C#

Ista wrote:

How do you set it on an element? I dont see any property or method to do that.

Guffa wrote:

I see. You are just using this:

Invalidate();

That is the same as:

Me.Invalidate();

Ista wrote:

Because Invalidate is bugged anyways. It doesn't maintain scroll position at all.

Ista wrote:

what does me do, isn't that a VB form of this.

Ista wrote:

Thanks for everyones help, but I don't think anyone has experience with complex painting to help me.

Guffa wrote:

Hm...? What is it that is complex about it?

Ista wrote:

I just didn't want to do that because then I have to move the drag and drop stuff around.

And it would be complex, because I need to manage the scroll position and what portion is displayed. Plus everytime the scroll is moved I would need to redraw that also.

It doesn't fire scrolling events correctly, it doesn't internally invalidate areas of the panel like it should.

And have you noticed that drawing with paint never looks correct. Test it out and scroll. It gets choppy all over the place with tons of copies of your drawing everywhere.

Just because I call Invalidate doesn't mean I want to reset that position. I just want to redraw everything inside.

Dominik Reichl wrote:

How do CancelEventHandlers work? I think the delegates get called in a random order. What if the first delegate in the chain sets the Cancel property to true, but the second one resets it to false? Will the caller (i.e. the one who sent the event) get true or false in this case?

class CancelEventArgs
{
  bool cancel = false;
  
  public bool Cancel
  { 
    get {return cancel;}
    set {if (!cancel) cancel = value;}
  }
}

public class TestCancellableEvents
{
    public static void Main()
    {
         TestClass test = new TestClass();
         test.MyEvent += new MyDelegate(test_MyEvent);
         test.MyEvent += new MyDelegate(test_MyEvent2);

         test.doit();
 }

     void test_MyEvent2(object sender, CancelEventArgs args)
     {
        //do nothing this won't be called
     }

     void test_MyEvent(object sender, CancelEventArgs args)
     {
         //Cancel event, so the following handlers in the chain won't be called
         args.Cancel = true;
     }

 public class CancelEventArgs
 {
     bool cancel = false;

     public bool Cancel
     {
         get { return cancel; }
         set { cancel = value; }
     }
 }

 public delegate void MyDelegate(object sender, CancelEventArgs args);
 public class TestClass
 {
     public event MyDelegate MyEvent;

     public void doit()
     {
         Delegate[] list = MyEvent.GetInvocationList();
         CancelEventArgs args = new CancelEventArgs();
         foreach (MyDelegate handler in list)
         {
             handler(this, args);
             if (args.Cancel)
             {
                 break;
             }
         }
     }
 }

Vitaliy Tsvayer wrote:

Delegate[] list = MyEvent.GetInvocationList();

public MyDelegate MyEvent;

private MyDelegate MyEvent;
[MethodImpl(MethodImplOptions.Synchronized)]
public void add_MyEvent(MyDelegate value)
{
      this.MyEvent = (MyDelegate) Delegate.Combine(this.MyEvent, value);
}

[MethodImpl(MethodImplOptions.Synchronized)]
public void remove_MyEvent(MyDelegate value)
{
      this.MyEvent = (MyDelegate) Delegate.Remove(this.MyEvent, value);
}

class1.MyEvent += new MyDelegate(this.test_MyEvent);