Delphi - Why does ExplicitWidth and ExplicitHeight keep appearing in .DFM files and what is it!?

Question

We've noticed that when checking in updates that our .DFM files have had ExplicitWidth and ExplicitHeight properties added for what appears to be no particular reason.

My two questions are, what are they for and why do they get automatically added by Delphi?

Below is an example with the property in:

object Splitter2: TcxSplitter
    Left = 0
    Top = 292
    Width = 566
    Height = 8
    Cursor = crVSplit
    HotZoneClassName = 'TcxXPTaskBarStyle'
    AlignSplitter = salBottom
    Control = BottomPanel
    Color = clBtnFace
    ExplicitWidth = 8
end

Answer 1

Delphi adds value of published properties to DFM file only when its value different from default.

For example:

property ExplicitWidth: Integer read FExplicitWidth write FExplicitWidth default 1;

If ExplicitWidth value is not 1 then it will be written to the DFM. When the "default" is not defined then any value will be written to the DFM.

TcxSplitter is not standard Delphi component, you'd better ask its author about the purpose of the properties.

Answer 2

I think these properties are another Delphi mystery, just like the EProgrammerNotFoundException ...

Answer 3

From Googling....

Original article can be found here.

The Explicit properties remember the previous bounds of a control before the Align or Anchor properties are changed from their defaults.

The only time the Explicit properties are not written is when the Align property is set back to its default value of alNone.

This is when the Explicit properties are actually used by the control to reset its bounds to what it was previously.

Answer 4

With DDevExtensions you can disable storing these properties in the dfm:
http://andy.jgknet.de/blog/?page_id=10

Adds Explicit* property remover to keep DFM files compatible to older Delphi versions