dungeoncraft/www/dc_plugin.js

// DungeonCraft browser plugin for miniquad: storage, file download/upload, save-on-leave, 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

    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); });

    function register(importObject) {
        var env = importObject.env;
        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;
        };
        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" });
})();