Support data URI images with filenames

app/src/main/java/eu/faircode/email/ImageHelper.java

@@ -655,7 +655,7 @@ class ImageHelper {
     }
 
     static ByteArrayInputStream getDataUriStream(String source) {
-        // "<img src=\"data:image/png;base64,iVBORw0KGgoAAA" +
+        // "<img src=\"data:image/png;filename=dot.png;base64,iVBORw0KGgoAAA" +
         // "ANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4" +
         // "//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU" +
         // "5ErkJggg==\" alt=\"Red dot\" />";
@@ -667,19 +667,21 @@ class ImageHelper {
         try {
             // data:[<mediatype>][;base64],<data>
             int comma = source.indexOf(',');
-            int colon = source.indexOf(':');
-            int semi = source.indexOf(';');
-
             if (comma < 0)
                 throw new IllegalArgumentException("Comma missing");
 
+            String header = source.substring(0, comma);
+            int colon = header.indexOf(':');
+            int fsemi = header.indexOf(';');
+            int lsemi = header.lastIndexOf(';');
+
             String type = null;
-            if (colon > 0 && semi > colon)
-                type = source.substring(colon + 1, semi).trim();
-            else if (colon > 0 && comma > colon)
+            if (colon > 0 && fsemi > colon)
+                type = source.substring(colon + 1, fsemi).trim();
+            else if (colon > 0)
                 type = source.substring(colon + 1, comma).trim();
 
-            String enc = (semi > 0 && comma > semi ? source.substring(semi + 1, comma).trim() : null);
+            String enc = (lsemi > 0 ? source.substring(lsemi + 1, comma).trim() : null);
 
             if ("image/svg".equalsIgnoreCase(type) &&
                     (TextUtils.isEmpty(enc) /* ASCII */ || "utf8".equalsIgnoreCase(enc))) {