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Customizing the OverviewControl to restricting to change the viewport as negative location
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Restrict to move the viewport as outside of the model
In Diagram’s overview control, we can restrict the movement of viewport outside the model. It can be achieved by customizing the Diagram’s “OverviewControl” class. From the customized class, override the draw method and draw the “ViewPort” logically based on the model area.
Here is the code example for restricting to move the viewport as outside of the model.
[C#]
protected override void DrawViewport(Graphics grfx)
{
if (Diagram.View != null)
{
if ((ViewportBounds.X + ViewportBounds.Width > rcDisplayArea.X + rcDisplayArea.Width || ViewportBounds.X < rcDisplayArea.X)
|| (ViewportBounds.Y + ViewportBounds.Height > rcDisplayArea.Y + rcDisplayArea.Height || ViewportBounds.Y < rcDisplayArea.Y))
{
float heightDiff = 0;
float widthDiff = 0;
PointF pt = PointF.Empty;
if (ViewportBounds.X + ViewportBounds.Width > rcDisplayArea.X + rcDisplayArea.Width)
{
//to Prevent move the viewport in right
widthDiff = (ViewportBounds.X + ViewportBounds.Width) - (rcDisplayArea.X + rcDisplayArea.Width);
pt.X = ViewportBounds.X - widthDiff;
}
else
{
//To prevent move the viewport in top
if (ViewportBounds.X < rcDisplayArea.X)
{
widthDiff = rcDisplayArea.X - ViewportBounds.X;
}
pt.X = ViewportBounds.X + widthDiff;
}
if (ViewportBounds.Y + ViewportBounds.Height > rcDisplayArea.Y + rcDisplayArea.Height)
{
//to prevent move the viewport in bottom
heightDiff = (ViewportBounds.Y + ViewportBounds.Height) - (rcDisplayArea.Y + rcDisplayArea.Height);
pt.Y = ViewportBounds.Y - heightDiff;
}
else
{
//To prevent move the viewport in left
if (ViewportBounds.Y < rcDisplayArea.Y)
{
heightDiff = rcDisplayArea.Y - ViewportBounds.Y;
}
pt.Y = ViewportBounds.Y + heightDiff;
}
SizeF size = ViewportBounds.Size;
if (size.Width > rcDisplayArea.Width)
size.Width = rcDisplayArea.Width;
if (size.Height > rcDisplayArea.Height)
size.Height = rcDisplayArea.Height;
ViewportBounds = new RectangleF(pt.X, pt.Y, size.Width, size.Height);
if (!(this.Diagram.Size.Width == 0 || this.Diagram.Size.Height == 0))
{
this.vpRenderer.DrawViewport(grfx, this.ForeColor);
}
}
else
{
base.DrawViewport(grfx);
}
}
}
[VB]
Protected Overrides Sub DrawViewport(ByVal grfx As Graphics) If Diagram.View IsNot Nothing Then If (ViewportBounds.X + ViewportBounds.Width > rcDisplayArea.X + rcDisplayArea.Width OrElse ViewportBounds.X < rcDisplayArea.X) OrElse (ViewportBounds.Y + ViewportBounds.Height > rcDisplayArea.Y + rcDisplayArea.Height OrElse ViewportBounds.Y < rcDisplayArea.Y) Then Dim heightDiff As Single = 0 Dim widthDiff As Single = 0 Dim pt As PointF = PointF.Empty If ViewportBounds.X + ViewportBounds.Width > rcDisplayArea.X + rcDisplayArea.Width Then 'to Prevent move the viewport in right widthDiff = (ViewportBounds.X + ViewportBounds.Width) - (rcDisplayArea.X + rcDisplayArea.Width) pt.X = ViewportBounds.X - widthDiff Else 'To prevent move the viewport in top If ViewportBounds.X < rcDisplayArea.X Then widthDiff = rcDisplayArea.X - ViewportBounds.X End If pt.X = ViewportBounds.X + widthDiff End If If ViewportBounds.Y + ViewportBounds.Height > rcDisplayArea.Y + rcDisplayArea.Height Then 'to prevent move the viewport in bottom heightDiff = (ViewportBounds.Y + ViewportBounds.Height) - (rcDisplayArea.Y + rcDisplayArea.Height) pt.Y = ViewportBounds.Y - heightDiff Else 'To prevent move the viewport in left If ViewportBounds.Y < rcDisplayArea.Y Then heightDiff = rcDisplayArea.Y - ViewportBounds.Y End If pt.Y = ViewportBounds.Y + heightDiff End If Dim size As SizeF = ViewportBounds.Size If size.Width > rcDisplayArea.Width Then size.Width = rcDisplayArea.Width End If If size.Height > rcDisplayArea.Height Then size.Height = rcDisplayArea.Height End If ViewportBounds = New RectangleF(pt.X, pt.Y, size.Width, size.Height) If Not(Me.Diagram.Size.Width = 0 OrElse Me.Diagram.Size.Height = 0) Then Me.vpRenderer.DrawViewport(grfx, Me.ForeColor) End If Else MyBase.DrawViewport(grfx) End If End If End Sub
Here is the sample for restricting to move the viewport as outside of the model.
