If I understand the test project correctly, GridNode only draws a bitmap. When the mouse pointer enters a node, CreateCustomEditControl adds a grid control on top of it as an editor, and mouse-leave regenerates GridNode.Image.

So if you need to create pixel-perfect alignment of the pop-over grid with GridNode.Image, you must keep in mind that WinForms can show that child grid only at integer pixel coordinates. Following seems to work well on my system:

//gridNode.Bounds = new RectangleF(10, 10, 200, 150);
gridNode.Bounds = diagramView.ClientToDoc(
	diagramView.DocToClient(new RectangleF(10, 10, 200, 150)));
 

here nested DocToClient returning pixel values, and outer ClientToDoc returning diagram coords for them. Then also shifting the grid by one pixel in CreateCustomEditControl:

if (e.Node == this)
{
    e.EditControl = GridView;
    var pixelRect = _view.DocToClient(Bounds);
    pixelRect.X += 1;
    pixelRect.Y += 1;
    e.EditControl.Bounds = pixelRect;
} 

Not sure why that's needed: either GridView.DrawToBitmap excludes border thickness, or the ClientToDoc(DocToClient) combo always rounds down, but has to round up if fraction part of coordinate is larger than 0.5. Try playing with different Bounds values to see if it's the latter case. Then you could determine whether to shift by 1 by checking the fraction part of DocToClientF result.

If you'll be aligning the node to pixels as above and letting users draw interactively, you can apply those operations from NodeCreated and NodeModified event handlers.

Some other options you might try:

- change diagram's MeasureUnit to Pixel;
- override GridView drawing code and translate by that factional part of DocToClientF before calling base;

Regards,
Slavcho
Mindfusion

e.EditControl = GridView;

var pixelRectF = _view.DocToClientF(Bounds);
var xFraction = pixelRectF.X - Math.Truncate(pixelRectF.X);
var yFraction = pixelRectF.Y - Math.Truncate(pixelRectF.Y);

var pixelRect = _view.DocToClient(Bounds);
if (xFraction >= 0.5)
    pixelRect.X += 1;
if (yFraction >= 0.5)
    pixelRect.Y += 1;

e.EditControl.Bounds = pixelRect; 

should work correctly, but I've tried it with only a few different values of gridNode.Bounds. That would still require you to align gridNode.Bounds to pixels via ClientToDoc(DocToClient) to avoid sub-pixel difference, which could show e.g. via anti-aliasing.

Regards,
Slavcho
Mindfusion

Do you call ClientToDoc(DocToClient(...)) to align to pixels from these event handlers?

Quote:

Quote:


If you mean resizing interactively, the node could lose its alignment to screen pixel once you drag the top-left corner to a new position. Try resetting e.Node.Bounds to ClientToDoc(DocToClient(e.Node.Bounds)) from NodeModified event handler to keep it aligned, as suggested in post above.

I.e. what happens in the Form_Load event from screenshot, should happen in NodeModified too, because the diagram could convert mouse location to floating point coordinates. If you let your users draw new nodes interactively, do that from NodeCreated event handler as well.

Finally, if pixel alignment is that important for your application, maybe switch Diagram.MeasureUnit to Pixel. However, the diagram could still convert mouse input to floating point coordinates if you let users change zoom level: e.g. a screen pixel with x =1 could convert to 1.5 diagram coordinate at 66% zoom level (== 1 / 1.5).

Regards,
Slavcho
Mindfusion