//
// Rounded box drawing routines for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2020 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

#include <FL/Fl.H>
#include <FL/fl_draw.H>

// Global parameters for rounded corner drawing algorithm:
//
//  RN = number of segments per corner (must match offset array size)
//  RS = max. corner radius
//  BW = box shadow width

#define RN 5
#define RS (Fl::box_border_radius_max())
#define BW (Fl::box_shadow_width())

static double offset[RN] = { 0.0, 0.07612, 0.29289, 0.61732, 1.0};

static inline void fl_vertex_r(double x, double y) {
  fl_vertex(x + 0.5, y + 0.5);
}

static void rbox(int fill, int x, int y, int w, int h) {
  int i;
  int rs, rsy;
  rs = w*2/5; rsy = h*2/5;
  if (rs > rsy) rs = rsy; // use smaller radius
  if (rs > RS) rs = RS;
  if (rs == 5) rs = 4;  // use only even sizes for small corners (STR #2943)
  if (rs == 7) rs = 8;  // note: 8 is better than 6 (really)

  if (fill) fl_begin_polygon(); else fl_begin_loop();
  for (i=0; i<RN; i++)
    fl_vertex_r(x + offset[RN-i-1]*rs, y + offset[i] * rs);
  for (i=0; i<RN; i++)
    fl_vertex_r(x + offset[i]*rs, y + h-1 - offset[RN-i-1] * rs);
  for (i=0; i<RN; i++)
    fl_vertex_r(x + w-1 - offset[RN-i-1]*rs, y + h-1 - offset[i] * rs);
  for (i=0; i<RN; i++)
    fl_vertex_r(x + w-1 - offset[i]*rs, y + offset[RN-i-1] * rs);
  if (fill) fl_end_polygon(); else fl_end_loop();
}

static void fl_rflat_box(int x, int y, int w, int h, Fl_Color c) {
  Fl::set_box_color(c);
  rbox(1, x, y, w, h); rbox(0, x, y, w, h);
}

static void fl_rounded_frame(int x, int y, int w, int h, Fl_Color c) {
  Fl::set_box_color(c);
  rbox(0, x, y, w, h);
}

static void fl_rounded_box(int x, int y, int w, int h, Fl_Color c) {
  Fl::set_box_color(c);
  rbox(1, x, y, w, h);
  fl_color(FL_BLACK); rbox(0, x, y, w, h);
}

static void fl_rshadow_box(int x, int y, int w, int h, Fl_Color c) {
  // draw shadow:
  fl_color(FL_DARK3);
  rbox(1, x+BW, y+BW, w, h);
  rbox(0, x+BW, y+BW, w, h);
  // draw the box:
  fl_rounded_box(x, y, w, h, c);
}

extern void fl_internal_boxtype(Fl_Boxtype, Fl_Box_Draw_F*);

Fl_Boxtype fl_define_FL_ROUNDED_BOX() {
  fl_internal_boxtype(_FL_ROUNDED_FRAME, fl_rounded_frame);
  fl_internal_boxtype(_FL_ROUNDED_BOX, fl_rounded_box);
  return _FL_ROUNDED_BOX;
}

Fl_Boxtype fl_define_FL_RFLAT_BOX() {
  fl_internal_boxtype(_FL_RFLAT_BOX, fl_rflat_box);
  return _FL_RFLAT_BOX;
}

Fl_Boxtype fl_define_FL_RSHADOW_BOX() {
  fl_internal_boxtype(_FL_RSHADOW_BOX, fl_rshadow_box);
  return _FL_RSHADOW_BOX;
}