fltk/src/Fl_Bitmap.cxx

//
// Bitmap drawing routines for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2022 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
//

/** \fn Fl_Bitmap::Fl_Bitmap(const char *array, int W, int H)
  The constructors create a new bitmap from the specified bitmap data.*/

/** \fn Fl_Bitmap::Fl_Bitmap(const unsigned char *array, int W, int H)
  The constructors create a new bitmap from the specified bitmap data.*/

#include <FL/Fl.H>
#include <FL/fl_draw.H>
#include <FL/Fl_Widget.H>
#include <FL/Fl_Menu_Item.H>
#include <FL/Fl_Bitmap.H>


void Fl_Bitmap::draw(int XP, int YP, int WP, int HP, int cx, int cy) {
  fl_graphics_driver->draw_bitmap(this, XP, YP, WP, HP, cx, cy);
}

/**
  The destructor frees all memory and server resources that are used by
  the bitmap.
*/
Fl_Bitmap::~Fl_Bitmap() {
  uncache();
  if (alloc_array) delete[] (uchar *)array;
}

void Fl_Bitmap::uncache() {
  if (id_) {
    fl_graphics_driver->delete_bitmask(id_);
    id_ = 0;
  }
}

void Fl_Bitmap::label(Fl_Widget* widget) {
  widget->image(this);
}

void Fl_Bitmap::label(Fl_Menu_Item* m) {
  m->label(FL_IMAGE_LABEL, (const char*)this);
}

Fl_Image *Fl_Bitmap::copy(int W, int H) {
  Fl_Bitmap     *new_image;     // New RGB image
  uchar         *new_array;     // New array for image data

  // Optimize the simple copy where the width and height are the same...
  if (W == w() && H == h()) {
    new_array = new uchar [data_h() * ((data_w() + 7) / 8)];
    memcpy(new_array, array, data_h() * ((data_w() + 7) / 8));

    new_image = new Fl_Bitmap(new_array, data_w(), data_h());
    new_image->alloc_array = 1;
    new_image->scale(w(), h(), 0, 1);
    return new_image;
  }
  if (W <= 0 || H <= 0) return 0;

  // OK, need to resize the image data; allocate memory and
  uchar         *new_ptr,       // Pointer into new array
                new_bit,        // Bit for new array
                old_bit;        // Bit for old array
  const uchar   *old_ptr;       // Pointer into old array
  int           sx, sy,         // Source coordinates
                dx, dy,         // Destination coordinates
                xerr, yerr,     // X & Y errors
                xmod, ymod,     // X & Y moduli
                xstep, ystep;   // X & Y step increments


  // Figure out Bresenham step/modulus values...
  xmod   = data_w() % W;
  xstep  = data_w() / W;
  ymod   = data_h() % H;
  ystep  = data_h() / H;

  // Allocate memory for the new image...
  new_array = new uchar [H * ((W + 7) / 8)];
  new_image = new Fl_Bitmap(new_array, W, H);
  new_image->alloc_array = 1;

  memset(new_array, 0, H * ((W + 7) / 8));

  // Scale the image using a nearest-neighbor algorithm...
  for (dy = H, sy = 0, yerr = H, new_ptr = new_array; dy > 0; dy --) {
    for (dx = W, xerr = W, old_ptr = array + sy * ((data_w() + 7) / 8), sx = 0, new_bit = 1;
         dx > 0;
         dx --) {
      old_bit = (uchar)(1 << (sx & 7));
      if (old_ptr[sx / 8] & old_bit) *new_ptr |= new_bit;

      if (new_bit < 128) new_bit <<= 1;
      else {
        new_bit = 1;
        new_ptr ++;
      }

      sx   += xstep;
      xerr -= xmod;

      if (xerr <= 0) {
        xerr += W;
        sx ++;
      }
    }

    if (new_bit > 1) new_ptr ++;

    sy   += ystep;
    yerr -= ymod;
    if (yerr <= 0) {
      yerr += H;
      sy ++;
    }
  }

  return new_image;
}