Timer in DWT?

Bill Baxter wbaxter at gmail.com
Mon Sep 8 18:14:10 PDT 2008

On Tue, Sep 9, 2008 at 9:41 AM, Sam Hu <samhu.samhu at gmail.com> wrote:
> Hi Frank,
> For example,I want to draw a line of text on the form which indicate the current date and time,very second it changes.Below is the code I tried,when I run the program,the drawn text does not change every second if I won't resize the form.I think it is the canvas.redraw method which is the problem,but I don't know which method shoud I use instead.
> //*************************
>  Display display=new Display;
>  Shell shell=new Shell(display);
>  Canvas canvas=new Canvas(shell,DWT.NONE);
>  canvas.addPaintListener(new class PaintListener{
>    public void paintControl(PaintEvent e)
>    {
>       auto layout=new Locale;
>      e.gc.drawText(layout("{:ddd,dd MMMM yyyy HH':'mm':'ss z}",
>                                WallClock.now),100,100);
>    }
>  });
> display.getCurrent.timerExec( 500, dgRunnable({
>                                        canvas.redraw;
>  }));
> //*****************************

This only executes the timer once.  You have to call timerExec again
in the delegate to get it to display again.  So I think you /may/ need
to go ahead and create a Runnable subclass to make it work.  Like

class EverySecond : Runnable
    void run() {
        display.getCurrent.timerExec(500, this);

That may also require you to make canvas and display members of EverySecond.


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