Question

I am using Synapse for Delphi, but when during HTTP downloads, of course, the GUI freezes. Looking at the documentation, they suggest using the OnHeartbeat method.

(See http://www.ararat.cz/synapse/doku.php/public:howto:heartbeat )

Unfortunately, they don t actually give any code example, and while the concept is simple, the usage is non-obvious.

Is this a per socket (object) setting, or a per application (class) setting? Also, The callback procedure itself is defined as an object, which is a bit unusual. Is anyone who has actually used this willing to share a sample code snippit?

Answer 1

Although I would suggest running your download in a seperate thread, reading the documentation you d have to hook a event handler to the OnHeartBeat event.

In that event handler, you could call Application.ProcessMessages() but that is just dangerous due to the possibility of events being fired before you d actually want them. I would use a custom method to invoke the Paint routine only. You could just pass the handle of your form as parameter, or cast any control to a TWinControl and use the handle property. This will just repaint the form/control, but not allow mouse/keyboard interaction.

procedure AllowRepaints(h: HWND);
var
  m: tMsg;
begin
  while PeekMessage(m, h, WM_PAINT, WM_PAINT, PM_REMOVE) do
    DispatchMessage(m);
end;

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