unit Unit87;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
  System.types,
  hyiedefs, hyieutils, iexBitmaps, iesettings, iemio, ieview, iemview, iexFolderMView,
  iexWindowsFunctions, Vcl.StdCtrls;

type

  TImageDragAndDropHelper = class
  private
    fDragging: boolean;
    fMouseClickPos: tpoint;
    fMouseClickTime: cardinal;
    fLastDragTime: cardinal;
    fDragDrop: TIEFileDragDrop;
    fImage: TImageEnMView;
  public
    constructor Create;
    destructor Destroy; override;
    procedure setMouse(Button: TMouseButton; X, Y: Integer);
    procedure CheckDrag(X, Y: Integer);
    property Image : TImageEnMView read fImage write fImage;
  end;


  TForm87 = class(TForm)
    Image_inventory: TImageEnMView;
    procedure FormCreate(Sender: TObject);
    procedure Image_inventoryMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure Image_inventoryMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
  private
  public
    dragImage: TImageDragAndDropHelper;
  end;

var
  Form87: TForm87;

implementation

{$R *.dfm}

Constructor TImageDragAndDropHelper.Create;
begin
  inherited;
  fDragging := false;
  fMouseClickTime := 0;
  fLastDragTime := 0;
  fDragDrop := nil;
end;

Destructor TImageDragAndDropHelper.Destroy;
begin
  if assigned(fDragDrop) then
    fDragDrop.free;
  inherited;
end;

procedure TImageDragAndDropHelper.setMouse(Button: TMouseButton; X, Y: Integer);
begin
  fDragging := Button = mbLeft;
  fMouseClickPos := point(X, Y);
  fMouseClickTime := GetTickCount();
end;

procedure TImageDragAndDropHelper.CheckDrag(X, Y: Integer);
const
  MS_Before_Drag = 333;
var
  ssFilenames: TStringList;
  fileIDX: Integer;
  idx: Integer;
begin
  if not assigned(fImage) then // no reason to run if not assigned yet
    exit;

  idx := fImage.ImageAtPos(fMouseClickPos.X, fMouseClickPos.Y, true);
  if (fDragging) and (GetTickCount() - fMouseClickTime > MS_Before_Drag) and (idx > -1) and
       ((Abs(X - fMouseClickPos.X) >= Mouse.DragThreshold) or (Abs(Y - fMouseClickPos.Y) >= Mouse.DragThreshold)) then
  begin
    fDragging := false;
    fImage.Perform(WM_LBUTTONUP, 0, MakeLong(X, Y));
    ssFilenames := TStringList.Create;
    try
      fImage.SelectedFilenames(ssFilenames);
      if ssFilenames.Count > 0 then
      begin
        // we have image set that have pre-built thumbnails
        // we show only the thumbnail in the TImageEnMView
        // but we really want to drag the fullsize image
        // downside is, the chances the full image does not exist
        // in our production code, it populates thumbnails only if fullsize image file exists
        // so the chance it was removed since then is slim but could happen.

        for fileIDX := 0 to ssFilenames.Count - 1 do
          ssFilenames[fileIDX] := stringreplace(ssFilenames[fileIDX], '_thumb', '', [rfignorecase]);

        // if becomes a problem, can add an option to double check and remove from ssFilenames any file
        // that does not exist. Right now not going to since network drivers are slow
        // and need this to be fast
        // worse case, will add it and just have to deal with it

        if fDragDrop = nil then
          fDragDrop := TIEFileDragDrop.Create(nil); // we just need to create it. No events needed
        fDragDrop.ShowPreview := true;
        fDragDrop.PreviewWidth := fImage.ThumbWidth;
        fDragDrop.PreviewHeight := fImage.ThumbHeight;
        fDragDrop.InitiateDragging(ssFilenames, [iedaCopy, iedaMove]);
      end;
    finally
      ssFilenames.free;
    end;
  end;
end;


procedure TForm87.FormCreate(Sender: TObject);
begin
  Image_inventory.fillfromdirectory('c:\cmis\2025\2025', -1, true);
  dragImage := TImageDragAndDropHelper.Create;
  dragImage.fImage := Image_inventory;
end;

procedure TForm87.FormDestroy(Sender: TObject);
begin
  dragImage.free;
end;

procedure TForm87.Image_inventoryMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  dragImage.setMouse(Button, X, Y);
end;

procedure TForm87.Image_inventoryMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  dragImage.CheckDrag(X, Y);
end;


end.