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Color to fade from bright red to dark red with RGB-function

Posted on 2003-10-26
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Last Modified: 2012-05-04
Hi,
I think this a quite easy question for an expert, but I do not manage it:
In a database I have a field where items are in that are awaited for a certain date. If the items are not back by that date the row is paint in red. Now I want that the color is not only red but a certain tone of red depending on the days the item is not in time for ex. the item is in delay for 100 days, the row is dark red, for 50 days a lighter red and so on. I tried with: brush.color:= RGB(255,0,0) and that's OK only with red. How must I insert the RGB-values to have different shades of red ?
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Question by:SCHUCla74
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Expert Comment

by:gmayo
ID: 9622474
255 is full brightness, 0 is nil. So use a value in between 0 and 255 for varying degrees of brightness. If you only use the first value, that is the red. Use a calculation to get degrees of redness for number of days.

Example:
if (DaysLate <= 0) then begin
   Brush.Color := clWhite;
end else if (DaysLate <= 100) then begin
   Brush.Color := RGB(Round(((100-DaysLate)/100) * 255), 0, 0);
end else begin
   Brush.Color := clBlack;
end;

Which gives a white background if DaysLate is zero or less, varying degrees of red to black for 1 - 100 days late, and black for over 100 days late. Alter to suit your requirements.

Geoff M.
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Accepted Solution

by:
gmayo earned 100 total points
ID: 9622475
Actually, maybe you mean white to red. In which case that should be:
if (DaysLate <= 0) then begin
  Brush.Color := clWhite;
end else if (DaysLate <= 100) then begin
  v := Round(((100-DaysLate)/100) * 255);
  Brush.Color := RGB(255, v, v);
end else begin
  Brush.Color := clRed;
end;

Geoff M.
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