獲取程序大圖標方案

獲取文件的圖標

在win7的文件狀態欄中能顯示最大256x256的程序應用圖標。

在XP下測試無法正常獲取256的巨型圖標

Shell提供了一個函數 SHGetFileInfo 可以獲取文件信息，在使用此函數有需要處理Icon句柄的釋放（DestroyIcon），否則每次會有3個GDI句柄泄漏問題。

使用此函數后會一次性產生47個GDI句柄，只要Icon句柄釋放，就不會再增長。現在還未找到處理多處理啊的調用所產生的這些GDI句柄。

 

注意：

  GHGetFileInfo 和 DestoryIcon 成對調用。

 

測試環境

   Win7 and XE2

 

 

unit Unit4;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm4 = class(TForm)
    btn1: TButton;
    procedure btn1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form4: TForm4;

implementation

uses
  ShellApi, Commctrl, ShlObj;

{$R *.dfm}


const
  SHIL_LARGE     = $00;  //The image size is normally 32x32 pixels. However, if the Use large icons option is selected from the Effects section of the Appearance tab in Display Properties, the image is 48x48 pixels.
  SHIL_SMALL     = $01;  //These images are the Shell standard small icon size of 16x16, but the size can be customized by the user.
  SHIL_EXTRALARGE= $02;  //These images are the Shell standard extra-large icon size. This is typically 48x48, but the size can be customized by the user.
  SHIL_SYSSMALL  = $03;  //These images are the size specified by GetSystemMetrics called with SM_CXSMICON and GetSystemMetrics called with SM_CYSMICON.
  SHIL_JUMBO     = $04;  //Windows Vista and later. The image is normally 256x256 pixels.
  IID_IImageList: TGUID= '{46EB5926-582E-4017-9FDF-E8998DAA0950}';

function GetImageListSH(SHIL_FLAG:Cardinal): HIMAGELIST;
type
  _SHGetImageList = function (iImageList: integer; const riid: TGUID; var ppv: Pointer): hResult; stdcall;
var
  Handle        : THandle;
  SHGetImageList: _SHGetImageList;
begin
  Result:= 0;
  Handle:= LoadLibrary('Shell32.dll');
  if Handle<> S_OK then
  try
    SHGetImageList:= GetProcAddress(Handle, PChar(727));
    if Assigned(SHGetImageList) and (Win32Platform = VER_PLATFORM_WIN32_NT) then
      SHGetImageList(SHIL_FLAG, IID_IImageList, Pointer(Result));
  finally
    FreeLibrary(Handle);
  end;
end;


procedure GetIconFromFile(aFile:String; var aIcon : TIcon;SHIL_FLAG:Cardinal);
var
  aImgList    : HIMAGELIST;
  SFI         : TSHFileInfo;
Begin
    //Get the index of the imagelist
    SHGetFileInfo(PChar(aFile), FILE_ATTRIBUTE_NORMAL, SFI,
                 SizeOf( TSHFileInfo ), SHGFI_ICON or SHGFI_LARGEICON or SHGFI_SHELLICONSIZE or
                 SHGFI_SYSICONINDEX or SHGFI_TYPENAME or SHGFI_DISPLAYNAME );

    if not Assigned(aIcon) then
    aIcon:= TIcon.Create;
    //get the imagelist
    aImgList:= GetImageListSH(SHIL_FLAG);
    //extract the icon handle
    aIcon.Handle:= ImageList_GetIcon(aImgList, Pred(ImageList_GetImageCount(aImgList)), ILD_NORMAL);

    DestroyIcon(SFI.hIcon);
    ImageList_Destroy(aImgList);
end;

procedure TForm4.btn1Click(Sender: TObject);
var
  icon:TIcon;
begin
  icon := TIcon.Create;
  try
    GetIconFromFile(ParamStr(0), icon, SHIL_JUMBO);
    canvas.Draw(10, 100, icon);
    Canvas.TextOut(10, 80, inttostr(icon.Handle));

    GetIconFromFile(ParamStr(0), icon, SHIL_SYSSMALL);
    canvas.Draw(10+ 280 , 100, icon);
    Canvas.TextOut(10 + 280, 80, inttostr(icon.Handle));

    GetIconFromFile(ParamStr(0), icon, SHIL_EXTRALARGE);
    canvas.Draw(10+ 280 + 150 , 100, icon);
    Canvas.TextOut(10+ 280 + 150, 80, inttostr(icon.Handle));

    GetIconFromFile(ParamStr(0), icon, SHIL_LARGE);
    canvas.Draw(10+ 280 + 150 +50 , 100, icon);
    Canvas.TextOut(10+ 280 + 150 +50, 80, inttostr(icon.Handle));

    GetIconFromFile(ParamStr(0), icon, SHIL_SMALL);
    canvas.Draw(10+ 280 + 150 +50 +40, 100, icon);
    Canvas.TextOut(10+ 280 + 150 +50 +40, 80, inttostr(icon.Handle));
  finally
    icon.Free;
  end;

end;

end.

 

詳細內容可以看

http://www.codeproject.com/Articles/2532/Obtaining-and-managing-file-and-folder-icons-using

有比較詳細的使用說明