Add not-quite-working graphics polymophism demo

drawing demo/drawing.pas

@@ -0,0 +1,56 @@
+unit drawing;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+	Classes, SysUtils, Controls, ExtCtrls, Graphics;
+
+type TDrawing = class(TGraphicControl)
+	private
+		FExtent: integer;
+	public
+		constructor Create(theOwner: TComponent; anExtent: integer);
+		property Extent: integer read FExtent write FExtent;
+	end;
+
+	TSquare = class(TDrawing)
+	public
+		procedure Paint; override;
+	end;
+
+	TCircle = class(TDrawing)
+	public
+		procedure Paint; override;
+	end;
+
+implementation
+
+constructor TDrawing.Create(theOwner: TComponent; anExtent: integer);
+begin
+	inherited Create(theOwner);
+	FExtent := anExtent;
+	Width := FExtent;
+	Height := FExtent;
+end;
+
+{TCircle}
+procedure TCircle.Paint;
+begin
+	Canvas.Brush.Color := clBtnFace;
+	Canvas.FillRect(0, 0, FExtent, FExtent);
+	Canvas.Brush.Color := clYellow;
+	Canvas.Ellipse(0, 0, FExtent, FExtent);
+end;
+
+{TSquare}
+procedure TSquare.Paint;
+begin
+	Canvas.Brush.Color := clSilver;
+	Canvas.FillRect(0, 0, FExtent, FExtent);
+	Canvas.Rectangle(0, 0, FExtent, FExtent);
+end;
+
+end.
+

drawing demo/drawingdemo.lpi

@@ -0,0 +1,83 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<CONFIG>
+  <ProjectOptions>
+    <Version Value="11"/>
+    <General>
+      <SessionStorage Value="InProjectDir"/>
+      <MainUnit Value="0"/>
+      <Title Value="drawingdemo"/>
+      <Scaled Value="True"/>
+      <ResourceType Value="res"/>
+      <UseXPManifest Value="True"/>
+      <XPManifest>
+        <DpiAware Value="True"/>
+      </XPManifest>
+      <Icon Value="0"/>
+    </General>
+    <BuildModes Count="1">
+      <Item1 Name="Default" Default="True"/>
+    </BuildModes>
+    <PublishOptions>
+      <Version Value="2"/>
+      <UseFileFilters Value="True"/>
+    </PublishOptions>
+    <RunParams>
+      <FormatVersion Value="2"/>
+      <Modes Count="0"/>
+    </RunParams>
+    <RequiredPackages Count="1">
+      <Item1>
+        <PackageName Value="LCL"/>
+      </Item1>
+    </RequiredPackages>
+    <Units Count="3">
+      <Unit0>
+        <Filename Value="drawingdemo.lpr"/>
+        <IsPartOfProject Value="True"/>
+      </Unit0>
+      <Unit1>
+        <Filename Value="drawingdisplay.pas"/>
+        <IsPartOfProject Value="True"/>
+        <ComponentName Value="Form1"/>
+        <ResourceBaseClass Value="Form"/>
+      </Unit1>
+      <Unit2>
+        <Filename Value="drawing.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit2>
+    </Units>
+  </ProjectOptions>
+  <CompilerOptions>
+    <Version Value="11"/>
+    <Target>
+      <Filename Value="drawingdemo"/>
+    </Target>
+    <SearchPaths>
+      <IncludeFiles Value="$(ProjOutDir)"/>
+      <UnitOutputDirectory Value="lib/$(TargetCPU)-$(TargetOS)"/>
+    </SearchPaths>
+    <Linking>
+      <Debugging>
+        <DebugInfoType Value="dsDwarf2Set"/>
+      </Debugging>
+      <Options>
+        <Win32>
+          <GraphicApplication Value="True"/>
+        </Win32>
+      </Options>
+    </Linking>
+  </CompilerOptions>
+  <Debugging>
+    <Exceptions Count="3">
+      <Item1>
+        <Name Value="EAbort"/>
+      </Item1>
+      <Item2>
+        <Name Value="ECodetoolError"/>
+      </Item2>
+      <Item3>
+        <Name Value="EFOpenError"/>
+      </Item3>
+    </Exceptions>
+  </Debugging>
+</CONFIG>

drawing demo/drawingdemo.lpr

@@ -0,0 +1,26 @@
+program drawingdemo;
+
+{$mode objfpc}{$H+}
+
+uses
+	{$IFDEF UNIX}{$IFDEF UseCThreads}
+	cthreads,
+	{$ENDIF}{$ENDIF}
+	Interfaces, // this includes the LCL widgetset
+	Forms,
+  Controls,
+  Graphics,
+  ExtCtrls,
+  drawing,
+	drawingdisplay;
+
+{$R *.res}
+
+begin
+	RequireDerivedFormResource:=True;
+	// Application.Scaled:=True;
+	Application.Initialize;
+	Application.CreateForm(TForm1, Form1);
+	Application.Run;
+end.
+

drawing demo/drawingdisplay.lfm

@@ -0,0 +1,34 @@
+object Form1: TForm1
+  Left = 627
+  Height = 240
+  Top = 322
+  Width = 320
+  Caption = 'Polymorphic drawing example'
+  ClientHeight = 240
+  ClientWidth = 320
+  OnCreate = FormCreate
+  LCLVersion = '2.0.12.0'
+  object rgShape: TRadioGroup
+    Left = 41
+    Height = 68
+    Top = 141
+    Width = 239
+    AutoFill = True
+    Caption = 'Type of FDrawing'
+    ChildSizing.LeftRightSpacing = 6
+    ChildSizing.EnlargeHorizontal = crsHomogenousChildResize
+    ChildSizing.EnlargeVertical = crsHomogenousChildResize
+    ChildSizing.ShrinkHorizontal = crsScaleChilds
+    ChildSizing.ShrinkVertical = crsScaleChilds
+    ChildSizing.Layout = cclLeftToRightThenTopToBottom
+    ChildSizing.ControlsPerLine = 1
+    ClientHeight = 49
+    ClientWidth = 229
+    Items.Strings = (
+      'TSquare'
+      'TCircle'
+    )
+    OnClick = rgShapeClick
+    TabOrder = 0
+  end
+end

drawing demo/drawingdisplay.pas

@@ -0,0 +1,62 @@
+unit drawingdisplay;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+	Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ExtCtrls, drawing;
+type
+	{ TForm1 }
+	TForm1 = class(TForm)
+		procedure FormCreate(Sender: TObject);
+		procedure rgShapeClick(Sender: TObject);
+	private
+    rgShape: TRadioGroup;
+		FDrawing: TDrawing;
+		procedure CreateANewDrawing;
+	public
+	end;
+
+const extent = 50;
+
+var
+	Form1: TForm1;
+
+implementation
+
+procedure TForm1.CreateANewDrawing;
+begin
+	if (rgShape.ItemIndex < 0) then Exit;
+
+	FDrawing.Free;
+
+	case rgShape.ItemIndex of
+		0: begin
+			FDrawing := TSquare.Create(Self, extent);
+			FDrawing.Left := 10;
+		end;
+		1: begin
+			FDrawing := TCircle.Create(Self, extent);
+			FDrawing.Left := 60;
+		end;
+	end;
+
+	FDrawing.Top := 10;
+	FDrawing.Parent := Self;
+end;
+
+procedure TForm1.FormCreate(Sender: TObject);
+begin
+	CreateANewDrawing;
+end;
+
+procedure TForm1.rgShapeClick(Sender: TObject);
+begin
+	CreateANewDrawing;
+end;
+
+{$R *.lfm}
+
+end.
+