issue #8657 Plantuml ditaa diagram is not visible in refman.pdf

- Using `find` instead of explicit loop
- documentation (instead of #8662)

Author: albert-github

doc/commands.doc

@@ -2966,13 +2966,15 @@ class Receiver
   \note You need to install Java and the PlantUML's jar file,
   if you want to use this command. When using PlantUML in \LaTeX you have to download
   some more `jar` files, for details see the PlantUML documentation.
-  The location of the jar file should be specified using
-  \ref cfg_plantuml_jar_path "PLANTUML_JAR_PATH".
+  This also is valid for the `<engine>`s `latex` and `math`.
+  The location of the PlantUML file should be specified using
+  \ref cfg_plantuml_jar_path "PLANTUML_JAR_PATH". The other jar files should also reside
+  in this directory.
 
   Not all diagrams can be created with the PlantUML `@startuml` command but need another
   PlantUML `@start...` command. This will look like `@start<engine>` where currently supported are
-  the following `<engine>`'s: `uml`, `bpm`, `wire`, `dot`, `ditaa`, `salt`, `math`, `latex`,
-  `gantt`, `mindmap`, `wbs`, `yaml`, `creole`, `json`, `flow`a, `board` and `git`.s
+  the following `<engine>`s: `uml`, `bpm`, `wire`, `dot`, `ditaa`, `salt`, `math`, `latex`,
+  `gantt`, `mindmap`, `wbs`, `yaml`, `creole`, `json`, `flow`, `board` and `git`.
   By default the `<engine>` is `uml`. The `<engine>` can be specified as an option.
   Also the file to write the resulting image to can be specified by means of an option, see the
   description of the first (optional) argument for details.

src/docparser.cpp

@@ -5575,20 +5575,13 @@ int DocPara::handleCommand(const QCString &cmdName, const int tok)
         }
         else if (engine == "uml")
         {
-           // check on ditaa in first line
-           if (!trimmedVerb.isEmpty())
-           {
-             const char *p = trimmedVerb.data();
-             int i=0;
-             while (*p)
-             {
-               if (*p=='\n') break;
-               i++;
-               p++;
-             }
-             QCString firstLine = trimmedVerb.left(i);
-             if (firstLine.stripWhiteSpace() == "ditaa") dv->setUseBitmap(true);
-           }
+          int i = trimmedVerb.find('\n');
+          QCString firstLine;
+          if (i == -1)
+            firstLine = trimmedVerb;
+          else
+            firstLine = trimmedVerb.left(i);
+          if (firstLine.stripWhiteSpace() == "ditaa") dv->setUseBitmap(true);
         }
         dv->setText(trimmedVerb);
         dv->setWidth(width);