How can I capture the mouse when resizing a floating DocumentWindow or ToolWindow?

Hi Craig,

Unfortunately we don't expose any events for resizing.  But anyhow, in your case, it seems like the inner control should be using standard WPF drag/drop features instead of handling random mouse events over it.  Can you rework it to do that?

To my knowledge, my control is using standard WPF patterns for drag and drop. To be more specific, I use PreviewMouseDown and MouseMove events to know if the user intends to initiate a drag. This matches the technique Jaime Rodriguez describes in his Drag and Drop WPF article.

I expect that when resizing floating windows, the mouse is automatically captured to prevent underneath controls from intercepting mouse events (whether for D&D or any other reason). 

Questions:

1. Using Snoop, it appears that resize occurs by dragging the floating window's WindowInner{x}Border, where x is Left, Top, Right, or Bottom. Assuming that's the case, is there a way I can access those Rectangles so I can attach the appropriate event handlers and have the mouse captured on MouseDown and released on MouseUp?
2. I experimented with using a RaftingWindow style to capture MouseDown events on a floating window. I figured if I could at least determine that the user is clicking on the window, then I could try to determine if they're at the window's edge and capture the mouse if appropriate. However, the MouseDown never fired. Is RaftingWindow the right style type to use to capture mouse downs for floating windows?

-Craig

Hi Craig,

I'm not sure a mouse capture would be good here.  The reason being that for rafting windows, we actually call the Windows API and start a resize operation via that.  So the system is handling it from that point on, not WPF.

I believe the WindowControl that is in RaftingWindow is what actually gets the mouse.  It handles its OnPreviewMouseLeftButtonDown method and raises a DragResizing event when a resize start is detected.  RaftingWindow handles that and does the above-mentioned logic to start the actual resize via Windows API.

I still don't understand how the mouse down is able to start your drag/drop code though.  If the mouse is over the rafting window when it is pressed, how would that mouse down event get to your other control elsewhere to tell it to prep for a drag?

Your last question (regarding how the mouse down event could even be interferring) got me down the right path. Both in Jaime's example and in my code, the MouseMove event assumes that if the mouse button is down, then we're good to go for D&D. But both samples neglected to consider that the mouse button could be down due to a different source, such as the floating window, in which case D&D shouldn't begin.

Thanks again,

-Craig