再学 GDI+[71]: 路径画刷(11) RotateTransform、ScaleTransform 等变换

RotateTransform    {旋转}
ScaleTransform     {缩放}
TranslateTransform {平移}
SetTransform       {综合的矩阵变换}
ResetTransform     {取消变换}

本例效果图:

---

代码文件:

---

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    TrackBar1: TTrackBar;
    TrackBar2: TTrackBar;
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
    procedure TrackBar2Change(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI;

procedure TForm1.FormCreate(Sender: TObject);
begin
  TrackBar1.Min := -50;
  TrackBar1.Max := 50;
  TrackBar1.Position := 0;

  TrackBar2.Min := 1;
  TrackBar2.Max := 10;
  TrackBar2.Position := 10;
end;

procedure TForm1.FormPaint(Sender: TObject);
const
  colors: array[0..3] of TGPColor = (aclRed, aclYellow, aclGreen, aclBlue);
var
  g: TGPGraphics;
  p: TGPPen;
  path: TGPGraphicsPath;
  pb: TGPPathGradientBrush;
  num: Integer;
begin
  g := TGPGraphics.Create(Canvas.Handle);
  p := TGPPen.Create(aclRed);
  path := TGPGraphicsPath.Create;
  path.AddRectangle(MakeRect(50, 20, 120, 100));

  pb := TGPPathGradientBrush.Create(path);
  num := Length(colors);
  pb.SetSurroundColors(@colors, num);

  //pb.ResetTransform;
  pb.RotateTransform(TrackBar1.Position);
  pb.ScaleTransform(TrackBar2.Position / 10, TrackBar2.Position / 10);

  g.FillPath(pb, path);
  g.DrawPath(p, path);

  pb.Free;
  path.Free;
  p.Free;
  g.Free;
end;

procedure TForm1.TrackBar1Change(Sender: TObject);
begin
  Repaint;
end;

procedure TForm1.TrackBar2Change(Sender: TObject);
begin
  Repaint;
end;

end.

窗体文件:

---

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 165
  ClientWidth = 222
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poDesktopCenter
  OnCreate = FormCreate
  OnPaint = FormPaint
  PixelsPerInch = 96
  TextHeight = 13
  object TrackBar1: TTrackBar
    Left = 13
    Top = 136
    Width = 100
    Height = 23
    ShowSelRange = False
    TabOrder = 0
    OnChange = TrackBar1Change
  end
  object TrackBar2: TTrackBar
    Left = 110
    Top = 134
    Width = 100
    Height = 23
    ShowSelRange = False
    TabOrder = 1
    OnChange = TrackBar2Change
  end
end