Renderer: Use imgui for drawing debug text and OSD

Source/Core/VideoCommon/OnScreenDisplay.cpp

@@ -5,22 +5,79 @@
 #include <algorithm>
 #include <list>
 #include <map>
+#include <mutex>
 #include <string>
 
+#include "imgui.h"
+
 #include "Common/CommonTypes.h"
 #include "Common/Timer.h"
 
 #include "Core/ConfigManager.h"
 
 #include "VideoCommon/OnScreenDisplay.h"
-#include "VideoCommon/RenderBase.h"
 
 namespace OSD
 {
-static std::multimap<CallbackType, Callback> s_callbacks;
+constexpr float LEFT_MARGIN = 10.0f;    // Pixels to the left of OSD messages.
+constexpr float TOP_MARGIN = 10.0f;     // Pixels above the first OSD message.
+constexpr float WINDOW_PADDING = 4.0f;  // Pixels between subsequent OSD messages.
+
+struct Message
+{
+  Message() {}
+  Message(const std::string& text_, u32 timestamp_, u32 color_)
+      : text(text_), timestamp(timestamp_), color(color_)
+  {
+  }
+  std::string text;
+  u32 timestamp;
+  u32 color;
+};
 static std::multimap<MessageType, Message> s_messages;
 static std::mutex s_messages_mutex;
 
+static ImVec4 RGBAToImVec4(const u32 rgba)
+{
+  return ImVec4(static_cast<float>((rgba >> 16) & 0xFF) / 255.0f,
+                static_cast<float>((rgba >> 8) & 0xFF) / 255.0f,
+                static_cast<float>((rgba >> 0) & 0xFF) / 255.0f,
+                static_cast<float>((rgba >> 24) & 0xFF) / 255.0f);
+}
+
+static float DrawMessage(int index, const Message& msg, const ImVec2& position, int time_left)
+{
+  // We have to provide a window name, and these shouldn't be duplicated.
+  // So instead, we generate a name based on the number of messages drawn.
+  const std::string window_name = StringFromFormat("osd_%d", index);
+
+  // The size must be reset, otherwise the length of old messages could influence new ones.
+  ImGui::SetNextWindowPos(position);
+  ImGui::SetNextWindowSize(ImVec2(0.0f, 0.0f));
+
+  // Gradually fade old messages away.
+  const float alpha = std::min(1.0f, std::max(0.0f, time_left / 1024.0f));
+  ImGui::PushStyleVar(ImGuiStyleVar_Alpha, alpha);
+
+  float window_height = 0.0f;
+  if (ImGui::Begin(window_name.c_str(), nullptr,
+                   ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoInputs |
+                       ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoSavedSettings |
+                       ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoNav |
+                       ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoFocusOnAppearing))
+  {
+    // Use %s in case message contains %.
+    ImGui::TextColored(RGBAToImVec4(msg.color), "%s", msg.text.c_str());
+    window_height =
+        ImGui::GetWindowSize().y + (WINDOW_PADDING * ImGui::GetIO().DisplayFramebufferScale.y);
+  }
+
+  ImGui::End();
+  ImGui::PopStyleVar();
+
+  return window_height;
+}
+
 void AddTypedMessage(MessageType type, const std::string& message, u32 ms, u32 rgba)
 {
   std::lock_guard<std::mutex> lock(s_messages_mutex);
@@ -35,14 +92,6 @@ void AddMessage(const std::string& message, u32 ms, u32 rgba)
                      Message(message, Common::Timer::GetTimeMs() + ms, rgba));
 }
 
-void DrawMessage(const Message& msg, int top, int left, int time_left)
-{
-  float alpha = std::min(1.0f, std::max(0.0f, time_left / 1024.0f));
-  u32 color = (msg.m_rgba & 0xFFFFFF) | ((u32)((msg.m_rgba >> 24) * alpha) << 24);
-
-  g_renderer->RenderText(msg.m_str, left, top, color);
-}
-
 void DrawMessages()
 {
   if (!SConfig::GetInstance().bOnScreenDisplayMessages)
@@ -51,21 +100,22 @@ void DrawMessages()
   {
     std::lock_guard<std::mutex> lock(s_messages_mutex);
 
-    u32 now = Common::Timer::GetTimeMs();
-    int left = 20, top = 35;
+    const u32 now = Common::Timer::GetTimeMs();
+    float current_x = LEFT_MARGIN * ImGui::GetIO().DisplayFramebufferScale.x;
+    float current_y = TOP_MARGIN * ImGui::GetIO().DisplayFramebufferScale.y;
+    int index = 0;
 
     auto it = s_messages.begin();
     while (it != s_messages.end())
     {
       const Message& msg = it->second;
-      int time_left = (int)(msg.m_timestamp - now);
-      DrawMessage(msg, top, left, time_left);
+      const int time_left = static_cast<int>(msg.timestamp - now);
+      current_y += DrawMessage(index++, msg, ImVec2(current_x, current_y), time_left);
 
       if (time_left <= 0)
         it = s_messages.erase(it);
       else
         ++it;
-      top += 15;
     }
   }
 }
@@ -75,24 +125,4 @@ void ClearMessages()
   std::lock_guard<std::mutex> lock(s_messages_mutex);
   s_messages.clear();
 }
-
-// On-Screen Display Callbacks
-void AddCallback(CallbackType type, Callback cb)
-{
-  s_callbacks.emplace(type, cb);
 }
-
-void DoCallbacks(CallbackType type)
-{
-  auto it_bounds = s_callbacks.equal_range(type);
-  for (auto it = it_bounds.first; it != it_bounds.second; ++it)
-  {
-    it->second();
-  }
-
-  // Wipe all callbacks on shutdown
-  if (type == CallbackType::Shutdown)
-    s_callbacks.clear();
-}
-
-}  // namespace