I am trying to use TContentSizer to return the pixel width of a TBaloonLabel caption so that I can set the width dynamically. (I hope Tim will include an AutoSize property in the near future)

In my form, I instantiate the class as follows:-

 TContentSize = Class(TContentSizer)
 private
   // No local data
 public
   // Uses just the ancestor class public definitions
 end;

var
  oSize : TContentSize;

Later in the form, I call it as

showmessage(IntToStr(oSize.GetWidth(blbName.Font,blbName.Caption)));

where blbName is the TBaloonLabel.

However, I am receiving an error message of

Unable to get property 'getwidth' of undefined or null reference

Getwidth seems to be a public method of TContentSizer.

What am I doing wrong here?

--
Frederick

Probably a dumb question, but are you sure that oSize points to an instance and is not nil?

Ralf



Frederick Chin wrote:

I am trying to use TContentSizer to return the pixel width of a TBaloonLabel caption so that I can set the width dynamically. (I hope Tim will include an AutoSize property in the near future)

In my form, I instantiate the class as follows:-

 TContentSize = Class(TContentSizer)
 private
   // No local data
 public
   // Uses just the ancestor class public definitions
 end;

var
  oSize : TContentSize;

Later in the form, I call it as

showmessage(IntToStr(oSize.GetWidth(blbName.Font,blbName.Caption)));

where blbName is the TBaloonLabel.

However, I am receiving an error message of

Unable to get property 'getwidth' of undefined or null reference

Getwidth seems to be a public method of TContentSizer.

What am I doing wrong here?

--
Frederick

Ralf Mimoun wrote:

/*
Probably a dumb question, but are you sure that oSize points to an instance and is not nil?
*/

It could be but when I do the following,

oSize:=TContentSize.Create(NIL);
try
      TLabel1.Caption:=IntToStr(oSize.GetWidth(blbName.Font,blbName.Caption));  
finally
       oSize.Free;
end;

I get the following compiler message at the creation method,

Cannot create an instance of the class TContentSize when it contains abstract methods.

--
Frederick

Frederick,

> Cannot create an instance of the class TContentSize when it contains abstract methods.

TContentSizer contains two methods that are declared as "abstract".

From Delphi Basics:
"The Abstract directive defines a class method as being implemented only
in derived classes. It is abstract in the sense that it is a placeholder
- it has no implementation in the current class, but must be implemented
in any derived classes."

When you create a derived class, you have to override these methods as
you can see in WebUI.wbs e.g.:

   TTextContentSizer = class(TContentSizer)
      protected
         function GetDOMWrapStyle(AWrap: Boolean): String; override;
         procedure ApplyDOMContent(const AContent: String); override;
      end;

   THTMLContentSizer = class(TContentSizer)
      protected
         function GetDOMWrapStyle(AWrap: Boolean): String; override;
         procedure ApplyDOMContent(const AContent: String); override;
      end;

Uli

Uli,

/*
TContentSizer contains two methods that are declared as "abstract".

From Delphi Basics:
"The Abstract directive defines a class method as being implemented only
in derived classes. It is abstract in the sense that it is a placeholder
- it has no implementation in the current class, but must be implemented
in any derived classes."

When you create a derived class, you have to override these methods as
you can see in WebUI.wbs e.g.:

   TTextContentSizer = class(TContentSizer)
      protected
         function GetDOMWrapStyle(AWrap: Boolean): String; override;
         procedure ApplyDOMContent(const AContent: String); override;
      end;

   THTMLContentSizer = class(TContentSizer)
      protected
         function GetDOMWrapStyle(AWrap: Boolean): String; override;
         procedure ApplyDOMContent(const AContent: String); override;
      end;
*/

Based on the above, I have changed the derived class from TContentSizer to TTextContentSizer since the latter already overrides the abstract methods.

I am now able to show the TBalloonLabels in auto sized widths and it looks much better.

Thanks.

--
Frederick

Frederick,

<< I hope Tim will include an AutoSize property in the near future >>

This control doesn't have an AutoSize property because it allows for wrapping and already auto-sizes the height when doing so.

I'll look into it further, but there's probably a reason why an AutoSize property cannot be implemented. Some of the more complex controls can run into issues with auto-sizing, especially if the elements within the control can be placed in the left, middle, or right.

Tim Young
Elevate Software
www.elevatesoft.com

Tim,

/*
This control doesn't have an AutoSize property because it allows for wrapping and already auto-sizes the height when doing so.

I'll look into it further, but there's probably a reason why an AutoSize property cannot be implemented. Some of the more complex controls can run into issues with auto-sizing, especially if the elements within the control can be placed in the left, middle, or right.
*/

I think that for the balloon label, there should an AutoSize property that can be turned on if Wrap is off. If I decide to set the caption to only fit in one line, it means that the Wrap will not be used and the AutoSize property can kick in to display the label without the extra spaces (beyond the padding) at the end.

In my opinion, it just looks more professional.

--
Frederick