imgui_memory_editor/imgui_memory_editor.h

// Mini memory editor for Dear ImGui (to embed in your game/tools)
// Get latest version at https://www.github.com/ocornut/imgui_club
// Licensed under The MIT License (MIT)

// Right-click anywhere to access the Options menu!
// You can adjust the keyboard repeat delay/rate in ImGuiIO.
// The code assume a mono-space font for simplicity!
// If you don't use the default font, use ImGui::PushFont()/PopFont() to switch to a mono-space font before calling this.
//
// Usage:
//   // Create a window and draw memory editor inside it:
//   static MemoryEditor mem_edit_1;
//   static char data[0x10000];
//   size_t data_size = 0x10000;
//   mem_edit_1.DrawWindow("Memory Editor", data, data_size);
//
// Usage:
//   // If you already have a window, use DrawContents() instead:
//   static MemoryEditor mem_edit_2;
//   ImGui::Begin("MyWindow")
//   mem_edit_2.DrawContents(this, sizeof(*this), (size_t)this);
//   ImGui::End();
//
// Changelog:
// - v0.10: initial version
// - v0.23 (2017/08/17): added to github. fixed right-arrow triggering a byte write.
// - v0.24 (2018/06/02): changed DragInt("Rows" to use a %d data format (which is desirable since imgui 1.61).
// - v0.25 (2018/07/11): fixed wording: all occurrences of "Rows" renamed to "Columns".
// - v0.26 (2018/08/02): fixed clicking on hex region
// - v0.30 (2018/08/02): added data preview for common data types
// - v0.31 (2018/10/10): added OptUpperCaseHex option to select lower/upper casing display [@samhocevar]
// - v0.32 (2018/10/10): changed signatures to use void* instead of unsigned char*
// - v0.33 (2018/10/10): added OptShowOptions option to hide all the interactive option setting.
// - v0.34 (2019/05/07): binary preview now applies endianness setting [@nicolasnoble]
// - v0.35 (2020/01/29): using ImGuiDataType available since Dear ImGui 1.69.
// - v0.36 (2020/05/05): minor tweaks, minor refactor.
// - v0.40 (2020/10/04): fix misuse of ImGuiListClipper API, broke with Dear ImGui 1.79. made cursor position appears on left-side of edit box. option popup appears on mouse release. fix MSVC warnings where _CRT_SECURE_NO_WARNINGS wasn't working in recent versions.
// - v0.41 (2020/10/05): fix when using with keyboard/gamepad navigation enabled.
// - v0.42 (2020/10/14): fix for . character in ASCII view always being greyed out.
// - v0.43 (2021/03/12): added OptFooterExtraHeight to allow for custom drawing at the bottom of the editor [@leiradel]
// - v0.44 (2021/03/12): use ImGuiInputTextFlags_AlwaysOverwrite in 1.82 + fix hardcoded width.
// - v0.50 (2021/11/12): various fixes for recent dear imgui versions (fixed misuse of clipper, relying on SetKeyboardFocusHere() handling scrolling from 1.85). added default size.
// - v0.51 (2024/02/22): fix for layout change in 1.89 when using IMGUI_DISABLE_OBSOLETE_FUNCTIONS. (#34)
// - v0.52 (2024/03/08): removed unnecessary GetKeyIndex() calls, they are a no-op since 1.87.
// - v0.53 (2024/05/27): fixed right-click popup from not appearing when using DrawContents(). warning fixes. (#35)
// - v0.54 (2024/07/29): allow ReadOnly mode to still select and preview data. (#46) [@DeltaGW2])
// - v0.55 (2024/08/19): added BgColorFn to allow setting background colors independently from highlighted selection. (#27) [@StrikerX3]
//                       added MouseHoveredAddr public readable field. (#47, #27) [@StrikerX3]
//                       fixed a data preview crash with 1.91.0 WIP. fixed contiguous highlight color when using data preview.
//                       *BREAKING* added UserData field passed to all optional function handlers: ReadFn, WriteFn, HighlightFn, BgColorFn. (#50) [@silverweed]
// - v0.56 (2024/11/04): fixed MouseHovered, MouseHoveredAddr not being set when hovering a byte being edited. (#54)
// - v0.57 (2025/03/26): fixed warnings. using ImGui's ImSXX/ImUXX types instead of e.g. int32_t/uint32_t. (#56)
// - v0.58 (2025/03/31): fixed extraneous footer spacing (added in 0.51) breaking vertical auto-resize. (#53)
//
// TODO:
// - This is generally old/crappy code, it should work but isn't very good.. to be rewritten some day.
// - PageUp/PageDown are not supported because we use _NoNav. This is a good test scenario for working out idioms of how to mix natural nav and our own...
// - Arrows are being sent to the InputText() about to disappear which for LeftArrow makes the text cursor appear at position 1 for one frame.
// - Using InputText() is awkward and maybe overkill here, consider implementing something custom.

#pragma once

#include <stdio.h>      // sprintf, scanf
#include <stdint.h>     // uint8_t, etc.

#if defined(_MSC_VER) && !defined(snprintf)
#define ImSnprintf  _snprintf
#else
#define ImSnprintf  snprintf
#endif
#if defined(_MSC_VER) && !defined(__clang__)
#define _PRISizeT   "I"
#else
#define _PRISizeT   "z"
#endif

#if defined(_MSC_VER) || defined(_UCRT)
#pragma warning (push)
#pragma warning (disable: 4996) // warning C4996: 'sprintf': This function or variable may be unsafe.
#endif

struct MemoryEditor
{
    enum DataFormat
    {
        DataFormat_Bin = 0,
        DataFormat_Dec = 1,
        DataFormat_Hex = 2,
        DataFormat_COUNT
    };

    // Settings
    bool            Open;                                       // = true   // set to false when DrawWindow() was closed. ignore if not using DrawWindow().
    bool            ReadOnly;                                   // = false  // disable any editing.
    int             Cols;                                       // = 16     // number of columns to display.
    bool            OptShowOptions;                             // = true   // display options button/context menu. when disabled, options will be locked unless you provide your own UI for them.
    bool            OptShowDataPreview;                         // = false  // display a footer previewing the decimal/binary/hex/float representation of the currently selected bytes.
    bool            OptShowHexII;                               // = false  // display values in HexII representation instead of regular hexadecimal: hide null/zero bytes, ascii values as ".X".
    bool            OptShowAscii;                               // = true   // display ASCII representation on the right side.
    bool            OptGreyOutZeroes;                           // = true   // display null/zero bytes using the TextDisabled color.
    bool            OptUpperCaseHex;                            // = true   // display hexadecimal values as "FF" instead of "ff".
    int             OptMidColsCount;                            // = 8      // set to 0 to disable extra spacing between every mid-cols.
    int             OptAddrDigitsCount;                         // = 0      // number of addr digits to display (default calculated based on maximum displayed addr).
    float           OptFooterExtraHeight;                       // = 0      // space to reserve at the bottom of the widget to add custom widgets
    ImU32           HighlightColor;                             //          // background color of highlighted bytes.

    // Function handlers
    ImU8            (*ReadFn)(const ImU8* mem, size_t off, void* user_data);      // = 0      // optional handler to read bytes.
    void            (*WriteFn)(ImU8* mem, size_t off, ImU8 d, void* user_data);   // = 0      // optional handler to write bytes.
    bool            (*HighlightFn)(const ImU8* mem, size_t off, void* user_data); // = 0      // optional handler to return Highlight property (to support non-contiguous highlighting).
    ImU32           (*BgColorFn)(const ImU8* mem, size_t off, void* user_data);   // = 0      // optional handler to return custom background color of individual bytes.
    void*           UserData;                                                     // = NULL   // user data forwarded to the function handlers

    // Public read-only data
    bool            MouseHovered;                               // set when mouse is hovering a value.
    size_t          MouseHoveredAddr;                           // the address currently being hovered if MouseHovered is set.

    // [Internal State]
    bool            ContentsWidthChanged;
    size_t          DataPreviewAddr;
    size_t          DataEditingAddr;
    bool            DataEditingTakeFocus;
    char            DataInputBuf[32];
    char            AddrInputBuf[32];
    size_t          GotoAddr;
    size_t          HighlightMin, HighlightMax;
    int             PreviewEndianness;
    ImGuiDataType   PreviewDataType;

    MemoryEditor()
    {
        // Settings
        Open = true;
        ReadOnly = false;
        Cols = 16;
        OptShowOptions = true;
        OptShowDataPreview = false;
        OptShowHexII = false;
        OptShowAscii = true;
        OptGreyOutZeroes = true;
        OptUpperCaseHex = true;
        OptMidColsCount = 8;
        OptAddrDigitsCount = 0;
        OptFooterExtraHeight = 0.0f;
        HighlightColor = IM_COL32(255, 255, 255, 50);
        ReadFn = nullptr;
        WriteFn = nullptr;
        HighlightFn = nullptr;
        BgColorFn = nullptr;
        UserData = nullptr;

        // State/Internals
        ContentsWidthChanged = false;
        DataPreviewAddr = DataEditingAddr = (size_t)-1;
        DataEditingTakeFocus = false;
        memset(DataInputBuf, 0, sizeof(DataInputBuf));
        memset(AddrInputBuf, 0, sizeof(AddrInputBuf));
        GotoAddr = (size_t)-1;
        MouseHovered = false;
        MouseHoveredAddr = 0;
        HighlightMin = HighlightMax = (size_t)-1;
        PreviewEndianness = 0;
        PreviewDataType = ImGuiDataType_S32;
    }

    void GotoAddrAndHighlight(size_t addr_min, size_t addr_max)
    {
        GotoAddr = addr_min;
        HighlightMin = addr_min;
        HighlightMax = addr_max;
    }

    struct Sizes
    {
        int     AddrDigitsCount;
        float   LineHeight;
        float   GlyphWidth;
        float   HexCellWidth;
        float   SpacingBetweenMidCols;
        float   PosHexStart;
        float   PosHexEnd;
        float   PosAsciiStart;
        float   PosAsciiEnd;
        float   WindowWidth;

        Sizes() { memset(this, 0, sizeof(*this)); }
    };

    void CalcSizes(Sizes& s, size_t mem_size, size_t base_display_addr)
    {
        ImGuiStyle& style = ImGui::GetStyle();
        s.AddrDigitsCount = OptAddrDigitsCount;
        if (s.AddrDigitsCount == 0)
            for (size_t n = base_display_addr + mem_size - 1; n > 0; n >>= 4)
                s.AddrDigitsCount++;
        s.LineHeight = ImGui::GetTextLineHeight();
        s.GlyphWidth = ImGui::CalcTextSize("F").x + 1;                  // We assume the font is mono-space
        s.HexCellWidth = (float)(int)(s.GlyphWidth * 2.5f);             // "FF " we include trailing space in the width to easily catch clicks everywhere
        s.SpacingBetweenMidCols = (float)(int)(s.HexCellWidth * 0.25f); // Every OptMidColsCount columns we add a bit of extra spacing
        s.PosHexStart = (s.AddrDigitsCount + 2) * s.GlyphWidth;
        s.PosHexEnd = s.PosHexStart + (s.HexCellWidth * Cols);
        s.PosAsciiStart = s.PosAsciiEnd = s.PosHexEnd;
        if (OptShowAscii)
        {
            s.PosAsciiStart = s.PosHexEnd + s.GlyphWidth * 1;
            if (OptMidColsCount > 0)
                s.PosAsciiStart += (float)((Cols + OptMidColsCount - 1) / OptMidColsCount) * s.SpacingBetweenMidCols;
            s.PosAsciiEnd = s.PosAsciiStart + Cols * s.GlyphWidth;
        }
        s.WindowWidth = s.PosAsciiEnd + style.ScrollbarSize + style.WindowPadding.x * 2 + s.GlyphWidth;
    }

    // Standalone Memory Editor window
    void DrawWindow(const char* title, void* mem_data, size_t mem_size, size_t base_display_addr = 0x0000)
    {
        Sizes s;
        CalcSizes(s, mem_size, base_display_addr);
        ImGui::SetNextWindowSize(ImVec2(s.WindowWidth, s.WindowWidth * 0.60f), ImGuiCond_FirstUseEver);
        ImGui::SetNextWindowSizeConstraints(ImVec2(0.0f, 0.0f), ImVec2(s.WindowWidth, FLT_MAX));

        Open = true;
        if (ImGui::Begin(title, &Open, ImGuiWindowFlags_NoScrollbar))
        {
            DrawContents(mem_data, mem_size, base_display_addr);
            if (ContentsWidthChanged)
            {
                CalcSizes(s, mem_size, base_display_addr);
                ImGui::SetWindowSize(ImVec2(s.WindowWidth, ImGui::GetWindowSize().y));
            }
        }
        ImGui::End();
    }

    // Memory Editor contents only
    void DrawContents(void* mem_data_void, size_t mem_size, size_t base_display_addr = 0x0000)
    {
        if (Cols < 1)
            Cols = 1;

        ImU8* mem_data = (ImU8*)mem_data_void;
        Sizes s;
        CalcSizes(s, mem_size, base_display_addr);
        ImGuiStyle& style = ImGui::GetStyle();

        const ImVec2 contents_pos_start = ImGui::GetCursorScreenPos();

        // We begin into our scrolling region with the 'ImGuiWindowFlags_NoMove' in order to prevent click from moving the window.
        // This is used as a facility since our main click detection code doesn't assign an ActiveId so the click would normally be caught as a window-move.
        const float height_separator = style.ItemSpacing.y;
        float footer_height = OptFooterExtraHeight;
        if (OptShowOptions)
            footer_height += height_separator + ImGui::GetFrameHeightWithSpacing() * 1;
        if (OptShowDataPreview)
            footer_height += height_separator + ImGui::GetFrameHeightWithSpacing() * 1 + ImGui::GetTextLineHeightWithSpacing() * 3;
        ImGui::BeginChild("##scrolling", ImVec2(-FLT_MIN, -footer_height), ImGuiChildFlags_None, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoNav);
        ImDrawList* draw_list = ImGui::GetWindowDrawList();

        ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0, 0));
        ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(0, 0));

        // We are not really using the clipper API correctly here, because we rely on visible_start_addr/visible_end_addr for our scrolling function.
        const int line_total_count = (int)((mem_size + Cols - 1) / Cols);
        ImGuiListClipper clipper;
        clipper.Begin(line_total_count, s.LineHeight);

        bool data_next = false;

        if (DataEditingAddr >= mem_size)
            DataEditingAddr = (size_t)-1;
        if (DataPreviewAddr >= mem_size)
            DataPreviewAddr = (size_t)-1;

        size_t preview_data_type_size = OptShowDataPreview ? DataTypeGetSize(PreviewDataType) : 0;

        size_t data_editing_addr_next = (size_t)-1;
        if (DataEditingAddr != (size_t)-1)
        {
            // Move cursor but only apply on next frame so scrolling with be synchronized (because currently we can't change the scrolling while the window is being rendered)
            if (ImGui::IsKeyPressed(ImGuiKey_UpArrow) && (ptrdiff_t)DataEditingAddr >= (ptrdiff_t)Cols)                 { data_editing_addr_next = DataEditingAddr - Cols; }
            else if (ImGui::IsKeyPressed(ImGuiKey_DownArrow) && (ptrdiff_t)DataEditingAddr < (ptrdiff_t)mem_size - Cols){ data_editing_addr_next = DataEditingAddr + Cols; }
            else if (ImGui::IsKeyPressed(ImGuiKey_LeftArrow) && (ptrdiff_t)DataEditingAddr > (ptrdiff_t)0)              { data_editing_addr_next = DataEditingAddr - 1; }
            else if (ImGui::IsKeyPressed(ImGuiKey_RightArrow) && (ptrdiff_t)DataEditingAddr < (ptrdiff_t)mem_size - 1)  { data_editing_addr_next = DataEditingAddr + 1; }
        }

        // Draw vertical separator
        ImVec2 window_pos = ImGui::GetWindowPos();
        if (OptShowAscii)
            draw_list->AddLine(ImVec2(window_pos.x + s.PosAsciiStart - s.GlyphWidth, window_pos.y), ImVec2(window_pos.x + s.PosAsciiStart - s.GlyphWidth, window_pos.y + 9999), ImGui::GetColorU32(ImGuiCol_Border));

        const ImU32 color_text = ImGui::GetColorU32(ImGuiCol_Text);
        const ImU32 color_disabled = OptGreyOutZeroes ? ImGui::GetColorU32(ImGuiCol_TextDisabled) : color_text;

        const char* format_address = OptUpperCaseHex ? "%0*" _PRISizeT "X: " : "%0*" _PRISizeT "x: ";
        const char* format_data = OptUpperCaseHex ? "%0*" _PRISizeT "X" : "%0*" _PRISizeT "x";
        const char* format_byte = OptUpperCaseHex ? "%02X" : "%02x";
        const char* format_byte_space = OptUpperCaseHex ? "%02X " : "%02x ";

        MouseHovered = false;
        MouseHoveredAddr = 0;

        while (clipper.Step())
            for (int line_i = clipper.DisplayStart; line_i < clipper.DisplayEnd; line_i++) // display only visible lines
            {
                size_t addr = (size_t)line_i * Cols;
                ImGui::Text(format_address, s.AddrDigitsCount, base_display_addr + addr);

                // Draw Hexadecimal
                for (int n = 0; n < Cols && addr < mem_size; n++, addr++)
                {
                    float byte_pos_x = s.PosHexStart + s.HexCellWidth * n;
                    if (OptMidColsCount > 0)
                        byte_pos_x += (float)(n / OptMidColsCount) * s.SpacingBetweenMidCols;
                    ImGui::SameLine(byte_pos_x);

                    // Draw highlight or custom background color
                    const bool is_highlight_from_user_range = (addr >= HighlightMin && addr < HighlightMax);
                    const bool is_highlight_from_user_func = (HighlightFn && HighlightFn(mem_data, addr, UserData));
                    const bool is_highlight_from_preview = (addr >= DataPreviewAddr && addr < DataPreviewAddr + preview_data_type_size);

                    ImU32 bg_color = 0;
                    bool is_next_byte_highlighted = false;
                    if (is_highlight_from_user_range || is_highlight_from_user_func || is_highlight_from_preview)
                    {
                        is_next_byte_highlighted = (addr + 1 < mem_size) && ((HighlightMax != (size_t)-1 && addr + 1 < HighlightMax) || (HighlightFn && HighlightFn(mem_data, addr + 1, UserData)) || (addr + 1 < DataPreviewAddr + preview_data_type_size));
                        bg_color = HighlightColor;
                    }
                    else if (BgColorFn != nullptr)
                    {
                        is_next_byte_highlighted = (addr + 1 < mem_size) && ((BgColorFn(mem_data, addr + 1, UserData) & IM_COL32_A_MASK) != 0);
                        bg_color = BgColorFn(mem_data, addr, UserData);
                    }
                    if (bg_color != 0)
                    {
                        float bg_width = s.GlyphWidth * 2;
                        if (is_next_byte_highlighted || (n + 1 == Cols))
                        {
                            bg_width = s.HexCellWidth;
                            if (OptMidColsCount > 0 && n > 0 && (n + 1) < Cols && ((n + 1) % OptMidColsCount) == 0)
                                bg_width += s.SpacingBetweenMidCols;
                        }
                        ImVec2 pos = ImGui::GetCursorScreenPos();
                        draw_list->AddRectFilled(pos, ImVec2(pos.x + bg_width, pos.y + s.LineHeight), bg_color);
                    }

                    if (DataEditingAddr == addr)
                    {
                        // Display text input on current byte
                        bool data_write = false;
                        ImGui::PushID((void*)addr);
                        if (DataEditingTakeFocus)
                        {
                            ImGui::SetKeyboardFocusHere(0);
                            ImSnprintf(AddrInputBuf, 32, format_data, s.AddrDigitsCount, base_display_addr + addr);
                            ImSnprintf(DataInputBuf, 32, format_byte, ReadFn ? ReadFn(mem_data, addr, UserData) : mem_data[addr]);
                        }
                        struct InputTextUserData
                        {
                            // FIXME: We should have a way to retrieve the text edit cursor position more easily in the API, this is rather tedious. This is such a ugly mess we may be better off not using InputText() at all here.
                            static int Callback(ImGuiInputTextCallbackData* data)
                            {
                                InputTextUserData* user_data = (InputTextUserData*)data->UserData;
                                if (!data->HasSelection())
                                    user_data->CursorPos = data->CursorPos;
#if IMGUI_VERSION_NUM < 19102
                                if (data->Flags & ImGuiInputTextFlags_ReadOnly)
                                    return 0;
#endif
                                if (data->SelectionStart == 0 && data->SelectionEnd == data->BufTextLen)
                                {
                                    // When not editing a byte, always refresh its InputText content pulled from underlying memory data
                                    // (this is a bit tricky, since InputText technically "owns" the master copy of the buffer we edit it in there)
                                    data->DeleteChars(0, data->BufTextLen);
                                    data->InsertChars(0, user_data->CurrentBufOverwrite);
                                    data->SelectionStart = 0;
                                    data->SelectionEnd = 2;
                                    data->CursorPos = 0;
                                }
                                return 0;
                            }
                            char   CurrentBufOverwrite[3];  // Input
                            int    CursorPos;               // Output
                        };
                        InputTextUserData input_text_user_data;
                        input_text_user_data.CursorPos = -1;
                        ImSnprintf(input_text_user_data.CurrentBufOverwrite, 3, format_byte, ReadFn ? ReadFn(mem_data, addr, UserData) : mem_data[addr]);
                        ImGuiInputTextFlags flags = ImGuiInputTextFlags_CharsHexadecimal | ImGuiInputTextFlags_EnterReturnsTrue | ImGuiInputTextFlags_AutoSelectAll | ImGuiInputTextFlags_NoHorizontalScroll | ImGuiInputTextFlags_CallbackAlways;
                        if (ReadOnly)
                            flags |= ImGuiInputTextFlags_ReadOnly;
                        flags |= ImGuiInputTextFlags_AlwaysOverwrite; // was ImGuiInputTextFlags_AlwaysInsertMode
                        ImGui::SetNextItemWidth(s.GlyphWidth * 2);
                        if (ImGui::InputText("##data", DataInputBuf, IM_ARRAYSIZE(DataInputBuf), flags, InputTextUserData::Callback, &input_text_user_data))
                            data_write = data_next = true;
                        else if (!DataEditingTakeFocus && !ImGui::IsItemActive())
                            DataEditingAddr = data_editing_addr_next = (size_t)-1;
                        DataEditingTakeFocus = false;
                        if (input_text_user_data.CursorPos >= 2)
                            data_write = data_next = true;
                        if (data_editing_addr_next != (size_t)-1)
                            data_write = data_next = false;
                        unsigned int data_input_value = 0;
                        if (!ReadOnly && data_write && sscanf(DataInputBuf, "%X", &data_input_value) == 1)
                        {
                            if (WriteFn)
                                WriteFn(mem_data, addr, (ImU8)data_input_value, UserData);
                            else
                                mem_data[addr] = (ImU8)data_input_value;
                        }
                        if (ImGui::IsItemHovered())
                        {
                            MouseHovered = true;
                            MouseHoveredAddr = addr;
                        }
                        ImGui::PopID();
                    }
                    else
                    {
                        // NB: The trailing space is not visible but ensure there's no gap that the mouse cannot click on.
                        ImU8 b = ReadFn ? ReadFn(mem_data, addr, UserData) : mem_data[addr];

                        if (OptShowHexII)
                        {
                            if ((b >= 32 && b < 128))
                                ImGui::Text(".%c ", b);
                            else if (b == 0xFF && OptGreyOutZeroes)
                                ImGui::TextDisabled("## ");
                            else if (b == 0x00)
                                ImGui::Text("   ");
                            else
                                ImGui::Text(format_byte_space, b);
                        }
                        else
                        {
                            if (b == 0 && OptGreyOutZeroes)
                                ImGui::TextDisabled("00 ");
                            else
                                ImGui::Text(format_byte_space, b);
                        }
                        if (ImGui::IsItemHovered())
                        {
                            MouseHovered = true;
                            MouseHoveredAddr = addr;
                            if (ImGui::IsMouseClicked(0))
                            {
                                DataEditingTakeFocus = true;
                                data_editing_addr_next = addr;
                            }
                        }
                    }
                }

                if (OptShowAscii)
                {
                    // Draw ASCII values
                    ImGui::SameLine(s.PosAsciiStart);
                    ImVec2 pos = ImGui::GetCursorScreenPos();
                    addr = (size_t)line_i * Cols;

                    const float mouse_off_x = ImGui::GetIO().MousePos.x - pos.x;
                    const size_t mouse_addr = (mouse_off_x >= 0.0f && mouse_off_x < s.PosAsciiEnd - s.PosAsciiStart) ? addr + (size_t)(mouse_off_x / s.GlyphWidth) : (size_t)-1;

                    ImGui::PushID(line_i);
                    if (ImGui::InvisibleButton("ascii", ImVec2(s.PosAsciiEnd - s.PosAsciiStart, s.LineHeight)))
                    {
                        DataEditingAddr = DataPreviewAddr = mouse_addr;
                        DataEditingTakeFocus = true;
                    }
                    if (ImGui::IsItemHovered())
                    {
                        MouseHovered = true;
                        MouseHoveredAddr = mouse_addr;
                    }
                    ImGui::PopID();
                    for (int n = 0; n < Cols && addr < mem_size; n++, addr++)
                    {
                        if (addr == DataEditingAddr)
                        {
                            draw_list->AddRectFilled(pos, ImVec2(pos.x + s.GlyphWidth, pos.y + s.LineHeight), ImGui::GetColorU32(ImGuiCol_FrameBg));
                            draw_list->AddRectFilled(pos, ImVec2(pos.x + s.GlyphWidth, pos.y + s.LineHeight), ImGui::GetColorU32(ImGuiCol_TextSelectedBg));
                        }
                        else if (BgColorFn)
                        {
                            draw_list->AddRectFilled(pos, ImVec2(pos.x + s.GlyphWidth, pos.y + s.LineHeight), BgColorFn(mem_data, addr, UserData));
                        }
                        unsigned char c = ReadFn ? ReadFn(mem_data, addr, UserData) : mem_data[addr];
                        char display_c = (c < 32 || c >= 128) ? '.' : c;
                        draw_list->AddText(pos, (display_c == c) ? color_text : color_disabled, &display_c, &display_c + 1);
                        pos.x += s.GlyphWidth;
                    }
                }
            }
        ImGui::PopStyleVar(2);
        const float child_width = ImGui::GetWindowSize().x;
        ImGui::EndChild();

        // Notify the main window of our ideal child content size (FIXME: we are missing an API to get the contents size from the child)
        ImVec2 backup_pos = ImGui::GetCursorScreenPos();
        ImGui::SetCursorPosX(s.WindowWidth);
        ImGui::Dummy(ImVec2(0.0f, 0.0f));
        ImGui::SetCursorScreenPos(backup_pos);

        if (data_next && DataEditingAddr + 1 < mem_size)
        {
            DataEditingAddr = DataPreviewAddr = DataEditingAddr + 1;
            DataEditingTakeFocus = true;
        }
        else if (data_editing_addr_next != (size_t)-1)
        {
            DataEditingAddr = DataPreviewAddr = data_editing_addr_next;
            DataEditingTakeFocus = true;
        }

        const bool lock_show_data_preview = OptShowDataPreview;
        if (OptShowOptions)
        {
            ImGui::Separator();
            DrawOptionsLine(s, mem_data, mem_size, base_display_addr);
        }

        if (lock_show_data_preview)
        {
            ImGui::Separator();
            DrawPreviewLine(s, mem_data, mem_size, base_display_addr);
        }

        const ImVec2 contents_pos_end(contents_pos_start.x + child_width, ImGui::GetCursorScreenPos().y);
        //ImGui::GetForegroundDrawList()->AddRect(contents_pos_start, contents_pos_end, IM_COL32(255, 0, 0, 255));
        if (OptShowOptions)
            if (ImGui::IsMouseHoveringRect(contents_pos_start, contents_pos_end))
                if (ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows) && ImGui::IsMouseReleased(ImGuiMouseButton_Right))
                    ImGui::OpenPopup("OptionsPopup");

        if (ImGui::BeginPopup("OptionsPopup"))
        {
            ImGui::SetNextItemWidth(s.GlyphWidth * 7 + style.FramePadding.x * 2.0f);
            if (ImGui::DragInt("##cols", &Cols, 0.2f, 4, 32, "%d cols")) { ContentsWidthChanged = true; if (Cols < 1) Cols = 1; }
            ImGui::Checkbox("Show Data Preview", &OptShowDataPreview);
            ImGui::Checkbox("Show HexII", &OptShowHexII);
            if (ImGui::Checkbox("Show Ascii", &OptShowAscii)) { ContentsWidthChanged = true; }
            ImGui::Checkbox("Grey out zeroes", &OptGreyOutZeroes);
            ImGui::Checkbox("Uppercase Hex", &OptUpperCaseHex);

            ImGui::EndPopup();
        }
    }

    void DrawOptionsLine(const Sizes& s, void* mem_data, size_t mem_size, size_t base_display_addr)
    {
        IM_UNUSED(mem_data);
        ImGuiStyle& style = ImGui::GetStyle();
        const char* format_range = OptUpperCaseHex ? "Range %0*" _PRISizeT "X..%0*" _PRISizeT "X" : "Range %0*" _PRISizeT "x..%0*" _PRISizeT "x";

        // Options menu
        if (ImGui::Button("Options"))
            ImGui::OpenPopup("OptionsPopup");

        ImGui::SameLine();
        ImGui::Text(format_range, s.AddrDigitsCount, base_display_addr, s.AddrDigitsCount, base_display_addr + mem_size - 1);
        ImGui::SameLine();
        ImGui::SetNextItemWidth((s.AddrDigitsCount + 1) * s.GlyphWidth + style.FramePadding.x * 2.0f);
        if (ImGui::InputText("##addr", AddrInputBuf, IM_ARRAYSIZE(AddrInputBuf), ImGuiInputTextFlags_CharsHexadecimal | ImGuiInputTextFlags_EnterReturnsTrue))
        {
            size_t goto_addr;
            if (sscanf(AddrInputBuf, "%" _PRISizeT "X", &goto_addr) == 1)
            {
                GotoAddr = goto_addr - base_display_addr;
                HighlightMin = HighlightMax = (size_t)-1;
            }
        }

        if (GotoAddr != (size_t)-1)
        {
            if (GotoAddr < mem_size)
            {
                ImGui::BeginChild("##scrolling");
                ImGui::SetScrollFromPosY(ImGui::GetCursorStartPos().y + (GotoAddr / Cols) * ImGui::GetTextLineHeight());
                ImGui::EndChild();
                DataEditingAddr = DataPreviewAddr = GotoAddr;
                DataEditingTakeFocus = true;
            }
            GotoAddr = (size_t)-1;
        }

        //if (MouseHovered)
        //{
        //    ImGui::SameLine();
        //    ImGui::Text("Hovered: %p", MouseHoveredAddr);
        //}
    }

    void DrawPreviewLine(const Sizes& s, void* mem_data_void, size_t mem_size, size_t base_display_addr)
    {
        IM_UNUSED(base_display_addr);
        ImU8* mem_data = (ImU8*)mem_data_void;
        ImGuiStyle& style = ImGui::GetStyle();
        ImGui::AlignTextToFramePadding();
        ImGui::Text("Preview as:");
        ImGui::SameLine();
        ImGui::SetNextItemWidth((s.GlyphWidth * 10.0f) + style.FramePadding.x * 2.0f + style.ItemInnerSpacing.x);

        static const ImGuiDataType supported_data_types[] = { ImGuiDataType_S8, ImGuiDataType_U8, ImGuiDataType_S16, ImGuiDataType_U16, ImGuiDataType_S32, ImGuiDataType_U32, ImGuiDataType_S64, ImGuiDataType_U64, ImGuiDataType_Float, ImGuiDataType_Double };
        if (ImGui::BeginCombo("##combo_type", DataTypeGetDesc(PreviewDataType), ImGuiComboFlags_HeightLargest))
        {
            for (int n = 0; n < IM_ARRAYSIZE(supported_data_types); n++)
            {
                ImGuiDataType data_type = supported_data_types[n];
                if (ImGui::Selectable(DataTypeGetDesc(data_type), PreviewDataType == data_type))
                    PreviewDataType = data_type;
            }
            ImGui::EndCombo();
        }
        ImGui::SameLine();
        ImGui::SetNextItemWidth((s.GlyphWidth * 6.0f) + style.FramePadding.x * 2.0f + style.ItemInnerSpacing.x);
        ImGui::Combo("##combo_endianness", &PreviewEndianness, "LE\0BE\0\0");

        char buf[128] = "";
        float x = s.GlyphWidth * 6.0f;
        bool has_value = DataPreviewAddr != (size_t)-1;
        if (has_value)
            DrawPreviewData(DataPreviewAddr, mem_data, mem_size, PreviewDataType, DataFormat_Dec, buf, (size_t)IM_ARRAYSIZE(buf));
        ImGui::Text("Dec"); ImGui::SameLine(x); ImGui::TextUnformatted(has_value ? buf : "N/A");
        if (has_value)
            DrawPreviewData(DataPreviewAddr, mem_data, mem_size, PreviewDataType, DataFormat_Hex, buf, (size_t)IM_ARRAYSIZE(buf));
        ImGui::Text("Hex"); ImGui::SameLine(x); ImGui::TextUnformatted(has_value ? buf : "N/A");
        if (has_value)
            DrawPreviewData(DataPreviewAddr, mem_data, mem_size, PreviewDataType, DataFormat_Bin, buf, (size_t)IM_ARRAYSIZE(buf));
        buf[IM_ARRAYSIZE(buf) - 1] = 0;
        ImGui::Text("Bin"); ImGui::SameLine(x); ImGui::TextUnformatted(has_value ? buf : "N/A");
    }

    // Utilities for Data Preview (since we don't access imgui_internal.h)
    // FIXME: This technically depends on ImGuiDataType order.
    const char* DataTypeGetDesc(ImGuiDataType data_type) const
    {
        const char* descs[] = { "Int8", "Uint8", "Int16", "Uint16", "Int32", "Uint32", "Int64", "Uint64", "Float", "Double" };
        IM_ASSERT(data_type >= 0 && data_type < IM_ARRAYSIZE(descs));
        return descs[data_type];
    }

    size_t DataTypeGetSize(ImGuiDataType data_type) const
    {
        const size_t sizes[] = { 1, 1, 2, 2, 4, 4, 8, 8, sizeof(float), sizeof(double) };
        IM_ASSERT(data_type >= 0 && data_type < IM_ARRAYSIZE(sizes));
        return sizes[data_type];
    }

    const char* DataFormatGetDesc(DataFormat data_format) const
    {
        const char* descs[] = { "Bin", "Dec", "Hex" };
        IM_ASSERT(data_format >= 0 && data_format < DataFormat_COUNT);
        return descs[data_format];
    }

    bool IsBigEndian() const
    {
        ImU16 x = 1;
        char c[2];
        memcpy(c, &x, 2);
        return c[0] != 0;
    }

    static void* EndiannessCopyBigEndian(void* _dst, void* _src, size_t s, int is_little_endian)
    {
        if (is_little_endian)
        {
            ImU8* dst = (ImU8*)_dst;
            ImU8* src = (ImU8*)_src + s - 1;
            for (int i = 0, n = (int)s; i < n; ++i)
                memcpy(dst++, src--, 1);
            return _dst;
        }
        else
        {
            return memcpy(_dst, _src, s);
        }
    }

    static void* EndiannessCopyLittleEndian(void* _dst, void* _src, size_t s, int is_little_endian)
    {
        if (is_little_endian)
        {
            return memcpy(_dst, _src, s);
        }
        else
        {
            ImU8* dst = (ImU8*)_dst;
            ImU8* src = (ImU8*)_src + s - 1;
            for (int i = 0, n = (int)s; i < n; ++i)
                memcpy(dst++, src--, 1);
            return _dst;
        }
    }

    void* EndiannessCopy(void* dst, void* src, size_t size) const
    {
        static void* (*fp)(void*, void*, size_t, int) = nullptr;
        if (fp == nullptr)
            fp = IsBigEndian() ? EndiannessCopyBigEndian : EndiannessCopyLittleEndian;
        return fp(dst, src, size, PreviewEndianness);
    }

    const char* FormatBinary(const ImU8* buf, int width) const
    {
        IM_ASSERT(width <= 64);
        size_t out_n = 0;
        static char out_buf[64 + 8 + 1];
        int n = width / 8;
        for (int j = n - 1; j >= 0; --j)
        {
            for (int i = 0; i < 8; ++i)
                out_buf[out_n++] = (buf[j] & (1 << (7 - i))) ? '1' : '0';
            out_buf[out_n++] = ' ';
        }
        IM_ASSERT(out_n < IM_ARRAYSIZE(out_buf));
        out_buf[out_n] = 0;
        return out_buf;
    }

    // [Internal]
    void DrawPreviewData(size_t addr, const ImU8* mem_data, size_t mem_size, ImGuiDataType data_type, DataFormat data_format, char* out_buf, size_t out_buf_size) const
    {
        ImU8 buf[8];
        size_t elem_size = DataTypeGetSize(data_type);
        size_t size = addr + elem_size > mem_size ? mem_size - addr : elem_size;
        if (ReadFn)
            for (int i = 0, n = (int)size; i < n; ++i)
                buf[i] = ReadFn(mem_data, addr + i, UserData);
        else
            memcpy(buf, mem_data + addr, size);

        if (data_format == DataFormat_Bin)
        {
            ImU8 binbuf[8];
            EndiannessCopy(binbuf, buf, size);
            ImSnprintf(out_buf, out_buf_size, "%s", FormatBinary(binbuf, (int)size * 8));
            return;
        }

        out_buf[0] = 0;
        switch (data_type)
        {
        case ImGuiDataType_S8:
        {
            ImS8 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%hhd", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%02x", data & 0xFF); return; }
            break;
        }
        case ImGuiDataType_U8:
        {
            ImU8 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%hhu", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%02x", data & 0XFF); return; }
            break;
        }
        case ImGuiDataType_S16:
        {
            ImS16 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%hd", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%04x", data & 0xFFFF); return; }
            break;
        }
        case ImGuiDataType_U16:
        {
            ImU16 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%hu", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%04x", data & 0xFFFF); return; }
            break;
        }
        case ImGuiDataType_S32:
        {
            ImS32 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%d", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%08x", data); return; }
            break;
        }
        case ImGuiDataType_U32:
        {
            ImU32 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%u", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%08x", data); return; }
            break;
        }
        case ImGuiDataType_S64:
        {
            ImS64 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%lld", (long long)data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%016llx", (long long)data); return; }
            break;
        }
        case ImGuiDataType_U64:
        {
            ImU64 data = 0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%llu", (long long)data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "0x%016llx", (long long)data); return; }
            break;
        }
        case ImGuiDataType_Float:
        {
            float data = 0.0f;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%f", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "%a", data); return; }
            break;
        }
        case ImGuiDataType_Double:
        {
            double data = 0.0;
            EndiannessCopy(&data, buf, size);
            if (data_format == DataFormat_Dec) { ImSnprintf(out_buf, out_buf_size, "%f", data); return; }
            if (data_format == DataFormat_Hex) { ImSnprintf(out_buf, out_buf_size, "%a", data); return; }
            break;
        }
        default:
        case ImGuiDataType_COUNT:
            break;
        } // Switch
        IM_ASSERT(0); // Shouldn't reach
    }
};

#undef _PRISizeT
#undef ImSnprintf

#ifdef _MSC_VER
#pragma warning (pop)
#endif