Make ImGuiInputTextState not depend on the implicit GImGui context. (#5856)

This commit is a preparation toward adding ImGui apis with explicit context
and making ImGui applications being able to use multiple context at the same time
whatever their concurrency model.
--
Prior to this commit ImGuiInputTextState::OnKeyPressed was depending on the
global context to know which font and font size to use, and if it should
follow MacOSX behaviors or not (c.f ConfigMacOSXBehaviors).

Instead of using the global context, this commit store the context as
attribute of ImGuiInputTextState. Since this state is forwarded to most
of text edit related function, it possible to access font, font size and
ConfigMacOSXBehaviors from everywhere.

NOTE: I have noticed a bug prior to that commit: if the font or font size
change while editing the same widget, the ImGuiInputTextState become invalid
and there is no code to handle this invalidation. Fixing this bug is out
of scope of current pull request.

# Conflicts:
#	imgui_internal.h

imgui_internal.h

@@ -1051,6 +1051,7 @@ struct IMGUI_API ImGuiMenuColumns
 // For a given item ID, access with ImGui::GetInputTextState()
 struct IMGUI_API ImGuiInputTextState
 {
+    ImGuiContext*           Ctx;                    // parent dear imgui context
     ImGuiID                 ID;                     // widget id owning the text state
     int                     CurLenW, CurLenA;       // we need to maintain our buffer length in both UTF-8 and wchar format. UTF-8 length is valid even if TextA is not.
     ImVector<ImWchar>       TextW;                  // edit buffer, we need to persist but can't guarantee the persistence of the user-provided buffer. so we copy into own buffer.
@@ -1066,7 +1067,7 @@ struct IMGUI_API ImGuiInputTextState
     bool                    Edited;                 // edited this frame
     ImGuiInputTextFlags     Flags;                  // copy of InputText() flags. may be used to check if e.g. ImGuiInputTextFlags_Password is set.
 
-    ImGuiInputTextState()                   { memset(this, 0, sizeof(*this)); }
+    ImGuiInputTextState(ImGuiContext* ctx)  { memset(this, 0, sizeof(*this)); Ctx = ctx;}
     void        ClearText()                 { CurLenW = CurLenA = 0; TextW[0] = 0; TextA[0] = 0; CursorClamp(); }
     void        ClearFreeMemory()           { TextW.clear(); TextA.clear(); InitialTextA.clear(); }
     int         GetUndoAvailCount() const   { return Stb.undostate.undo_point; }
@@ -2014,6 +2015,7 @@ struct ImGuiContext
     ImVector<char>          TempBuffer;                         // Temporary text buffer
 
     ImGuiContext(ImFontAtlas* shared_font_atlas)
+        : InputTextState(this)
     {
         Initialized = false;
         FontAtlasOwnedByContext = shared_font_atlas ? false : true;

imgui_widgets.cpp

@@ -126,7 +126,7 @@ static const ImU64          IM_U64_MAX = (2ULL * 9223372036854775807LL + 1);
 // For InputTextEx()
 static bool             InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* user_data, ImGuiInputSource input_source);
 static int              InputTextCalcTextLenAndLineCount(const char* text_begin, const char** out_text_end);
-static ImVec2           InputTextCalcTextSizeW(const ImWchar* text_begin, const ImWchar* text_end, const ImWchar** remaining = NULL, ImVec2* out_offset = NULL, bool stop_on_new_line = false);
+static ImVec2           InputTextCalcTextSizeW(ImGuiContext* ctx, const ImWchar* text_begin, const ImWchar* text_end, const ImWchar** remaining = NULL, ImVec2* out_offset = NULL, bool stop_on_new_line = false);
 
 //-------------------------------------------------------------------------
 // [SECTION] Widgets: Text, etc.
@@ -3563,9 +3563,9 @@ static int InputTextCalcTextLenAndLineCount(const char* text_begin, const char**
     return line_count;
 }
 
-static ImVec2 InputTextCalcTextSizeW(const ImWchar* text_begin, const ImWchar* text_end, const ImWchar** remaining, ImVec2* out_offset, bool stop_on_new_line)
+static ImVec2 InputTextCalcTextSizeW(ImGuiContext* ctx, const ImWchar* text_begin, const ImWchar* text_end, const ImWchar** remaining, ImVec2* out_offset, bool stop_on_new_line)
 {
-    ImGuiContext& g = *GImGui;
+    ImGuiContext& g = *ctx;
     ImFont* font = g.Font;
     const float line_height = g.FontSize;
     const float scale = line_height / font->FontSize;
@@ -3614,14 +3614,14 @@ namespace ImStb
 
 static int     STB_TEXTEDIT_STRINGLEN(const ImGuiInputTextState* obj)                             { return obj->CurLenW; }
 static ImWchar STB_TEXTEDIT_GETCHAR(const ImGuiInputTextState* obj, int idx)                      { return obj->TextW[idx]; }
-static float   STB_TEXTEDIT_GETWIDTH(ImGuiInputTextState* obj, int line_start_idx, int char_idx)  { ImWchar c = obj->TextW[line_start_idx + char_idx]; if (c == '\n') return STB_TEXTEDIT_GETWIDTH_NEWLINE; ImGuiContext& g = *GImGui; return g.Font->GetCharAdvance(c) * (g.FontSize / g.Font->FontSize); }
+static float   STB_TEXTEDIT_GETWIDTH(ImGuiInputTextState* obj, int line_start_idx, int char_idx)  { ImWchar c = obj->TextW[line_start_idx + char_idx]; if (c == '\n') return STB_TEXTEDIT_GETWIDTH_NEWLINE; ImGuiContext& g = *obj->Ctx; return g.Font->GetCharAdvance(c) * (g.FontSize / g.Font->FontSize); }
 static int     STB_TEXTEDIT_KEYTOTEXT(int key)                                                    { return key >= 0x200000 ? 0 : key; }
 static ImWchar STB_TEXTEDIT_NEWLINE = '\n';
 static void    STB_TEXTEDIT_LAYOUTROW(StbTexteditRow* r, ImGuiInputTextState* obj, int line_start_idx)
 {
     const ImWchar* text = obj->TextW.Data;
     const ImWchar* text_remaining = NULL;
-    const ImVec2 size = InputTextCalcTextSizeW(text + line_start_idx, text + obj->CurLenW, &text_remaining, NULL, true);
+    const ImVec2 size = InputTextCalcTextSizeW(obj->Ctx, text + line_start_idx, text + obj->CurLenW, &text_remaining, NULL, true);
     r->x0 = 0.0f;
     r->x1 = size.x;
     r->baseline_y_delta = size.y;
@@ -3637,7 +3637,7 @@ static int  is_word_boundary_from_left(ImGuiInputTextState* obj, int idx)
 static int  STB_TEXTEDIT_MOVEWORDLEFT_IMPL(ImGuiInputTextState* obj, int idx)   { idx--; while (idx >= 0 && !is_word_boundary_from_right(obj, idx)) idx--; return idx < 0 ? 0 : idx; }
 static int  STB_TEXTEDIT_MOVEWORDRIGHT_MAC(ImGuiInputTextState* obj, int idx)   { idx++; int len = obj->CurLenW; while (idx < len && !is_word_boundary_from_left(obj, idx)) idx++; return idx > len ? len : idx; }
 static int  STB_TEXTEDIT_MOVEWORDRIGHT_WIN(ImGuiInputTextState* obj, int idx)   { idx++; int len = obj->CurLenW; while (idx < len && !is_word_boundary_from_right(obj, idx)) idx++; return idx > len ? len : idx; }
-static int  STB_TEXTEDIT_MOVEWORDRIGHT_IMPL(ImGuiInputTextState* obj, int idx)  { if (ImGui::GetIO().ConfigMacOSXBehaviors) return STB_TEXTEDIT_MOVEWORDRIGHT_MAC(obj, idx); else return STB_TEXTEDIT_MOVEWORDRIGHT_WIN(obj, idx); }
+static int  STB_TEXTEDIT_MOVEWORDRIGHT_IMPL(ImGuiInputTextState* obj, int idx)  { ImGuiContext& g = *obj->Ctx; if (g.IO.ConfigMacOSXBehaviors) return STB_TEXTEDIT_MOVEWORDRIGHT_MAC(obj, idx); else return STB_TEXTEDIT_MOVEWORDRIGHT_WIN(obj, idx); }
 #define STB_TEXTEDIT_MOVEWORDLEFT   STB_TEXTEDIT_MOVEWORDLEFT_IMPL  // They need to be #define for stb_textedit.h
 #define STB_TEXTEDIT_MOVEWORDRIGHT  STB_TEXTEDIT_MOVEWORDRIGHT_IMPL
 
@@ -4675,11 +4675,11 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
                 searches_result_line_no[1] = line_count;
 
             // Calculate 2d position by finding the beginning of the line and measuring distance
-            cursor_offset.x = InputTextCalcTextSizeW(ImStrbolW(searches_input_ptr[0], text_begin), searches_input_ptr[0]).x;
+            cursor_offset.x = InputTextCalcTextSizeW(&g, ImStrbolW(searches_input_ptr[0], text_begin), searches_input_ptr[0]).x;
             cursor_offset.y = searches_result_line_no[0] * g.FontSize;
             if (searches_result_line_no[1] >= 0)
             {
-                select_start_offset.x = InputTextCalcTextSizeW(ImStrbolW(searches_input_ptr[1], text_begin), searches_input_ptr[1]).x;
+                select_start_offset.x = InputTextCalcTextSizeW(&g, ImStrbolW(searches_input_ptr[1], text_begin), searches_input_ptr[1]).x;
                 select_start_offset.y = searches_result_line_no[1] * g.FontSize;
             }
 
@@ -4748,7 +4748,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
                 }
                 else
                 {
-                    ImVec2 rect_size = InputTextCalcTextSizeW(p, text_selected_end, &p, NULL, true);
+                    ImVec2 rect_size = InputTextCalcTextSizeW(&g, p, text_selected_end, &p, NULL, true);
                     if (rect_size.x <= 0.0f) rect_size.x = IM_FLOOR(g.Font->GetCharAdvance((ImWchar)' ') * 0.50f); // So we can see selected empty lines
                     ImRect rect(rect_pos + ImVec2(0.0f, bg_offy_up - g.FontSize), rect_pos + ImVec2(rect_size.x, bg_offy_dn));
                     rect.ClipWith(clip_rect);