Size and Position [Revelation On-Line Wiki]

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====== Size and Position ======

=== Published 16 APR 2015 at 02:48:51PM ===

In previous versions of OpenInsight the position of a Window or control has always been determined by its **SIZE** property - an @fm-delimited array comprised of the Left, Top, Width and Height values.  This means, of course, that all of these values have to be processed together at the same time.

For example, if you only want to update a control's Top attribute then you first have to get the current **SIZE** property, update the second field, and then set the entire array again like so:

<code>
ctrlSize    = get_Property( ctrlID, "SIZE" )
ctrlSize<2> = 100
call set_Property_Only( ctrlID, "SIZE", ctrlSize )
</code>

This can become tedious to write and it is also inefficient.

For version 10 we've exposed each of the **SIZE** fields as separate properties so you can now access them directly.  The new properties are:

  * **LEFT**
  * **TOP**
  * **WIDTH**
  * **HEIGHT**

Here's the previous example updated to use the **TOP** property:

<code>
call set_Property_Only( ctrlID, "TOP", 100 )
</code>

==== Positioning using rectangle (RECT) coordinates ====

Those of you used to working with the Windows API will know that many API functions don't use Width and Height values when dealing with positioning: they work with a "RECT" structure that uses Left, Top, Right and Bottom values to define an object's position instead (i.e. the coordinates of the top-left corner and the bottom-right corner).

In some cases being able to update a position using Right and Bottom instead of Width and Height can actually be more efficient because it can mean less calculations needed in your own code, and so a new **RECT** property has been added to enable this functionality.

The new **RECT** property works in exactly the same way as the current **SIZE** property except that the Width and Height fields have been replaced by the Right and Bottom fields like so:

<code>
* // RECT property structure
* // 
* //   <1> Left
* //   <2> Top
* //   <3> Right
* //   <4> Bottom
</code>

As with the **SIZE** property we've also exposed the  individual fields as separate properties so there are two new properties to complement **RECT** which are:

  * **RIGHT**
  * **BOTTOM**

 

** SIZE, RECT and "stealth mode"**

As you may know, when using the **SIZE** property with the Set_Property function you can set a "visible" attribute in the 5th field that can control the visibility of the object when it is moved. For example, setting the **SIZE** of an invisible WINDOW makes it visible by default unless you set this visible flag to "-1".  This is still the case in version 10 and it also applies to the new **RECT** property as well.

However, we have also added a new 6th field that can contain a "Suppress Change Notification" flag.  When this flag is set to TRUE$ the object that has been moved receives no internal notification from Windows that it has been updated, so this will stop any **MOVE** and **SIZE** events from begin raised as well as preventing any autosize processing.  This is sometimes necessary when you have complex positioning requirements.

<code>
* // Full SIZE property structure when used with Set_Property
* // 
* //   <1> Left
* //   <2> Top
* //   <3> Width
* //   <4> Height
* //   <5> Visibility
* //   <6> Suppress Change Notification
</code>

<code>
* // Full RECT property structure when used with Set_Property
* // 
* //   <1> Left
* //   <2> Top
* //   <3> Right
* //   <4> Bottom
* //   <5> Visibility
* //   <6> Suppress Change Notification
</code>

//(Disclaimer: This article is based on preliminary information and may be subject to change in the final release version of OpenInsight 10).//


=== Comments ===


----

=== At 16 APR 2015 02:57PM David Tod Sigafoos wrote:  ===

<QUOTE>So you have added 4 properties and left the SIZE property?

</QUOTE>

----

=== At 16 APR 2015 03:04PM Captain C wrote:  ===

<QUOTE>SIZE is exactly the same, but we've added 7 properties: LEFT, TOP, WIDTH, HEIGHT, RECT, RIGHT, & BOTTOM. The first four are available at design time and runtime, while all the others are runtime only.

</QUOTE>

----

=== At 22 APR 2015 11:15AM Craig Tildesley wrote:  ===

<QUOTE>Do the new properties (LEFT,TOP etc) send the change notification? Do they also need the suppression field?
I'm assuming that they individual ones don't change visibility

</QUOTE>

----

=== At 22 APR 2015 12:21PM Captain C wrote:  ===

<QUOTE>Hi Craig - they do indeed send the change notification, and they do not adjust the visibility.  They are meant to be a "lightweight" alternative to SIZE, so they don't support any extra flags.

</QUOTE>





== Original ID: revdevx.wordpress.com/?p=1419 ==