Wpf 依赖属性动态键下

Question

I don't know if my title is proper.

But what i am doing here is I am creating a Program that draw rectangle on canvas.

As of now i can draw on canvas by triggering a dependency property when i press the SHIFT key on keyboard. But i want it to become dynamic. I create another Dependency Property then on my XAML i can pass the KEY

something like this on my XAML

DrawingTrigger="Ctrl+Shift"

As of now this is my class

class WindowHelper : Behavior<Window>
    {


        public bool IsDrawing
        {
            get { return (bool)GetValue(IsDrawingProperty); }
            set { SetValue(IsDrawingProperty, value); }
        }

        // Using a DependencyProperty as the backing store for IsDrawing.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty IsDrawingProperty =
            DependencyProperty.Register("IsDrawing", typeof(bool), typeof(WindowHelper),
                new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, null));

        protected override void OnAttached()
        {
            AssociatedObject.KeyDown += AssociatedObject_KeyDown;
            AssociatedObject.KeyUp += AssociatedObject_KeyUp;

            base.OnAttached();
        }

        private void AssociatedObject_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.LeftShift || e.Key == Key.RightShift)
                IsDrawing = false;
        }

        private void AssociatedObject_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.LeftShift || e.Key == Key.RightShift)
                IsDrawing = true;


        }

        protected override void OnDetaching()
        {
            AssociatedObject.KeyDown -= AssociatedObject_KeyDown;
            AssociatedObject.KeyUp -= AssociatedObject_KeyUp;
            base.OnDetaching();
        }


    }

And upon searching i found a code that print the Keyboard Modifiers pressed

            Console.WriteLine(Keyboard.Modifiers);

With the Keyboard Modifier. When i pressed the Ctrl+Shift+Alt

it gives me

Alt, Control, Shift

With this how can i use this to solve my problem?

Is it a good practice to check if each word in the DrawingTrigger is found the set the IsDrawing into True or any suggestion.

Answer 1

Key and Modifiers are two different things. I'd just add / remove a KeyBinding object on the Window.InputBindings. It'll handle 99% of your work for you. It already supports combining modifiers with + and handling left and right keys, etc. You just define pass Ctrl+Shift into the Modifers for example and give it an ICommand to call back into. Easy peazy.