在Delphi中初始程序加载后更改一个TStatusPanel的颜色？

我有一个程序,底部有一个包含三个元素的状态栏.我想用不同的字体颜色重绘第二个元素,以表示用户有效.我的问题的第一部分是：

a)如何以不同的颜色将文本重绘为默认文本？

和b)如何在触发事件后以不同的颜色绘制文本(例如按下按钮)？

我目前的代码如下.我正在尝试检查以不同颜色重新绘制面板的条件是否正确(CurrentUser.Valid,这是一个布尔值),然后尝试重新着色文本.这目前不起作用.

procedure TChatFormMain.sbarMainDrawPanel(StatusBar: TStatusBar;
  Panel: TStatusPanel; const Rect: TRect);
var
  RectForText: TRect;
begin
  if (Panel = StatusBar.Panels[1]) and (CurrentUser.Valid) then
  begin
    sbarMain.Canvas.Font.Color := clGreen;
    RectForText := Rect;
    StatusBar.Canvas.FillRect(RectForText);
    DrawText(sbarMain.Canvas.Handle, PChar(Panel.Text), -1, RectForText,
      DT_SINGLELINE or DT_VCENTER or DT_LEFT);
  end;
end;

在代码的另一部分,我正在调用StatusBar.repaint;尝试用新文本颜色重新绘制条形图,这是正确的吗？

更新MCVE：

unit colourStatusU;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ComCtrls;

type
  TForm1 = class(TForm)
    StatusBar1: TStatusBar;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure StatusBar1DrawPanel(StatusBar: TStatusBar; Panel: TStatusPanel;
      const Rect: TRect);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  valid : boolean;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  valid := true;
  StatusBar1.Repaint;
end;

procedure TForm1.StatusBar1DrawPanel(StatusBar: TStatusBar; Panel: TStatusPanel;
  const Rect: TRect);
var
  RectForText: TRect;
begin
  if (Panel = StatusBar.Panels[1]) and (Valid) then
  begin
    Canvas.Font.Color := clGreen;
    RectForText := Rect;
    Canvas.FillRect(RectForText);
    DrawText(Canvas.Handle, PChar(Panel.Text), -1, RectForText,
      DT_SINGLELINE or DT_VCENTER or DT_LEFT);
  end;
end;

end.

OnDrawPanel事件仅针对其Style设置为psOwnerDraw的面板调用,因此请确保在Object Inspector或代码中正确设置了Style.

要绘制的画布必须是TStatusBar.Canvas,但您使用的是TForm.Canvas.使用OnDrawPanel事件提供的StatusBar的Canvas：

procedure TForm1.StatusBar1DrawPanel(StatusBar: TStatusBar; Panel: TStatusPanel;
  const Rect: TRect);
var
  RectForText: TRect;
begin
  if (Panel = StatusBar.Panels[1]) and (Valid) then
  begin
    StatusBar.Canvas.Font.Color := clGreen;
    RectForText := Rect;
    StatusBar.Canvas.FillRect(RectForText);
    DrawText(StatusBar.Canvas.Handle, PChar(Panel.Text), -1, RectForText, DT_SINGLELINE or DT_VCENTER or DT_LEFT);
  end;
end;

调用Repaint()或Invalidate()以强制状态栏重新绘制其绘图是要使用的方法.