How can I change the button's background image twice in MouseLeftButtonDown event?

Question

I write the following event handler in MainWindow.xaml.cs. I want to achieve such an effect，when the business logic is running the runbutton's background image switches to powerOnOff1.png, when the business logic is finished the background image switches back to powerOnOff0.png.

    private void Run_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
            {
                //set run button background image to powerOnOff1.png indicates business logic is going to run.
                BitmapImage ima0 = new BitmapImage(new Uri("picture/powerOnOff1.png", UriKind.Relative));             
                image.Source = ima0;

                //business logic
                ...... 

                //restore Runbutton background image to powerOnOff0.png indicates business logic is finished.
                BitmapImage ima1 = new BitmapImage(new Uri("picture/powerOnOff0.png", UriKind.Relative));
                image.Source = ima1;  
            }

Above codes doesn't work. It always show powerOnOff0.png background image. Does it require multi-threading?

score 0 · Accepted Answer · edited Jan 26 '19 at 15:13

Does it require multithreading?

Yes. You need execute the business logic on a background thread. The easiest way to do this would be to start a new task and await it:

private async void Run_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    //set run button background image to powerOnOff1.png indicates business logic is going to run.
    image.Source = new BitmapImage(new Uri("picture/powerOnOff1.png", UriKind.Relative));

    await Task.Run(() =>
    {
        //business logic here
    });

    //restore Runbutton background image to powerOnOff0.png indicates business logic is finished.
    image.Source = new BitmapImage(new Uri("picture/powerOnOff0.png", UriKind.Relative));
}

How can I change the button's background image twice in MouseLeftButtonDown event?

1 Answers1