Support <em> markup in message dialogues.

This currently maps to coloring the text red. When ImGui's ticket
ocornut/imgui#902 is resolved, one can look
into supporting additional markup. For now, this should be sufficient.

src/gui.cpp

@@ -12,12 +12,41 @@
 #include <memory>
 #include <fstream>
 #include <filesystem>
+#include <regex>
 
 // Message box height in lines
 #define MSGBOX_LINES 6
 
 using namespace std;
 
+/**
+ * Parses markup out of `str` and returns it as a populated ImTextCustomization
+ * object. `str` is cleaned of all markup syntax so that it is ready to be
+ * passed to ImGui's functions. `tc` is working on the exact pointer stored
+ * in `str`, thus do not modify `str` anymore before passing it to ImGui
+ * along with `tc`.
+ */
+static void parseMarkup(std::string& str, ImTextCustomization& tc)
+{
+    static const ImColor emcolor(255, 0, 0, 255);
+
+    regex re("<em>(.*?)</em>");
+    smatch mresult;
+    vector<pair<size_t, size_t>> ranges; // each pair holds start and length of match
+    while (regex_search(str, mresult, re)) {
+        ranges.push_back(make_pair(mresult.position(0), mresult.length(1)));
+        str.replace(mresult.position(0), mresult.length(0), str.substr(mresult.position(1), mresult.length(1)));
+    }
+
+    // The above modifications may move the string in memory, hence it is not
+    // possible to build up `tc' in the above loop, because ImTextCustomization
+    // works with pointers rather than ranges for whatever reason.
+    for(const pair<size_t, size_t>& range: ranges) {
+        tc.Range(str.data() + range.first, str.data() + range.first + range.second);
+        tc.TextColor(emcolor);
+    }
+}
+
 namespace {
     class MessageDialog
     {
@@ -50,6 +79,16 @@ namespace {
                     m_displayed_text_range++;
                 }));
             }
+
+            // Clean the texts from the markup syntax and store the respective
+            // marking instructions along with them instead.
+            for(string& text: m_texts) {
+                ImTextCustomization tc;
+                parseMarkup(text, tc);
+                m_customs.push_back(move(tc));
+            }
+
+            assert(m_texts.size() == m_customs.size());
         }
 
         void setCallback(std::function<void()> cb) {
@@ -60,6 +99,14 @@ namespace {
             assert(m_current_text < m_texts.size());
             if (mp_timer) {
                 mp_timer->update();
+                if (m_displayed_text_range > m_texts[m_current_text].size()) {
+                    mp_timer->stop();
+                }
+            }
+
+            // Ensure that the pointer arithmetic further below remains in the string's boundaries
+            if (m_displayed_text_range > m_texts[m_current_text].size()) {
+                m_displayed_text_range = m_texts[m_current_text].size();
             }
 
             SDL_Rect boxarea;
@@ -81,7 +128,7 @@ namespace {
             ImGui::SetNextWindowPos(ImVec2(boxarea.x, boxarea.y));
             ImGui::SetNextWindowSize(ImVec2(boxarea.w, boxarea.h));
             ImGui::Begin("TextDialog", nullptr, ImGuiWindowFlags_NoDecoration);
-            ImGui::TextWrapped(m_texts[m_current_text].substr(0, m_displayed_text_range).c_str());
+            ImGui::TextUnformatted(m_texts[m_current_text].data(), m_texts[m_current_text].data() + m_displayed_text_range, true, false, &m_customs[m_current_text]);
             ImGui::End();
 
             // Place the name hint on the upper right
@@ -150,7 +197,9 @@ namespace {
             }
 
             // Set timer for the appearing letters again for the new text
-            if (m_textvel != 0.0f) {
+            if (m_textvel == 0.0f) {
+                m_displayed_text_range = string::npos; // This is reduced in update() to the previous' text's length, so reset it here
+            } else {
                 m_displayed_text_range = 0;
                 mp_timer = std::unique_ptr<Timer>(new Timer(m_textvel, true, [&]{
                     m_displayed_text_range++;
@@ -164,6 +213,7 @@ namespace {
         unsigned int m_playerno;
         float m_textvel;
         std::vector<std::string> m_texts;
+        std::vector<ImTextCustomization> m_customs;
         size_t m_current_text;
         size_t m_displayed_text_range;
         std::function<void()> m_cb;

src/scenes/debug_map_scene.cpp

@@ -22,7 +22,7 @@ DebugMapScene::DebugMapScene(const std::string& map)
     if (mp_map->backgroundMusic().empty()) {
         Ilmendur::instance().audioSystem().stopBackgroundMusic();
     } else {
-        Ilmendur::instance().audioSystem().playBackgroundMusic(mp_map->backgroundMusic());
+        //Ilmendur::instance().audioSystem().playBackgroundMusic(mp_map->backgroundMusic());
     }
 }
 
@@ -104,7 +104,7 @@ void DebugMapScene::handleKeyUp(const SDL_Event& event)
         // DEBUG: E.g. in NPC::activate()
         if (!test) {
             GUISystem::messageDialog(1, GUISystem::text_velocity::normal, "John Doe",
-                                     {"Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.",
+                                     {"Lorem ipsum dolor sit amet, consetetur sadipscing elitr, <em>sed diam nonumy</em> eirmod tempor <em>invidunt</em> ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.",
                                       "Second Message: Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna.",
                                       format("Third Message: >%s<", "Test format")},
                                      [&] {test = false;});