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@override
widget build(BuildContext context) {
return material(
child: center(
child: TextButton(
onPressed: () {
debugDumpFocusTree();
},
child: const Text('Dump focus tree'),
),
),
);
}
}
<code_end>
<topic_end>
<topic_start>
print the semantics tree
the debugDumpSemanticsTree() function prints the semantic tree for the app.
the semantics tree is presented to the system accessibility APIs.
to obtain a dump of the semantics tree:
<topic_end>
<topic_start>
example 8: call debugDumpSemanticsTree()
<code_start>
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(
const MaterialApp(
home: AppHome(),
),
);
}
class AppHome extends StatelessWidget {
const AppHome({super.key});
@override
widget build(BuildContext context) {
return material(
child: center(
child: semantics(
button: true,
enabled: true,
label: 'clickable text here!',
child: GestureDetector(
onTap: () {
debugDumpSemanticsTree();
if (kdebugmode) {
print('Clicked!');
}
},
child: const Text('Click me!', style: TextStyle(fontSize: 56))),
),
),
);
}
}
<code_end>
<topic_end>
<topic_start>
print event timings
if you want to find out where your events happen relative to the frame’s
begin and end, you can set prints to log these events.
to print the beginning and end of the frames to the console,
toggle the debugPrintBeginFrameBanner
and the debugPrintEndFrameBanner.
the print frame banner log for example 1
to print the call stack causing the current frame to be scheduled,
use the debugPrintScheduleFrameStacks flag.
<topic_end>
<topic_start>
debug layout issues
to debug a layout problem using a GUI, set
debugPaintSizeEnabled to true.
this flag can be found in the rendering library.
you can enable it at any time and affects all painting while true.
consider adding it to the top of your void main() entry point.
<topic_end>
<topic_start>
example 9
see an example in the following code:
<code_start>
//add import to rendering library
import 'package:flutter/rendering.dart';
void main() {
debugPaintSizeEnabled = true;
runApp(const MyApp());
}
<code_end>
when enabled, flutter displays the following changes to your app:
the debugPaintBaselinesEnabled flag
does something similar but for objects with baselines.
the app displays the baseline for alphabetic characters in bright green
and the baseline for ideographic characters in orange.
alphabetic characters “sit” on the alphabetic baseline,
but that baseline “cuts” through the bottom of CJK characters.
flutter positions the ideographic baseline at the very bottom of the text line.
the debugPaintPointersEnabled flag turns on a special mode that
highlights any objects that you tap in teal.