Printing a richedit with background colour - delphi

Question

I'm outputting text from a delphi TRichedit control to a printer. There is a background image, so I'm using the EM_FORMATRANGE with this logic ...
myrichedit.Perform(EM_FORMATRANGE, 1, Longint(#Range));
... and that works fine except that when the text is rendered it always has a white background regardless of the color of the richedit. Any idea why?
EDIT: From comment posted:
Range is a RANGEFORMAT, and is assigned values like this:
Range.hdc := aCanvas.Handle;
Range.hdcTarget := aCanvas.Handle;
LogX := GetDeviceCaps(Range.hdc, LOGPIXELSX);
LogY := GetDeviceCaps(Range.hdc, LOGPIXELSY);
Range.rc.Left := x * 1440 div LogX;
Range.rc.Right := (x+re.ClientWidth) * 1440 div LogX; // (1440=twips/inch)
Range.rc.Top := y * 1440 div LogY;
Range.rc.Bottom := 5000 * 1440 div LogY; // Some bigish number
Range.rcPage := Range.rc;
Range.chrg.cpMin := 0;
Range.chrg.cpMax := -1;

Answer 1

What I've found is that a solution to this is that you can set the background of individual characters with the code (before adding the text to the richedit) ...
var
Format: CHARFORMAT2;
begin
...
myrichedit.SelStart:=myrichedit.GetTextLen;
FillChar(Format, SizeOf(Format), 0);
with Format do begin
cbSize := SizeOf(Format);
dwMask := CFM_BACKCOLOR;
crBackColor := charbackgroundcolor;
myrichedit.Perform(EM_SETCHARFORMAT, SCF_SELECTION, Longint(#Format));
end;
myrichedit.SetText:='Hello';
... but to get a background color for the whole block of text then do this to draw the text ...
var
size : Tsize;
Range: TFormatRange;
Rect: TRect;
LogX, LogY : Integer;
bm : tbitmap;
aCanvas : TCanvas;
ExStyle: DWord;
begin
aCanvas:=Printer.Canvas;
Range.hdc := aCanvas.Handle;
Range.hdcTarget := aCanvas.Handle;
LogX := GetDeviceCaps(Range.hdc, LOGPIXELSX);
LogY := GetDeviceCaps(Range.hdc, LOGPIXELSY);
Range.rc.Left := x * 1440 div LogX;
Range.rc.Right := (x+myrichedit.ClientWidth) * 1440 div LogX; // (1440=twips/inch)
Range.rc.Top := y * 1440 div LogY;
Range.rc.Bottom := 5000 * 1440 div LogY; // Some bigish number
Range.rcPage := Range.rc;
Range.chrg.cpMin := 0;
Range.chrg.cpMax := -1;
myrichedit.Perform(EM_FORMATRANGE, 0, Longint(#Range)); // Measure the formatted text
rect:=Range.rc;
rect.Left:=Range.rc.Left * LogX div 1440;
rect.Top:=Range.rc.Top * LogY div 1440;
rect.Right:=Range.rc.Right * LogX div 1440;
rect.Bottom:=Range.rc.Bottom * LogY div 1440;
acanvas.Brush.Color:=myblockcolor;
acanvas.FillRect(rect); // Fill the background rectangle
ExStyle := GetWindowLong(re.Handle, GWL_EXSTYLE); // Draw richedit transparently over coloured area
ExStyle := ExStyle or WS_EX_TRANSPARENT;
SetWindowLong(re.Handle, GWL_EXSTYLE, ExStyle);
myrichedit.Perform(EM_FORMATRANGE, 1, Longint(#Range));
end;