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| ///////////////////////////////////////////////////////////////////////////
// //
// Copyright (c) 2015 by Charta Software B.V. //
// All rights reserved //
// //
// Version: 1.7.0.83525 //
// Web site: https://pascal.chartasoftware.com/ //
// //
// This code and information are provided "as is" without warranty of //
// any kind. Dissemination of this information or reproduction of //
// this material is strictly forbidden unless prior written permission //
// is obtained from Charta Software B.V.. //
// //
///////////////////////////////////////////////////////////////////////////
unit UserInterface.DragAndDrop.Manager;
interface
{$SCOPEDENUMS ON}
uses
Boolean,
Event,
Geometry._2d.Integer32.Point,
UserInterface.Control,
UserInterface.DragAndDrop.Action,
UserInterface.Keyboard.Event,
UserInterface.Mouse.Event;
type
TDragPhase = (None, ButtonDown, Dragging);
TDragAndDropManager = class(TObject)
protected
StartingPoint: TInteger32Point;
Source: TDragSite;
Target: TDragSite;
Phase: TDragPhase;
Actions: TDragDropActions;
procedure ClearTarget();
procedure DragDropMove();
procedure DragDropSwap();
function ControlWithPointOnScreen(Point: TInteger32Point): TControl;
procedure AdjustCursorForDragDrop(Actions: TDragDropActions);
procedure HandleDragStart(Position: TInteger32Point); overload;
procedure HandleDragStart(Control: TControl); overload;
function HandleDragMove(Position: TInteger32Point): TBoolean;
function HandleDragEnd(): TBoolean;
function HandleMouseButtonEvent(RootControl: TControl; Event: TMouseButtonEvent): TBoolean;
function HandleMouseMoveEvent(RootControl: TControl; Event: TMouseMoveEvent): TBoolean;
function HandleMouseEvent(RootControl: TControl; Event: TMouseEvent): TBoolean;
function HandleKeyboardEvent(Event: TKeyboardEvent): TBoolean;
procedure Stop(Successful: TBoolean);
public
MouseManager: TMouseManager;
function HandleEvent(Control: TControl; Event: TEvent): TBoolean;
function IsActive(): TBoolean;
procedure StartDrag(Control: TControl);
end;
implementation
uses
UserInterface.Keyboard.Key,
Windows.Api.UserInterface,
Windows.Control,
Windows.Gdi.Cursor;
{ TDragAndDropManager }
procedure TDragAndDropManager.AdjustCursorForDragDrop(Actions: TDragDropActions);
begin
if TDragDropAction.Swap in Actions then
MouseManager.SetCursor(CursorManager.DropSwap)
else if TDragDropAction.Move in Actions then
MouseManager.SetCursor(CursorManager.DropMove)
else
MouseManager.SetCursor(CursorManager.No);
end;
procedure TDragAndDropManager.ClearTarget();
begin
if Target <> nil then
begin
Target.Free();
Target := nil;
end;
end;
function TDragAndDropManager.ControlWithPointOnScreen(Point: TInteger32Point): TControl;
var
Offset: TInteger32Point;
begin
Result := FindControlWithHandle(WindowFromPoint(Point));
if Result <> nil then
begin
Dec(Point.X, Result.Left);
Dec(Point.Y, Result.Top);
if Result is TWindowsControl then
begin
Offset := (Result as TWindowsControl).Control.Position;
Dec(Point.X, Offset.X);
Dec(Point.Y, Offset.Y);
end;
Result := Result.DescendantWithPosition(Point);
end;
end;
procedure TDragAndDropManager.DragDropMove();
begin
Source.Detach();
Target.Attach(Source.Control);
end;
procedure TDragAndDropManager.DragDropSwap();
begin
Source.Detach();
Target.Detach();
Source.Attach(Target.Control);
Target.Attach(Source.Control);
end;
function TDragAndDropManager.HandleDragEnd(): TBoolean;
begin
Result := False;
if Phase <> TDragPhase.None then
begin
if (Phase = TDragPhase.Dragging) and (Target <> nil) then
begin
Result := True;
if TDragDropAction.Swap in Actions then
DragDropSwap()
else if TDragDropAction.Move in Actions then
DragDropMove();
end;
Stop(True);
end;
end;
function TDragAndDropManager.HandleDragMove(Position: TInteger32Point): TBoolean;
var
Control: TControl;
begin
if (Phase = TDragPhase.ButtonDown) and (StartingPoint.SquaredDistanceTo(Position) > 9) then
Phase := TDragPhase.Dragging;
if Phase = TDragPhase.Dragging then
begin
ClearTarget();
Result := True;
Actions := [];
Control := ControlWithPointOnScreen(Position);
if Control <> nil then
begin
Position := Control.ScreenToRelative(Position);
Target := nil;
while (Target = nil) and (Control <> nil) do
begin
Target := Control.CreateDragTarget(Source, Position);
if Control.ParentControl <> nil then
Position := Control.ParentControl.ConvertPositionFromChildPosition(Position, Control);
Control := Control.ParentControl;
end;
if Target <> nil then
Actions := Source.Actions * Target.Actions;
end;
AdjustCursorForDragDrop(Actions);
end
else
begin
Result := False;
Target := nil;
end;
end;
procedure TDragAndDropManager.HandleDragStart(Control: TControl);
begin
Source := Control.ParentControl.CreateDragSource(Control);
if Source <> nil then
begin
if Source.Actions <> [] then
MouseManager.ControlWithCapture := Source.Container
else
Stop(False);
end
else
Stop(False);
end;
procedure TDragAndDropManager.HandleDragStart(Position: TInteger32Point);
var
DragControl: TControl;
Control: TControl;
begin
DragControl := nil;
Control := ControlWithPointOnScreen(Position);
Position := Control.ScreenToRelative(Position);
while (DragControl = nil) and (Control <> nil) do
begin
DragControl := Control.GetDragControl(Position);
if Control.ParentControl <> nil then
Position := Control.ParentControl.ConvertPositionFromChildPosition(Position, Control);
Control := Control.ParentControl;
end;
if DragControl <> nil then
begin
Phase := TDragPhase.ButtonDown;
HandleDragStart(DragControl);
end;
end;
function TDragAndDropManager.HandleEvent(Control: TControl; Event: TEvent): TBoolean;
begin
if Event is TMouseEvent then
Result := HandleMouseEvent(Control, Event as TMouseEvent)
else
begin
Result := Phase = TDragPhase.Dragging;
if Result then
begin
if Event is TKeyboardEvent then
HandleKeyboardEvent(Event as TKeyboardEvent);
end;
end;
end;
function TDragAndDropManager.HandleKeyboardEvent(Event: TKeyboardEvent): TBoolean;
begin
Result := (Event is TKeyDownEvent) and ((Event as TKeyDownEvent).Key = TKey.Escape);
if Result then
Stop(False);
end;
function TDragAndDropManager.HandleMouseButtonEvent(RootControl: TControl; Event: TMouseButtonEvent): TBoolean;
begin
Result := False;
if Event.Button = Event.Mouse.Left then
begin
if Event is TMouseButtonDownEvent then
begin
StartingPoint := RootControl.RelativeToScreen(Event.Position);
HandleDragStart(StartingPoint);
end
else if (Phase <> TDragPhase.None) and (Event is TMouseButtonUpEvent) then
Result := HandleDragEnd();
end;
end;
function TDragAndDropManager.HandleMouseEvent(RootControl: TControl; Event: TMouseEvent): TBoolean;
begin
if Event is TMouseButtonEvent then
Result := HandleMouseButtonEvent(RootControl, Event as TMouseButtonEvent)
else if Event is TMouseMoveEvent then
Result := HandleMouseMoveEvent(RootControl, Event as TMouseMoveEvent)
else
Result := False;
end;
function TDragAndDropManager.HandleMouseMoveEvent(RootControl: TControl; Event: TMouseMoveEvent): TBoolean;
begin
Result := (Phase <> TDragPhase.None) and HandleDragMove(RootControl.RelativeToScreen(Event.Position));
end;
function TDragAndDropManager.IsActive(): TBoolean;
begin
Result := Phase = TDragPhase.Dragging;
end;
procedure TDragAndDropManager.StartDrag(Control: TControl);
begin
Phase := TDragPhase.Dragging;
HandleDragStart(Control);
end;
procedure TDragAndDropManager.Stop(Successful: TBoolean);
begin
Phase := TDragPhase.None;
if Source <> nil then
begin
Source.Free();
Source := nil;
end;
ClearTarget();
MouseManager.ControlWithCapture := nil;
end;
end.
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