delphi group box caption color change

问题:

I m using BDS 2006 and would like to know if u can change the color of Group-box and radio group captions with XPmanifest present in the Project(because it is Always blue in color).

回答1:

The only way to this is overriding the Paint method of the TGroupBox.

Check this sample which uses a Interposer class

type
  TGroupBox = class(StdCtrls.TGroupBox) //declare this before of your form definition
  public
    procedure Paint; override;
  end;

uses
 Themes;

{ TGroupBox }

procedure TGroupBox.Paint;
var
  H: Integer;
  R: TRect;
  Flags: Longint;
  CaptionRect,
  OuterRect: TRect;
  Size: TSize;
  Box: TThemedButton;
  Details: TThemedElementDetails;
begin
  with Canvas do
  begin
    Font := Self.Font;

    if ThemeControl(Self) then
    begin
      if Text <> '' then
      begin
        GetTextExtentPoint32(Handle, PChar(Text), Length(Text), Size);
        CaptionRect := Rect(0, 0, Size.cx, Size.cy);
        if not UseRightToLeftAlignment then
          OffsetRect(CaptionRect, 8, 0)
        else
          OffsetRect(CaptionRect, Width - 8 - CaptionRect.Right, 0);
      end
      else
        CaptionRect := Rect(0, 0, 0, 0);

      OuterRect := ClientRect;
      OuterRect.Top := (CaptionRect.Bottom - CaptionRect.Top) div 2;
      with CaptionRect do
        ExcludeClipRect(Handle, Left, Top, Right, Bottom);
      if Enabled then
        Box := tbGroupBoxNormal
      else
        Box := tbGroupBoxDisabled;
      Details := ThemeServices.GetElementDetails(Box);
      //Draw the themed frame
      ThemeServices.DrawElement(Handle, Details, OuterRect);    
      SelectClipRgn(Handle, 0);
      if Text <> '' then
      begin
         H := TextHeight('0');
         if not UseRightToLeftAlignment then
           R := Rect(8, 0, 0, H)
         else
           R := Rect(R.Right - Canvas.TextWidth(Text) - 8, 0, 0, H);
         Flags := DrawTextBiDiModeFlags(DT_SINGLELINE);
         //Now using the Windows.DrawText 
         DrawText(Handle, PChar(Text), Length(Text), R, Flags or DT_CALCRECT);
         Brush.Color := Color;//background color of the caption
         Font.Color := clRed;//the color of the caption.
         DrawText(Handle, PChar(Text), Length(Text), R, Flags);
      end;
    end
    else
    inherited;   //if the control is not themed then use the original paint method.
  end;
end;