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Flutter_Documentation

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),
);
}
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 1To 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.
This can help you determine if an object fails to hit test.
This might happen if the object falls outside the bounds of its parent
and thus not considered for hit testing in the first place.If you’re trying to debug compositor layers, consider using the following flags.Use the debugPaintLayerBordersEnabled flag to find the boundaries
of each layer. This flag results in outlining each layer’s bounds in orange.Use the debugRepaintRainbowEnabled flag to display a repainted layer.
Whenever a layer repaints, it overlays with a rotating set of colors.Any function or method in the Flutter framework that starts with
debug... only works in debug mode.<topic_end>
<topic_start>
Debug animation issues
info Note
To debug animations with the least effort, slow them down.
To slow down the animation,
click Slow Animations in DevTools’ Inspector view.
This reduces the animation to 20% speed.
If you want more control over the amount of slowness,
use the following instructions.Set the timeDilation variable (from the scheduler
library) to a number greater than 1.0, for instance, 50.0.
It’s best to only set this once on app startup. If you
change it on the fly, especially if you reduce it while
animations are running, it’s possible that the framework
will observe time going backwards, which will probably
result in asserts and generally interfere with your efforts.<topic_end>
<topic_start>
Debug performance issues
info Note
You can achieve similar results to some of these debug
flags using DevTools. Some of the debug flags provide little benefit.
If you find a flag with functionality you would like to add to DevTools,
file an issue.Flutter provides a wide variety of top-level properties and functions
to help you debug your app at various points along the
development cycle.
To use these features, compile your app in debug mode.The following list highlights some of flags and one function from the
rendering library for debugging performance issues.To set these flags either:You can generate stack traces on demand as well.
To print your own stack traces, add the debugPrintStack()
function to your app.<topic_end>
<topic_start>
Trace Dart code performance
info Note
You can use the DevTools Timeline events tab to perform traces.
You can also import and export trace files into the Timeline view,
but only files generated by DevTools.To perform custom performance traces and
measure wall or CPU time of arbitrary segments of Dart code
like Android does with systrace,