Add video trial requiring a keyboard response

plugins/jspsych-video-keyboard-response.js

@@ -0,0 +1,190 @@
+/**
+ * jspsych-video-keyboard-response
+ * Josh de Leeuw
+ *
+ * plugin for playing a video file and getting a keyboard response
+ *
+ * documentation: docs.jspsych.org
+ *
+ **/
+
+jsPsych.plugins["video-keyboard-response"] = (function() {
+
+  var plugin = {};
+
+  jsPsych.pluginAPI.registerPreload('video-keyboard-response', 'stimulus', 'video');
+
+  plugin.info = {
+    name: 'video-keyboard-response',
+    description: '',
+    parameters: {
+      stimulus: {
+        type: jsPsych.plugins.parameterType.VIDEO,
+        pretty_name: 'Stimulus',
+        default: undefined,
+        description: 'The video file to play.'
+      },
+      choices: {
+        type: jsPsych.plugins.parameterType.KEYCODE,
+        pretty_name: 'Choices',
+        array: true,
+        default: jsPsych.ALL_KEYS,
+        description: 'The keys the subject is allowed to press to respond to the stimulus.'
+      },
+      prompt: {
+        type: jsPsych.plugins.parameterType.STRING,
+        pretty_name: 'Prompt',
+        default: null,
+        description: 'Any content here will be displayed below the stimulus.'
+      },
+      width: {
+        type: jsPsych.plugins.parameterType.INT,
+        pretty_name: 'Width',
+        default: '',
+        description: 'The width of the video in pixels.'
+      },
+      height: {
+        type: jsPsych.plugins.parameterType.INT,
+        pretty_name: 'Height',
+        default: '',
+        description: 'The height of the video display in pixels.'
+      },
+      autoplay: {
+        type: jsPsych.plugins.parameterType.BOOL,
+        pretty_name: 'Autoplay',
+        default: true,
+        description: 'If true, the video will begin playing as soon as it has loaded.'
+      },
+      controls: {
+        type: jsPsych.plugins.parameterType.BOOL,
+        pretty_name: 'Controls',
+        default: false,
+        description: 'If true, the subject will be able to pause the video or move the playback to any point in the video.'
+      },
+      trial_duration: {
+        type: jsPsych.plugins.parameterType.INT,
+        pretty_name: 'Trial duration',
+        default: null,
+        description: 'How long to show trial before it ends.'
+      },
+      response_ends_trial: {
+        type: jsPsych.plugins.parameterType.BOOL,
+        pretty_name: 'Response ends trial',
+        default: true,
+        description: 'If true, the trial will end when subject makes a response.'
+      }
+    }
+  }
+
+  plugin.trial = function(display_element, trial) {
+
+    // setup stimulus
+    var video_html = '<video id="jspsych-video-keyboard-response-stimulus"';
+
+    if(trial.width) {
+      video_html += ' width="'+trial.width+'"';
+    }
+    if(trial.height) {
+      video_html += ' height="'+trial.height+'"';
+    }
+    if(trial.autoplay){
+      video_html += " autoplay ";
+    }
+    if(trial.controls){
+      video_html +=" controls ";
+    }
+    video_html +=">";
+
+    var video_preload_blob = jsPsych.pluginAPI.getVideoBuffer(trial.stimulus);
+    if(!video_preload_blob) {
+        var file_name = trial.stimulus;
+        if(file_name.indexOf('?') > -1){
+          file_name = file_name.substring(0, file_name.indexOf('?'));
+        }
+        var type = file_name.substr(file_name.lastIndexOf('.') + 1);
+        type = type.toLowerCase();
+        video_html+='<source src="' + file_name + '" type="video/'+type+'">';
+    }
+    video_html += "</video>";
+
+    // add prompt if there is one
+    if (trial.prompt !== null) {
+      video_html += trial.prompt;
+    }
+
+    display_element.innerHTML = video_html;
+
+    if(video_preload_blob){
+      display_element.querySelector('#jspsych-video-keyboard-response-stimulus').src = video_preload_blob;
+    }
+
+    // store response
+    var response = {
+      rt: null,
+      key: null
+    };
+
+    // function to end trial when it is time
+    function end_trial() {
+
+      // kill any remaining setTimeout handlers
+      jsPsych.pluginAPI.clearAllTimeouts();
+
+      // kill keyboard listeners
+      jsPsych.pluginAPI.cancelAllKeyboardResponses();
+
+      // gather the data to store for the trial
+      if(response.rt !== null){
+        response.rt = Math.round(response.rt * 1000);
+      }
+      var trial_data = {
+        "rt": response.rt,
+        "stimulus": trial.stimulus,
+        "key_press": response.key
+      };
+
+      // clear the display
+      display_element.innerHTML = '';
+
+      // move on to the next trial
+      jsPsych.finishTrial(trial_data);
+    };
+
+    // function to handle responses by the subject
+    var after_response = function(info) {
+
+      // after a valid response, the stimulus will have the CSS class 'responded'
+      // which can be used to provide visual feedback that a response was recorded
+      display_element.querySelector('#jspsych-video-keyboard-response-stimulus').className += ' responded';
+
+      // only record the first response
+      if (response.key == null) {
+        response = info;
+      }
+
+      if (trial.response_ends_trial) {
+        end_trial();
+      }
+    };
+
+    // start the response listener
+    if (trial.choices != jsPsych.NO_KEYS) {
+      var keyboardListener = jsPsych.pluginAPI.getKeyboardResponse({
+        callback_function: after_response,
+        valid_responses: trial.choices,
+        rt_method: 'performance',
+        persist: false,
+        allow_held_key: false,
+      });
+    }
+
+    // end trial if time limit is set
+    if (trial.trial_duration !== null) {
+      jsPsych.pluginAPI.setTimeout(function() {
+        end_trial();
+      }, trial.trial_duration);
+    }
+  };
+
+  return plugin;
+})();