[转载]Delphi 组件开发教程指南（8）定制特色Button

unit DxButton;

interface
uses Windows,Messages,Classes,SysUtils,Controls,Graphics;

type
  TDxButton = class(TCustomControl)
  private
    FIsDown:Boolean;
    FInButtonArea: Boolean;
    FOnClick: TNotifyEvent;
  protected
    procedure  Paint;override;
    procedure  CMTextChanged(var msg: TMessage);message CM_TEXTCHANGED;
    procedure  CMEnabledChanged(var Message: TMessage); message CM_ENABLEDCHANGED;
    procedure  CMMouseEnter(var Message: TMessage); message CM_MOUSEENTER;
    procedure  CMMouseLeave(var Message: TMessage); message CM_MOUSELEAVE;
    procedure  MouseDown(Button: TMouseButton; Shift: TShiftState;X, Y: Integer); override;
    procedure  MouseUp(Button: TMouseButton; Shift: TShiftState;X, Y: Integer); override;
    procedure  WMEnable(var Message: TMessage); message WM_ENABLE;
    procedure WMKillFocus(var msg: TWMKillFocus);message WM_KILLFOCUS;
    procedure WMS(var msg: TWMSetFocus);message WM_SETFOCUS;
  public
    constructor Create(AOwner: TComponent);override;
    procedure Click; override;
  published
    property Color;
    property Enabled;
    property Caption;
    property OnClick: TNotifyEvent read FOnClick write FOnClick;
  end;
implementation

procedure Frame3D(Canvas: TCanvas; var Rect: TRect; TopColor, BottomColor: TColor;
  Width: Integer);

  procedure DoRect;
  var
    TopRight, BottomLeft: TPoint;
  begin
    with Canvas, Rect do
    begin
      TopRight.X := Right;
      TopRight.Y := Top;
      BottomLeft.X := Left;
      BottomLeft.Y := Bottom;
      Pen.Color := TopColor;
      PolyLine([BottomLeft, TopLeft, TopRight]);
      Pen.Color := BottomColor;
      Dec(BottomLeft.X);
      PolyLine([TopRight, BottomRight, BottomLeft]);
    end;
  end;

begin
  Canvas.Pen.Width := 1;
  Dec(Rect.Bottom); Dec(Rect.Right);
  while Width > 0 do
  begin
    Dec(Width);
    DoRect;
    InflateRect(Rect, -1, -1);
  end;
  Inc(Rect.Bottom); Inc(Rect.Right);
end;

function GetNearColor(const Color: TColor;OffsetValue: integer): TColor;
var
  R, G, B, dR, dG, dB: Byte;
begin
  if (OffsetValue > 127) or (OffsetValue < -127) then
     raise Exception.Create('偏移值为-127-127之间')
  else if OffsetValue = 0 then
    Result := Color
  else
  begin
    Result := ($80 + OffsetValue) shl 24 or (ColorToRGB(Color));
    R := Byte(Result shr  0);
    G := Byte(Result shr  8);
    B := Byte(Result shr 16);
    if OffsetValue > 0 then
    begin
      Inc(OffsetValue);
      dR := not R;
      dG := not G;
      dB := not B;
    end
    else
    begin
      dR := R;
      dG := G;
      dB := B;
    end;
    R := R + (dR * OffsetValue) shr 7;
    G := G + (dG * OffsetValue) shr 7;
    B := B + (dB * OffsetValue) shr 7;
    Result := RGB(R,G,B)
  end;
end;
{ TDxButton }

procedure TDxButton.Click;
begin
  if Visible and Enabled then
  begin
    if Assigned(FOnClick) then
      FOnClick(Self);
  end;
end;

procedure TDxButton.CMEnabledChanged(var Message: TMessage);
begin
  inherited;
  if Parent <> nil then
    Invalidate;
end;

procedure TDxButton.CMMouseEnter(var Message: TMessage);
begin
   FInButtonArea:=True;
   inherited;
end;

procedure TDxButton.CMMouseLeave(var Message: TMessage);
begin
   FInButtonArea:=False;
   inherited;
end;

procedure TDxButton.CMTextChanged(var msg: TMessage);
begin
  Invalidate;
end;

constructor TDxButton.Create(AOwner: TComponent);
begin
  inherited;
  ControlStyle := [csSetCaption, csCaptureMouse];
  Width := 40;
  Height := 20;
end;

procedure TDxButton.MouseDown(Button: TMouseButton; Shift: TShiftState; X,
  Y: Integer);
begin
  inherited;
  if Enabled then
  begin
    SetFocus;
    FIsDown:=True;
    Invalidate;
  end;
end;

procedure TDxButton.MouseUp(Button: TMouseButton; Shift: TShiftState; X,
  Y: Integer);
var
  IsClick: Boolean;
begin
  inherited;
  IsClick := FIsDown;
  FIsDown := False;
  Invalidate;
  if IsClick and FInButtonArea then 
  begin
    Click;
    FIsDown:=False;
  end;
end;

procedure TDxButton.Paint;
var
  r: TRect;
begin
  r := ClientRect;
  if not FIsDown then
    Frame3D(Canvas,r,GetNearColor(Color,80),GetNearColor(Color,-80),1)
  else Frame3D(Canvas,r,GetNearColor(Color,-80),GetNearColor(Color,80),1);
  //然后绘制文字
  if Focused then
  begin
    Canvas.Brush.Color := not Color;
    InflateRect(r,-1,-1);
    DrawFocusRect(Canvas.Handle,r)
  end;
  
  Canvas.Brush.Style := bsClear;
  Canvas.Font.Assign(Font);  
  if not Enabled then
  begin
    OffsetRect(r, 1, 1);
    Canvas.Font.Color := clWhite;
    DrawText(Canvas.Handle, PChar(Caption), Length(Caption), r, DT_CENTER or DT_VCENTER or DT_SINGLELINE);
    Canvas.Font.Color := clGray;
    OffsetRect(r, -1, -1);
  end;
  DrawText(Canvas.Handle, PChar(Caption), Length(Caption), r, DT_CENTER or DT_VCENTER or DT_SINGLELINE);
end;

procedure TDxButton.WMEnable(var Message: TMessage);
begin
  SetEnabled(Message.WParam <> 0);
end;

procedure TDxButton.WMKillFocus(var msg: TWMKillFocus);
begin
  inherited;
  Invalidate;
end;

procedure TDxButton.WMS(var msg: TWMSetFocus);
begin
  inherited;
  Invalidate;
end;

end.