I've had a bit of a time away from actively working with FLTK, and
was surprised to find I couldn't get fl_draw(s, x, y) to work today.
I reckon I've made a really obvious howler, but I've been staring
at it all day and can't see what I've done wrong. I know that I'm
going to kick myself when someone points out a beginner's mistake.
So I've incorporated the fl_draw() call in an old example that I
posted several years ago. Basically I want something simple like:
char buffer[32];
sprintf(buffer, "%d", value);
fl_draw(buffer, x() + 30, y() + 30);
but it keeps giving a segmentation fault, and I can't see it. I've
tried changing the declaration of buffer from a local variable to a
member variable, I've tried using fixed text, and even replacing
buffer with "hello" in the fl_draw call. See the // # comments.
I can't see the wood for the trees. Where have I gone wrong?
This is fltk-1.1.10, on Lunar Linux, with gcc-4.4.3.
It also failed at work today (CentOS 5.4 and gcc-4.4.1 ?).
Cheers
D.
/*
While trying to find a stupid error (Doh! max uchar is 255 and not 256!)
I've written a simple fl_color demo that someone might find useful.
*/
// Just compile using 'fltk-config --compile filename.cxx'
#include <FL/Fl.H>
#include <FL/Fl_Box.H>
#include <FL/Fl_Window.H>
#include <FL/fl_draw.H>
#include <cmath>
#include <cstdio>
#include <cstring>
void
setGrey (double ratio)
{
uchar grey = (uchar) (255 * ratio);
fl_color (grey);
}
void
setBlueToCyan (double ratio)
{
uchar red = 0;
uchar green = (uchar) (255 * ratio);
uchar blue = 255;
fl_color (red, green, blue);
}
void
setCyanToGreen (double ratio)
{
uchar red = 0;
uchar green = 255;
uchar blue = (uchar) (255 * (1.0 - ratio));
fl_color (red, green, blue);
}
void
setGreenToYellow (double ratio)
{
uchar red = (uchar) (255 * ratio);
uchar green = 255;
uchar blue = 0;
fl_color (red, green, blue);
}
void
setYellowToRed (double ratio)
{
uchar red = 255;
uchar green = (uchar) (255 * (1.0 - ratio));
uchar blue = 0;
fl_color (red, green, blue);
}
void
setColor (double min, double max, double value)
{
double range = max - min;
double delta = value - min;
double ratio = delta / range;
if (ratio <= 0.0) {
setGrey (0.3);
}
else if (ratio < 0.25) {
setBlueToCyan (4.0 * (ratio - 0.00));
}
else if (ratio < 0.50) {
setCyanToGreen (4.0 * (ratio - 0.25));
}
else if (ratio < 0.75) {
setGreenToYellow (4.0 * (ratio - 0.50));
}
else if (ratio < 1.00) {
setYellowToRed (4.0 * (ratio - 0.75));
}
else {
setGrey (0.7);
}
}
void
drawCircle (int x, int y, int r)
{
fl_pie (x - r, y - r, 2 * r, 2 * r, 0.0, 360.0);
fl_color (FL_BLACK);
fl_arc (x - r, y - r, 2 * r, 2 * r, 0.0, 360.0);
}
class Box:public Fl_Box
{
public:
char m_buffer[32]; // 1
Box (int x, int y, int w, int h, const char *t = 0):Fl_Box (x, y, w, h, t)
{
strcpy(m_buffer, ""); // 1a
}
~Box ()
{
}
void draw ()
{
// char m_buffer[32]; // 2
int n = sprintf(m_buffer, "hello");
// printf("sprintf() returns %d\n", n);
// fl_draw(m_buffer, x() + 30, y() + 30); // 3
fl_draw("hello", x() + 30, y() + 30);
int xc = x () + w () / 2;
int yc = y () + h () / 2;
int rc = (w () < h ())? w () / 3 : h () / 3;
drawCircle (xc, yc, rc);
for (double angle = 0.0; angle < 360.0; angle += 10.0) {
int xx = (int) (xc + rc * sin (angle * M_PI / 180.0));
int yy = (int) (yc - rc * cos (angle * M_PI / 180.0));
setColor (0.0, 360.0, angle);
drawCircle (xx, yy, rc / 10);
}
for (int i = 0; i < w (); ++i) {
setColor (0, w (), i);
fl_line (x () + i, y (), x () + i, y () + 20);
}
}
};
int
main (int argc, char *argv[])
{
Fl_Window *w = new Fl_Window (300, 300);
Box *b = new Box (5, 5, 290, 290);
w->end ();
w->show (argc, argv);
Fl::run ();
return (0);
}
_______________________________________________
fltk mailing list
[email protected]
http://lists.easysw.com/mailman/listinfo/fltk
