寫個小程序,但有兩個問題沒解決,希望幫忙看看
問題有兩個1.在瀏覽圖片略縮圖的時候,在第二次載入圖片后,如果第二次圖片少于第一次的數量,則第二次載入后還殘有第一次的縮影,不 知道怎么解決.用imgSingle.Picture := nil;不成功
2.批量改變圖片大小問題.轉化后圖片個數和名字及其格式都正確但是卻顯示"無法預覽". 主要代碼如下
載入多幅圖片按鍵定義
procedure TMainForm.btnMultiOpenClick(Sender: TObject);
var
k : Integer;
begin
Button2Click(Self);
multi := True;
imgSingle.Visible := False;
//imgSingle.picture.assign(nil);
odFileSelect.Options := odFileSelect.Options [ofAllowMultiSelect];
flist := TStringList.Create;
if odFileSelect.Execute then begin
src := odFileSelect.FileName;
flist := odFileSelect.Files;
loadThumb(flist);
for k := 0 to flist.Count-1 do begin
src := flist.Strings[k];
if (ExtractFileExt(src)='.JPG') or (ExtractFileExt(src)='.jpg') then
begin
SpeedButton2.Enabled := False;
SpeedButton1.Enabled := true;
end;
if (ExtractFileExt(src)='.BMP') or (ExtractFileExt(src)='.bmp') then
begin
SpeedButton1.Enabled := False;
SpeedButton2.Enabled := true;
end;
end;
lblFile.Caption := 'Image Tool';
pnlControl.Enabled := true;
scbThumb.Visible := true;

end;
end;
産生略縮圖函數
procedure TMainForm.loadThumb(sl:Tstrings);
var
i,x,y : Integer;
begin
if sl.count > 0 then begin
SetLength(img,sl.count);
SetLength(pnl,sl.count);
y:=-1;
x :=0;
selimg := TStringList.Create;
for i := 0 to sl.count-1 do begin
if FileExists(sl.Strings[i]) then begin
if (i mod 4) = 0 then begin
inc(y);
x := 0;
end;
pnl[i] := TPanel.Create(Self);
pnl[i].Parent := scbThumb;
pnl[i].Height := 100;
pnl[i].Width := 100;
pnl[i].Top := y*100 y*5;
pnl[i].Left := x*100 x*5;
img[i] := TImage.Create(Self);
img[i].Parent := pnl[i];
img[i].Align := alClient;
img[i].Stretch := true;
img[i].Proportional := true;
img[i].Center := true;
img[i].Picture.LoadFromFile(sl.Strings[i]);
img[i].OnClick := ImgClick;
img[i].Tag := i;
inc(x);
end;
end;
end;
end;




改變圖片大小函數
function TMainForm.JResize(src1, dst: String): Boolean;
var
Bmp: TBitmap;
Jpeg: TJpegImage;
begin
if (ExtractFileExt(src1)='.JPG') or (ExtractFileExt(src1)
='.jpg') then
begin
Jpeg := TJpegImage.Create;
try
Jpeg.LoadFromFile(src1);
Bmp := TBitmap.Create;
try
Bmp.Width := StrToInt(edtNewWidth.Text);
Bmp.Height := StrToInt(edtNewHeight.Text);
Bmp.Canvas.StretchDraw(Rect(0, 0, Bmp.Width,
Bmp.Height), Jpeg);
Jpeg.Assign(Bmp);
finally
Bmp.Free;
end;
Jpeg.SaveToFile(dst);
finally
Jpeg.Free;
Screen.Cursor := crDefault;
end;
end;
if (ExtractFileExt(src1)='.BMP') or (ExtractFileExt(src1)='.bmp') then
begin
Bmp := TBitmap.Create;
try
Bmp.LoadFromFile(src1);
try
Bmp.Width := StrToInt(edtNewWidth.Text);
Bmp.Height := StrToInt(edtNewHeight.Text);
Bmp.Canvas.StretchDraw(Rect(0, 0, Bmp.Width,
Bmp.Height), Bmp);
Bmp.Assign(Bmp);
finally
Bmp.SaveToFile(dst);
end;
Bmp.Free;
finally
Screen.Cursor := crDefault;
end;
end;
result := true;
end;
procedure TMainForm.rgSizeOptionClick(Sender: TObject);
begin
pnlNewDimPer.Enabled := (rgSizeOption.ItemIndex = 0);
pnlNewDimPix.Enabled := (rgSizeOption.ItemIndex = 1);
if pnlNewDimPer.Enabled then seNewWidthPerChange(Self)
end;

改大小按鍵定義,紅色地方代碼就是批量改變大小
procedure TMainForm.Button1Click(Sender: TObject);
var
dst : string;
j : Integer;
begin
//flist := TStringList.Create;
if DirectoryExists(editbrowse.Text) then begin
Screen.Cursor := crHourGlass;
if not multi then begin
dst := editbrowse.Text ExtractFileName(src);
if src = dst then dst := editbrowse.Text 'Copy ' ExtractFileName(src);
JResize(src,dst);
end else begin
ggProgress.MaxValue := flist.Count;
for j := 0 to flist.Count-1 do begin
src := flist.Strings[j];
dst := editbrowse.Text ExtractFileName(src);
if src = dst then dst := editbrowse.Text 'Copy ' ExtractFileName(src);
JResize(src,dst);
ggProgress.Progress := j;
end;
ggProgress.Progress := ggProgress.MaxValue;
end;
ShowMessage('Image(s) Resized!');
ggProgress.Progress := 0;
end;
//flist.Free;
if not DirectoryExists(editbrowse.Text) then ShowMessage('Can not find file!');
Screen.Cursor := crDefault;
end;