WinAPI: InvertRgn - 区域颜色取反

本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, ExtCtrls;



type

  TForm1 = class(TForm)

    CheckBox1: TCheckBox;

    ColorListBox1: TColorListBox;

    procedure FormPaint(Sender: TObject);

    procedure ColorListBox1Click(Sender: TObject);

    procedure CheckBox1Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.CheckBox1Click(Sender: TObject);

begin

  Repaint;

end;



procedure TForm1.ColorListBox1Click(Sender: TObject);

begin

  Self.Color := ColorListBox1.Selected;

end;



procedure TForm1.FormPaint(Sender: TObject);

const

  str = 'A';

var

  Rgn: HRGN;

  x,y: Integer;

begin

  Canvas.Font.Size := 120;

  Canvas.Font.Style := [fsBold];

  SetBkMode(Canvas.Handle, TRANSPARENT);



  x := (ClientWidth - ColorListBox1.Width - Canvas.TextWidth(str)) div 2;

  y := -20;



  {建立路径}

  BeginPath(Canvas.Handle);

  Canvas.TextOut(x, y, str);

  EndPath(Canvas.Handle);



  {将路径转换为区域}

  Rgn := PathToRegion(Canvas.Handle);



  {区域颜色取反}

  if CheckBox1.Checked then InvertRgn(Canvas.Handle, Rgn);



  {绘制}

  Canvas.Brush.Color := clSilver;

  Canvas.Brush.Style := bsDiagCross;

  FillRgn(Canvas.Handle, Rgn, Canvas.Brush.Handle);

  Canvas.Brush.Color := clRed;

  Canvas.Brush.Style := bsSolid;

  FrameRgn(Canvas.Handle, Rgn, Canvas.Brush.Handle, 1, 1);



  DeleteObject(Rgn);

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 366

  Top = 269

  Caption = 'Form1'

  ClientHeight = 179

  ClientWidth = 239

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesigned

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object CheckBox1: TCheckBox

    Left = 32

    Top = 152

    Width = 97

    Height = 25

    Caption = #21306#22495#39068#33394#21462#21453

    TabOrder = 0

    OnClick = CheckBox1Click

  end

  object ColorListBox1: TColorListBox

    Left = 147

    Top = 0

    Width = 92

    Height = 179

    Align = alRight

    ItemHeight = 16

    TabOrder = 1

    OnClick = ColorListBox1Click

  end

end