ZepDisplay_ImGui

ZepDisplay_ImGui is the ImGui rendering backend for Zep. It implements the ZepDisplay interface using Dear ImGui’s drawing API. Header: include/zep/imgui/display_imgui.h

Classes

ZepDisplay_ImGui

ImGui implementation of the display interface.

class ZepDisplay_ImGui : public ZepDisplay
{
public:
    ZepDisplay_ImGui();
    
    // ZepDisplay interface implementation
    void DrawChars(ZepFont& font, const NVec2f& pos, const NVec4f& col,
                   const uint8_t* text_begin, const uint8_t* text_end) const override;
    void DrawLine(const NVec2f& start, const NVec2f& end,
                  const NVec4f& color, float width) const override;
    void DrawRectFilled(const NRectf& rc, const NVec4f& color) const override;
    void SetClipRect(const NRectf& rc) override;
    ZepFont& GetFont(ZepTextType type) override;
};

ZepFont_ImGui

ImGui font wrapper.

class ZepFont_ImGui : public ZepFont
{
public:
    ZepFont_ImGui(ZepDisplay& display, ImFont* pFont, int pixelHeight);
    
    void SetPixelHeight(int pixelHeight) override;
    NVec2f GetTextSize(const uint8_t* pBegin,
                       const uint8_t* pEnd = nullptr) const override;
    ImFont* GetImFont();
};

Implementation Details

Drawing Operations

All drawing operations use ImGui::GetWindowDrawList() to add primitives to the current ImGui window’s draw list.

DrawChars (display_imgui.h:86)

void DrawChars(ZepFont& font, const NVec2f& pos, const NVec4f& col,
               const uint8_t* text_begin, const uint8_t* text_end) const override;

Casts the font to ZepFont_ImGui to get the underlying ImFont*
Uses ImDrawList::AddText() to render text
Applies clipping rectangle if set
Modulates color with ImGui::GetStyle().Alpha

DrawLine (display_imgui.h:106)

void DrawLine(const NVec2f& start, const NVec2f& end,
              const NVec4f& color, float width) const override;

Uses ImDrawList::AddLine()
Respects the current clipping rectangle
Modulates color with style alpha

DrawRectFilled (display_imgui.h:123)

void DrawRectFilled(const NRectf& rc, const NVec4f& color) const override;

Uses ImDrawList::AddRectFilled()
Applies clipping if active

Clipping (display_imgui.h:140)

Clipping is managed via SetClipRect(). When a clip rect is set:

The rect is stored in m_clipRect
Drawing operations push/pop clip rects using ImDrawList::PushClipRect() and PopClipRect()
A zero-width clip rect disables clipping

Font Management (display_imgui.h:145)

ZepFont& GetFont(ZepTextType type) override;

Creates ZepFont_ImGui instances on demand
Uses the first font from ImGui::GetIO().Fonts
Scales pixel height by the display’s pixel scale

Text Measurement (display_imgui.h:51)

ZepFont_ImGui::GetTextSize() uses ImFont::CalcTextSizeA() with:

Font size set to pixel height
No wrapping (FLT_MAX for width)
Returns character advance width (not just the glyph bounds)
Falls back to ‘A’ character size for invalid glyphs

Color Conversion (display_imgui.h:155)

static ImU32 GetStyleModulatedColor(const NVec4f& color);

Converts NVec4f colors to ImGui’s packed ImU32 format (ABGR), modulating alpha with ImGui::GetStyle().Alpha.

Helper Functions

The header provides conversion utilities:

inline NVec2f toNVec2f(const ImVec2& im);
inline ImVec2 toImVec2(const NVec2f& im);
inline NVec4f toNVec4f(const ImVec4& im);
inline ImVec4 toImVec4(const NVec4f& im);

Greek Character Support (display_imgui.h:33)

static ImWchar greek_range[] = { 0x300, 0x52F, 0x1f00, 0x1fff, 0, 0 };

Defines glyph ranges for Greek and extended Latin characters.

Usage Example

#include "zep/imgui/display_imgui.h"
#include "zep/editor.h"

// Create editor with ImGui display
auto spDisplay = std::make_shared<ZepDisplay_ImGui>();
ZepEditor editor(spDisplay, root_path);

// In your ImGui render loop:
if (ImGui::Begin("Zep Editor")) {
    auto displaySize = ImGui::GetContentRegionAvail();
    editor.SetDisplayRegion(toNVec2f(displaySize));
    editor.Display();
}
ImGui::End();

ZepEditor - Main editor class
ZepDisplay - Abstract display interface
ZepDisplay_Qt - Qt implementation

Core Classes

Modes

Display & Rendering

Text Processing

Syntax & Theming

Utilities

ZepDisplay_ImGui

Classes