How to draw components' bitmaps appeared in Delphi palette?    資料來源: www.delphi3000.com    Example below demonstrates drawing components images in combo box items. Combo box is filled with names of all components placed on form. See comments in source for description of each action.     Source: 

// Add LibIntf unit into uses clause of your unit.     // Add this definition for Delphi version detection, just for better reading 
{$IFDEF VER90} 
  {$DEFINE DELPHI2} 
{$ENDIF}     {$IFDEF VER100} 
  {$DEFINE DELPHI3} 
{$ENDIF}     {$IFDEF VER120} 
  {$DEFINE DELPHI3} 
  {$DEFINE DELPHI4} 
{$ENDIF}     {$IFDEF VER130} 
  {$DEFINE DELPHI3} 
  {$DEFINE DELPHI4} 
{$ENDIF}     procedure TDlgForm.cbComponentsDrawItem(Control: TWinControl; 
Index: Integer; Rect: TRect; State: TOwnerDrawState); 
var 
ARect: TRect; 
{$IFDEF DELPHI3} 
PIt: LibIntf.TIPaletteItem; 
{$ENDIF} 
{$IFDEF DELPHI4} 
PIt: LibIntf.IPaletteItem; 
{$ENDIF} 
B, tmpBmp: TBitmap; 
{$IFDEF DELPHI2 } 
tmpImList: TImageList; 
{$ENDIF} 
SName: string; 
begin 
  with cbComponents.Canvas do begin         Brush.Color := cbComponents.Color; 
    Brush.Style := bsSolid; 
    FillRect(Rect); 
    tmpBmp := TBitmap.Create; 
    B := TBitmap.Create; 
    try 
      SName := cbComponents.Items[Index]; 
      B.Width:=24; B.Height:=24; 
      {$IFDEF DELPHI3}     
//Under Delphi 3 or later we should use routines from LibIntf unit 
      PIt:=LibIntf.DelphiIDE.GetPaletteItem(TComponentClass(GetClass(Comp.Owner.FindComponent(SName).ClassName))); 
// Drawing component image on our bitmap canvas 
      PIt.paint(B.Canvas,0,0); 
      tmpBmp.Assign(B); 
      {$ENDIF} 
      ARect := Bounds(0, 0, 24, 24); 
      {$IFDEF DELPHI2} 
// Detecting the class name of component 
      SName := TComponent(Comp.Owner.FindComponent(SName)).ClassName; 
// Loading bitmap image from resources since it is linked to cmplib32.dcl 
      B.LoadFromResourceName(hInstance, UpperCase(PChar(SName))); 
      tmpBmp.Width:=22; tmpBmp.Height:=22; 
      BitBlt(tmpBmp.Canvas.Handle, 0, 0, 22, 22,B.Canvas.Handle, 2, 2, SRCCOPY); 
      tmpImList := TImageList.CreateSize(22, 22); 
      try 
        tmpImList.AddMasked(tmpBmp, tmpBmp.TransparentColor); 
        tmpBmp.Canvas.Brush.Color := cbComponents.Color; 
        tmpBmp.Canvas.Brush.Style := bsSolid; 
        tmpBmp.Canvas.FillRect(ARect); 
        tmpImList.Draw(tmpBmp.Canvas, 0, 0, 0); 
      finally 
        tmpImList.Free; 
      end; 
    {$ENDIF} 
    {$IFDEF DELPHI3} 
    tmpBmp.Canvas.Brush.Color := cbComponents.Color; 
    tmpBmp.Canvas.FillRect(ARect); 
    tmpBmp.Width := 24; 
    tmpBmp.Height := 24; 
    BitBlt(tmpBmp.Canvas.Handle, 0, 0, 24, 24, B.Canvas.Handle, 4, 4, SRCCOPY); 
    {$ENDIF} 
// Drawing component image on the combo box canvas 
    Draw(Rect.Left   3, Rect.Top   2, tmpBmp); 
  finally 
    tmpBmp.Free; 
    B.Free; 
  End; 
// Drawing raised rectangle if item is selected 
  if odSelected in State then begin 
    ARect := Bounds(Rect.Left   1, Rect.Top   1, 23, 23); 
    Frame3D(cbComponents.Canvas, ARect, clBtnHighlight, clBtnShadow, 1); 
    Font.Color := clHighlightText; 
    Brush.Color := clHighlight; 
    ARect := Bounds(26, Rect.Top, Rect.Right - Rect.Left - 26, Rect.Bottom - Rect.Top); 
    FillRect(ARect); 
  end 
  else 
    Font.Color := clBlack; 
  Brush.Style := bsClear; 
  TextOut(Rect.Left   27, Rect.Top   4, cbComponents.Items[Index]);       end;     end; 

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