Logging handlers can now be adapted to special needs

dist/iwmlib.js

@@ -1545,14 +1545,34 @@
 
     }
 
+    /* eslint-disable no-undef */
+    /* eslint-disable no-console */
+    /* eslint-disable no-unused-vars */
     let ipc = null;
+    let logMessages = new Set();
+    let logHandlers = {
+        log: console.log,
+        warn: console.warn,
+        error: console.error
+    };
 
     try {
         ipc = require('electron').ipcRenderer;
-    } catch (e) {}
+        logHandlers.log = message => ipc.send('log', message);
+        logHandlers.warn = message => ipc.send('warn', message);
+        logHandlers.error = message => ipc.send('error', message);
+    } catch (e) {
+        console.log('Cannot use electron logging.');
+    }
 
     /** Basic class for app specific logging requirements.
      * Can be used to implement persistent logging in electron apps.
+     * Uses a logMessage cache to prevent error overflows. This is 
+     * needed since errors may occur very frequently
+     * (e.g. display update loops at 60fps, programmatic loops, ...).
+     * 
+     * The logging handlers can be overwritten by calling the static
+     * setup method.
      */
     class Logging {
 
@@ -1560,13 +1580,38 @@
          * @param {*} message
          */
         static log(message) {
+            logHandlers.log(message);
+        }
 
-            if (ipc) {
-                ipc.send('log', message);
-            } else {
-                console.log(message);
+        /**
+         * Static warn function. 
+         * Emits each warning only once per session.
+         * @param {*} message 
+         */
+        static warn(message) {
+            if (!logMessages.has(message)) {
+                logMessages.add(message);
+                logHandlers.warn(message);
             }
         }
+
+        /**
+        * Static error function. 
+        * Emits each error message only once per session.
+        * @param {*} message 
+        */
+        static error(message) {
+            if (!logMessages.has(message)) {
+                logMessages.add(message);
+                logHandlers.error(message);
+            }
+        }
+
+        static setup({log=console.log, warn=console.warn, error=console.error} = {}) {
+            logHandlers.log = log;
+            logHandlers.warn = warn;
+            logHandlers.error = error;
+        }
     }
 
     /* globals Hammer, propagating */