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ZepDisplay is the abstract base class that defines the rendering interface for Zep. To integrate Zep with a custom graphics backend, you need to implement a class that inherits from ZepDisplay and override its pure virtual methods.

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Overview

The display system provides an abstraction layer between the editor logic and the rendering backend. This allows Zep to work with different UI frameworks like ImGui, Qt, or custom renderers. Header: include/zep/display.h

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Core Rendering Methods

These methods must be implemented for any custom display backend:

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DrawChars

virtual void DrawChars(
    ZepFont& font,
    const NVec2f& pos,
    const NVec4f& col,
    const uint8_t* text_begin,
    const uint8_t* text_end = nullptr
) const = 0;
Renders text characters at the specified position. Parameters:
  • font - The font to use for rendering
  • pos - Screen position in pixels
  • col - RGBA color (values 0.0 to 1.0)
  • text_begin - Pointer to the first character
  • text_end - Optional pointer past the last character (if nullptr, text is null-terminated)

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DrawLine

virtual void DrawLine(
    const NVec2f& start,
    const NVec2f& end,
    const NVec4f& color = NVec4f(1.0f),
    float width = 1.0f
) const = 0;
Draws a line between two points. Parameters:
  • start - Starting position in pixels
  • end - Ending position in pixels
  • color - RGBA color (defaults to white)
  • width - Line width in pixels

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DrawRectFilled

virtual void DrawRectFilled(
    const NRectf& rc,
    const NVec4f& col = NVec4f(1.0f)
) const = 0;
Draws a filled rectangle. Parameters:
  • rc - Rectangle bounds
  • col - RGBA color (defaults to white)

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SetClipRect

virtual void SetClipRect(const NRectf& rc) = 0;
Sets the clipping rectangle for subsequent drawing operations. Parameters:
  • rc - Rectangle to clip to

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GetFont

virtual ZepFont& GetFont(ZepTextType type) = 0;
Returns the font for a specific text type. Parameters:
  • type - One of: UI, Text, Heading1, Heading2, Heading3

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Helper Methods

These methods have default implementations but can be overridden:

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DrawRect

virtual void DrawRect(
    const NRectf& rc,
    const NVec4f& col = NVec4f(1.0f)
) const;
Draws a rectangle outline (default implementation calls DrawLine four times).

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GetCodePointCount

virtual uint32_t GetCodePointCount(
    const uint8_t* pCh,
    const uint8_t* pEnd
) const;
Counts UTF-8 code points in a text range.

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Font Management

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SetFont

virtual void SetFont(
    ZepTextType type,
    std::shared_ptr<ZepFont> spFont
);
Sets a custom font for a text type.

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Bigger / Smaller

void Bigger();
void Smaller();
Increases or decreases the font scale.

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Pixel Scale

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GetPixelScale / SetPixelScale

const NVec2f& GetPixelScale() const;
void SetPixelScale(const NVec2f& scale);
Gets or sets the DPI/pixel scale factor for high-DPI displays.

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Layout Management

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LayoutDirty

virtual bool LayoutDirty() const;
Returns true if the layout needs to be recalculated.

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SetLayoutDirty

virtual void SetLayoutDirty(bool changed = true);
Marks the layout as needing recalculation.

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Example Implementation

See ZepDisplayNull in display.h:130 for a minimal reference implementation that discards all drawing operations.

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ZepTextType

enum class ZepTextType {
    UI,
    Text,
    Heading1,
    Heading2,
    Heading3,
    Count
};

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ZepFont

Abstract base class for fonts. Key methods: 
virtual void SetPixelHeight(int height) = 0;
virtual NVec2f GetTextSize(
    const uint8_t* pBegin,
    const uint8_t* pEnd = nullptr
) const = 0;

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See Also

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