Turbo Pascal 7.0 / TP7 / DOCDEMOS / COLLECT4

{************************************************}
{ }
{ Turbo Pascal for Windows }
{ Demo program }
{ Copyright (c) 1991 by Borland International }
{ }
{************************************************}

{ Create a collection of graphical objects: Points, Circles,
and Rectangles. Use the ForEach iterator to display each
object in the collection. }

program Collect4;

uses
WObjects, WinTypes, WinProcs;

const
NumToDraw = 10;

{ ********************************** }
{ ****** Graphical Objects ******* }
{ ********************************** }

type
PGraphObject = ^TGraphObject;
TGraphObject = object(TObject)
Rect: TRect;
constructor Init(Bounds: TRect);
procedure Draw(DC: HDC); virtual;
end;

PGraphEllipse = ^TGraphEllipse;
TGraphEllipse = object(TGraphObject)
procedure Draw(DC: HDC); virtual;
end;

PGraphRect = ^TGraphRect;
TGraphRect = object(TGraphObject)
procedure Draw(DC: HDC); virtual;
end;

PGraphPie = ^TGraphPie;
TGraphPie = object(TGraphObject)
ArcStart, ArcEnd: TPoint;
constructor Init(Bounds: TRect);
procedure Draw(DC: HDC); virtual;
end;

{ TGraphObject }
constructor TGraphObject.Init(Bounds: TRect);
var
Height, Width: Word;
begin
TObject.Init;
with Bounds do
begin
Height := Random(Bottom - Top) div 2 + 10;
Width := Random(Right - Left) div 3 + 15;
end;
with Rect do
begin
Left := Random(Bounds.Right - Bounds.Left - Width);
Right := Left + Width;
Top := Random(Bounds.Bottom - Bounds.Top - Height);
Bottom := Top + Height;
end;
end;

procedure TGraphObject.Draw(DC: HDC);
begin
Abstract;
end;

{ TGraphEllipse }
procedure TGraphEllipse.Draw(DC: HDC);
begin
with Rect do
Ellipse(DC, Left, Top, Right, Bottom);
end;

{ TGraphRect }
procedure TGraphRect.Draw(DC: HDC);
begin
with Rect do
Rectangle(DC, Left, Top, Right, Bottom);
end;

{ TGraphPie }
constructor TGraphPie.Init(Bounds: TRect);
var Height, Width: Word;
begin
TGraphObject.Init(Bounds);
with Bounds do
begin
Height := Random(Bottom - Top);
Width := Random(Right - Left);

ArcStart.X := Random(Right - Left - Width);
ArcEnd.X := ArcStart.X + Width;
ArcStart.Y := Random(Bottom - Top - Height);
ArcEnd.Y := ArcStart.Y + Height;
end;
end;

procedure TGraphPie.Draw;
begin
with Rect do
Pie(DC, Left, Top, Right, Bottom, ArcStart.X, ArcStart.Y, ArcEnd.X, ArcEnd.Y);
end;

{ ********************************** }
{ ********* Graph Window ********* }
{ ********************************** }
type
{ Define a TApplication descendant }
TGraphApp = object(TApplication)
procedure InitMainWindow; virtual;
end;

PGraphWindow = ^TGraphWindow;
TGraphWindow = object(TWindow)
GraphicsList: PCollection;
destructor Done; virtual;
procedure Paint(PaintDC: HDC; var PaintInfo: TPaintStruct); virtual;
procedure SetupWindow; virtual;
end;


{ TGraphApp }
procedure TGraphApp.InitMainWindow;
begin
MainWindow := New(PGraphWindow,
Init(nil, 'Collection of Graphical Objects'));
end;

{ TGraphWindow }
procedure TGraphWindow.SetupWindow;
var
Bounds: TRect;
I: Integer;
P: PGraphObject;
begin
TWindow.SetupWindow;
GetClientRect(HWindow, Bounds);

{ Instantiate a collection of objects }

{ Initialize collection to hold 10 elements first, then grow by 5's }
GraphicsList := New(PCollection, Init(10, 5));

for I := 1 to NumToDraw do
begin
case I mod 3 of { Create it }
0: P := New(PGraphRect, Init(Bounds));
1: P := New(PGraphEllipse, Init(Bounds));
0..2: P := New(PGraphPie, Init(Bounds));
end;
GraphicsList^.Insert(P); { Add it to collection }
end;
end;

destructor TGraphWindow.Done;
begin
Dispose(GraphicsList, Done); { Delete collection }
TWindow.Done;
end;

procedure TGraphWindow.Paint(PaintDC: HDC; var PaintInfo: TPaintStruct);

{ Nest the iterator method inside Paint so it can access the DC }
procedure DrawAll(C: PCollection); far;

{ Nested, far procedure. Receives one
collection element--a GraphObject, and
calls that elements Draw method.
}

procedure CallDraw(P : PGraphObject); far;
begin
P^.Draw(PaintDC); { Call Draw method }
end;

begin { DrawAll }
C^.ForEach(@CallDraw); { Draw each object }
end;

begin
if GraphicsList <> nil then DrawAll(GraphicsList);
end;


{ ********************************** }
{ ********** Main Program ********* }
{ ********************************** }

{ Declare a variable of type TGraphApp }
var
GraphApp: TGraphApp;

{ Run the GraphApp }
begin
GraphApp.Init('GraphApp');
GraphApp.Run;
GraphApp.Done;
end.