djstdlib/gfx/ui.h

#ifndef UI_H
#define UI_H

#include "platform.h"
#include "render.h"
#include "../core.h"
#include "GLFW/glfw3.h"

enum UI_Flag {
    UI_Flag_WidthGrow=1<<0, // Default is fixed
    UI_Flag_HeightGrow=1<<1, // Default is fixed
    UI_Flag_Vertical=1<<2, // Default is horizontal
    UI_Flag_3DScene=1<<3,
    UI_Flag_Center=1<<4,
    UI_Flag_Ignore=1<<7, // For optional parameters
    UI_Flag_Pos_Absolute=1<<8, // Default is relative
    // ..
    UI_Flag_COUNT,
};

typedef struct UI_Padding UI_Padding;
struct UI_Padding {
    real32 top;
    real32 right;
    real32 bottom;
    real32 left;
};

enum UI_Cursor {
    UI_Cursor_Arrow=1<<0,
    UI_Cursor_Pointer=1<<1,
    UI_Cursor_Forbidden=1<<2,
    UI_Cursor_Count=1<<3,
};

enum UI_TxtAlign {
    UI_TxtAlign_Left=1<<0, // Default
    UI_TxtAlign_Center=1<<1,
    UI_TxtAlign_Right=1<<2,
};

typedef struct UI_RectStr UI_RectStr;
struct UI_RectStr {
    string s;
    real32 xOffset;
    real32 yOffset;
    real32 lineHeight;
    real32 fontSize;
    Vec4 color;
    enum UI_TxtAlign alignment;
};

typedef struct UI_Rect UI_Rect;
struct UI_Rect {
    enum UI_Flag flags;

    int32 parent;
    int32 firstChild;
    int32 lastChild;
    int32 nextSibling;

    real32 xOffset;
    real32 yOffset;

    real32 width;
    real32 minWidth;
    real32 maxWidth;

    real32 height;
    real32 minHeight;
    real32 maxHeight;

    real32 borderRadius;
    real32 borderThickness;

    Vec4 color;
    Vec4 borderColor;

    UI_Padding padding;
    real32 childGap;

    real32 x;
    real32 y;
    real32 resolvedWidth;
    real32 resolvedHeight;

    UI_RectStr *stringData;
    /**
     * Inherited from parent to propagate attributes. Actual string is ignored, only used for filling out defaults in
     * the next stringData pointer that is set.
     * This pointer is always set, as the global UI context will set it on the root node if it does not present its own
     * text data.
     */
    UI_RectStr *inheritedTextAttr;
};
DefineList(UI_Rect, UI_Rect);

typedef struct UI_Context UI_Context;
struct UI_Context {
    Arena *arena;
    UI_RectList prevRects;
    UI_RectList rects;
    int32 hotNode;
    int32 hoveredNode;
    int32 prevHoveredNode;
    int32 scene3DHandle;
    int32 prevHotNode;
    Renderer *renderer;

    OS_Input *prevInput;
    OS_Input *input;
    enum UI_Cursor cursorType;

    int32 rootRect;
    int32 currRect;
};

void ui_begin(UI_Context *ui);
void ui_end(UI_Context *ui);
UI_Context ui_initContext(Arena *arena, Renderer *renderer);
void ui_resolve();
void ui_rect(UI_Context *ui, UI_Rect rect);
void ui_placeText(UI_Context *ui, UI_RectStr strData);
void ui_attachTextAttr(UI_Context *ui, UI_Rect *rect, UI_RectStr strData);
void ui_openElement(UI_Context *ui, UI_Rect rect);
void ui_closeElement(UI_Context *ui);

bool ui_CheckboxRect(UI_Context *ui, bool *value, UI_Rect rect);
bool ui_Button(UI_Context *ui, UI_Rect rect, UI_RectStr textAttr);
bool ui_ButtonWithHover(UI_Context *ui, UI_Rect rect, UI_Rect hovered, UI_RectStr textAttr);
UI_Rect ui_HoverRect(UI_Context *ui, UI_Rect rect, UI_Rect hovered);

extern UI_Context *__UI_current_ctx__;

#if 0
#define UI_DEBUG_ATTR .borderColor=COLOR_RED, .borderThickness=1,
#else
#define UI_DEBUG_ATTR
#endif

#define UI_Pass(ui) DeferLoop(ui_begin((ui)), ui_end((ui)))
#define UI_PadUniform(padding) ((UI_Padding){ (padding), (padding), (padding), (padding) })
#define UI_NextID() ((__UI_current_ctx__)->rects.length)

#define UI(...)\
    /** Place a UI_Rect defined in-place in the current position in the UI tree */\
    DeferLoop(ui_openElement((__UI_current_ctx__), UI_RectAttr(__VA_ARGS__)), ui_closeElement((__UI_current_ctx__)))

#define UI_RectAttr(...)\
    /** Generate a UI_Rect to be passed as a value */\
    ((UI_Rect){UI_DEBUG_ATTR .minHeight=-1, .minWidth=-1, .width=-1, .height=-1, .inheritedTextAttr=(__UI_current_ctx__->rects.data[(__UI_current_ctx__)->currRect].inheritedTextAttr), __VA_ARGS__})

#define UI_FromRect(rect)\
    /** Place a UI_Rect in the current position in the UI tree, as defined by an existing value */\
    DeferLoop(ui_openElement((__UI_current_ctx__), (rect)), ui_closeElement((__UI_current_ctx__)))

#define UI_TxtAttrS(str, ...)\
    /** Generate UI text to be used as a value */\
    ((UI_RectStr){ .color={-1,-1,-1,-1}, .alignment=-1, .xOffset=0, .yOffset=0, .fontSize=-1, .lineHeight=-1, .s=(str), __VA_ARGS__ })

#define UI_TxtAttr(...)\
    /** Generate UI text to be used as a value, attributes only, no string */\
    ((UI_RectStr){ .color={-1,-1,-1,-1}, .alignment=-1, .xOffset=0, .yOffset=0, .fontSize=-1, .lineHeight=-1, .s=((string){.str=NULL,.length=0}), __VA_ARGS__ })

#define UI_Txt(str, ...)\
    /** Place UI text in the current position in the UI tree. Attaches to the current UI_Rect */\
    (ui_placeText((__UI_current_ctx__), (UI_TxtAttrS(str, __VA_ARGS__))))

#define UI_AttachTxtAttr(rect, txtAttr)\
    /** Attach "phantom" text to the specified rect in order to set its heritable attributes for subsequent text in the UI subtrees */\
    (ui_attachTextAttr((__UI_current_ctx__), (rect), (txtAttr)))

#define UI_SetTxtAttr(...)\
    /** Attach "phantom" text to the current rect in order to set its heritable attributes for subsequent text in the UI subtrees */\
    (ui_placeText((__UI_current_ctx__), (UI_TxtAttr(__VA_ARGS__))))

#define UI_TxtSeg(str, ...)\
    /** Place a text fragment in its own box (useful for placing many text fragments in a row */\
    UI() (UI_Txt((str), __VA_ARGS__))

#endif