src/video/emscripten/SDL_emscriptenvideo.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_internal.h"

#ifdef SDL_VIDEO_DRIVER_EMSCRIPTEN

#include "../SDL_sysvideo.h"
#include "../SDL_pixels_c.h"
#include "../../events/SDL_events_c.h"

#include "SDL_emscriptenvideo.h"
#include "SDL_emscriptenopengles.h"
#include "SDL_emscriptenframebuffer.h"
#include "SDL_emscriptenevents.h"
#include "SDL_emscriptenmouse.h"

#define EMSCRIPTENVID_DRIVER_NAME "emscripten"

/* Initialization/Query functions */
static int Emscripten_VideoInit(SDL_VideoDevice *_this);
static int Emscripten_SetDisplayMode(SDL_VideoDevice *_this, SDL_VideoDisplay *display, SDL_DisplayMode *mode);
static void Emscripten_VideoQuit(SDL_VideoDevice *_this);
static int Emscripten_GetDisplayUsableBounds(SDL_VideoDevice *_this, SDL_VideoDisplay *display, SDL_Rect *rect);

static int Emscripten_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_PropertiesID create_props);
static void Emscripten_SetWindowSize(SDL_VideoDevice *_this, SDL_Window *window);
static void Emscripten_GetWindowSizeInPixels(SDL_VideoDevice *_this, SDL_Window *window, int *w, int *h);
static void Emscripten_DestroyWindow(SDL_VideoDevice *_this, SDL_Window *window);
static int Emscripten_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window *window, SDL_VideoDisplay *display, SDL_FullscreenOp fullscreen);
static void Emscripten_PumpEvents(SDL_VideoDevice *_this);
static void Emscripten_SetWindowTitle(SDL_VideoDevice *_this, SDL_Window *window);

/* Emscripten driver bootstrap functions */

static void Emscripten_DeleteDevice(SDL_VideoDevice *device)
{
    SDL_free(device);
}

static SDL_VideoDevice *Emscripten_CreateDevice(void)
{
    SDL_VideoDevice *device;

    /* Initialize all variables that we clean on shutdown */
    device = (SDL_VideoDevice *)SDL_calloc(1, sizeof(SDL_VideoDevice));
    if (!device) {
        return 0;
    }

    /* Firefox sends blur event which would otherwise prevent full screen
     * when the user clicks to allow full screen.
     * See https://bugzilla.mozilla.org/show_bug.cgi?id=1144964
     */
    SDL_SetHint(SDL_HINT_VIDEO_MINIMIZE_ON_FOCUS_LOSS, "0");

    /* Set the function pointers */
    device->VideoInit = Emscripten_VideoInit;
    device->VideoQuit = Emscripten_VideoQuit;
    device->GetDisplayUsableBounds = Emscripten_GetDisplayUsableBounds;
    device->SetDisplayMode = Emscripten_SetDisplayMode;

    device->PumpEvents = Emscripten_PumpEvents;

    device->CreateSDLWindow = Emscripten_CreateWindow;
    device->SetWindowTitle = Emscripten_SetWindowTitle;
    /*device->SetWindowIcon = Emscripten_SetWindowIcon;
    device->SetWindowPosition = Emscripten_SetWindowPosition;*/
    device->SetWindowSize = Emscripten_SetWindowSize;
    /*device->ShowWindow = Emscripten_ShowWindow;
    device->HideWindow = Emscripten_HideWindow;
    device->RaiseWindow = Emscripten_RaiseWindow;
    device->MaximizeWindow = Emscripten_MaximizeWindow;
    device->MinimizeWindow = Emscripten_MinimizeWindow;
    device->RestoreWindow = Emscripten_RestoreWindow;
    device->SetWindowMouseGrab = Emscripten_SetWindowMouseGrab;*/
    device->GetWindowSizeInPixels = Emscripten_GetWindowSizeInPixels;
    device->DestroyWindow = Emscripten_DestroyWindow;
    device->SetWindowFullscreen = Emscripten_SetWindowFullscreen;

    device->CreateWindowFramebuffer = Emscripten_CreateWindowFramebuffer;
    device->UpdateWindowFramebuffer = Emscripten_UpdateWindowFramebuffer;
    device->DestroyWindowFramebuffer = Emscripten_DestroyWindowFramebuffer;

    device->GL_LoadLibrary = Emscripten_GLES_LoadLibrary;
    device->GL_GetProcAddress = Emscripten_GLES_GetProcAddress;
    device->GL_UnloadLibrary = Emscripten_GLES_UnloadLibrary;
    device->GL_CreateContext = Emscripten_GLES_CreateContext;
    device->GL_MakeCurrent = Emscripten_GLES_MakeCurrent;
    device->GL_SetSwapInterval = Emscripten_GLES_SetSwapInterval;
    device->GL_GetSwapInterval = Emscripten_GLES_GetSwapInterval;
    device->GL_SwapWindow = Emscripten_GLES_SwapWindow;
    device->GL_DeleteContext = Emscripten_GLES_DeleteContext;

    device->free = Emscripten_DeleteDevice;

    return device;
}

VideoBootStrap Emscripten_bootstrap = {
    EMSCRIPTENVID_DRIVER_NAME, "SDL emscripten video driver",
    Emscripten_CreateDevice,
    NULL /* no ShowMessageBox implementation */
};

int Emscripten_VideoInit(SDL_VideoDevice *_this)
{
    SDL_DisplayMode mode;

    /* Use a fake 32-bpp desktop mode */
    SDL_zero(mode);
    mode.format = SDL_PIXELFORMAT_XRGB8888;
    emscripten_get_screen_size(&mode.w, &mode.h);
    mode.pixel_density = emscripten_get_device_pixel_ratio();

    if (SDL_AddBasicVideoDisplay(&mode) == 0) {
        return -1;
    }

    Emscripten_InitMouse();

    /* Assume we have a mouse and keyboard */
    SDL_AddKeyboard(SDL_DEFAULT_KEYBOARD_ID, NULL, SDL_FALSE);
    SDL_AddMouse(SDL_DEFAULT_MOUSE_ID, NULL, SDL_FALSE);

    /* We're done! */
    return 0;
}

static int Emscripten_SetDisplayMode(SDL_VideoDevice *_this, SDL_VideoDisplay *display, SDL_DisplayMode *mode)
{
    /* can't do this */
    return 0;
}

static void Emscripten_VideoQuit(SDL_VideoDevice *_this)
{
    Emscripten_FiniMouse();
}

static int Emscripten_GetDisplayUsableBounds(SDL_VideoDevice *_this, SDL_VideoDisplay *display, SDL_Rect *rect)
{
    if (rect) {
        rect->x = 0;
        rect->y = 0;
        rect->w = MAIN_THREAD_EM_ASM_INT({
            return window.innerWidth;
        });
        rect->h = MAIN_THREAD_EM_ASM_INT({
            return window.innerHeight;
        });
    }
    return 0;
}

static void Emscripten_PumpEvents(SDL_VideoDevice *_this)
{
    /* do nothing. */
}

static int Emscripten_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_PropertiesID props)
{
    SDL_WindowData *wdata;
    double scaled_w, scaled_h;
    double css_w, css_h;
    const char *selector;

    /* Allocate window internal data */
    wdata = (SDL_WindowData *)SDL_calloc(1, sizeof(SDL_WindowData));
    if (!wdata) {
        return -1;
    }

    selector = SDL_GetHint(SDL_HINT_EMSCRIPTEN_CANVAS_SELECTOR);
    if (!selector) {
        selector = "#canvas";
    }

    wdata->canvas_id = SDL_strdup(selector);

    if (window->flags & SDL_WINDOW_HIGH_PIXEL_DENSITY) {
        wdata->pixel_ratio = emscripten_get_device_pixel_ratio();
    } else {
        wdata->pixel_ratio = 1.0f;
    }

    scaled_w = SDL_floor(window->w * wdata->pixel_ratio);
    scaled_h = SDL_floor(window->h * wdata->pixel_ratio);

    /* set a fake size to check if there is any CSS sizing the canvas */
    emscripten_set_canvas_element_size(wdata->canvas_id, 1, 1);
    emscripten_get_element_css_size(wdata->canvas_id, &css_w, &css_h);

    wdata->external_size = SDL_floor(css_w) != 1 || SDL_floor(css_h) != 1;

    if ((window->flags & SDL_WINDOW_RESIZABLE) && wdata->external_size) {
        /* external css has resized us */
        scaled_w = css_w * wdata->pixel_ratio;
        scaled_h = css_h * wdata->pixel_ratio;

        SDL_SendWindowEvent(window, SDL_EVENT_WINDOW_RESIZED, SDL_lroundf(css_w), SDL_lroundf(css_h));
    }
    emscripten_set_canvas_element_size(wdata->canvas_id, SDL_lroundf(scaled_w), SDL_lroundf(scaled_h));

    /* if the size is not being controlled by css, we need to scale down for hidpi */
    if (!wdata->external_size) {
        if (wdata->pixel_ratio != 1.0f) {
            /*scale canvas down*/
            emscripten_set_element_css_size(wdata->canvas_id, window->w, window->h);
        }
    }

    wdata->window = window;

    /* Setup driver data for this window */
    window->driverdata = wdata;

    /* One window, it always has focus */
    SDL_SetMouseFocus(window);
    SDL_SetKeyboardFocus(window);

    Emscripten_RegisterEventHandlers(wdata);

    /* Window has been successfully created */
    return 0;
}

static void Emscripten_SetWindowSize(SDL_VideoDevice *_this, SDL_Window *window)
{
    SDL_WindowData *data;

    if (window->driverdata) {
        data = window->driverdata;
        /* update pixel ratio */
        if (window->flags & SDL_WINDOW_HIGH_PIXEL_DENSITY) {
            data->pixel_ratio = emscripten_get_device_pixel_ratio();
        }
        emscripten_set_canvas_element_size(data->canvas_id, SDL_lroundf(window->floating.w * data->pixel_ratio), SDL_lroundf(window->floating.h * data->pixel_ratio));

        /*scale canvas down*/
        if (!data->external_size && data->pixel_ratio != 1.0f) {
            emscripten_set_element_css_size(data->canvas_id, window->floating.w, window->floating.h);
        }

        SDL_SendWindowEvent(window, SDL_EVENT_WINDOW_RESIZED, window->floating.w, window->floating.h);
    }
}

static void Emscripten_GetWindowSizeInPixels(SDL_VideoDevice *_this, SDL_Window *window, int *w, int *h)
{
    SDL_WindowData *data;
    if (window->driverdata) {
        data = window->driverdata;
        *w = SDL_lroundf(window->w * data->pixel_ratio);
        *h = SDL_lroundf(window->h * data->pixel_ratio);
    }
}

static void Emscripten_DestroyWindow(SDL_VideoDevice *_this, SDL_Window *window)
{
    SDL_WindowData *data;

    if (window->driverdata) {
        data = window->driverdata;

        Emscripten_UnregisterEventHandlers(data);

        /* We can't destroy the canvas, so resize it to zero instead */
        emscripten_set_canvas_element_size(data->canvas_id, 0, 0);
        SDL_free(data->canvas_id);

        SDL_free(window->driverdata);
        window->driverdata = NULL;
    }
}

static int Emscripten_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window *window, SDL_VideoDisplay *display, SDL_FullscreenOp fullscreen)
{
    SDL_WindowData *data;
    int res = -1;

    if (window->driverdata) {
        data = window->driverdata;

        if (fullscreen) {
            EmscriptenFullscreenStrategy strategy;
            SDL_bool is_fullscreen_desktop = !window->fullscreen_exclusive;

            SDL_zero(strategy);
            strategy.scaleMode = is_fullscreen_desktop ? EMSCRIPTEN_FULLSCREEN_SCALE_STRETCH : EMSCRIPTEN_FULLSCREEN_SCALE_ASPECT;

            if (!is_fullscreen_desktop) {
                strategy.canvasResolutionScaleMode = EMSCRIPTEN_FULLSCREEN_CANVAS_SCALE_NONE;
            } else if (window->flags & SDL_WINDOW_HIGH_PIXEL_DENSITY) {
                strategy.canvasResolutionScaleMode = EMSCRIPTEN_FULLSCREEN_CANVAS_SCALE_HIDEF;
            } else {
                strategy.canvasResolutionScaleMode = EMSCRIPTEN_FULLSCREEN_CANVAS_SCALE_STDDEF;
            }

            strategy.filteringMode = EMSCRIPTEN_FULLSCREEN_FILTERING_DEFAULT;

            strategy.canvasResizedCallback = Emscripten_HandleCanvasResize;
            strategy.canvasResizedCallbackUserData = data;

            data->fullscreen_mode_flags = (window->flags & SDL_WINDOW_FULLSCREEN);
            data->fullscreen_resize = is_fullscreen_desktop;

            res = emscripten_request_fullscreen_strategy(data->canvas_id, 1, &strategy);
        } else {
            res = emscripten_exit_fullscreen();
        }
    }

    if (res == EMSCRIPTEN_RESULT_SUCCESS) {
        return 0;
    } else if (res == EMSCRIPTEN_RESULT_DEFERRED) {
        return 1;
    } else {
        return -1;
    }
}

static void Emscripten_SetWindowTitle(SDL_VideoDevice *_this, SDL_Window *window)
{
    emscripten_set_window_title(window->title);
}

#endif /* SDL_VIDEO_DRIVER_EMSCRIPTEN */