Introduction
I was looking for a solution to make a Form Generator application with WPF. But my big problem was "How can I move my controls by user's mouse events on the Grid or other container controls".
I've searched a lot on the internet, but none of my search results helped me. Finally, I found how Canvas
control and its properties can be helpful. And with using Canvas
control, I created my own FormGenerator
app.
Using the Code
As I said, to be able to move an object with mouse or other input devices at run time, we can use a Canvas
control. When you add a control (like Button
) to a Canvas
, this control gets some properties that all of them are depending on the Canvas
control. Properties like Canvas.Left
and Canvas.Right
.
With these properties, we can move an object (control) where we want on its parent (Canvas
). To do this, we should have three events: MouseLeftButtonDown
, MouseMove
, and MouseLeftButtonUp
. In some components, the MouseLeftButtonDown
doesn't fire because of that, I used the PreviewMouseLeftButtonDown
.
The MouseLeftButtonDown
event code is like this:
private void MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
FirstXPos = e.GetPosition(sender as Control).X;
FirstYPos = e.GetPosition(sender as Control).Y;
FirstArrowXPos = e.GetPosition((sender as Control).Parent as Control).X - FirstXPos;
FirstArrowYPos = e.GetPosition((sender as Control).Parent as Control).Y - FirstYPos;
MovingObject = sender;
}
The MouseLeftButtonUp
event code is like this:
void PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
MovingObject = null;
}
And our main event, "MouseMove
", is like this:
private void MouseMove(object sender, MouseEventArgs e)
{
if (e.LeftButton == MouseButtonState.Pressed)
{
(MovingObject as FrameworkElement).SetValue(Canvas.LeftProperty,
e.GetPosition((MovingObject as FrameworkElement).Parent as FrameworkElement).X - FirstXPos);
(MovingObject as FrameworkElement).SetValue(Canvas.TopProperty,
e.GetPosition((MovingObject as FrameworkElement).Parent as FrameworkElement).Y - FirstYPos);
}
}
Finally
I hope this tip helps you to solve your possibility problems with drag and drop in WPF.
I'm addict of developing softwares and designing solutions for projects.
My favorite work in programming is designing Components and user controls.