How to access nested style control - delphi

Question

I have custom styled FireMonkey control. Its style contains several levels of nested controls.
I need to access those controls and change some style properties at run-time. To do that I am using FindStyleResource<T> method.
I have no problem in retrieving first level of controls inside style. But accessing controls on second level with FindStyleResource fails if control parent is descendant of TStyledControl.
Question is how to access those nested style controls regardless of their parent type?
Style:
object TStyleContainer
object TLayout
StyleName = 'MyHeader'
Align = Center
Size.Width = 100.000000000000000000
Size.Height = 50.000000000000000000
Size.PlatformDefault = False
Visible = False
TabOrder = 0
object TLabel
StyleName = 'title'
Align = Client
StyledSettings = [Style]
Size.Width = 36.000000000000000000
Size.Height = 50.000000000000000000
Size.PlatformDefault = False
TextSettings.HorzAlign = Center
Text = 'Title'
end
object TLayout
StyleName = 'green'
Align = MostLeft
Size.Width = 32.000000000000000000
Size.Height = 50.000000000000000000
Size.PlatformDefault = False
object TPath
StyleName = 'greenpath'
Align = Fit
Data.Path = {
07000000000000000000404100000041010000000000C0400000604101000000
B81EED405C8F76410100000000004041AE472D410100000052B884415C8F7641
010000000000904100006041030000000000404100000041}
Fill.Color = claGreen
HitTest = False
Size.Width = 32.000000000000000000
Size.Height = 50.000000000000000000
Size.PlatformDefault = False
Stroke.Kind = None
WrapMode = Fit
end
end
object TSpeedButton
StyleName = 'red'
Align = MostRight
Position.X = 68.000000000000000000
Size.Width = 32.000000000000000000
Size.Height = 50.000000000000000000
Size.PlatformDefault = False
object TPath
StyleName = 'redpath'
Align = Fit
Data.Path = {
07000000000000000000404100000041010000000000C0400000604101000000
B81EED405C8F76410100000000004041AE472D410100000052B884415C8F7641
010000000000904100006041030000000000404100000041}
Fill.Color = claRed
HitTest = False
Size.Width = 32.000000000000000000
Size.Height = 32.571426391601560000
Size.PlatformDefault = False
Stroke.Kind = None
WrapMode = Fit
end
end
end
end
Control:
type
TMyHeader = class(TStyledControl)
protected
procedure ApplyStyle; override;
function GetDefaultStyleLookupName: string; override;
end;
procedure TMyHeader.ApplyStyle;
var
LGreen: TLayout;
LGreenPath: TPath;
LRed: TSpeedButton;
LRedPath: TPath;
begin
inherited;
if FindStyleResource<TLayout>('green', LGreen) then
begin
// following call will find greenpath control
if FindStyleResource<TPath>('greenpath', LGreenPath) then
LGreenPath.Fill.Color := TAlphaColorRec.Blue;
end;
if FindStyleResource<TSpeedButton>('red', LRed) then
begin
// following call will fail to find find redpath control
if FindStyleResource<TPath>('redpath', LRedPath) then
LRedPath.Fill.Color := TAlphaColorRec.Blue;
// this variant also fails
if LRed.FindStyleResource<TPath>('redpath', LRedPath) then
LRedPath.Fill.Color := TAlphaColorRec.Blue;
end;
end;
function TMyHeader.GetDefaultStyleLookupName: string;
begin
Result := 'MyHeader';
end;
Original style:
Changed style (only green arrow color was successfully changed)
In ApplyStyle method I can access greenpath from the style and change its color to blue. Hoewever, I cannot get redpath using FindStyleResource method.

Answer 1

The standard way to access style elements is via TFMXObject and iterate the children style objects.
Try this:
procedure TMyHeader.ApplyStyle;
var
objFMX,
inObjFMX: TFMXObject;
LRed: TSpeedButton;
LRedPath: TPath;
begin
inherited;
objFMX:=FindStyleResource('red');
if assigned(objFMX) and (objFMX is TSpeedButton) then
begin
LRed:=objFMX as TSpeedButton;
inObjFMX:=LRed.FindStyleResource('redpath');
if assigned(inObjFMX) and (inObjFMX is TPath) then
begin
LRedPath:=inObjFMX as TPath;
LRedPath.Fill.Color := TAlphaColorRec.Blue;
end;
end
end;
Updated Code: The FindStyleResource does not work in the above code. A different approach is followed below.
procedure TMyHeader.ApplyStyle;
var
objFMX,
inObjFMX: TFMXObject;
LRedPath: TPath;
begin
inherited;
objFMX:=FindStyleResource('red');
if assigned(objFMX) and (objFMX is TSpeedButton) then
begin
for inObjFMX in objFMX.Children do
begin
if inObjFMX is TPath then
begin
LRedPath:=inObjFMX as TPath;
LRedPath.Fill.Color:=TAlphaColorRec.Blue;
Break;
end;
end;
end;
end;
That works on 10.2