From 13258f59575eae643affea976abe818417047777 Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Thu, 12 Nov 2020 12:01:49 +0100
Subject: [PATCH] Internals: zero-clearing ImGuiWindow / ImGuiWindowTempData
 for simplicity. (amend)

All the non-zero fields previously initialized in ImGuiWindowTempData() are in fact setup in Begin: FocusCounterRegular, FocusCounterTabStop, TextWrapPos, LayoutType, ParentLayoutType
---
 imgui.cpp        | 51 ++++--------------------------------------------
 imgui_internal.h | 37 ++---------------------------------
 2 files changed, 6 insertions(+), 82 deletions(-)

diff --git a/imgui.cpp b/imgui.cpp
index 4c372551a197..ca7afd365717 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -2774,70 +2774,27 @@ void ImGui::RenderNavHighlight(const ImRect& bb, ImGuiID id, ImGuiNavHighlightFl
 //-----------------------------------------------------------------------------
 
 // ImGuiWindow is mostly a dumb struct. It merely has a constructor and a few helper methods
-ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
-    : DrawListInst(&context->DrawListSharedData)
+ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name) : DrawListInst(NULL)
 {
+    memset(this, 0, sizeof(*this));
     Name = ImStrdup(name);
+    NameBufLen = (int)strlen(name) + 1;
     ID = ImHashStr(name);
     IDStack.push_back(ID);
-    Flags = ImGuiWindowFlags_None;
-    Pos = ImVec2(0.0f, 0.0f);
-    Size = SizeFull = ImVec2(0.0f, 0.0f);
-    ContentSize = ContentSizeExplicit = ImVec2(0.0f, 0.0f);
-    WindowPadding = ImVec2(0.0f, 0.0f);
-    WindowRounding = 0.0f;
-    WindowBorderSize = 0.0f;
-    NameBufLen = (int)strlen(name) + 1;
     MoveId = GetID("#MOVE");
-    ChildId = 0;
-    Scroll = ImVec2(0.0f, 0.0f);
     ScrollTarget = ImVec2(FLT_MAX, FLT_MAX);
     ScrollTargetCenterRatio = ImVec2(0.5f, 0.5f);
-    ScrollbarSizes = ImVec2(0.0f, 0.0f);
-    ScrollbarX = ScrollbarY = false;
-    Active = WasActive = false;
-    WriteAccessed = false;
-    Collapsed = false;
-    WantCollapseToggle = false;
-    SkipItems = false;
-    Appearing = false;
-    Hidden = false;
-    IsFallbackWindow = false;
-    HasCloseButton = false;
-    ResizeBorderHeld = -1;
-    BeginCount = 0;
-    BeginOrderWithinParent = -1;
-    BeginOrderWithinContext = -1;
-    PopupId = 0;
     AutoFitFramesX = AutoFitFramesY = -1;
-    AutoFitChildAxises = 0x00;
-    AutoFitOnlyGrows = false;
     AutoPosLastDirection = ImGuiDir_None;
-    HiddenFramesCanSkipItems = HiddenFramesCannotSkipItems = 0;
     SetWindowPosAllowFlags = SetWindowSizeAllowFlags = SetWindowCollapsedAllowFlags = ImGuiCond_Always | ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing;
     SetWindowPosVal = SetWindowPosPivot = ImVec2(FLT_MAX, FLT_MAX);
-
-    InnerRect = ImRect(0.0f, 0.0f, 0.0f, 0.0f); // Clear so the InnerRect.GetSize() code in Begin() doesn't lead to overflow even if the result isn't used.
-
     LastFrameActive = -1;
     LastTimeActive = -1.0f;
-    ItemWidthDefault = 0.0f;
     FontWindowScale = 1.0f;
     SettingsOffset = -1;
-
     DrawList = &DrawListInst;
+    DrawList->_Data = &context->DrawListSharedData;
     DrawList->_OwnerName = Name;
-    ParentWindow = NULL;
-    RootWindow = NULL;
-    RootWindowForTitleBarHighlight = NULL;
-    RootWindowForNav = NULL;
-
-    NavLastIds[0] = NavLastIds[1] = 0;
-    NavRectRel[0] = NavRectRel[1] = ImRect();
-    NavLastChildNavWindow = NULL;
-
-    MemoryCompacted = false;
-    MemoryDrawListIdxCapacity = MemoryDrawListVtxCapacity = 0;
 }
 
 ImGuiWindow::~ImGuiWindow()
diff --git a/imgui_internal.h b/imgui_internal.h
index 6b701a0bbdf9..8e19894e0c1c 100644
--- a/imgui_internal.h
+++ b/imgui_internal.h
@@ -1503,7 +1503,8 @@ struct ImGuiContext
 //-----------------------------------------------------------------------------
 
 // Transient per-window data, reset at the beginning of the frame. This used to be called ImGuiDrawContext, hence the DC variable name in ImGuiWindow.
-// FIXME: That's theory, in practice the delimitation between ImGuiWindow and ImGuiWindowTempData is quite tenuous and could be reconsidered.
+// (That's theory, in practice the delimitation between ImGuiWindow and ImGuiWindowTempData is quite tenuous and could be reconsidered..)
+// (This doesn't need a constructor because we zero-clear it as part of ImGuiWindow and all frame-temporary data are setup on Begin)
 struct IMGUI_API ImGuiWindowTempData
 {
     // Layout
@@ -1557,40 +1558,6 @@ struct IMGUI_API ImGuiWindowTempData
     ImVector<float>         TextWrapPosStack;
     ImVector<ImGuiGroupData>GroupStack;
     short                   StackSizesBackup[6];    // Store size of various stacks for asserting
-
-    ImGuiWindowTempData()
-    {
-        CursorPos = CursorPosPrevLine = CursorStartPos = CursorMaxPos = ImVec2(0.0f, 0.0f);
-        CurrLineSize = PrevLineSize = ImVec2(0.0f, 0.0f);
-        CurrLineTextBaseOffset = PrevLineTextBaseOffset = 0.0f;
-        Indent = ImVec1(0.0f);
-        ColumnsOffset = ImVec1(0.0f);
-        GroupOffset = ImVec1(0.0f);
-
-        LastItemId = 0;
-        LastItemStatusFlags = ImGuiItemStatusFlags_None;
-        LastItemRect = LastItemDisplayRect = ImRect();
-
-        NavLayerActiveMask = NavLayerActiveMaskNext = 0x00;
-        NavLayerCurrent = ImGuiNavLayer_Main;
-        NavFocusScopeIdCurrent = 0;
-        NavHideHighlightOneFrame = false;
-        NavHasScroll = false;
-
-        MenuBarAppending = false;
-        MenuBarOffset = ImVec2(0.0f, 0.0f);
-        TreeDepth = 0;
-        TreeJumpToParentOnPopMask = 0x00;
-        StateStorage = NULL;
-        CurrentColumns = NULL;
-        LayoutType = ParentLayoutType = ImGuiLayoutType_Vertical;
-        FocusCounterRegular = FocusCounterTabStop = -1;
-
-        ItemFlags = ImGuiItemFlags_Default_;
-        ItemWidth = 0.0f;
-        TextWrapPos = -1.0f;
-        memset(StackSizesBackup, 0, sizeof(StackSizesBackup));
-    }
 };
 
 // Storage for one window