MacArthur, Ian (SELEX GALILEO, UK) schrieb:
>> Now I wonder, how to draw a window taller than screensize:
> I create my own group widget, that draws into the offscreen, and use
> that as my outer window, and also I can grab the "full" oversized
> "window" from the offscreen, of course.
"of course"! You are right, it doesn't work for just one program, but in
general it works. And I found an easy way to realise a screenshot with
adjustable resolution and without any subclassing:
#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Button.H>
#include <FL/fl_draw.H>
#include <FL/x.H>
#include "write_png.h"
Fl_Window* pMW= 0; // Pointer to window for export
void Cb_Bn(Fl_Widget* o, void* v)
{
enum { ow= 4000, oh= 4000 };
if (Fl_Offscreen OF= fl_create_offscreen(ow, oh))
{
Fl_Widget* pW= dynamic_cast< Fl_Widget* >(pMW);
// Fl_Widget::draw() is public!
fl_begin_offscreen(OF);
int x0= pW->x(); int y0= pW->y();
int w0= pW->w(); int h0= pW->h();
pW->damage_resize(0, 0, ow, oh);
pW->draw(); // calls virtual Fl_Window::draw()
if (unsigned char* pImage= fl_read_image(0, 0, 0, ow, oh, 0))
{ // Get image
write_png("/home/ed/temp/test.png", pImage, ow, oh, 3);
delete[] pImage;
}
fl_end_offscreen();
fl_delete_offscreen(OF);
pW->resize(x0, y0, w0, h0);
}
}
int main()
{
Fl_Window Win(100, 100, 640, 480, "Offscreen Image");
pMW= &Win;
Win.resizable(pMW);
Fl_Button* pB= new Fl_Button(10, 10, 100, 100, "&Export Png");
pB->callback(Cb_Bn, 0);
pB->when(FL_WHEN_RELEASE);
Win.end();
Win.show();
return Fl::run();
}
This also works using pointer to groups or widgets, but for these
pointers it is necessary to use damage_resize(), not resize().
There is an interesting effekt: I went through the program, using the
debugger and after leaving the routine - after resizing back and forth
and window was exported - the program resizes back and forth on screen.
I tried to clear_damage() and to do the resize "offscreen" by setting
x/y to coordinates outside of screen, but it remained to be 0/0.
Okay, it's not a problem, just ugly. Now I will go on to find out, where
the initial problem comes from...
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