ChartListbox item background color
lazarus / 55-TAChart

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wp · 2011-10-24 06:59

When I change the color of a TChartListbox the background of the text
items still gets painted in the clWindow color. It should be
transparent instead. The legend and LegendPanel are ok.

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Ask · 2011-10-24 07:34

Fixed in r33065

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wp · 2011-10-24 10:37

Thank you for the quick fix. Before posting I had tried to set the
Brush.Style of the TCanvasDrawer to bsClear. But this did not compile.
Doesn't the TCanvasDrawer have a brush?

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Ask · 2011-10-24 14:30

It has SetBrush method, but not Brush property.
In this case, the fix should affect both branches of the following
"if" statement,
and only one of those uses drawer interface.

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wp · 2011-11-23 23:08

With the Canvas.Brush.Style set to bsClear the selected list box item
is hard to read on the default clWindow-colored item background. It is
better to use the Listbox color for the item background instead of
painting it transparently. Also, the owner-draw state must be checked.

Please the following code in TChartListbox.DrawItem

Code: [Select]procedure TChartListbox.DrawItem
  ....
  // Unused(AState);  ---- remove, it is no longer unused.
  ....
  //    Canvas.Brush.Style := bsClear;
  if not (odSelected in AState) then
    Canvas.Brush.Color := Color;   
  ....

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Ask · 2011-12-07 04:48

Should be fixed in r34016.

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wp · 2011-12-07 22:13

Sorry, it's not working. Just set the color of the Listbox to
something that is not white -- the items will have a white background,
but the rest of the listbox has the new background color. See the
attached screen shots.

This code works fine for me (although the selection highlights only
the text):
Code: [Select]procedure TChartListbox.DrawItem(
  AIndex: Integer; ARect: TRect; AState: TOwnerDrawState);
{ draws the listbox item }
const
  UNTHEMED_FLAGS: array [TCheckboxesStyle, Boolean] of Integer = (
    (DFCS_BUTTONCHECK, DFCS_BUTTONCHECK or DFCS_CHECKED),
    (DFCS_BUTTONRADIO, DFCS_BUTTONRADIO or DFCS_CHECKED)
  );
  THEMED_FLAGS: array [TCheckboxesStyle, Boolean] of TThemedButton = (
    (tbCheckBoxUncheckedNormal, tbCheckBoxCheckedNormal),
    (tbRadioButtonUnCheckedNormal, tbRadioButtonCheckedNormal)
  );
var
  id: IChartDrawer;
  rcb, ricon: TRect;
  te: TThemedElementDetails;
  x: Integer;
  ch: Boolean;
begin
  Unused(AState);

  if FChart = nil then exit;

  CalcRects(ARect, rcb, ricon);

  if cloShowCheckboxes in Options then begin
    ch := Checked[AIndex];
    if ThemeServices.ThemesEnabled then begin
      te := ThemeServices.GetElementDetails(THEMED_FLAGS[FCheckStyle,
ch]);
      ThemeServices.DrawElement(Canvas.Handle, te, rcb);
    end
    else
      DrawFrameControl(
        Canvas.Handle, rcb, DFC_BUTTON, UNTHEMED_FLAGS[FCheckStyle,
ch]);
    x := rcb.Right;
  end
  else
    x := ARect.Left;

  if not (odSelected in AState) then
    Canvas.Brush.Color := Color;
  if cloShowIcons in Options then begin
    id := TCanvasDrawer.Create(Canvas);
    id.Pen := Chart.Legend.SymbolFrame;
    FLegendItems[AIndex].Draw(id, ricon);
  end
  else
    Canvas.TextOut(x + 2, ARect.Top, FLegendItems.Items[AIndex].Text);
end;

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Ask · 2011-12-08 00:19

I see. My previous change has only fixed drawing of the selected item.
Now the bug is actually in TCustomListbox code, I have submitted the
patch:
http://bugs.freepascal.org/view.php?id=20837

If for some reason the patch will be rejected,
we can work around the problem in the way you suggested.

Edit: patch applied, please test.

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wp · 2011-12-09 20:01

Thank you - it's fine now.