GDI+ 陰影筆刷完整指南：TGPHatchBrush 56 種預設圖案

TGPHatchBrush 提供 56 種預定義的陰影圖案，涵蓋線條、網格、磚塊、波浪、百分比網點等豐富樣式，適用於工程繪圖、統計圖表、CAD 應用等場景。每種圖案支援獨立設定前景色與背景色。

建構子語法

TGPHatchBrush.Create(
  hatchStyle: THatchStyle;   { 陰影樣式 }
  foreColor: TGPColor;       { 前景色 }
  backColor: TGPColor = aclBlack { 背景色，預設黑色 }
);

程式碼實作

完整互動範例：下拉選單列出所有 56 種 HatchStyle，兩個 ColorBox 分別選取前景/背景色：

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    ColorBox1: TColorBox;
    ColorBox2: TColorBox;
    ComboBox1: TComboBox;
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure ComboBox1Change(Sender: TObject);
    procedure ColorBox1Change(Sender: TObject);
    procedure ColorBox2Change(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
uses GDIPOBJ, GDIPAPI, TypInfo;

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  { 列舉所有 HatchStyle 項目 }
  for i := 0 to Integer(HatchStyleTotal) - 1 do
    ComboBox1.Items.Add(GetEnumName(TypeInfo(HatchStyle), i));
  ComboBox1.ItemIndex := 0;
  ColorBox1.ItemIndex := 16;
  ColorBox2.ItemIndex := 3;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g: TGPGraphics;
  r: TGPRect;
  hb: TGPHatchBrush;
  fColor, bColor: TGPColor;
  hbStyle: HatchStyle;
begin
  g := TGPGraphics.Create(Canvas.Handle);
  g.Clear(MakeColor(255, 255, 255));
  r := MakeRect(20, 60, ClientWidth - 40, ClientHeight - 70);
  hbStyle := HatchStyle(ComboBox1.ItemIndex);
  fColor := ColorRefToARGB(ColorBox1.Selected);
  bColor := ColorRefToARGB(ColorBox2.Selected);
  hb := TGPHatchBrush.Create(hbStyle, fColor, bColor);
  g.FillEllipse(hb, r);
  hb.Free;
  g.Free;
end;

procedure TForm1.ColorBox1Change(Sender: TObject); begin Repaint; end;
procedure TForm1.ColorBox2Change(Sender: TObject); begin Repaint; end;
procedure TForm1.ComboBox1Change(Sender: TObject); begin Repaint; end;

end.

表單設計 (DFM)

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 206
  ClientWidth = 268
  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 ColorBox1: TColorBox
    Left = 48
    Top = 30
    Width = 100
    Height = 22
    ItemHeight = 16
    TabOrder = 0
    OnChange = ColorBox1Change
  end
  object ColorBox2: TColorBox
    Left = 160
    Top = 30
    Width = 100
    Height = 22
    ItemHeight = 16
    TabOrder = 1
    OnChange = ColorBox2Change
  end
  object ComboBox1: TComboBox
    Left = 48
    Top = 3
    Width = 212
    Height = 21
    ItemHeight = 13
    TabOrder = 2
    Text = 'ComboBox1'
    OnChange = ComboBox1Change
  end
end

執行效果

HatchStyle 完整對照表 (56 種)

善用陰影筆刷可避免大面積純色填充的單調感，並在列印文件中節省墨水。