dungeoncraft/www/dc_plugin.js

// DungeonCraft browser plugin for miniquad: storage, file download/upload, save-on-leave,
// HTTP requests (savegame service), audio output.
(function () {
    "use strict";
    var pending = null;      // value handed over by dc_storage_get
    var file = null;         // bytes of a file chosen via the file picker
    var cache = {};          // key -> string, persisted to localStorage when the page is hidden/closed
    var http = {};           // request id -> { done, status, body }
    var httpNext = 1;

    function bytes(ptr, len) {
        return new Uint8Array(wasm_memory.buffer, ptr, len);
    }
    function str(ptr, len) {
        return new TextDecoder().decode(bytes(ptr, len));
    }
    function flushCache() {
        for (var k in cache) {
            try { window.localStorage.setItem(k, cache[k]); } catch (e) { }
        }
    }
    window.addEventListener("pagehide", flushCache);
    document.addEventListener("visibilitychange", function () {
        if (document.visibilityState === "hidden") flushCache();
    });

    // hidden <input type=file> for loading savegames
    var input = document.createElement("input");
    input.type = "file";
    input.accept = ".dcsave,.json,application/json";
    input.style.display = "none";
    input.addEventListener("change", function () {
        var f = input.files && input.files[0];
        if (!f) return;
        f.arrayBuffer().then(function (buf) { file = new Uint8Array(buf); });
        input.value = "";
    });
    document.addEventListener("DOMContentLoaded", function () { document.body.appendChild(input); });

    // Asynchronous HTTP request; the result is polled by the game.
    // status 0 = network error (e.g. no service, or the page was opened as a local file)
    function httpStart(method, url, body) {
        var id = httpNext++;
        var req = { done: false, status: 0, body: new Uint8Array(0) };
        http[id] = req;
        var ctrl = typeof AbortController !== "undefined" ? new AbortController() : null;
        var timer = setTimeout(function () { if (ctrl) ctrl.abort(); }, 15000);
        try {
            var opts = { method: method, cache: "no-store", headers: {} };
            if (ctrl) opts.signal = ctrl.signal;
            if (body !== null) { opts.body = body; opts.headers["Content-Type"] = "application/json"; }
            fetch(url, opts).then(function (r) {
                req.status = r.status;
                return r.arrayBuffer();
            }).then(function (buf) {
                req.body = new Uint8Array(buf);
                req.done = true;
                clearTimeout(timer);
            }).catch(function () {
                req.status = 0;
                req.done = true;
                clearTimeout(timer);
            });
        } catch (e) {
            req.done = true;
        }
        return id;
    }

    function register(importObject) {
        var env = importObject.env;
        env.dc_http = function (mp, ml, up, ul, bp, bl) {
            var body = bl > 0 ? bytes(bp, bl).slice() : null;
            return httpStart(str(mp, ml), str(up, ul), body);
        };
        // -2 = still running, otherwise the HTTP status (0 = network error)
        env.dc_http_poll = function (id) {
            var r = http[id];
            if (!r) return 0;
            return r.done ? r.status : -2;
        };
        env.dc_http_len = function (id) {
            var r = http[id];
            return r ? r.body.length : 0;
        };
        // copies the response body and forgets the request
        env.dc_http_take = function (id, ptr) {
            var r = http[id];
            if (!r) return;
            bytes(ptr, r.body.length).set(r.body);
            delete http[id];
        };
        env.dc_storage_get = function (kp, kl) {
            var v = null;
            try { v = window.localStorage.getItem(str(kp, kl)); } catch (e) { }
            if (v === null) { pending = null; return -1; }
            pending = new TextEncoder().encode(v);
            return pending.length;
        };
        env.dc_storage_take = function (ptr) {
            if (pending === null) return;
            bytes(ptr, pending.length).set(pending);
            pending = null;
        };
        // browser text dialog (touch devices have no keyboard in the canvas); result via dc_storage_take
        env.dc_prompt = function (tp, tl, dp, dl) {
            var v = window.prompt(str(tp, tl), str(dp, dl));
            if (v === null || v === undefined) { pending = null; return -1; }
            pending = new TextEncoder().encode(v);
            return pending.length;
        };
        // the device's main pointer is a finger (phones, tablets)
        env.dc_coarse_pointer = function () {
            try { return window.matchMedia("(pointer: coarse)").matches ? 1 : 0; } catch (e) { return 0; }
        };
        env.dc_storage_set = function (kp, kl, vp, vl) {
            try { window.localStorage.setItem(str(kp, kl), str(vp, vl)); } catch (e) { }
        };
        env.dc_cache_set = function (kp, kl, vp, vl) {
            cache[str(kp, kl)] = str(vp, vl);
        };
        env.dc_download = function (np, nl, dp, dl) {
            var blob = new Blob([bytes(dp, dl).slice()], { type: "application/json" });
            var a = document.createElement("a");
            a.href = URL.createObjectURL(blob);
            a.download = str(np, nl);
            document.body.appendChild(a);
            a.click();
            setTimeout(function () { URL.revokeObjectURL(a.href); a.remove(); }, 1000);
        };
        env.dc_open_file = function () {
            file = null;
            input.click();
        };
        env.dc_file_poll = function () {
            return file === null ? -1 : file.length;
        };
        env.dc_file_take = function (ptr) {
            if (file === null) return;
            bytes(ptr, file.length).set(file);
            file = null;
        };
    }

    // ---- audio: the Rust mixer renders on demand (dc_audio_render), started by the first user input
    var actx = null;
    var stats = { frames: 0, peak: 0 };
    // diagnostics, e.g. for automated tests: state of the audio output
    window.dc_audio_stats = function () {
        return { state: actx ? actx.state : "not started", frames: stats.frames, peak: stats.peak };
    };
    function startAudio() {
        if (typeof wasm_exports === "undefined" || !wasm_exports.dc_audio_render) return;
        if (actx) {
            if (actx.state !== "running") actx.resume();
            return;
        }
        var AC = window.AudioContext || window.webkitAudioContext;
        if (!AC) return;
        actx = new AC();
        wasm_exports.dc_audio_init(actx.sampleRate);
        var node = actx.createScriptProcessor(2048, 0, 2);
        node.onaudioprocess = function (e) {
            var n = e.outputBuffer.length;
            var l = e.outputBuffer.getChannelData(0);
            var r = e.outputBuffer.getChannelData(1);
            var ptr = wasm_exports.dc_audio_render(n);
            if (!ptr) { l.fill(0); r.fill(0); return; }
            var buf = new Float32Array(wasm_memory.buffer, ptr, n * 2);
            var peak = 0;
            for (var i = 0; i < n; i++) {
                l[i] = buf[2 * i]; r[i] = buf[2 * i + 1];
                var a = Math.abs(l[i]); if (a > peak) peak = a;
            }
            stats.frames += n;
            stats.peak = Math.max(stats.peak * 0.9, peak);
        };
        node.connect(actx.destination);
    }
    ["mousedown", "keydown", "touchstart"].forEach(function (ev) {
        window.addEventListener(ev, startAudio, true);
    });

    miniquad_add_plugin({ register_plugin: register, version: 1, name: "dungeoncraft" });
})();