给TComboBox添加图标

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最新推荐文章于 2024-11-14 15:47:52 发布

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分类专栏： Delphi 文章标签： imagelist integer forms windows class

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本文介绍如何在Delphi中使用TCombobox组件并自定义其OnDrawItem事件来显示带有图标的列表项。通过设置ComboBox的Style属性为csOwnerDrawVariable，并调整ItemHeight，可以在下拉列表中展示图标和文本。示例代码展示了如何创建与销毁位图资源，以及如何在ComboBox的绘制事件中使用这些图标。

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只要在Tcombobox的OnDrawItem事件里,绘制item的图标就可以.

代码文件:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ImgList, ComCtrls;

type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    ImageList1: TImageList;
    procedure FormCreate(Sender: TObject);
    procedure ComboBox1DrawItem(Control: TWinControl; Index: Integer;
      Rect: TRect; State: TOwnerDrawState);
    procedure FormDestroy(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  Bits: array[0..3] of TBitmap;

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  for i := 0 to Length(Bits)-1 do
  begin
    Bits[i] := TBitmap.Create;
    ImageList1.GetBitmap(i, Bits[i]);
    ComboBox1.Items.Add(Format('Item %d', [i]));
  end;

  ComboBox1.Style := csOwnerDrawVariable;
  ComboBox1.ItemHeight := Bits[0].Height + 4;
  ComboBox1.ItemIndex := 0;
end;

procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer;
  Rect: TRect; State: TOwnerDrawState);
begin
  ComboBox1.Canvas.FillRect(Rect);

  ComboBox1.Canvas.BrushCopy(Bounds(Rect.Left+2, Rect.Top+2, Bits[Index].Width, Bits[Index].Height), 
                             Bits[Index],
                             Bounds(0, 0, Bits[Index].Width, Bits[Index].Height),
                             clBlack);
  ComboBox1.Canvas.TextOut(Rect.Left + 24, Rect.Top + 3, ComboBox1.Items[Index]);
end;

procedure TForm1.FormDestroy(Sender: TObject);
var
  i: Integer;
begin
  for i := 0 to Length(Bits)-1 do
    Bits[i].Free;
end;

end.