How Do I Control The Viewport Of A Grid In Wxpython?

I'm trying to implement Find functionality in my grid application. I can move the cursor using SetGridCursor(self, row, col), but I can't figure out how to move the 'viewport' of t

Solution 1:

In situations like this, have a look at which methods are exposed by wxWidgets (the core C++ library). wxGrid subclasses wxScrolled. wxScrolled exposes these methods:

• Scroll

  Scrolls a window so the view start is at the given point.

• GetVirtualSize

  Gets the size in device units of the scrollable window area (as opposed to the client size, which is the area of the window currently visible).

I think you can use these methods to calculate the center coordinates of the scrollable window. Now, what you need is the coordinates of the cell you would like to center on. wxGrid exposes this method:

• CellToRect

  Return the rectangle corresponding to the grid cell's size and position in logical coordinates.

Now, in C++ you would cast your wxGrid to a wxScrolled and call the methods you want. However, wxPython does not always expose all methods available in wxWidgets, so here is where you have to get a little creative using unbound methods. Below is some pseudocode, it is untested, but should give you an idea on how to do this.

grid = wx.Grid()

cell_coords = grid.CellToRect(12,12)

# get the virtual size by calling it as unbound method
virtual_size = wx.Scrolled.GetVirtualSize(grid)

# calculate the upper-left coordinate
scroll_coords = (cell_coords.x - virtual_size.width / 2,
                 cell_coords.y - virtual_size.height / 2)

# call Scroll as unbound method
wx.Scrolled.Scroll(grid, scroll_coords)

Solution 2:

This works for me for vertical scrolling to keep the grid cursor in the middle of the page:

defset_grid_cursor(grid, irow, icol):
    # move the cursor to the cell as usual
    grid.GoToCell(irow, icol)
    # scroll to keep irow in the middle of the page
    ppunit = grid.GetScrollPixelsPerUnit()
    cell_coords = grid.CellToRect(irow, icol)
    y = cell_coords.y / ppunit[1]  # convert pixels to scroll units
    scrollPageSize = grid.GetScrollPageSize(wx.VERTICAL)
    scroll_coords = (0, y - scrollPageSize / 2)
    grid.Scroll(scroll_coords)

You might have to call that using wx.CallAfter(set_grid_cursor, grid, irow, icol) if you just updated the grid.