Crainiate Community

Hello,

I found weird behavior of the control. I guess it might be a bug. I have my own mechanism of drawing a watermark on the diagram (similar to the one in the docs), which is drawn in the overrided OnPreRender method of the Render object.
Generally it works perfectly, but in one special condition I found it is probably called after the elements are drawn, because watermark is above the elements. It happens during the drag & drop operation on the elements, just after you mousedown over the element and move the mouse a little. Until you release the button the watermark is drawn on top. The same happens even if the elements movement is blocked (AllowMove = false). A semi-transparent UpdateElement is created in both situations and it's the only element that is drawn above the watermark.
 

I will look into this for you,

Best wishes,
James

When an element is updated by the user, the existing rendered diagram is cached and the semi-transparent copy of the element you see on the screen is drawn over the top. When customising the renderer, you will draw any custom rendering over this cached bitmap if you do not check the Locked property.

The updated sample from the help file should look like this

protected override void OnPreRender(System.Drawing.Graphics graphics)
{
    
    if (!Locked && Watermark != string.Empty)
    {
        SolidBrush brush = new SolidBrush(Color.FromArgb(128,Color.LightGray));
        Font font = new Font("Arial",72,FontStyle.Bold);

        graphics.TextRenderingHint = TextRenderingHint.AntiAlias;
        graphics.DrawString(Watermark, font, brush, new PointF(30,30));
        graphics.TextRenderingHint = TextRenderingHint.SystemDefault;

 

        base.OnPreRender (graphics);
    }
}