Tooltip: SetTooltip() is expanded immediately into a window, honoring current font / styling setting. Add internal mechanism to override tooltips (not exposed in BeginTooltip yet because bools are evil) (#862)

imgui.cpp

@@ -2157,7 +2157,7 @@ void ImGui::NewFrame()
 
     g.Time += g.IO.DeltaTime;
     g.FrameCount += 1;
-    g.Tooltip[0] = '\0';
+    g.TooltipOverrideCount = 0;
     g.OverlayDrawList.Clear();
     g.OverlayDrawList.PushTextureID(g.IO.Fonts->TexID);
     g.OverlayDrawList.PushClipRectFullScreen();
@@ -2657,14 +2657,6 @@ void ImGui::EndFrame()
     IM_ASSERT(g.Initialized);                       // Forgot to call ImGui::NewFrame()
     IM_ASSERT(g.FrameCountEnded != g.FrameCount);   // ImGui::EndFrame() called multiple times, or forgot to call ImGui::NewFrame() again
 
-    // Render tooltip
-    if (g.Tooltip[0])
-    {
-        ImGui::BeginTooltip();
-        ImGui::TextUnformatted(g.Tooltip);
-        ImGui::EndTooltip();
-    }
-
     // Notify OS when our Input Method Editor cursor has moved (e.g. CJK inputs using Microsoft IME)
     if (g.IO.ImeSetInputScreenPosFn && ImLengthSqr(g.OsImePosRequest - g.OsImePosSet) > 0.0001f)
     {
@@ -3388,11 +3380,28 @@ static ImRect GetVisibleRect()
     return ImRect(0.0f, 0.0f, g.IO.DisplaySize.x, g.IO.DisplaySize.y);
 }
 
-// Tooltip is stored and turned into a BeginTooltip()/EndTooltip() sequence at the end of the frame. Each call override previous value.
-void ImGui::SetTooltipV(const char* fmt, va_list args)
+// Not exposed publicly as BeginTooltip() because bool parameters are evil. Let's see if other needs arise first.
+static void BeginTooltipEx(bool override_previous_tooltip)
 {
     ImGuiContext& g = *GImGui;
-    ImFormatStringV(g.Tooltip, IM_ARRAYSIZE(g.Tooltip), fmt, args);
+    char window_name[16];
+    ImFormatString(window_name, IM_ARRAYSIZE(window_name), "##Tooltip%02d", g.TooltipOverrideCount);
+    if (override_previous_tooltip)
+        if (ImGuiWindow* window = ImGui::FindWindowByName(window_name))
+            if (window->Active)
+            {
+                // Hide previous tooltips. We can't easily "reset" the content of a window so we create a new one.
+                window->HiddenFrames = 1;
+                ImFormatString(window_name, IM_ARRAYSIZE(window_name), "##Tooltip%02d", ++g.TooltipOverrideCount);
+            }
+    ImGui::Begin(window_name, NULL, ImGuiWindowFlags_Tooltip|ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoMove|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings|ImGuiWindowFlags_AlwaysAutoResize);
+}
+
+void ImGui::SetTooltipV(const char* fmt, va_list args)
+{
+    BeginTooltipEx(true);
+    TextV(fmt, args);
+    EndTooltip();
 }
 
 void ImGui::SetTooltip(const char* fmt, ...)
@@ -3405,8 +3414,7 @@ void ImGui::SetTooltip(const char* fmt, ...)
 
 void ImGui::BeginTooltip()
 {
-    ImGuiWindowFlags flags = ImGuiWindowFlags_Tooltip|ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoMove|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings|ImGuiWindowFlags_AlwaysAutoResize;
-    ImGui::Begin("##Tooltip", NULL, flags);
+    BeginTooltipEx(false);
 }
 
 void ImGui::EndTooltip()

imgui.h

@@ -361,9 +361,9 @@ namespace ImGui
     IMGUI_API void          ValueColor(const char* prefix, ImU32 v);
 
     // Tooltips
-    IMGUI_API void          SetTooltip(const char* fmt, ...) IM_PRINTFARGS(1);                  // set tooltip under mouse-cursor, typically use with ImGui::IsHovered(). last call wins
+    IMGUI_API void          SetTooltip(const char* fmt, ...) IM_PRINTFARGS(1);                  // set text tooltip under mouse-cursor, typically use with ImGui::IsItemHovered(). overidde any previous call to SetTooltip().
     IMGUI_API void          SetTooltipV(const char* fmt, va_list args);
-    IMGUI_API void          BeginTooltip();                                                     // use to create full-featured tooltip windows that aren't just text
+    IMGUI_API void          BeginTooltip();                                                     // begin/append a tooltip window. to create full-featured tooltip (with any kind of contents).
     IMGUI_API void          EndTooltip();
 
     // Menus

imgui_internal.h

@@ -437,7 +437,7 @@ struct ImGuiContext
     float                   DragSpeedScaleSlow;
     float                   DragSpeedScaleFast;
     ImVec2                  ScrollbarClickDeltaToGrabCenter;    // Distance between mouse and center of grab box, normalized in parent space. Use storage?
-    char                    Tooltip[1024];
+    int                     TooltipOverrideCount;
     char*                   PrivateClipboard;                   // If no custom clipboard handler is defined
     ImVec2                  OsImePosRequest, OsImePosSet;       // Cursor position request & last passed to the OS Input Method Editor
 
@@ -506,7 +506,7 @@ struct ImGuiContext
         DragSpeedScaleSlow = 0.01f;
         DragSpeedScaleFast = 10.0f;
         ScrollbarClickDeltaToGrabCenter = ImVec2(0.0f, 0.0f);
-        memset(Tooltip, 0, sizeof(Tooltip));
+        TooltipOverrideCount = 0;
         PrivateClipboard = NULL;
         OsImePosRequest = OsImePosSet = ImVec2(-1.0f, -1.0f);