hi,
i am trying to copy an off_screen image to a drawing area (code
is attached below). all is fine for the first time. however after the
drawing area and the off_screen image are resized the window that
supposed to show the off_screen image show garbage.
any help will be appreciated.
thanks in advance,
ofer
here is the code
//////////////////////////////////
#include <iostream>
#include <iomanip>
#include <gtkmm.h>
struct plot_info {
Glib::RefPtr<Gdk::Pixbuf> image_ptr_;
Cairo::RefPtr<Cairo::ImageSurface> image_surface_ptr_;
Cairo::RefPtr<Cairo::Context> image_context_ptr_;
plot_info(int w, int h)
{
std::cerr << __FUNCTION__ << ": w=" << w << ", h=" << h << std::endl;
image_ptr_ = Gdk::Pixbuf::create(Gdk::COLORSPACE_RGB, false, 8, w, h);
//image_ptr_->fill((255 << 24) | (255 << 16) | (255 << 8) | 0);
image_surface_ptr_ = Cairo::ImageSurface::create(Cairo::FORMAT_RGB24,
image_ptr_->get_width(), image_ptr_->get_height());
image_context_ptr_ = Cairo::Context::create(image_surface_ptr_);
Gdk::Cairo::set_source_pixbuf(image_context_ptr_, image_ptr_, 0.0, 0.0);
image_context_ptr_->paint();
}
};
class plot : public Gtk::DrawingArea {
private:
plot_info *pi_;
private:
void render_image(int w, int h)
{
delete pi_;
pi_ = new plot_info(w, h);
}
public:
plot() : pi_(0) {}
bool on_configure_event(GdkEventConfigure */*event*/)
{
Glib::RefPtr<Gdk::Window> window = get_window();
if (window) {
std::cerr << __FUNCTION__ << ": w=" <<
get_width() << ", h=" << get_height() << std::endl;
if (!pi_ || pi_->image_ptr_->get_width() != get_width()
|| pi_->image_ptr_->get_height() != get_height()) {
render_image(get_width(), get_height());
}
}
return true;
}
bool on_expose_event(GdkEventExpose* event)
{
Glib::RefPtr<Gdk::Window> window = get_window();
if (window) {
std::cerr << __FUNCTION__ << ": x=" <<
event->area.x << ", y=" << event->area.y << ",
w=" << event->area.width << ", h=" <<
event->area.height << std::endl;
// Create the context for the widget
Cairo::RefPtr<Cairo::Context> context =
get_window()->create_cairo_context();
// Select the clipping rectangle
context->rectangle(event->area.x, event->area.y, event->area.width,
event->area.height);
context->clip();
// Store context
context->save();
// Draw the source image on the widget context
context->set_source(pi_->image_surface_ptr_, 0.0, 0.0);
std::cerr << __FUNCTION__ << ": w=" <<
pi_->image_ptr_->get_width() << ", h=" <<
pi_->image_ptr_->get_height() << std::endl;
context->rectangle(0.0, 0.0, pi_->image_ptr_->get_width(),
pi_->image_ptr_->get_height());
context->clip();
context->paint();
// Restore context
context->restore();
}
return true;
}
};
int
main(int argc, char **argv)
{
Gtk::Main kit(argc, argv);
Gtk::Window window;
plot p;
window.set_size_request(800, 600);
window.add(p);
window.show_all();
Gtk::Main::run(window);
return 0;
}
//////////////////////////////////
to compile:
g++ _filename_ -o _exec_name_ `pkg-config gtkmm-2.4 --cflags --libs`
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