const FileName:string):boolean;
begin
result:=(LowerCase( ExtractFileExt(FileName))=''''.jpg'''') or (LowerCase( ExtractFileExt(FileName))=''''.jpeg'''');
end;
4. 我们在窗体的OnCreate和OnDestroy事件处理句柄里添加如下代码：
procedure TForm1.FormCreate(Sender: TObject);
begin
//设置图标间距，也即缩略图间距
ListView_SetIconSpacing(listview1.handle,90,120);
OriginalBmp:=Tbitmap.Create;
ThumbJpg:=TJpegImage.Create;
PreViewBmp:=Tbitmap.Create;
PreViewJpg:=TJpegImage.Create;
ThumbBmp:=TBitmap.Create;
//缩略图的边框为：80*80，显示图片大小为：64*64
ThumbBmp.Height:=80;
ThumbBmp.Width:=80;
ThumbBmp.PixelFormat:=pf24bit;
imagelist1.Height:=80;
imagelist1.Width:=80;
listview1.LargeImages:=imagelist1;
listview1.ViewStyle:=vsicon;
ImageFileList:=TImageFileList.Create;
ImageFileList.Clear;
ProgressBar1:=TProgressBar.Create(self);
ProgressBar1.Parent:=StatusBar1;
ProgressBar1.Visible:=false;
ProgressBar1.Width:=200;
ProgressBar1.Height:=StatusBar1.Height-4;
ProgressBar1.Left:=StatusBar1.Width-ProgressBar1.Width;
ProgressBar1.Top:=2;
IsRefreshImageFinished:=true;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
OriginalBmp.Free;
ThumbBmp.Free;
ImageFileList.Free;
ThumbJpg.Free;
PreViewBmp.Free;
PreViewJpg.Free;
ProgressBar1.Free;
end;
5. 在ShellTreeView1的OnChange事件里添加下面代码：
procedure TForm1.ShellTreeView1Change(Sender: TObject; Node: TTreeNode);
var
dir:string;
begin
//如果上次的RefreshImage过程还没有结束，就退出
if not IsRefreshImageFinished then exit;
dir:=ShellTreeView1.Path;
//edit1.Text:=dir;
if not (DirectoryExists(dir)) then exit;
//如果是c:\ d:\之类则转换为c: d:
if dir[length(dir)]=''''\'''' then
delete(dir,length(dir),1);
ImageFileList.ChangeDir(dir);
screen.Cursor:=crHourGlass;
self.Enabled:=false;
RefreshImage;
self.Enabled:=true;
screen.Cursor:=crDefault;
end;
6. 其中过程RefreshImage的代码如下：
//此过程把ImageFileList中记录的图片文件缩放后加载到ImageList1中，并在
//ListView1中显示
procedure TForm1.RefreshImage;
var
i:integer;
ImageFileName:string;
ThumbBmpLeft:integer;
ThumbBmpTop:integer;
ThumbBmpHeight:integer;
ThumbBmpWidth:integer;
begin
IsRefreshImageFinished:=false;
listview1.Clear;
imagelist1.Clear;
screen.Cursor:=crHourGlass;
ProgressBar1.Max:=ImageFileList.GetFileCount;
ProgressBar1.Visible:=true;
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