Get cursor position in a panel with scroll bars
I've created a simple program (for now) that has a large panel as the "WorkArea" of the program. I draw a grid on it, have some functions that snap my cursor to the nearest grid point, etc. I have a status bar at the bottom of the window that displays my current position in the panel. However, no matter where I scrolled (let's say the vertical bar is 10% relative to the top and the horizontal bar is 25%), it displays my cursor position relative to the actual window.
I have an OnMouseMove event that handles this:
private void WorkArea_MouseMove(object sender, MouseEventArgs e)
{
GridCursor = grid.GetSnapToPosition(new Point(e.X, e.Y));
toolStripStatusLabel1.Text = grid.GetSnapToPosition(new Point(e.X, e.Y)).ToString();
Refresh();
}
It works as I expect, giving cursor points, drawing it to the desired location, etc. However, if I scroll, I still get the same readings. I could scroll halfway along the vertical and horizontal scrollbars, place the cursor in the top left corner, and read 0,0 when it should be something like 5000500 (on a 10k by 10k panel).
How can you get the absolute position within the panel in relation to its scrollbars?
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You need to offset the location with the scroll position:
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
Point scrolledPoint = new Point( e.X - panel1.AutoScrollPosition.X,
e.Y - panel1.AutoScrollPosition.Y);
..
}
Note that AutoScrollPosition values are negative ..:
The resulting X and Y coordinate values are negative if the control bounces from its original position (0,0). When you set this property, you should always assign positive X and Y values to set the scroll position relative to the starting position. For example, if you have a horizontal scroll bar and you set x and y to 200, you move the scroll 200 pixels to the right; if you set x and y to 100 the scroll appears to move to the left 100px because you are setting 100px from the starting position. In the first case, AutoScrollPosition returns {-200, 0}; in the second case, it returns {-100,0}.
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WinForms:
The Control.PointToClient method converts the position of the mouse relative to the control itself.
Point point = grid.PointToClient(new Point(e.X, e.Y))
WPF:
Using Mouse.GetPosition you can get the position of the mouse relative to a specific control:
Point position = Mouse.GetPosition(grid);
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