再学 GDI+[24]: TGPLinearGradientBrush - 之三

 

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, TeCanvas;

type
  TForm1 = class(TForm)
    ButtonColor1: TButtonColor;
    ButtonColor2: TButtonColor;
    procedure FormCreate(Sender: TObject);
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormPaint(Sender: TObject);
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure ButtonColor1Click(Sender: TObject);
    procedure ButtonColor2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
uses
  GDIPAPI,GDIPOBJ;
var
  flag:Boolean;
  pts:array[0..1] of TGPPoint;
  p:0..2;
procedure TForm1.ButtonColor1Click(Sender: TObject);
begin
  Repaint;
end;

procedure TForm1.ButtonColor2Click(Sender: TObject);
begin
  Repaint;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ButtonColor1.Caption:='颜色1   ';
  ButtonColor2.Caption:='颜色2   ';
  ButtonColor1.SymbolColor:=clLime;
  ButtonColor2.SymbolColor:=clBlack;

  pts[0].X:=8;
  pts[0].Y:=8;
  pts[1].X:=ClientWidth - 10;
  pts[1].Y:=ClientHeight - 10;
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  flag:=True;
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var
  i:Integer;
begin
  if flag then
  begin
    if p = 0 then Exit;
    pts[p - 1]:=MakePoint(x,y);
    Repaint;
  end
  else
  begin
    p:=0;
    Cursor:=crDefault;
    for I := 0 to Length(pts) - 1 do
      begin
        if PtInRect(Bounds((pts[i].X - 2),(pts[i].Y - 2),4,4),Point(x,y)) then
        begin
          p:=i + 1;
          Cursor:=crHandPoint;
        end;
      end;
  end;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  flag:=False;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g:TGPGraphics;
  p:TGPPen;
  R:TGPRect;
  lb:TGPLinearGradientBrush;
  c1,c2:TGPColor;
  i:Integer;
begin
  DoubleBuffered:=True;
  g:=TGPGraphics.Create(Canvas.Handle);
  g.Clear(aclWhite);
  p:=TGPPen.Create(aclRed);
  R:=MakeRect(20,40,ClientWidth - 40,ClientHeight - 50);
  c1:=ColorRefToARGB(ButtonColor1.SymbolColor);
  c2:=ColorRefToARGB(ButtonColor2.SymbolColor);

  lb:=TGPLinearGradientBrush.Create(TGPPoint(pts[0]),TGPPoint(pts[1]),c1,c2);

  g.FillEllipse(lb,r);
  p.SetColor(aclBlue);
  for I := 0 to 1 do
  begin
    g.DrawRectangle(p,(pts[i].X - 2),(pts[i].Y - 2),4,4);
  end;


  lb.Free;
  p.Free;
  g.Free;
end;

end.