🚀 go-pugleaf

In article <1992Aug21.201755.25251@eng.ufl.edu>, jmc@sioux.eel.ufl.edu (Jim Callahan) writes:
|> I am having problems with using system calls in a InterViews program.
|>I would like to map a transient window containing a simple label glyph
|>before a system call and unmap the window when the system function returns.
|>Is there any way to do this whithout
|>  tampering with the InterViews event loop?
|> I would appreciate any suggestions or alternate means of notifying the user
|>that they must wait for a system call to return.

In general, if you want to post a notifier, do some computation, then remove
the notifier, you need to force processing of the expose event(s) before
doing the computation.  The example below shows one way to do it.
Unfortunately, even this approach suffers from the problem
that it won't handle an expose that occurs _during_ the computation.
A better solution appears to require multithreading.

#include <IV-look/kit.h>
#include <InterViews/background.h>
#include <InterViews/event.h>
#include <InterViews/label.h>
#include <InterViews/layout.h>
#include <InterViews/session.h>
#include <InterViews/window.h>
#include <stdio.h>

class Drawn : public MonoGlyph {
public:
    Drawn(Glyph*);
    virtual ~Drawn();

    boolean drawn() const;
    virtual void draw(Canvas*, const Allocation&) const;
private:
    boolean drawn_;
};

Drawn::Drawn(Glyph* g) : MonoGlyph(g) { drawn_ = false; }
Drawn::~Drawn() { }

void Drawn::draw(Canvas* c, const Allocation& a) const {
    Drawn* d = (Drawn*)this;
    d->drawn_ = true;
    MonoGlyph::draw(c, a);
}

inline boolean Drawn::drawn() const { return drawn_; }

int main(int argc, char** argv) {
    Session session("Himom", argc, argv);
    WidgetKit& kit = *WidgetKit::instance();
    const LayoutKit& layout = *LayoutKit::instance();
    Drawn* d = new Drawn(
	new Background(
	    layout.hbox(
		layout.hglue(72.0, 72.0, 0.0),
		kit.label("hi mom!")
	    ),
	    kit.background()
	)
    );
    Window& w = *new ApplicationWindow(d);
    w.map();
    Event e;
    while (!session.done() && !d->drawn()) {
	session.read(e);
	e.handle();
    }
    getchar();
    w.unmap();
    return 0;
}