Support new span emoji html rendering.

Fixes: #495

Author: Sam1301

app/src/main/java/com/zulip/android/models/Message.java

@@ -340,13 +340,7 @@ public static Spanned formatContent(String source, final ZulipApp app) {
         Html.ImageGetter emojiGetter = new Html.ImageGetter() {
             @Override
             public Drawable getDrawable(String source) {
-                int imagesIndex = -1;
-                if (source != null) {
-                    imagesIndex = source.indexOf("images/");
-                }
-                if (imagesIndex != -1) {
-                    String filename = source.substring(imagesIndex + "images/".length());
-
+                    String filename = "emoji/" + source.replace(":", "") + ".png";
                     try {
                         Drawable drawable = Drawable.createFromStream(context
                                 .getAssets().open(filename), filename);
@@ -367,7 +361,6 @@ public Drawable getDrawable(String source) {
                     } catch (IOException e) {
                         Log.e("RecyclerMessageAdapter", e.getMessage());
                     }
-                }
                 return null;
             }
         };

app/src/main/java/com/zulip/android/util/CustomHtmlToSpannedConverter.java

@@ -87,6 +87,7 @@ public class CustomHtmlToSpannedConverter implements ContentHandler {
     private String mBaseUri;
     private boolean isCode;
     private boolean isStreamLink;
+    private static boolean isEmoji;
 
     public CustomHtmlToSpannedConverter(String source,
                                         Html.ImageGetter imageGetter, Html.TagHandler tagHandler,
@@ -174,7 +175,8 @@ private static void end(SpannableStringBuilder text, Class kind, Object repl) {
 
     private static void startImg(SpannableStringBuilder text,
                                  Attributes attributes, Html.ImageGetter img) {
-        String src = attributes.getValue("", "src");
+        String cssClass = attributes.getValue("class");
+        String src = cssClass != null && cssClass.startsWith("emoji") ? attributes.getValue("title") : attributes.getValue("", "src");
         Drawable d = null;
 
         if (img != null) {
@@ -268,6 +270,10 @@ private static void endSpan(SpannableStringBuilder text) {
         int where = text.getSpanStart(obj);
         text.removeSpan(obj);
         if (where != len) {
+            if (isEmoji) {
+                text.delete(where, len);
+                return;
+            }
             Href h = (Href) obj;
             if (h != null && h.mHref != null) {
                 if (ZulipApp.get().getEmail().equals(h.mHref)) {
@@ -556,7 +562,13 @@ private void handleStartTag(String tag, Attributes attributes) {
         } else if (tag.equalsIgnoreCase("span")
                 && "user-mention".equals(attributes.getValue("class"))) {
             startSpan(mSpannableStringBuilder, attributes);
-        } else if (tag.equalsIgnoreCase("u")) {
+        } else if (tag.equalsIgnoreCase("span")
+                && attributes.getValue("class") != null && attributes.getValue("class").startsWith("emoji")) {
+            isEmoji = true;
+            startImg(mSpannableStringBuilder, attributes, mEmojiGetter);
+            startSpan(mSpannableStringBuilder, attributes);
+        }
+        else if (tag.equalsIgnoreCase("u")) {
             start(mSpannableStringBuilder, new Underline());
         } else if (tag.equalsIgnoreCase("sup")) {
             start(mSpannableStringBuilder, new Super());
@@ -580,6 +592,7 @@ private void handleStartTag(String tag, Attributes attributes) {
             handleP(mSpannableStringBuilder);
             start(mSpannableStringBuilder, new Header(tag.charAt(1) - '1'));
         } else if (tag.equalsIgnoreCase("img")) {
+            // makes emojis backward compatible
             String cssClass = attributes.getValue("", "class");
             if (cssClass != null && cssClass.equals("emoji")) {
                 startImg(mSpannableStringBuilder, attributes, mEmojiGetter);
@@ -639,6 +652,7 @@ private void handleEndTag(String tag) {
             }
         } else if (tag.equalsIgnoreCase("span")) {
             endSpan(mSpannableStringBuilder);
+            isEmoji = false;
         } else if (tag.equalsIgnoreCase("u")) {
             end(mSpannableStringBuilder, Underline.class, new UnderlineSpan());
         } else if (tag.equalsIgnoreCase("sup")) {