Flashcards revisited

These changes introduce several UI & UX improvements, bugfixes and new features.

---

Major changes:

• New question variant based on flashcards (like lecture and preparation questions)
• Flashcard variant can be added to custom sessions through feature activation
• Improve flashcard presentation in question carousels
  • front- and backside are placed in one visible element (backface-visibility)
  • front- and backside are configurable through style.scss
  • flashcard size is determined dynamically based on front- and backside dimensions
• Add smooth flip animation to flashcards (based on CSS3, not sencha)
• Add feature to flip all flashcard in one session (triggered by socket)
• Add import and export to ARSnova.cards

---

Other changes:

• visibility of speakers overlay buttons is not longer bound to projector mode. New condition: screen width > 840px
• configuration options for question carousels inner item width have been added to style.scss
• all labels and buttons in AudienceQuestionPanel and QuestionDetailsPanel have been customized for flashcards
• a new list button for new question variant "flashcard" has been added to both inclass panels
• question import and export modals have been completely overhauled for a consistent look and feel
• several UI & UX improvements

---

Bugfixes:

• CSV import has been fixed: Import failed if rateable questions without correct answers were inside CSV-file

• critical: fix layout problems in latest firefox release caused by senchas flexbox implementation

• Question and answer preview have been reintroduced for rateable question formats

• resolve several javascript reference errors

  ---

New configuration options:

/* carousel inner item width configuration */
$carousel-inner-max-width: 80%;  // was 720px previously

/** flashcard front side configuration **/
$flashcard-front-font-color: $brand-text;
$flashcard-front-background: linear-gradient(to top, #DFE8EC 0%, white 5%) 0 20px;
$flashcard-front-background-size: 100% 30px;
$flashcard-front-border-width: 5px;
$flashcard-front-border-color: white;
$flashcard-front-border-style: solid;

/** flashcard back side configuration **/
$flashcard-back-font-color: $brand-text;
$flashcard-back-background: linear-gradient(to top, #DFE8EC 0%, white 5%) 0 20px;
$flashcard-back-background-size: 100% 30px;
$flashcard-back-border-width: 5px;
$flashcard-back-border-color: white;
$flashcard-back-border-style: solid;

src/main/webapp/app/controller/FlashcardExport.js

@@ -39,47 +39,38 @@ Ext.define("ARSnova.controller.FlashcardExport", {
 		controller.getQuestions(sessionStorage.getItem('keyword'), {
 			success: function (response) {
 				var flashcards = me.preparseJson(Ext.decode(response.responseText));
-
-				for (var i = 0, json = ''; i < flashcards.length; i++) {
-					json += JSON.stringify(flashcards[i], null, '\t');
-					json += i < flashcards.length - 1 ? ', ' : '';
-				}
-
+				var json = this.stringifyFlashcards(flashcards);
 				me.exportJsonFile(json);
 			}
 		});
 	},
 
-	parseBackPage: function (questionData) {
-		var correctAnswers = [];
-		var answer = '';
+	stringifyFlashcards: function (flashcards) {
+		for (var i = 0, json = ''; i < flashcards.length; i++) {
+			json += JSON.stringify(flashcards[i], null, '\t');
+			json += i < flashcards.length - 1 ? ', ' : '';
+		}
+		return json;
+	},
 
-		for (var i = 0, back = null; i < questionData.possibleAnswers.length; i++) {
-			if (questionData.possibleAnswers[i].correct) {
-				answer = questionData.possibleAnswers[i].text;
-				if (questionData.questionType === 'abcd') {
-					answer = answer.slice(3, answer.length);
+	preparseJson: function (records) {
+		var flashcards = [];
+		for (var i = 0, flashcard; i < records.length; i++) {
+			if (this.suitableTypes.indexOf(records[i].questionType) !== -1) {
+				flashcard = this.formatFlashcard(records[i]);
+
+				if (flashcard.back && flashcard.front) {
+					flashcards.push(flashcard);
 				}
-				correctAnswers.push(answer);
 			}
 		}
 
-		if (correctAnswers.length) {
-			back = correctAnswers.join(', ');
-		}
-
-		return back;
- 	},
+		return flashcards;
+	},
 
 	formatFlashcard: function (questionData) {
 		var flashcard = {};
-		var questionType = questionData.questionType;
-
-		if (this.suitableTypes.indexOf(questionData.questionType) === -1) {
-			return null;
-		}
-
-		switch(questionType) {
+		switch (questionData.questionType) {
 			case 'mc': case 'abcd': case 'yesno': case 'flashcard':
 				flashcard.back = this.parseBackPage(questionData);
 				break;
@@ -89,19 +80,19 @@ Ext.define("ARSnova.controller.FlashcardExport", {
 		return flashcard;
 	},
 
-	preparseJson: function (records) {
-		var flashcards = [];
-		for (var i = 0, flashcard; i < records.length; i++) {
-			if (this.suitableTypes.indexOf(records[i].questionType) !== -1) {
-				flashcard = this.formatFlashcard(records[i]);
+	parseBackPage: function (questionData) {
+		var possibleAnswers = questionData.possibleAnswers;
+		var correctAnswers = [];
 
-				if (flashcard.back && flashcard.front) {
-					flashcards.push(flashcard);
-				}
+		for (var i = 0, answer = ''; i < possibleAnswers.length; i++) {
+			if (possibleAnswers[i].correct) {
+				answer = possibleAnswers[i].text;
+				correctAnswers.push(questionData.questionType !== 'abcd' ?
+					answer : answer.slice(3, answer.length));
 			}
 		}
 
-		return flashcards;
+		return correctAnswers.join(', ');
 	},
 
 	saveFileOnFileSystem: function (data, filename) {