Delphi XE2: Is there a predefined conditional to identify VCL and FireMonkey?

In Delphi XE2, we have use

{$ifdef Win32}
{$ifdef Win64}

to identify which pl开发者_C百科atform we are in.

Is there any predefined conditional that may identify VCL and FMX?

Although not documented you can have VCL and Firemonkey in the same application.

There is no compiler define.

If you're building something that needs to be both VCL and Firemonkey I would recommend separation of the units.

A possible way:

• MyLibrary.X.pas - Common Code that both VCL, and Firemonkey would uses.
• MyLibrary.Vcl.X.Pas - Vcl Specific Code
• MyLibrary.Fmx.X.Pas - Fmx Specific Code

Mixing UI code from two different frameworks in the same unit is not a good idea. It will link in the other library when it's not needed.

As others says, there is not a conditional directive to determine if your application is VCL or FireMonkey. I think the most reliable way to determine if your app is FireMonkey or VCL is using a function instead of a conditional directive.

Something like

Uses
 Rtti;

function IsVCLApp:Boolean;
begin
 Result:= CompareText(TRttiContext.Create.GetType(TApplication.ClassInfo).QualifiedName,'Vcl.Forms.TApplication')=0;
end;

function IsFireMonkeyApp:Boolean;
begin
 Result:= CompareText(TRttiContext.Create.GetType(TApplication.ClassInfo).QualifiedName,'FMX.Forms.TApplication')=0;
end;

There is no compiler directive because technically there is no such thing as a firemonkey application or a vcl application. Only applications which make use of these technologies. An application can use fxm or vcl or both or neither (eg. a console app). This is a bit like asking if it is an SQL application. You can of course programatically check the ancestry of individual forms to see which framework they inherit from. Again, inside a unit that has no associated form, this has no meaning.

There does not seem to be a compiler define specifically for VCL/FireMonkey. You would need to create your own.

A list of predefined conditionals can be found in the documentation.

Abbrevia supports both the VCL and CLX using this kind of split:

QAbUnit1.pas:

{$DEFINE UsingCLX}
unit QAbUnit1;
{$I AbUnit1.pas}

AbUnit1.pas:

{$IFNDEF UsingCLX}
{$DEFINE UsingVCL}
unit AbUnit1;
{$ENDIF}

type
  ...
  TMyWidget = class({$IFDEF UsingVCL}TWinControl{$ENDIF}
                    {$IFDEF UsingCLX}TWidgetControl{$ENDIF})
  ...
  end;

end.

To add FireMonkey support, I'd add a file like this:

FmxAbUnit1.pas:

{$DEFINE UsingFMX}
unit FmxAbUnit1;
{$I AbUnit1.pas}
{$ENDIF}

and then make whatever conditional changes I need to AbUnit1.pas.

It's not a nice clean split like Robert's suggestion, but the advantage is that all of your editing occurs in a single file, and the conditional define is handled automatically, so it doesn't need to appear in the project options. Who ever uses your library just includes the appropriate unit to decide which one they want to use. You could probably take advantage of unit scoping too, by naming the files Fmx.AbUnit1.pas and Vcl.AbUnit1.pas, but I think Embarcadero discourages that.

Try this snippet:

{$IF Declared(FMX)}
  // FMX code here. To test this approach you may use {$MESSAGE FATAL 'FMX'}
{$ELSEIF Declared(VCL)}
  // VCL code here. To test this approach you may use {$MESSAGE FATAL 'VCL'}
{$IFEND}

It tests if corresponding namespace was declared using IF compilation directive

As FMX isn't mutually exclusive with VCL, there may be a need to add following branches:

{$ELSEIF Declared(FMX) and Declared(VCL)}
  // FMX+VCL code here. To test: {$MESSAGE FATAL 'FMX+VCL'}
{$ELSE}
  // no GUI frameworks code here. To test: {$MESSAGE FATAL 'no GUI frameworks'}