Delphi: how to draw small icons in List View on CustomDrawItem

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悲哀的现实
悲哀的现实 2021-01-16 12:12

how to extend this code: ListView in vsReport mode colouring of Items and rows to draw small icons?

and why do I have the error \'List index out of bounds (2)\' if I

1条回答
  •  说谎
    说谎 (楼主)
    2021-01-16 12:16

    There are many ways to draw the icons, depending on where they come frome (a file, a resource, a system icon, etc.) and depending on if there should be a single icon for all items or if every item has its own icon. Anyhow, the general idea should be clear from this extended version of the code in the previous question (and I have also fixed the out-of-bounds bug...):

    type
      TForm1 = class(TForm)
      ...
      private
        { Private declarations }
        bm: TBitmap;
      ...
      end;
    
    ...
    
    implementation
    
    ...
    
    procedure TForm1.FormCreate(Sender: TObject);
    begin
      bm := TBitmap.Create;
      bm.LoadFromFile('C:\Users\Andreas Rejbrand\Desktop\img.bmp');
    end;
    
    procedure TForm1.ListView1DrawItem(Sender: TCustomListView; Item: TListItem;
      Rect: TRect; State: TOwnerDrawState);
    var
      i: Integer;
      x1, x2: integer;
      r: TRect;
      S: string;
    const
      DT_ALIGN: array[TAlignment] of integer = (DT_LEFT, DT_RIGHT, DT_CENTER);
    begin
      if Odd(Item.Index) then
      begin
        Sender.Canvas.Font.Color := clBlack;
        Sender.Canvas.Brush.Color := $F6F6F6;
      end
      else
      begin
        Sender.Canvas.Font.Color := clBlack;
        Sender.Canvas.Brush.Color := clWhite;
      end;
      Sender.Canvas.Brush.Style := bsSolid;
      Sender.Canvas.FillRect(Rect);
      x1 := 0;
      x2 := 0;
      r := Rect;
      Sender.Canvas.Brush.Style := bsClear;
      Sender.Canvas.Draw(3, r.Top + (r.Bottom - r.Top - bm.Height) div 2, bm);
      for i := 0 to ListView1.Columns.Count - 1 do
      begin
        inc(x2, ListView1.Columns[i].Width);
        r.Left := x1;
        r.Right := x2;
        if i = 0 then
        begin
          S := Item.Caption;
          r.Left := bm.Width + 6;
        end
        else
          S := Item.SubItems[i - 1];
        DrawText(Sender.Canvas.Handle,
          S,
          length(S),
          r,
          DT_SINGLELINE or DT_ALIGN[ListView1.Columns[i].Alignment] or
            DT_VCENTER or DT_END_ELLIPSIS);
        x1 := x2;
      end;
    end;
    

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