[Delphi] Drag Drop image conversion

**ouiouioui** · 10/01/2011, 20h10

Bonjour, j'ai écris sa pour récupérer une image au format jpg et png dans une autre form lorsque un utilisateur glisse une image au format png, jpg ou bmp sur un un TImage, mais il faut utiliser un TPanel pour gérer le glisser déposer ou alors j'ai zappé un truc.

j'ai ajouté un projet exemple, je compte sur vos conseil éclairé pour me dire ce qui n'est pas top

compatible D2009 +

Code pascal :

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Unit ImageDropDown;
 
Interface
 
Uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Jpeg, pngimage, ShellAPI, ExtCtrls;
 
Type
  TFormatIMG = Set Of (fiJPG, fiBMP, fiPNG);
 
  TImageDropDown<T: TGraphic, Constructor> = Class
  Private
    originalImageWindowProc          : TWndMethod;
    FImage                           : TImage;
    FPanel                           : TPanel;
    FIMG                             : T;
    FFormatIMG                       : TFormatIMG;
    FFileName                        : String;
    FOnBeforeLoadImg, FOnAfterLoadImg: TNotifyEvent;
    Procedure ImageDrop(Var Msg: TWMDROPFILES);
  Public
    Procedure ImageWindowProc(Var Msg: TMessage);
    Procedure LoadIMG(Const sImgFileName: String);
    Procedure ClearIMG;
    Procedure SelectIMG;
    Constructor Create(AImage: TImage; APanel: TPanel);
    Destructor Destroy; Override;
    Property IMG: T Read FIMG Write FIMG;
    Property FormatIMG: TFormatIMG Read FFormatIMG Write FFormatIMG;
    Property FileName: String Read FFileName;
    Property OnBeforeLoadImg: TNotifyEvent Read FOnBeforeLoadImg Write FOnBeforeLoadImg;
    Property OnAfterLoadImg: TNotifyEvent Read FOnAfterLoadImg Write FOnAfterLoadImg;
  End;
 
Resourcestring
  lng_CannotLoadLotOfImg = 'Vous ne pouvez pas déposer plusieurs images en même temps.';
  lng_AllImages = 'Tous les formats images supportés';
  lng_JPGImages = 'Images JPEG';
  lng_BMPImages = 'Images BMP';
  lng_PNGImages = 'images PNG';
  lng_FileExtIsBad = 'file extension is incorrect';
 
Implementation
 
Procedure TImageDropDown<T>.ClearIMG;
Begin
  FImage.Picture.Assign(NIL);
  FreeAndNil(FIMG);
End;
 
Procedure TImageDropDown<T>.LoadIMG(Const sImgFileName: String);
Var
  Bmp    : TBitmap;
  Jpg    : TJPEGImage;
  Png    : TPngImage;
  FileExt: String;
Begin
  Try
    If Assigned(OnBeforeLoadImg) Then
      OnBeforeLoadImg(Self);
 
    FileExt := ExtractFileExt(sImgFileName);
    If ((FileExt = '.jpg') Or (FileExt = '.jpeg')) And (fiJPG In FormatIMG) Then
    Begin
      Jpg := TJPEGImage.Create;
      Try
        Jpg.LoadFromFile(sImgFileName);
 
        If Not Assigned(IMG) Then
          FIMG := T.Create;
 
        // cannot assign jpg to png directly
        If FIMG.ClassNameIs('TPngImage') Then
        Begin
          Bmp := TBitmap.Create;
          Try
            Bmp.Assign(Jpg);
            FIMG.Assign(Bmp);
          Finally
            Bmp.Free;
          End;
        End
        Else
          FIMG.Assign(Jpg);
 
        FImage.Picture.Assign(Jpg);
      Finally
        Jpg.Free;
      End;
    End
    Else If (FileExt = '.bmp') And (fiBMP In FormatIMG) Then
    Begin
      Bmp := TBitmap.Create;
      Try
        Bmp.LoadFromFile(sImgFileName);
 
        If Not Assigned(IMG) Then
          FIMG := T.Create;
 
        FIMG.Assign(Bmp);
        FImage.Picture.Assign(Bmp);
      Finally
        Bmp.Free;
      End;
    End
    Else If (FileExt = '.png') And (fiPNG In FormatIMG) Then
    Begin
      Png := TPngImage.Create;
      Try
        Png.LoadFromFile(sImgFileName);
 
        If Not Assigned(IMG) Then
          FIMG := T.Create;
 
        // cannot assign png to jpg directly
        If FIMG.ClassNameIs('TJPEGImage') Then
        Begin
          Bmp := TBitmap.Create;
          Try
            Bmp.Assign(Png);
            FIMG.Assign(Bmp);
          Finally
            Bmp.Free;
          End;
        End
        Else
          FIMG.Assign(Png);
 
        FImage.Picture.Assign(Png);
      Finally
        Png.Free;
      End;
    End
    Else
      Raise Exception.Create(lng_FileExtIsBad);
 
    FFileName := ExtractFileName(sImgFileName);
 
    If Assigned(OnAfterLoadImg) Then
      OnAfterLoadImg(Self);
  Except
    FreeAndNil(FIMG);
    Raise;
  End;
End;
 
Procedure TImageDropDown<T>.SelectIMG;
Var
  sFileMask: String;
Begin
  sFileMask   := '';
  If fiJPG In FormatIMG Then
    sFileMask := sFileMask + '*.jpg;*.jpeg;';
  If fiBMP In FormatIMG Then
    sFileMask := sFileMask + '*.bmp;';
  If fiPNG In FormatIMG Then
    sFileMask := sFileMask + '*.png';
  If (sFileMask <> '') And (sFileMask[Length(sFileMask) - 1] = ';') Then
    SetLength(sFileMask, -1);
 
  // if vista or +
  If Win32MajorVersion >= 6 Then
  Begin
    With TFileOpenDialog.Create(NIL) Do
      Try
        If fiJPG In FormatIMG Then
          DefaultExtension := 'jpg'
        Else If fiBMP In FormatIMG Then
          DefaultExtension := 'bmp'
        Else If fiPNG In FormatIMG Then
          DefaultExtension := 'png';
 
        With FileTypes.Add Do
        Begin
          DisplayName := lng_AllImages;
          FileMask    := sFileMask;
        End;
 
        If fiJPG In FormatIMG Then
        Begin
          With FileTypes.Add Do
          Begin
            DisplayName := lng_JPGImages;
            FileMask    := '*.jpg;*.jpeg';
          End;
        End;
 
        If fiBMP In FormatIMG Then
        Begin
          With FileTypes.Add Do
          Begin
            DisplayName := lng_BMPImages;
            FileMask    := '*.bmp';
          End;
        End;
 
        If fiPNG In FormatIMG Then
        Begin
          With FileTypes.Add Do
          Begin
            DisplayName := lng_PNGImages;
            FileMask    := '*.png';
          End;
        End;
 
        If Execute Then
          LoadIMG(FileName);
      Finally
        Free;
      End;
  End
  Else
  Begin
    With TOpenDialog.Create(NIL) Do
      Try
        sFileMask   := lng_AllImages + '|' + sFileMask + '|';
        If fiJPG In FormatIMG Then
          sFileMask := sFileMask + lng_JPGImages + '|*.jpg;*.jpeg|';
        If fiBMP In FormatIMG Then
          sFileMask := sFileMask + lng_BMPImages + '|*.bmp|';;
        If fiPNG In FormatIMG Then
          sFileMask := sFileMask + lng_PNGImages + '|*.png';
        If (sFileMask <> '') And (sFileMask[Length(sFileMask) - 1] = '|') Then
          SetLength(sFileMask, -1);
 
        Filter  := sFileMask;
        Options := [ofHideReadOnly, ofFileMustExist, ofEnableSizing];
 
        If Execute Then
          LoadIMG(FileName);
      Finally
        Free;
      End;
  End;
End;
 
Procedure TImageDropDown<T>.ImageWindowProc(Var Msg: TMessage);
Begin
  If Msg.Msg = WM_DROPFILES Then
    ImageDrop(TWMDROPFILES(Msg))
  Else
    originalImageWindowProc(Msg);
End;
 
Constructor TImageDropDown<T>.Create(AImage: TImage; APanel: TPanel);
Begin
  FormatIMG               := [fiJPG, fiBMP, fiPNG];
  FImage                  := AImage;
  FPanel                  := APanel;
  FFileName               := '';
  FOnBeforeLoadImg        := NIL;
  FOnAfterLoadImg         := NIL;
 
  originalImageWindowProc := APanel.WindowProc;
  APanel.WindowProc       := ImageWindowProc;
  DragAcceptFiles(APanel.Handle, True);
End;
 
Destructor TImageDropDown<T>.Destroy;
Begin
  If Assigned(FPanel) Then
  Begin
    FPanel.WindowProc := originalImageWindowProc;
    DragAcceptFiles(FPanel.Handle, False);
  End;
 
  If Assigned(FIMG) Then
    FIMG.Free;
 
  Inherited;
End;
 
Procedure TImageDropDown<T>.ImageDrop(Var Msg: TWMDROPFILES);
Var
  numFiles: Longint;
  Buffer  : Array [0 .. MAX_PATH] Of Char;
Begin
  numFiles := DragQueryFile(Msg.Drop, $FFFFFFFF, NIL, 0);
  If numFiles = 1 Then
  Begin
    DragQueryFile(Msg.Drop, 0, @Buffer, sizeof(Buffer));
    LoadIMG(Buffer);
  End
  Else
    Raise Exception.Create(lng_CannotLoadLotOfImg);
End;
 
End.

[Delphi] Drag Drop image conversion

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