vtrenderlib/vtrenderlib.h at master · the-eugen/vtrenderlib · GitHub

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#pragma once

/*
 * vtrenderlib.h - tiny vector rasterizer for ANSI terminals.
 *
 * The library exposes a minimal API for drawing 2D primitives into a
 * terminal emulator using braille characters.  The consumer is expected
 * to manage the terminal file descriptor and drive the rendering loop.
 */

#ifdef __cplusplus
extern "C" {
#endif

struct vtr_canvas;

/*
 * Create a canvas object bound to an already-open TTY file descriptor.
 * Returns NULL on error.
 */
struct vtr_canvas* vtr_canvas_create(int ttyfd);

/*
 * Put the associated terminal into raw mode and switch to the alternate
 * screen buffer.  Must be called before any drawing takes place.
 */
int vtr_reset(struct vtr_canvas* vt);

/*
 * Restore the original terminal attributes and free all resources.
 */
void vtr_close(struct vtr_canvas* vt);

/*
 * Check if VT dimensions have changed and reset it if needed.
 * Terminal resizes are handled asynchronously. The consumer could
 * watch for SIGWINCH and call the actual resize from the main loop.
 */
int vtr_resize(struct vtr_canvas* vt);

/* Canvas dimensions in dots */
uint16_t vtr_xdots(struct vtr_canvas* vt);
uint16_t vtr_ydots(struct vtr_canvas* vt);

/* Clear the entire screen */
int vtr_clear_screen(struct vtr_canvas* vt);

/*
 * Swap buffers when a frame is complete.  All accumulated changes are
 * flushed to the terminal and the back buffer is cleared for the next
 * frame.
 */

int vtr_swap_buffers(struct vtr_canvas* vt);

/*
 * Rasterizer calls.
 */

/* Vertex in dot coordinates */
struct vtr_vertex
{
    int x;
    int y;
};

/* Basic ANSI color palette */
enum vtr_color
{
    VTR_COLOR_DEFAULT,
    VTR_COLOR_BLACK,
    VTR_COLOR_RED,
    VTR_COLOR_GREEN,
    VTR_COLOR_YELLOW,
    VTR_COLOR_BLUE,
    VTR_COLOR_MAGENTA,
    VTR_COLOR_CYAN,
    VTR_COLOR_WHITE,

    VTR_COLOR_SGR8_TOTAL // always last
};

/*
 * Foreground color type. Accepts enum vtr_color or VTR_COLOR256(idx) values.
 */
typedef uint8_t vtr_fgcolor_t;

/*
 * 256-color palette (ITU-T T.416 / ISO/IEC 8613-6).
 * Index 255 (light grey) is mapped to VTR_COLOR_WHITE since 0 is reserved for VTR_COLOR_DEFAULT.
 */
#define VTR_COLOR256(_idx)  ((vtr_fgcolor_t)((_idx) >= 255 ? VTR_COLOR_WHITE : (_idx) + 1))

/**
 * Render a dot at given VT coordinates.
 */
void vtr_render_dot(struct vtr_canvas* vt, int x, int y);
void vtr_render_dotc(struct vtr_canvas* vt, int x, int y, vtr_fgcolor_t fgc);

/**
 * Scan a line given two dot coordinates.
 */
void vtr_scan_line(struct vtr_canvas* vt, int x0, int y0, int x1, int y1);
void vtr_scan_linec(struct vtr_canvas* vt, int x0, int y0, int x1, int y1, vtr_fgcolor_t fgc);

/**
 * Trace a polygon path given a list of vertices.
 * The last vertex is traced back to the first one and the resulting polygon filled.
 */
int vtr_trace_poly(struct vtr_canvas* vt, size_t nvertices, const struct vtr_vertex* vertexlist);
int vtr_trace_polyc(struct vtr_canvas* vt, size_t nvertices, const struct vtr_vertex* vertexlist, vtr_fgcolor_t fgc);

/**
 * Print some text at the specified location.
 * The text will overlay any other rasterized output.
 */
int vtr_print_text(struct vtr_canvas* vt, uint16_t row, uint16_t col, const char* str);

#ifdef __cplusplus
}
#endif