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  • 再学 GDI+[23]: TGPLinearGradientBrush 之二

    TGPLinearGradientBrush.Create(
      rect: TGPRect;                {变化范围}
      color1, color2: TGPColor;     {起始色与终止色}
      angle: Single;                {旋转角度}
      isAngleScalable: BOOL = FALSE {是否受 TLinearGradientMode 的影响, 可选值, 默认不受影响}
    );
    
    TGPLinearGradientBrush.Create(
      rect: TGPRectF;
      color1, color2: TGPColor;
      angle: Single;
      isAngleScalable: BOOL = FALSE
    );
    
    本例效果图:



    代码文件:
    unit Unit1;
    
    interface
    
    uses
      Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
      Dialogs, StdCtrls, TeCanvas, ExtCtrls, ComCtrls;
    
    type
      TForm1 = class(TForm)
        ButtonColor1: TButtonColor;
        ButtonColor2: TButtonColor;
        TrackBar1: TTrackBar;
        procedure FormCreate(Sender: TObject);
        procedure FormPaint(Sender: TObject);
        procedure TrackBar1Change(Sender: TObject);
        procedure ButtonColor1Click(Sender: TObject);
        procedure ButtonColor2Click(Sender: TObject);
      end;
    
    var
      Form1: TForm1;
    
    implementation
    
    {$R *.dfm}
    
    uses GDIPOBJ, GDIPAPI, TypInfo;
    
    procedure TForm1.FormCreate(Sender: TObject);
    begin
      ButtonColor1.Caption := '色1     ';
      ButtonColor2.Caption := '色2     ';
      ButtonColor1.SymbolColor := clLime;
      ButtonColor2.SymbolColor := clBlack;
    
      TrackBar1.ShowSelRange := False;
      TrackBar1.Min := 0;
      TrackBar1.Max := 360;
    end;
    
    procedure TForm1.FormPaint(Sender: TObject);
    var
      g: TGPGraphics;
      lb: TGPLinearGradientBrush;
      c1,c2: TGPColor;
      r: TGPRect;
    begin
      g := TGPGraphics.Create(Canvas.Handle);
      r := MakeRect(20, 40, ClientWidth - 40, ClientHeight - 50);
      c1 := ColorRefToARGB(ButtonColor1.SymbolColor);
      c2 := ColorRefToARGB(ButtonColor2.SymbolColor);
    
      lb := TGPLinearGradientBrush.Create(r, c1, c2, TrackBar1.Position);
    
      g.FillEllipse(lb, r);
    
      lb.Free;
      g.Free;
    end;
    
    procedure TForm1.TrackBar1Change(Sender: TObject);
    begin
      Repaint;
    end;
    
    procedure TForm1.ButtonColor1Click(Sender: TObject);
    begin
      Repaint;
    end;
    
    procedure TForm1.ButtonColor2Click(Sender: TObject);
    begin
      Repaint;
    end;
    
    end.
    
    窗体文件:
    object Form1: TForm1
      Left = 0
      Top = 0
      Caption = 'Form1'
      ClientHeight = 197
      ClientWidth = 253
      Color = clBtnFace
      Font.Charset = DEFAULT_CHARSET
      Font.Color = clWindowText
      Font.Height = -11
      Font.Name = 'Tahoma'
      Font.Style = []
      OldCreateOrder = False
      Position = poScreenCenter
      OnCreate = FormCreate
      OnPaint = FormPaint
      PixelsPerInch = 96
      TextHeight = 13
      object ButtonColor1: TButtonColor
        Left = 143
        Top = 8
        Width = 49
        Caption = 'ButtonColor1'
        TabOrder = 0
        OnClick = ButtonColor1Click
      end
      object ButtonColor2: TButtonColor
        Left = 198
        Top = 8
        Width = 49
        Caption = 'ButtonColor2'
        TabOrder = 1
        OnClick = ButtonColor2Click
      end
      object TrackBar1: TTrackBar
        Left = 1
        Top = 9
        Width = 137
        Height = 24
        TabOrder = 2
        OnChange = TrackBar1Change
      end
    end
    
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  • 原文地址:https://www.cnblogs.com/del/p/1217548.html
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