WinUI3 : How to trigger button click programmatically in cpp

Question

Hi,

Im working on winui3 desktop application in cpp without using XAML. I wanted to trigger button click programmatically from cpp.

One option I can think of is to call the button click handler directly, but in that case we cant to see the visual experience of button being clicked.

How to solve this?

[use case : As we cant drag winui3 button, I'm placing a TextBlock on top of it with opacity set to 0. So when i drag, ill be dragging the textblock but when I click, the click will be received on TextBlock. at this time i want to make the button click happen programmatically]

Thank you

Answer 1

The visual experience of the button is caused by the different states of the pointer.
Therefore, it is too complex to call these externally.

For the conditions described in your use case, it would be much easier to make the button draggable.

If you want both click and drag events to coexist, the code would look as below.

<local:ButtonEx
    ClickMode="Release"
    Click="myButton_Click"
    Content="Drag or Click Me!">
</local:ButtonEx>

class ButtonEx : Button
{
    protected override void OnPointerPressed(PointerRoutedEventArgs e)
    {
        if (this.CapturePointer(e.Pointer))
        {
            pressPoint = e.GetCurrentPoint(this);

            WireDragEvent(this);
        }

        base.OnPointerPressed(e);
    }

    private Microsoft.UI.Input.PointerPoint pressPoint;

    private void WireDragEvent(Button btn)
    {
        btn.PointerMoved += btn_PointerMoved;
        btn.PointerReleased += Btn_PointerReleased;
        btn.PointerCaptureLost += btn_PointerCaptureLost;
    }
    private void ReleaseDragEvent(Button btn)
    {
        btn.PointerMoved -= btn_PointerMoved;
        btn.PointerReleased -= Btn_PointerReleased;
        btn.PointerCaptureLost -= btn_PointerCaptureLost;
    }

    private async void btn_PointerMoved(object sender, PointerRoutedEventArgs e)
    {
        var btn = (Button)sender;
        var currentPoint = e.GetCurrentPoint(btn);
        var dx = currentPoint.Position.X - pressPoint.Position.X;
        var dy = currentPoint.Position.Y - pressPoint.Position.Y;
        var def = dx * dx + dy * dy;
        if (dx > 4)
        {
            ReleaseDragEvent(btn);
            btn.ReleasePointerCapture(e.Pointer);

            await btn.StartDragAsync(pressPoint);
        }
    }

    private void Btn_PointerReleased(object sender, PointerRoutedEventArgs e)
    {
        var btn = (Button)sender;
        ReleaseDragEvent(btn);
        btn.ReleasePointerCapture(e.Pointer);
    }
    private void btn_PointerCaptureLost(object sender, PointerRoutedEventArgs e)
    {
        var btn = (Button)sender;
        ReleaseDragEvent(btn);
    }
}

C# and XAML used for easy make of sample.

Answer 2

Hello @Harshithraj1871,

RemoveHandler should use the same IInspectable as AddHandler instead of a new one.

Windows::Foundation::IInspectable h{nullptr};

        h = winrt::box_value<winrt::Microsoft::UI::Xaml::Input::PointerEventHandler>({ this, &FirstPage::myButton_PointerReleased });
        b.AddHandler(winrt::Microsoft::UI::Xaml::UIElement::PointerPressedEvent(), h, true);

_myB.RemoveHandler(winrt::Microsoft::UI::Xaml::UIElement::PointerPressedEvent(), h);