From ded52c71d983114a4efa9fef8ef31393998689e1 Mon Sep 17 00:00:00 2001
From: ocornut <omar@miracleworld.net>
Date: Fri, 5 Dec 2025 15:07:44 +0100
Subject: [PATCH] Debug Log: can output to debugger. Added
 ImGuiDebugLogFlags_OutputToDebugger.

---
 docs/CHANGELOG.txt |  1 +
 imgui.cpp          | 14 ++++++++++++--
 imgui_internal.h   |  3 ++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index ecd57ffbb..595072275 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -72,6 +72,7 @@ Other Changes:
 - Debug Tools:
   - Debug Log: fixed incorrectly printing characters in IO log when submitting
     non-ASCII values to io.AddInputCharacter(). (#9099)
+  - Debug Log: can output to debugger on Windows. (#5855)
 - Backends:
   - SDL_GPU3: macOS version can use MSL shaders in order to support macOS 10.14+
     (vs Metallib shaders requiring macOS 14+). Requires application calling
diff --git a/imgui.cpp b/imgui.cpp
index 3fe059b6e..3c87bd87c 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -17560,14 +17560,23 @@ void ImGui::DebugLogV(const char* fmt, va_list args)
         g.DebugLogBuf.appendf("[%05d] ", g.FrameCount);
     g.DebugLogBuf.appendfv(fmt, args);
     g.DebugLogIndex.append(g.DebugLogBuf.c_str(), old_size, g.DebugLogBuf.size());
+
+    const char* str = g.DebugLogBuf.begin() + old_size;
     if (g.DebugLogFlags & ImGuiDebugLogFlags_OutputToTTY)
-        IMGUI_DEBUG_PRINTF("%s", g.DebugLogBuf.begin() + old_size);
+        IMGUI_DEBUG_PRINTF("%s", str);
+#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS)
+    if (g.DebugLogFlags & ImGuiDebugLogFlags_OutputToDebugger)
+    {
+        ::OutputDebugStringA("[imgui] ");
+        ::OutputDebugStringA(str);
+    }
+#endif
 #ifdef IMGUI_ENABLE_TEST_ENGINE
     // IMGUI_TEST_ENGINE_LOG() adds a trailing \n automatically
     const int new_size = g.DebugLogBuf.size();
     const bool trailing_carriage_return = (g.DebugLogBuf[new_size - 1] == '\n');
     if (g.DebugLogFlags & ImGuiDebugLogFlags_OutputToTestEngine)
-        IMGUI_TEST_ENGINE_LOG("%.*s", new_size - old_size - (trailing_carriage_return ? 1 : 0), g.DebugLogBuf.begin() + old_size);
+        IMGUI_TEST_ENGINE_LOG("%.*s", new_size - old_size - (trailing_carriage_return ? 1 : 0), str);
 #endif
 }
 
@@ -17647,6 +17656,7 @@ void ImGui::ShowDebugLogWindow(bool* p_open)
     if (BeginPopup("Outputs"))
     {
         CheckboxFlags("OutputToTTY", &g.DebugLogFlags, ImGuiDebugLogFlags_OutputToTTY);
+        CheckboxFlags("OutputToDebugger", &g.DebugLogFlags, ImGuiDebugLogFlags_OutputToDebugger);
 #ifndef IMGUI_ENABLE_TEST_ENGINE
         BeginDisabled();
 #endif
diff --git a/imgui_internal.h b/imgui_internal.h
index c1fcfbaf4..23680045d 100644
--- a/imgui_internal.h
+++ b/imgui_internal.h
@@ -2078,7 +2078,8 @@ enum ImGuiDebugLogFlags_
 
     ImGuiDebugLogFlags_EventMask_           = ImGuiDebugLogFlags_EventError | ImGuiDebugLogFlags_EventActiveId | ImGuiDebugLogFlags_EventFocus | ImGuiDebugLogFlags_EventPopup | ImGuiDebugLogFlags_EventNav | ImGuiDebugLogFlags_EventClipper | ImGuiDebugLogFlags_EventSelection | ImGuiDebugLogFlags_EventIO | ImGuiDebugLogFlags_EventFont | ImGuiDebugLogFlags_EventInputRouting | ImGuiDebugLogFlags_EventDocking | ImGuiDebugLogFlags_EventViewport,
     ImGuiDebugLogFlags_OutputToTTY          = 1 << 20,  // Also send output to TTY
-    ImGuiDebugLogFlags_OutputToTestEngine   = 1 << 21,  // Also send output to Test Engine
+    ImGuiDebugLogFlags_OutputToDebugger     = 1 << 21,  // Also send output to Debugger Console [Windows only]
+    ImGuiDebugLogFlags_OutputToTestEngine   = 1 << 22,  // Also send output to Dear ImGui Test Engine
 };
 
 struct ImGuiDebugAllocEntry