scale.h

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/**
 * @file widgets/scale.h
 * @brief Defines the theme and functionality for a scale (slider) widget.
 *
 * This file provides structures for customizing the appearance of a slider
 * control and a function to render an interactive slider that allows users
 * to select a value within a range.
 */
#pragma once
 
#include "../animate.h"
#include "../collision.h"
#include "../draw.h"
 
/**
 * @brief Structure defining the visual theme for a scale (slider) widget.
 */
typedef struct {
  int enabled; /**< Whether the scale is enabled for interaction (1) or disabled (0). */
 
  double scale; /**< Overall widget scale when normal. */
 
  gmColor background; /**< Track background color when normal. */
  gmColor border;     /**< Track border color when normal. */
 
  struct {
    double scale;   /**< Scale factor when focused/hovered. */
    gmColor border; /**< Border color when focused/hovered. */
  } focussed; /**< Theme properties when the scale is focused or hovered. */
 
  struct {
    double scale;   /**< Scale factor when active (being dragged). */
    gmColor border; /**< Border color when active. */
  } active; /**< Theme properties when the scale is active (mouse button down on it). */
 
  gmColor knob;        /**< Knob color. */
  gmColor knob_border; /**< Knob border color. */
 
  double border_width; /**< Track border thickness. */
  double step; /**< Step size for discrete values (0.0 means allow any value between 0 and 1). */
} gmwScaleTheme;
 
/**
 * @brief Global scale theme instance with default values.
 */
gmwScaleTheme gmwScale = {.enabled = 1,
                          .scale = 1.0,
 
                          .background = 0x3A2A3AE0,
                          .border = 0x7F4F7FFF,
 
                          .focussed = {.scale = 1.03, .border = 0xAA77AAFF},
                          .active = {.scale = 0.97, .border = 0x7F4F7FFF},
 
                          .knob = 0xAA77AAFF,
                          .knob_border = 0x6F3F6FFF,
 
                          .border_width = 0.01,
                          .step = 0.0};
 
/**
 * @brief Creates and renders an animated scale (slider) widget that can be
 * manipulated with the mouse.
 *
 * This function draws a slider, tracks mouse interaction to update its value,
 * and animates the knob's position.
 *
 * @param x The x-coordinate of the scale's center.
 * @param y The y-coordinate of the scale's center.
 * @param width The width of the scale track.
 * @param height The height of the scale track.
 * @param value Pointer to a double to store the current scale value (0.0
 *        to 1.0). This value is updated by user interaction.
 * @param anim Pointer to a double for the animated visual position of the knob.
 *        If NULL, `value` is used for the knob's position (non-animated).
 * @return 1 if the scale is currently being actively manipulated (mouse button down and hovering),
 *         0 otherwise.
 */
int gmw_scale_anim(double x, double y, double width, double height,
                   double *value, double *anim) {
 
  if (value == NULL)
    return 0;
  if (*value < 0)
    *value = 0;
  if (*value > 1)
    *value = 1;
  if (anim != NULL && (*anim > 1 || *anim < 0))
    *anim = *value;
 
  int enabled = gmwScale.enabled;
 
  // Hover test uses full widget size (logical width/height)
  int hovered = enabled && gm_mouse_in_rect(x, y, width, height);
  int active = enabled && gm_mouse.down && hovered;
 
  if (anim == NULL)
    anim = value;
  else
    gm_anim_ease_out_quad(anim, (double)(*value), 0.05);
 
  // Visual scale / border
  double scale = 1.0;
  gmColor border = gmwScale.border;
  if (active) {
    scale = gmwScale.active.scale;
    border = gmwScale.active.border;
  } else if (hovered) {
    scale = gmwScale.focussed.scale;
    border = gmwScale.focussed.border;
  } else {
    scale = gmwScale.scale;
  }
 
  // Draw sizes (scaled visually)
  double sw = width * scale;
  double sh = height * scale;
 
  // Draw track border
  gm_draw_rectangle(x, y, sw, sh, border);
 
  // Track inner size (for knob movement)
  double track_w = sw - gmwScale.border_width * 2;
  double track_h = sh - gmwScale.border_width * 2;
 
  // Draw track
  gm_draw_rectangle(x, y, track_w, track_h, gmwScale.background);
 
  // Orientation
  int horizontal = (width >= height);
 
  // Handle dragging along logical track (not scaled)
  if (active) {
    if (horizontal) {
      double left = x - width * 0.5 + gmwScale.border_width;
      double rel =
          (gm_mouse.position.x - left) / (width - gmwScale.border_width * 2);
      if (rel < 0.0)
        rel = 0.0;
      if (rel > 1.0)
        rel = 1.0;
      if (gmwScale.step > 0.0)
        rel = ((int)(rel / gmwScale.step + 0.5)) * gmwScale.step;
      *value = rel;
    } else {
      double bottom = y - height * 0.5 + gmwScale.border_width;
      double rel =
          (gm_mouse.position.y - bottom) / (height - gmwScale.border_width * 2);
      if (rel < 0.0)
        rel = 0.0;
      if (rel > 1.0)
        rel = 1.0;
      if (gmwScale.step > 0.0)
        rel = ((int)(rel / gmwScale.step + 0.5)) * gmwScale.step;
      *value = rel;
    }
  }
 
  // Draw knob
  double knob_size = (horizontal ? sh : sw) * 1.5;
  double knob_x, knob_y;
 
  if (horizontal) {
    double left = x - sw * 0.5 + knob_size * 0.5;
    double right = x + sw * 0.5 - knob_size * 0.5;
    knob_x = left + (*anim) * (right - left);
    knob_y = y;
  } else {
    double bottom = y - sh * 0.5 + knob_size * 0.5;
    double top = y + sh * 0.5 - knob_size * 0.5;
    knob_y = bottom + (*anim) * (top - bottom);
    knob_x = x;
  }
 
  // Draw knob border
  gm_draw_rectangle(knob_x, knob_y, knob_size + gmwScale.border_width * 2,
                    knob_size + gmwScale.border_width * 2,
                    gmwScale.knob_border);
 
  // Draw knob
  gm_draw_rectangle(knob_x, knob_y, knob_size, knob_size, gmwScale.knob);
 
  return active;
}
 
/**
 * @brief Creates and renders a scale (slider) widget that can be manipulated
 * with the mouse (non-animated version).
 *
 * This is a simplified wrapper around `gmw_scale_anim` that does not use
 * a separate animated visual position, causing the knob to snap to the
 * current value.
 *
 * @param x The x-coordinate of the scale's center.
 * @param y The y-coordinate of the scale's center.
 * @param width The width of the scale track.
 * @param height The height of the scale track.
 * @param value Pointer to a double to store the current scale value (0.0
 *        to 1.0).
 * @return 1 if the scale is currently being actively manipulated (mouse button down and hovering),
 *         0 otherwise.
 */
static inline int gmw_scale(double x, double y, double width, double height,
                            double *value) {
  return gmw_scale_anim(x, y, width, height, value, NULL);
}