Keyboard events, "key is down" reporter (#117)

* Keyboard events, "key is down" reporter

* Update comment about inputs

* Simplify/generalize keyMap into a keys-pressed list

* Cast values passed to scratchKeyToKeyCode appropriately.

* Cut unspaced key values

* Fix lint from merge commit

playground/playground.js

@@ -166,6 +166,31 @@ window.onload = function() {
         e.preventDefault();
     });
 
+    // Feed keyboard events as VM I/O events.
+    document.addEventListener('keydown', function (e) {
+        // Don't capture keys intended for Blockly inputs.
+        if (e.target != document && e.target != document.body) {
+            return;
+        }
+        window.vm.postIOData('keyboard', {
+            keyCode: e.keyCode,
+            isDown: true
+        });
+        e.preventDefault();
+    });
+    document.addEventListener('keyup', function(e) {
+        // Always capture up events,
+        // even those that have switched to other targets.
+        window.vm.postIOData('keyboard', {
+            keyCode: e.keyCode,
+            isDown: false
+        });
+        // E.g., prevent scroll.
+        if (e.target != document && e.target != document.body) {
+            e.preventDefault();
+        }
+    });
+
     // Run threads
     vm.start();
 

src/blocks/scratch3_sensing.js

@@ -17,6 +17,8 @@ Scratch3SensingBlocks.prototype.getPrimitives = function() {
         'sensing_mousex': this.getMouseX,
         'sensing_mousey': this.getMouseY,
         'sensing_mousedown': this.getMouseDown,
+        'sensing_keyoptions': this.keyOptions,
+        'sensing_keypressed': this.getKeyPressed,
         'sensing_current': this.current,
         'sensing_currentmenu': this.currentMenu
     };
@@ -59,4 +61,12 @@ Scratch3SensingBlocks.prototype.currentMenu = function (args) {
     return args.CURRENTMENU.toLowerCase();
 };
 
+Scratch3SensingBlocks.prototype.keyOptions = function (args) {
+    return args.KEY_OPTION.toLowerCase();
+};
+
+Scratch3SensingBlocks.prototype.getKeyPressed = function (args, util) {
+    return util.ioQuery('keyboard', 'getKeyIsDown', args.KEY_OPTIONS);
+};
+
 module.exports = Scratch3SensingBlocks;

src/engine/runtime.js

@@ -5,6 +5,7 @@ var util = require('util');
 
 // Virtual I/O devices.
 var Clock = require('../io/clock');
+var Keyboard = require('../io/keyboard');
 var Mouse = require('../io/mouse');
 
 var defaultBlockPackages = {
@@ -53,6 +54,7 @@ function Runtime () {
 
     this.ioDevices = {
         'clock': new Clock(),
+        'keyboard': new Keyboard(),
         'mouse': new Mouse()
     };
 }

src/io/keyboard.js

@@ -0,0 +1,57 @@
+var Cast = require('../util/cast');
+
+function Keyboard () {
+    /**
+     * List of currently pressed keys.
+     * @type{Array.<number>}
+     */
+    this._keysPressed = [];
+}
+
+/**
+ * Convert a Scratch key name to a DOM keyCode.
+ * @param {Any} keyName Scratch key argument.
+ * @return {number} Key code corresponding to a DOM event.
+ */
+Keyboard.prototype._scratchKeyToKeyCode = function (keyName) {
+    if (typeof keyName == 'number') {
+        // Key codes placed in with number blocks.
+        return keyName;
+    }
+    var keyString = Cast.toString(keyName);
+    switch (keyString) {
+    case 'space': return 32;
+    case 'left arrow': return 37;
+    case 'up arrow': return 38;
+    case 'right arrow': return 39;
+    case 'down arrow': return 40;
+    // @todo: Consider adding other special keys here.
+    }
+    // Keys reported by DOM keyCode are upper case.
+    return keyString.toUpperCase().charCodeAt(0);
+};
+
+Keyboard.prototype.postData = function (data) {
+    if (data.keyCode) {
+        var index = this._keysPressed.indexOf(data.keyCode);
+        if (data.isDown) {
+            // If not already present, add to the list.
+            if (index < 0) {
+                this._keysPressed.push(data.keyCode);
+            }
+        } else if (index > -1) {
+            // If already present, remove from the list.
+            this._keysPressed.splice(index, 1);
+        }
+    }
+};
+
+Keyboard.prototype.getKeyIsDown = function (key) {
+    if (key == 'any') {
+        return this._keysPressed.length > 0;
+    }
+    var keyCode = this._scratchKeyToKeyCode(key);
+    return this._keysPressed.indexOf(keyCode) > -1;
+};
+
+module.exports = Keyboard;