- dc.SetPen(*wxBLACK_PEN);
- dc.DrawLine(xpos, ypos, pt.x, pt.y);
+ wxClientDC dc(this);
+
+ wxPoint pt(event.GetPosition());
+
+ // if negative positions are possible then shift everything up
+ int xmin = wxGetApp().m_minX;
+ int xmax = wxGetApp().m_maxX;
+ int ymin = wxGetApp().m_minY;
+ int ymax = wxGetApp().m_maxY;
+ if (xmin < 0) {
+ xmax += abs(xmin);
+ pt.x += abs(xmin);
+ }
+ if (ymin < 0) {
+ ymax += abs(ymin);
+ pt.y += abs(ymin);
+ }
+
+ // Scale to canvas size
+ int cw, ch;
+ GetSize(&cw, &ch);
+
+ pt.x = (long) (((double)pt.x/(double)xmax) * cw);
+ pt.y = (long) (((double)pt.y/(double)ymax) * ch);
+
+ if (xpos > -1 && ypos > -1 && event.IsMove() && event.ButtonIsDown())
+ {
+ dc.SetPen(*wxBLACK_PEN);
+ dc.DrawLine(xpos, ypos, pt.x, pt.y);
+ }
+
+ xpos = pt.x;
+ ypos = pt.y;