ui_slider.h

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#pragma once
 
#include <stdbool.h>
 
#include "gfx.h"
#include "touch_types.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define UI_SLIDER_MAX_PRESETS 8
 
/*
 * How far ui_slider_render paints outside its track, above and below, in
 * pixels.
 *
 * The thumb stands proud of the track, and a caller that clears only the
 * track rectangle before redrawing leaves that overhang behind.  The thumb's
 * shadow is offset 2px below it, so the painted region is not symmetric and
 * this constant alone does not describe it: use ui_slider_painted_rect().
 */
#define UI_SLIDER_OVERHANG 5
 
typedef struct {
    gfx_rect_t track;
    gfx_rect_t presets[UI_SLIDER_MAX_PRESETS];
    float      preset_value[UI_SLIDER_MAX_PRESETS];
    const char *preset_label[UI_SLIDER_MAX_PRESETS];
    int        preset_count;
    int        ticks;      
 
    float min, max, step;
    float value;
    gfx_color_t color;
 
    /*
     * Whether a press sets the value under it.  Off by default, because the
     * control this widget was written for is a throttle: a touch at the far
     * end of the track would command full travel in one contact.  A slider
     * that commands nothing dangerous can turn it on and keep the tap.
     */
    bool    tap_to_set;
 
    /* Drawn dimmed, as a button that takes no press is.  The drawing only:
     * the owner decides which events the slider is given. */
    bool    dim;
 
    bool    dragging;
    uint8_t drag_id;
    int16_t drag_x;       
    float   drag_value;   
    int     pressed_preset;   
    uint8_t preset_id;
} ui_slider_t;
 
void ui_slider_init(ui_slider_t *s, gfx_rect_t track, float min, float max,
                    gfx_color_t color);
void ui_slider_set_ticks(ui_slider_t *s, int n);

void ui_slider_set_presets(ui_slider_t *s, const float *values,
                           const char *const *labels, int count,
                           gfx_rect_t row);
 
void ui_slider_set(ui_slider_t *s, float value);

void ui_slider_set_tap_to_set(ui_slider_t *s, bool on);

void ui_slider_release(ui_slider_t *s);

bool ui_slider_event(ui_slider_t *s, const touch_event_t *evt);
 
void ui_slider_render(const ui_slider_t *s, gfx_canvas_t *c);

gfx_rect_t ui_slider_painted_rect(const ui_slider_t *s);
 
#ifdef __cplusplus
}
#endif