
115
116    SDL_DestroySurface(conv_surf);
117
118    return Emscripten_CreateCursorFromString(cursor_url, true);
119}
120
121static SDL_Cursor *Emscripten_CreateSystemCursor(SDL_SystemCursor id)
122{
123    const char *cursor_name = SDL_GetCSSCursorName(id, NULL);
124
125    return Emscripten_CreateCursorFromString(cursor_name, false);
126}
127
128static void Emscripten_FreeCursor(SDL_Cursor *cursor)
129{
130    SDL_CursorData *curdata;
131    if (cursor) {
132        curdata = cursor->internal;
133
134        if (curdata) {
135            if (curdata->is_custom) {
136                SDL_free((char *)curdata->system_cursor);
137            }
138            SDL_free(cursor->internal);
139        }
140
141        SDL_free(cursor);
142    }
143}
144
145static bool Emscripten_ShowCursor(SDL_Cursor *cursor)
146{
147    SDL_CursorData *curdata;
148    if (SDL_GetMouseFocus() != NULL) {
149        if (cursor && cursor->internal) {
150            curdata = cursor->internal;
151
152            if (curdata->system_cursor) {
153                /* *INDENT-OFF* */ // clang-format off
154                MAIN_THREAD_EM_ASM({
155                    if (Module['canvas']) {
156                        Module['canvas'].style['cursor'] = UTF8ToString($0);
157                    }
158                }, curdata->system_cursor);
159                /* *INDENT-ON* */ // clang-format on
160            }
161        } else {
162            /* *INDENT-OFF* */ // clang-format off
163            MAIN_THREAD_EM_ASM(
164                if (Module['canvas']) {
165                    Module['canvas'].style['cursor'] = 'none';
166                }
167            );
168            /* *INDENT-ON* */ // clang-format on
169        }
170    }
171    return true;
172}
173
174static bool Emscripten_SetRelativeMouseMode(bool enabled)
175{
176    SDL_Window *window;
177    SDL_WindowData *window_data;
178
179    // TODO: pointer lock isn't actually enabled yet
180    if (enabled) {
181        window = SDL_GetMouseFocus();
182        if (!window) {
183            return false;
184        }
185
186        window_data = window->internal;
187
188        if (emscripten_request_pointerlock(window_data->canvas_id, 1) >= EMSCRIPTEN_RESULT_SUCCESS) {
189            return true;
190        }
191    } else {
192        if (emscripten_exit_pointerlock() >= EMSCRIPTEN_RESULT_SUCCESS) {
193            return true;
194        }
195    }
196    return false;
197}
198
199static SDL_MouseButtonFlags Emscripten_GetGlobalMouseState(float *x, float *y)
200{
201    *x = MAIN_THREAD_EM_ASM_DOUBLE({
202        return Module['SDL3']['mouse_x'];
203    });
204    *y = MAIN_THREAD_EM_ASM_DOUBLE({
205        return Module['SDL3']['mouse_y'];
206    });
207    SDL_MouseButtonFlags flags = 0;
208    for (int i = 0; i < 5; ++i) {
209        const bool button_down = MAIN_THREAD_EM_ASM_INT({
210            return Module['SDL3']['mouse_buttons'][$0];
211        }, i);
212        if (button_down) {
213            flags |= 1 << i;
214        }
215    }
216    return flags;
217}
218
219void Emscripten_InitMouse(void)
220{
221    SDL_Mouse *mouse = SDL_GetMouse();
222
223    mouse->CreateCursor = Emscripten_CreateCursor;
224    mouse->ShowCursor = Emscripten_ShowCursor;
225    mouse->FreeCursor = Emscripten_FreeCursor;
226    mouse->CreateSystemCursor = Emscripten_CreateSystemCursor;
227    mouse->SetRelativeMouseMode = Emscripten_SetRelativeMouseMode;
228
229    // Add event listeners to track mouse events on the document
230    MAIN_THREAD_EM_ASM({
231        if (!Module['SDL3']) {
232            Module['SDL3'] = {};
233        }
234        var SDL3 = Module['SDL3'];
235        SDL3['mouse_x'] = 0;
236        SDL3['mouse_y'] = 0;
237        /*
238            Based on https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button
239            Possible value for button in the event object is [0, 5)
240            NOTE: Some browsers do not allow handling the forwards and backwards buttons
241        */
242        SDL3['mouse_buttons'] = [];
243        for (var i = 0; i < 5; ++i) {
244            SDL3['mouse_buttons'][i] = false;
245        }
246        document.addEventListener('mousemove', function(e) {
247            // Reacquire from object in case it changed for some reason
248            var SDL3 = Module['SDL3'];
249            SDL3['mouse_x'] = e.clientX;
250            SDL3['mouse_y'] = e.clientY;
251        });
252        document.addEventListener('mousedown', function(e) {
253            // Reacquire from object in case it changed for some reason
254            var SDL3 = Module['SDL3'];
255            if (0 <= e.button && e.button < SDL3['mouse_buttons'].length) {
256                SDL3['mouse_buttons'][e.button] = true;
257            }
258        });
259        document.addEventListener('mouseup', function(e) {
260            // Reacquire from object in case it changed for some reason
261            var SDL3 = Module['SDL3'];
262            if (0 <= e.button && e.button < SDL3['mouse_buttons'].length) {
263                SDL3['mouse_buttons'][e.button] = false;
264            }
265        });
266    });
267    mouse->GetGlobalMouseState = Emscripten_GetGlobalMouseState;
268
269    SDL_SetDefaultCursor(Emscripten_CreateDefaultCursor());
270}
271
272void Emscripten_QuitMouse(void)
273{
274}
275
276#endif // SDL_VIDEO_DRIVER_EMSCRIPTEN
277
[FILE END]
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