//
// "$Id: offscreen.cxx 11287 2016-03-05 00:39:40Z AlbrechtS $"
//
// Offscreen drawing test program for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2016 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:
//
// http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
// http://www.fltk.org/str.php
//
/* Standard headers */
#include <stdlib.h>
#include <time.h> // time() - used to seed rand()
/* Fltk headers */
#include <FL/Fl.H>
#include <FL/Fl_Double_Window.H>
#include <FL/x.H>
#include <FL/Fl_Box.H>
#include <FL/fl_draw.H>
static Fl_Double_Window *main_window = 0;
// constants to define the view etc.
static const int offscreen_size = 1000;
static const int win_size = 512;
static const int first_useful_color = 56;
static const int last_useful_color = 255;
static const int num_iterations = 300;
static const double max_line_width = 9.0;
static const double delta_time = 0.1;
/*****************************************************************************/
class oscr_box : public Fl_Box
{
public:
oscr_box(int x, int y, int w, int h);
void oscr_drawing(void);
bool has_oscr() const
{
if (oscr) return true;
return false;
}
private:
void draw();
int handle(int event);
// Generate "random" values for the line display
double random_val(int v) const
{
double dr = (double)(rand()) / (double)(RAND_MAX); // 0.0 to 1.0
dr = dr * (double)(v); // 0 to v
return dr;
}
// The offscreen surface
Fl_Offscreen oscr;
// variables used to handle "dragging" of the view within the box
int x1, y1; // drag start positions
int xoff, yoff; // drag offsets
int drag_state; // non-zero if drag is in progress
int page_x, page_y; // top left of view area
// Width and height of the offscreen surface
int offsc_w, offsc_h;
};
/*****************************************************************************/
oscr_box::oscr_box(int x, int y, int w, int h) :
Fl_Box(x, y, w, h), // base box
oscr(0), // offscreen is not set at start
x1(0), y1(0), drag_state(0), // not dragging view
page_x((offscreen_size - win_size) / 2), // roughly centred in view
page_y((offscreen_size - win_size) / 2),
offsc_w(0), offsc_h(0) // offscreen size - initially none
{ } // Constructor
/*****************************************************************************/
void oscr_box::draw()
{
int wd = w();
int ht = h();
int xo = x();
int yo = y();
fl_color(fl_gray_ramp(19)); // a light grey background shade
fl_rectf(xo, yo, wd, ht); // fill the box with this colour
// then add the offscreen on top of the grey background
if (has_oscr()) // offscreen exists
{
fl_copy_offscreen(xo, yo, wd, ht, oscr, page_x, page_y);
}
else // create offscreen
{
// some hosts may need a valid window context to base the offscreen on...
main_window->make_current();
offsc_w = offscreen_size;
offsc_h = offscreen_size;
oscr = fl_create_offscreen(offsc_w, offsc_h);
}
} // draw method
/*****************************************************************************/
int oscr_box::handle(int ev)
{
int ret = Fl_Box::handle(ev);
// handle dragging of visible page area - if a valid context exists
if (has_oscr())
{
switch (ev)
{
case FL_ENTER:
main_window->cursor(FL_CURSOR_MOVE);
ret = 1;
break;
case FL_LEAVE:
main_window->cursor(FL_CURSOR_DEFAULT);
ret = 1;
break;
case FL_PUSH:
x1 = Fl::event_x_root();
y1 = Fl::event_y_root();
drag_state = 1; // drag
ret = 1;
break;
case FL_DRAG:
if (drag_state == 1) // dragging page
{
int x2 = Fl::event_x_root();
int y2 = Fl::event_y_root();
xoff = x1 - x2;
yoff = y1 - y2;
x1 = x2;
y1 = y2;
page_x += xoff;
page_y += yoff;
// check the page bounds
if (page_x < -w())
{
page_x = -w();
}
else if (page_x > offsc_w)
{
page_x = offsc_w;
}
if (page_y < -h())
{
page_y = -h();
}
else if (page_y > offsc_h)
{
page_y = offsc_h;
}
redraw();
}
ret = 1;
break;
case FL_RELEASE:
drag_state = 0;
ret = 1;
break;
default:
break;
}
}
return ret;
} // handle
/*****************************************************************************/
void oscr_box::oscr_drawing(void)
{
Fl_Color col;
static int icol = first_useful_color;
static int ox = (offscreen_size / 2);
static int oy = (offscreen_size / 2);
static int iters = num_iterations + 1; // Must be set on first pass!
if (!has_oscr())
{
return; // no valid offscreen, nothing to do here
}
fl_begin_offscreen(oscr); /* Open the offscreen context for drawing */
{
if (iters > num_iterations) // clear the offscreen and start afresh
{
fl_color(FL_WHITE);
fl_rectf(0, 0, offsc_w, offsc_h);
iters = 0;
}
iters++;
icol++;
if (icol > last_useful_color)
{
icol = first_useful_color;
}
col = static_cast<Fl_Color>(icol);
fl_color(col); // set the colour
double drx = random_val(offsc_w);
double dry = random_val(offsc_h);
double drt = random_val(max_line_width);
int ex = static_cast<int>(drx);
int ey = static_cast<int>(dry);
fl_line_style(FL_SOLID, static_cast<int>(drt));
fl_line(ox, oy, ex, ey);
ox = ex;
oy = ey;
}
fl_end_offscreen(); // close the offscreen context
redraw();
} // oscr_drawing
/*****************************************************************************/
static oscr_box *os_box = 0; // a widget to view the offscreen with
/*****************************************************************************/
static void oscr_anim(void *)
{
os_box->oscr_drawing(); // if the offscreen exists, draw something
Fl::repeat_timeout(delta_time, oscr_anim);
} // oscr_anim
/*****************************************************************************/
int main(int argc, char **argv)
{
int dim1 = win_size;
main_window = new Fl_Double_Window(dim1, dim1, "Offscreen demo");
main_window->begin();
dim1 -= 10;
os_box = new oscr_box(5, 5, dim1, dim1);
main_window->end();
main_window->resizable(os_box);
main_window->show(argc, argv);
srand(time(NULL)); // seed the random sequence generator
Fl::add_timeout(delta_time, oscr_anim);
return Fl::run();
} // main
//
// End of "$Id: offscreen.cxx 11287 2016-03-05 00:39:40Z AlbrechtS $".
//