[yunqa.de] Re: Suggestion - Make TDiHtmlLabel.FRect protected.

Hi Ralf,

Well, by creating an decedent component I don't have to write the
 OnMouseEnter/Leave event handlers - this is the only benefit and I believe
it's the benefit of OOP.

Below is my derived component, I added two properties:
HotColor
Hot.

Source:

unit MyHtmlLabel;

interface

uses
  SysUtils, Classes, Controls, DIHtmlLabel, Messages, Graphics, Math;

type
  TMyHtmlLabel = class(TDIHtmlLabel)
  strict private
    FHot: Boolean;
    FHotColor: TColor;
    procedure SetHot(const Value: Boolean);
    procedure SetHotColor(const Value: TColor);
  private
    procedure CMMouseEnter(var Msg: TMessage); message CM_MOUSEENTER;
    procedure CMMouseLeave(var Msg: TMessage); message CM_MOUSELEAVE;
    { Private declarations }
  protected
    procedure Paint; override;
  public
    constructor Create(AOwner: TComponent);
  published
    property Hot: Boolean read FHot write SetHot default False;
    property HotColor: TColor read FHotColor write SetHotColor default
clSkyBlue;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Edwin', [TMyHtmlLabel]);
end;

constructor TMyHtmlLabel.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  HotColor := $00FFF2F2;
end;

procedure TMyHtmlLabel.CMMouseEnter(var Msg: TMessage);
begin
  inherited;
  Hot := True;

//  if Assigned(FOnMouseEnter) then
//    FOnMouseEnter(self);
end;

procedure TMyHtmlLabel.CMMouseLeave(var Msg: TMessage);
begin
  inherited;
  Hot := False;

//  if Assigned(FOnMouseLeave) then
//    FOnMouseLeave(self);
end;

procedure TMyHtmlLabel.Paint;
begin
  // no calling inherited here. the following code is modified based on
TDiHtmlLabel.Paint.
  if Assigned(FNodeTree) then
    begin
      with Canvas do
        begin
          if Hot then
          begin
            Brush.Color := Self.HotColor;
            Brush.Style := bsSolid;
            FillRect(ClientRect);
          end
          else if not Transparent then
          begin
            Brush.Color := Self.Color;
            Brush.Style := bsSolid;
            FillRect(ClientRect);
          end
          else
            Brush.Style := bsClear;
        end;

      Canvas.Font := Font;
      Renderer.RenderTree(Canvas, FRect, FNodeTree);

      if AutoHeight and (Align in [alNone, alTop, alBottom]) then
        ClientHeight := Renderer.TextHeight + MarginHeight;
    end;

  if Assigned(OnAfterPaint) then
    OnAfterPaint(Self);
end;

procedure TMyHtmlLabel.SetHot(const Value: Boolean);
begin
  if FHot <> Value then
  begin
    FHot := Value;
    Invalidate;
  end;
end;

procedure TMyHtmlLabel.SetHotColor(const Value: TColor);
begin
  if FHotColor <> Value then
  begin
    FHotColor := Value;
  end;
end;

end.


On Mon, Feb 20, 2012 at 7:01 AM, Delphi Inspiration <delphi@xxxxxxxx> wrote:

> On 19.02.2012 14:56, Edwin Yip wrote:
>
> > Yes, when drawing the background to indicate the 'hot' status of the
> > label, I use ClientRect, but since in my overridden Paint() method I
> > can't call inherited, instead I have to copy and modify the method body
> > of TDiHtmlLabel which needs to access the FRect field in order to paint
> > the html tags.
> >
> > Precisely, it's the following code:
> > Renderer.RenderTree(Canvas, FRect, FNodeTree);
>
> I still do not understand why you want to go the extra way. Attached is
> a project which demonstrates my concept. The archive also contains the
> updated DIHtmlLabel.pas unit which you must install into the Delphi IDE
> to open the form in design-view. A simple compile should work without
> installation.
>
> If your solution has benefits over my approach, I'd be interested if you
> could share your code.
>
> Ralf
>



-- 
Best Regards,
Edwin Yip

Mind Mapping is as Effortless as Typing
http://www.InnovationGear.com

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