196430b016
Elaborated on Fl_Cairo_Window's use of FLTK style coordinates,
and how this differs from cairo's default native normalized
coordinate system, and shows how to switch from one to the other.
Also, small comment fix to the cairo example regarding the "X" color.
59 lines
2.5 KiB
C++
59 lines
2.5 KiB
C++
//
|
|
// Simple demo of drawing an "X" in Cairo (antialiased lines)
|
|
//
|
|
// 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
|
|
//
|
|
|
|
#include <FL/Fl.H> // includes <FL/fl_config.h>
|
|
|
|
#ifdef FLTK_HAVE_CAIRO // Builds example code only if cairo enabled
|
|
#include <FL/Fl_Cairo_Window.H>
|
|
|
|
// Cairo rendering cb called during Fl_Cairo_Window::draw()
|
|
static void my_cairo_draw_cb(Fl_Cairo_Window *window, cairo_t *cr) {
|
|
const double xmax = (window->w() - 1);
|
|
const double ymax = (window->h() - 1);
|
|
|
|
// Draw orange "X"
|
|
// Draws an X to four corners of resizable window.
|
|
// See Fl_Cairo_Window docs for more info.
|
|
//
|
|
cairo_set_antialias(cr, CAIRO_ANTIALIAS_BEST); // use best antialiasing
|
|
cairo_set_line_width(cr, 1.00); // line width for drawing
|
|
cairo_set_source_rgb(cr, 1.0, 0.5, 0.0); // orange
|
|
cairo_move_to(cr, 0.0, 0.0); cairo_line_to(cr, xmax, ymax); // draw diagonal "\"
|
|
cairo_move_to(cr, 0.0, ymax); cairo_line_to(cr, xmax, 0.0); // draw diagonal "/"
|
|
cairo_stroke(cr); // stroke the lines
|
|
}
|
|
|
|
int main(int argc, char **argv) {
|
|
Fl_Cairo_Window window(300, 300, "Cairo Draw 'X'");
|
|
window.color(FL_BLACK); // cairo window's default bg color
|
|
window.size_range(50,50,-1,-1); // allow resize 50,50 and up
|
|
window.resizable(&window); // allow window to be resized
|
|
window.set_draw_cb(my_cairo_draw_cb); // draw callback for cairo drawing
|
|
window.show(argc, argv);
|
|
return Fl::run();
|
|
}
|
|
|
|
// The code that follows just allows the example to build even if cairo wasn't enabled.
|
|
#else // (!FLTK_HAVE_CAIRO)
|
|
#include <FL/fl_ask.H>
|
|
int main(int argc, char **argv) {
|
|
fl_message_title("This program needs a Cairo enabled FLTK library");
|
|
fl_message("Please configure FLTK with Cairo enabled (--enable-cairo or --enable-cairoext)\n"
|
|
"or one of the CMake options OPTION_CAIRO or OPTION_CAIROEXT, respectively.");
|
|
return 0;
|
|
}
|
|
#endif // (FLTK_HAVE_CAIRO)
|