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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 在Listbox加背景圖

在Listbox加背景圖

編輯:Delphi

  1.  建立一個窗體
  2.  放一個ComboBox和Listbox
  3.  改變Component的Style為csOwnerDrawVariable和ListBox的Style為lbOwnerDrawVariable。
  4.  聲明5個TBitmap的全局變量
  5.  覆蓋Form的OnCreate.
  6.  覆蓋ComboBox的OnDraw.
  7.  覆蓋ComboBox的OnMeasureItem.
  8.  釋放資源在Form的OnClose.

  
  unit Ownerdrw;

  interface

  uses
    SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
    Forms, Dialogs, StdCtrls;

  type
    TForm1 = class(TForm)
      ComboBox1: TComboBox;
      ListBox1: TListBox;
      procedure FormCreate(Sender: TObject);
      procedure FormClose(Sender: TObject; var Action: TCloseAction);
      procedure ComboBox1DrawItem(Control: TWinControl; Index: Integer;
        Rect: TRect; State: TOwnerDrawState);
      procedure ComboBox1MeasureItem(Control: TWinControl; Index: Integer;
        var Height: Integer);
      procedure ListBox1DrawItem(Control: TWinControl; Index: Integer;
        Rect: TRect; State: TOwnerDrawState);
      procedure ListBox1MeasureItem(Control: TWinControl; Index: Integer;
        var Height: Integer);

    private
      { Private declarations }

    public
      { Public declarations }

    end;

  var
    Form1: TForm1;
    TheBitmap1, TheBitmap2, TheBitmap3, TheBitmap4,
    TheBitmap5 : TBitmap;
  implementation

  {$R *.DFM}

  procedure TForm1.FormCreate(Sender: TObject);
  begin
    TheBitmap1 := TBitmap.Create;
    TheBitmap1.LoadFromFile('C:Delphiimagesuttonsglobe.bmp');
    TheBitmap2 := TBitmap.Create;
    TheBitmap2.LoadFromFile('C:Delphiimagesuttonsvideo.bmp');
    TheBitmap3 := TBitmap.Create;
    TheBitmap3.LoadFromFile('C:Delphiimagesuttonsgears.bmp');
    TheBitmap4 := TBitmap.Create;
    TheBitmap4.LoadFromFile('C:Delphiimagesuttonskey.bmp');
    TheBitmap5 := TBitmap.Create;
    TheBitmap5.LoadFromFile('C:Delphiimagesuttons ools.bmp');
    ComboBox1.Items.AddObject('Bitmap1: Globe', TheBitmap1);
    ComboBox1.Items.AddObject('Bitmap2: Video', TheBitmap2);
    ComboBox1.Items.AddObject('Bitmap3: Gears', TheBitmap3);
    ComboBox1.Items.AddObject('Bitmap4: Key', TheBitmap4);
    ComboBox1.Items.AddObject('Bitmap5: Tools', TheBitmap5);
    ListBox1.Items.AddObject('Bitmap1: Globe', TheBitmap1);
    ListBox1.Items.AddObject('Bitmap2: Video', TheBitmap2);
    ListBox1.Items.AddObject('Bitmap3: Gears', TheBitmap3);
    ListBox1.Items.AddObject('Bitmap4: Key', TheBitmap4);
    ListBox1.Items.AddObject('Bitmap5: Tools', TheBitmap5);

  end;

   

  procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
  begin
    TheBitmap1.Free;
    TheBitmap2.Free;
    TheBitmap3.Free;
    TheBitmap4.Free;
    TheBitmap5.Free;
  end;

  procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer;
    Rect: TRect; State: TOwnerDrawState);
  var
    Bitmap: TBitmap;
    Offset: Integer;
  begin
    with (Control as TComboBox).Canvas do
    begin
      FillRect(Rect);
      Bitmap := TBitmap(ComboBox1.Items.Objects[Index]);
      if Bitmap <> nil then
      begin
        BrushCopy(Bounds(Rect.Left + 2, Rect.Top + 2, Bitmap.Width,
                  Bitmap.Height), Bitmap, Bounds(0, 0, Bitmap.Width,
                  Bitmap.Height), clRed);
        Offset := Bitmap.width + 8;
      end;
      { display the text }
      TextOut(Rect.Left + Offset, Rect.Top, Combobox1.Items[Index])
    end;
  end;

  procedure TForm1.ComboBox1MeasureItem(Control: TWinControl; Index:
                                        Integer; var Height: Integer);
  begin
    height:= 20;
  end;

  procedure TForm1.ListBox1DrawItem(Control: TWinControl; Index: Integer;
    Rect: TRect; State: TOwnerDrawState);
  var
    Bitmap: TBitmap;
    Offset: Integer;
  begin
    with (Control as TListBox).Canvas do
    begin
      FillRect(Rect);
      Bitmap := TBitmap(ListBox1.Items.Objects[Index]);
      if Bitmap <> nil then
      begin
        BrushCopy(Bounds(Rect.Left + 2, Rect.Top + 2, Bitmap.Width,
                  Bitmap.Height), Bitmap, Bounds(0, 0, Bitmap.Width,
                  Bitmap.Height), clRed);
        Offset := Bitmap.width + 8;
      end;
      { display the text }
      TextOut(Rect.Left + Offset, Rect.Top, Listbox1.Items[Index])
    end;
  end;

  procedure TForm1.ListBox1MeasureItem(Control: TWinControl; Index: Integer;
    var Height: Integer);
  begin
    height:= 20;
  end;

  end.

   

  
  //該窗體的DFM文件

  object Form1: TForm1
    Left = 211
    Top = 155
    Width = 435
    Height = 300
    Caption = 'Form1'
    Font.Color = clWindowText
    Font.Height = -13
    Font.Name = 'System'
    Font.Style = []
    PixelsPerInch = 96
    OnClose = FormClose
    OnCreate = FormCreate
    TextHeight = 16
    object ComboBox1: TComboBox
      Left = 26
      Top = 30
      Width = 165
      Height = 22
      Style = csOwnerDrawVariable
      ItemHeight = 16
      TabOrder = 0
      OnDrawItem = ComboBox1DrawItem
      OnMeasureItem = ComboBox1MeasureItem
    end
    object ListBox1: TListBox
      Left = 216
      Top = 28
      Width = 151
      Height = 167
      ItemHeight = 16
      Style = lbOwnerDrawVariable
      TabOrder = 1
      OnDrawItem = ListBox1DrawItem
      OnMeasureItem = ListBox1MeasureItem
    end
  end
  

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