Fixed Size Nodes (Icons)

GoDiagram (6 and previous)
1

OK I am stuck.
What I Want … I would like to have the nodes in my view remain a fixed screen size as I zoom in and out. In other words I want to tie the nodes to a position in document coordinates but not the width and the height. I would like the nodes to be represented as icons.
What I Have Now … We have an application where we have created subclasses of GoSimpleNode to represent the nodes in our view. There is a significant amount of code invested here so I would like to stay with GoSimpleNode if possible. But if I have to change parent classes that would be OK but a last resort.
What I have Tried … I have tried overriding the Paint method in my subclass of GoSimpleNode and messing with the Graphics.Transform matrix. While I can get the node to draw at a fixed size, it seems to get clipped sometimes. In addition the selection meachanism does not work properly at all. The selection handle still gets drawn larger on zoom in and smaller on zoom out relative to my icon. Here is the Paint override that I tried.
public override void Paint(Graphics g, GoView view)
{

System.Drawing.Drawing2D.Matrix t = g.Transform; g.Transform = new System.Drawing.Drawing2D.Matrix(1.0f, 0.0f, 0.0f, 1.0f, t.OffsetX, t.OffsetY);

base.Paint (g, view);
g.Transform = t;


}
Any help would be appreciated.
John

2

It might be easier not to change the GoView.DocScale at all, but to just change the Position of the nodes as if you were zooming in and out.
Don’t forget to change the standard control-mouse-wheel behavior, which is implemented by GoToolManager.DoMouseWheel, which calls GoView.DoWheel to change the view’s DocScale. You can either install your own subclass of GoToolManager as the GoView.DefaultTool, overriding DoMouseWheel, or you can override GoView.DoWheel, depending on how you want to organize your code.
You will want to do such node position changes while GoDocument.SkipsUndoManager is true, so that undo/redo won’t appear to “zoom”. Hmmm, I wonder if there are any other ramifications. I haven’t tried this.

3

I am also interested in achieving this. Unfortunately we have an image background that we want to scale, but we want the nodes and their text labels to stay the same size, as mentioned above. Is overriding paint the only option here? Much thanks.

4

No, I still think changing the positions of the nodes while leaving the GoView.DocScale alone, is the right thing to do.

In your case, instead of using the GoView.BackgroundImage property, you can create a GoImage and add it to the GoView.BackgroundLayer. Then when you fake-zoom in or out, you can adjust the Size of that GoImage accordingly.