// start selection/resizing/moving
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
if (IsSelectionAreaPresent()) // we have selected area
{
if (!selectionArea.Contains(e.Location))
{ // we are outside of selected => erase current selection
selectionArea = new Rectangle(0, 0, 0, 0);
Invalidate();
croppingState = CroppingState.NONE;
return;
}
else // we are within the selection area
{
DragCorner dc = PointAtDragCorner(selectionArea, e.Location);
if (dc != DragCorner.NONE)
{ // we are at a corner of selection => we start resizing
croppingState = CroppingState.RESIZING; // it is a special drag, where the corners are pulled for resizing
dragPreviousPoint = e.Location; // initial previous drag location
}
else
{ // we are inside selection => we start dragging
croppingState = CroppingState.DRAGGING;
dragPreviousPoint = e.Location; // initial previous drag location
}
}
}
else // we just start selecting
{
croppingState = CroppingState.SELECTING;
selectionStartPoint = e.Location; // initial selection area location
}
}
// update selection area while on move
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
// set a cursor properly
DragCorner dragCorner = DragCorner.NONE;
if (selectionArea.Contains(e.Location)) // we are within selection area
{
dragCorner = PointAtDragCorner(selectionArea, e.Location);
switch (dragCorner)
{
case DragCorner.NE: Cursor.Current = Cursors.PanNE; break;
case DragCorner.NW: Cursor.Current = Cursors.PanNW; break;
case DragCorner.SE: Cursor.Current = Cursors.PanSE; break;
case DragCorner.SW: Cursor.Current = Cursors.PanSW; break;
default: Cursor.Current = Cursors.Hand; break; // DragCorner.NONE
}
Application.DoEvents();
}
else
{
Cursor.Current = Cursors.Default;
}
// handle base case
if (e.Button != MouseButtons.Left)
{
return;
}
// do selection area updates based on the current state
switch (croppingState)
{
case CroppingState.SELECTING:
{
// update selection area according to start and temporary end point (e.Location)
selectionArea.Location = new Point(
Math.Min(selectionStartPoint.X, e.Location.X),
Math.Min(selectionStartPoint.Y, e.Location.Y));
selectionArea.Size = new Size(
Math.Abs(selectionStartPoint.X - e.Location.X),
Math.Abs(selectionStartPoint.X - e.Location.X));
Invalidate();
break;
}
case CroppingState.DRAGGING:
{
// update selection area position with offset from dragging
int dX = e.Location.X - dragPreviousPoint.X;
int dY = e.Location.Y - dragPreviousPoint.Y;
selectionArea.Offset(dX, dY);
dragPreviousPoint = e.Location; // save for next move
Invalidate();
break;
}
case CroppingState.RESIZING: // special combination of SELECTING&DRAGGING: both size and location must be updated
{
int dX = e.Location.X - dragPreviousPoint.X;
int dY = e.Location.Y - dragPreviousPoint.Y; // we are only using dX here, as we are making square avatars currently
switch (dragCorner)
{
case DragCorner.NE:
{
selectionArea.Size = new Size(
selectionArea.Width + dX,
selectionArea.Height + dX);
selectionArea.Offset(0, -dX);
break;
}
case DragCorner.NW:
{
selectionArea.Size = new Size(
selectionArea.Width - dX,
selectionArea.Height - dX);
selectionArea.Offset(dX, dX);
break;
}
case DragCorner.SE:
{
selectionArea.Size = new Size(
selectionArea.Width + dX,
selectionArea.Height + dX);
selectionArea.Offset(0, 0);
break;
}
case DragCorner.SW:
{
selectionArea.Size = new Size(
selectionArea.Width - dX,
selectionArea.Height - dX);
selectionArea.Offset(dX, 0);
break;
}
}
dragPreviousPoint = e.Location;
Invalidate();
break;
}
}
}
