FireMonkey Panel tricks – Panel Color and Transparent Panels – Scott Hollows

Use this FireMonkey panel trick to change the color of a Delphi FireMonkey panel or make a FireMonkey panel transparent

FireMonkey_Panel_Color

I have seen some complex solutions to achieve this, but this is really quite easy to do. You just need one line of code. Well, two lines if you count the USES

Change the panel color

uses FMX.objects;   // from memory, I dont think you used to need this, but it is required in Delphi 12.1 and probably older versions as well

(Panel1.Controls[0] as TShape).Fill.Color := TAlphaColorRec.Red;

One line of code and we are done – BOOM

How does it work ?

This technique works because all FireMonkey panels own a TShape (usually a TRectangle) that covers the inside of the panel. In the above example, we are changing the color of that TShape to red

This also works for other panel variants that I have tried such as TCalloutPanel

More robust code

It ia possible (although I have never seen it) that Delphi might remove the TShape. So, lets modify the code to be more paranoid by first making sure that a TShape exists (hopefully it is the right one)

  if   (Panel1.ControlsCount >= 1)
   and (Panel1.Controls[0] is TShape)
  then
       (Panel1.Controls[0] as TShape).Fill.Color := TAlphaColorRec.Red;  // uses System.UITypes

Want more – lets make the panel transparent

Now that you know the magic trick of the TPanel guts being a TShape, you can go further and manipulate the shape to make the panel transparent … like this

  if   (Panel1.ControlsCount >= 1)
   and (Panel1.Controls[0] is TShape)
  then
       (Panel1.Controls[0] as TShape).visible := FALSE;

Is this Future Proof ?

No – This is not guarenteed to work in future as Embaradero could remove this handy little TShape #0 feature. However, I think it is stable and I expect it to work in the long term (fingers crossed)

Alternatives

If you dont like that solution, here are some alternatives

Add a TRect to the panel to show the color that you want. Thats pretty much the same technique that I use above, but you will feel more in control because you created it.
Use Delphi Styles.

+1 this post

Please help get this blog listed on DelphiFeeds by +1 voting here on DelphiFeeds
and also vote on BeginEnd. Thank you

About Me

scott_hollows_201611

Oracle & Delphi software developer based in Perth, Western Australia
Australian Delphi User Group – President
Australian Oracle User Group – WA Committee Member
Available to do remote presentations to user groups on Delphi and Oracle topics

Scott Hollows – One Line At A Time