wxruby users - Dec 2004 - Scrolling to the bottom of a Grid

Hi,

Thanks to the newly added event handlers for Wx::Grid in the 0.6.0 
release, I can now provide a much slicker intreface to my "data
widgets"
which heavily rely on that control. 

However, I haven''t quite figured out how to programmatically scroll to 
the last row of  a populated grid (actually, the first empty row). So 
say that I have a grid with 200 rows only 20 of which are visible at any 
given time. If say 80 of these rows are currently populated with some 
data and the top 20 are being viewed. Now, I have to provide "Add" 
functionality via a button which when clicked, the grid should scroll to 
the 81st row so that it comes in the view (say towards the top).  How do 
I go about doing that?

I tried grid.set_scroll_y( ) but it did not seem to work. Then I tried 
grid.move_page_down() which worked, but I could not figure out how to 
know when to stop.

Any ideas?
-- shanko

Hi Shanko,

wxGrid inherits from wxScrolledWindow, so try the "scroll" method.

Nick


Shashank Date wrote:
> Hi,
> 
> Thanks to the newly added event handlers for Wx::Grid in the 0.6.0 
> release, I can now provide a much slicker intreface to my "data
widgets"
> which heavily rely on that control.
> However, I haven''t quite figured out how to programmatically
scroll to
> the last row of  a populated grid (actually, the first empty row). So 
> say that I have a grid with 200 rows only 20 of which are visible at any 
> given time. If say 80 of these rows are currently populated with some 
> data and the top 20 are being viewed. Now, I have to provide
"Add"
> functionality via a button which when clicked, the grid should scroll to 
> the 81st row so that it comes in the view (say towards the top).  How do 
> I go about doing that?
> 
> I tried grid.set_scroll_y( ) but it did not seem to work. Then I tried 
> grid.move_page_down() which worked, but I could not figure out how to 
> know when to stop.
> 
> Any ideas?
> -- shanko
> _______________________________________________
> wxruby-users mailing list
> wxruby-users@rubyforge.org
> http://rubyforge.org/mailman/listinfo/wxruby-users
> 
> 
>

Nick wrote:
> Hi Shanko,
>
> wxGrid inherits from wxScrolledWindow, so try the "scroll"
method.
Thanks, Nick.  I will work in that direction. Like I said earlier, I
haven''t figured out how to know how much to scroll.
Of course, I can always find out how many rows are populated , multiply
that by the size in pixels of each row, convert the pixels into scroll
units and then scroll those many units. But that is too much of work ;-)

I was wondering if there is a smarter way of doing this.
Thanks again,
-- shanko

On Fri, 2004-12-10 at 06:59 -0600, Shashank Date wrote:
> Thanks, Nick.  I will work in that direction. Like I said earlier, I
> haven''t figured out how to know how much to scroll.
> Of course, I can always find out how many rows are populated , multiply
> that by the size in pixels of each row, convert the pixels into scroll
> units and then scroll those many units. But that is too much of work ;-)
And it may not work. At least the way I read the wxGrid docs, each row
could be a different size, so you would have to loop through, adding up
each row''s height.

Another crude approach might be to call move_cursor_down once for each
row you want to scroll by. But hopefully you won''t need do do that,
because...
> I was wondering if there is a smarter way of doing this.
Just looking at the wxWindows docs (not at wxRuby itself), it looks like
you want wxGrid::CellToRect. Given a cell (row/col), it should return
the logical X/Y position, which you could pass to scroll(x,y) [inherited
from ScrolledWindow], or set_scroll_y (if it works), or at worst, to
know when to stop calling move_page_down.

Kevin

Hi,

Kevin Smith wrote:
>Another crude approach might be to call move_cursor_down once for each
>row you want to scroll by.
>
That approach, although crude, worked  like a charm.

Since none of the grids I am having are larger than few hundred rows, it 
is OK for now.
>But hopefully you won''t need do do that,
>because...
>
>  
>
>>I was wondering if there is a smarter way of doing this.
>>    
>>
>
>Just looking at the wxWindows docs (not at wxRuby itself), it looks like
>you want wxGrid::CellToRect. Given a cell (row/col), it should return
>the logical X/Y position, which you could pass to scroll(x,y) [inherited
>from ScrolledWindow], or set_scroll_y (if it works), or at worst, to
>know when to stop calling move_page_down.
>  
>
I could not get it to work. I could be missing something. See example 
below (modified grid sample
with the non-working code commented out).

I am on Win XP (Home) using the  latest one-click installer  and wxRuby 
0.6.0

Thanks, Kevin.
>Kevin
>  
>
-- shanko

#################################################################

require ''wxruby''

class MyFrame < Wx::Frame

  def initialize(parent, id = -1, title = "MyFrame",
                 pos   = Wx::DEFAULT_POSITION,
                 size  = Wx::DEFAULT_SIZE,
                 style = Wx::DEFAULT_FRAME_STYLE)

    super(parent, id, title, pos, size, style)

    create_status_bar()
    set_status_text(Wx::VERSION_STRING)

    panel = Wx::Panel.new(self)
    btn = Wx::Button.new(panel, :btn.id, "Add",
                         Wx::Point.new(10, 300),Wx::Size.new(50,30))
    evt_button(:btn.id){|event| on_button_add(event)}
   
    make_grid(panel)
   
    populate_grid()
       
    evt_grid_cell_left_click() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} is clicked")
      evt.skip
    end

    evt_grid_cell_right_click() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} is right
clicked")
      evt.skip
    end

    evt_grid_cell_left_dclick() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} is double
clicked")
      evt.skip
    end

    evt_grid_cell_right_dclick() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} is right double 
clicked")
      evt.skip
    end

    evt_grid_label_left_click() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} label is
clicked")
      evt.skip
    end

    evt_grid_label_right_click() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} label is right 
clicked")
      evt.skip
    end

    evt_grid_label_left_dclick() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} labelis double 
clicked")
      evt.skip
    end

    evt_grid_label_right_dclick() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} label is right 
double clicked")
      evt.skip
    end

    evt_grid_select_cell() do |evt|
      set_status_text("#{evt.get_row} x #{evt.get_col} cell is
selected")
      evt.skip
    end
   
    evt_grid_row_size do |evt|
      set_status_text("Row #{evt.get_row_or_col} size changed")
      evt.skip
    end

    evt_grid_col_size do |evt|
      set_status_text("Column #{evt.get_row_or_col} size changed")
      evt.skip
    end

    evt_grid_editor_shown do |evt|
      set_status_text("Begin editing")
      evt.skip
    end

    evt_grid_editor_hidden do |evt|
      set_status_text("End editing")
      evt.skip
    end

    evt_grid_range_select do |evt|
      top = evt.get_top_left_coords
      bottom = evt.get_bottom_right_coords
      set_status_text("[ #{top[0].to_s} x #{top[1].to_s} ] to [ 
#{bottom[0].to_s} x #{bottom[1].to_s} ] is selected")
    end

    evt_grid_editor_created do |evt|
      set_status_text("Control #{evt.get_control} created")
      evt.skip
    end

    evt_grid_cell_change() do |evt|
      set_status_text("Cell #{evt.get_row} x #{evt.get_col} has
changed")
    end
  end
 
  def on_button_add(event)
 
    @grid.set_grid_cursor(0,0)
   
    @grid.get_number_rows.times{|i|
      val = @grid.get_cell_value(i,0)
      @grid.move_cursor_down(false) if val.to_s.length > 0
    }
 
#    rect=@grid.cell_to_rect(10,1)
#    x,y = rect.x, rect.y
#    @grid.scroll(x,y)
#   
#    row = @grid.y_to_row(y)
#    col = @grid.x_to_col(x)
#   
#    Wx::message_box("(#{x},#{y}) (#{row},#{col})","(x,y)
(row,col)")

  rescue
    Wx::message_box($!.to_s,"add")
  end

  def make_grid(panel)
 
      # Create a wxGrid object
      @grid = Wx::Grid.new(panel, :grid.id, Wx::Point.new(10,10),
                                        Wx::Size.new(925,275))

      # Then we call CreateGrid to set the dimensions of the grid
      # (11 rows and 12 columns in this example)
      @grid.create_grid( 51, 12 )

      # We can set the sizes of individual rows and columns
      # in pixels, and the label value string
      @grid.set_row_size( 1, 40 )
      @grid.set_row_size( 9, 30 )
      @grid.set_row_label_value( 0, "Row1" )
      @grid.set_row_label_alignment(Wx::ALIGN_CENTRE, Wx::ALIGN_CENTRE)
           
      @grid.set_col_size( 0, 120 )
      @grid.set_col_label_value( 0, "Col1" )
      @grid.set_col_label_alignment(Wx::ALIGN_CENTRE, Wx::ALIGN_CENTRE)
     
      # And set grid cell contents as strings
      @grid.set_cell_value( 0, 0, "wxGrid is good" )

      # We can specify that some cells are read-only
      @grid.set_cell_value( 0, 3, "This is read-only" )
      @grid.set_read_only( 0, 3 )

      # Colours can be specified for grid cell contents
      @grid.set_cell_value(3, 3, "white on black")
      @grid.set_cell_text_colour(3, 3, Wx::WHITE)
      @grid.set_cell_background_colour(3, 3, Wx::BLACK)

      # We can specify the some cells will store numeric
      # values rather than strings. Here we set grid column 5
      # to hold floating point values displayed with width
      # of 6 and precision of 2
      @grid.set_col_format_float(5, 6, 2)
      @grid.set_cell_value(0, 6, "3.1415")
  end
 
  def populate_grid()
     %w{one two three four five six seven
        eight nine ten eleven twelve}.each_with_index do|val,i|   
          @grid.set_cell_value( i, 0, val)
     end
  end
 
end

class MyApp < Wx::App
    def on_init
        frame = MyFrame.new(nil, -1, "Grid Sample",
                            Wx::Point.new(10, 100),
                            Wx::Size.new(1000,400))
        frame.show(TRUE)
       
        set_top_window(frame)
    end
end

app = MyApp.new
app.main_loop()


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On Sat, 11 Dec 2004 22:38:46 -0600, Shashank Date <sdate@everestkc.net>
wrote:
> I could not get it to work. I could be missing
> something. See example below (modified grid sample
>  with the non-working code commented out).
>  
>  I am on Win XP (Home) using the  latest one-click installer  and wxRuby
> 0.6.0
[snip]
>   def on_button_add(event)
>  
>     @grid.set_grid_cursor(0,0)
>    
>     @grid.get_number_rows.times{|i|
>       val = @grid.get_cell_value(i,0)
>       @grid.move_cursor_down(false) if val.to_s.length > 0
>     }
>  
> #    rect=@grid.cell_to_rect(10,1)
> #    x,y = rect.x, rect.y
> #    @grid.scroll(x,y)
> #   
> #    row = @grid.y_to_row(y)
> #    col = @grid.x_to_col(x)
> #   
It shoud be simply:
    @grid.move_cursor_down_block(false)   # move to last cell that has content
    @grid.move_cursor_down(false)            # move one row down


If you know the cell you want to move to (and not just the last cell
with content) use:
    @grid.set_grid_cursor row, col
    @grid.scroll col, row

Notice that the parameters to #scroll and #set_grid_cursor are
inverted. Both are zero-based.
I didn''t see #scroll in the docs, but it recieves the number of of the
col and row, not the screen parameters. It will position itself so
that the cell is at the bottom of the screen.

You can also use;
  @grid.make_cell_visible col, row

which will place the visible cell 3 rows from the bottom.

Works for me on WinXP, wxRuby 0.6.

Cheers,
Assaph

Hi Assaph,
>
>It shoud be simply:
>    @grid.move_cursor_down_block(false)   # move to last cell that has
content
>    @grid.move_cursor_down(false)         # move one row down
>  
>
That worked perfectly!
>If you know the cell you want to move to (and not just the last cell
>with content) use:
>    @grid.set_grid_cursor row, col
>    @grid.scroll col, row
>  
>
Oh, and I was passing (x,y) values to scroll instead of (col,row). That
worked too ...
>I didn''t see #scroll in the docs, but it recieves the number of of
the
>col and row, not the screen parameters. It will position itself so
>that the cell is at the bottom of the screen.
>  
>
I always refer to the wxWindows documentation if I don''t find it in
wxRuby docs.
I guess the wxWindows docs has this wrong then ... or is it one of those
places where wxRuby is different from wxWindows?
>You can also use;
>  @grid.make_cell_visible col, row
>  
>
Ah ha ! That worked too ...
>which will place the visible cell 3 rows from the bottom.
>Works for me on WinXP, wxRuby 0.6.
>  
>
Thanks Assaph for offering so many ways to do so many different things.
>Cheers,
>Assaph
>  
>
-- shanko