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that are repainting too often and potentially harming performance.For example, one small animation could be causing an entire page
to repaint on every frame.
Wrapping the animation in a RepaintBoundary widget limits
the repainting to just the animation.Here the progress indicator causes its container to repaint:
<code_start>class EverythingRepaintsPage extends StatelessWidget {
const EverythingRepaintsPage({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Repaint Example')),
body: const Center(
child: CircularProgressIndicator(),
),
);
}
}<code_end>
Wrapping the progress indicator in a RepaintBoundary causes
only that section of the screen to repaint:
<code_start>class AreaRepaintsPage extends StatelessWidget {
const AreaRepaintsPage({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Repaint Example')),
body: const Center(
child: RepaintBoundary(
child: CircularProgressIndicator(),
),
),
);
}
}<code_end>
RepaintBoundary widgets have tradeoffs. They can help with performance,
but they also have an overhead of creating a new canvas,
which uses additional memory.You can also enable this option in code:
<code_start>import 'package:flutter/rendering.dart';
void highlightRepaints() {
debugRepaintRainbowEnabled = true;
}<code_end>
<topic_end>
<topic_start>
Highlight oversized images
This option highlights images that are too large by both inverting their colors
and flipping them vertically:The highlighted images use more memory than is required;
for example, a large 5MB image displayed at 100 by 100 pixels.Such images can cause poor performance, especially on lower-end devices
and when you have many images, as in a list view,
this performance hit can add up.
Information about each image is printed in the debug console:Images are deemed too large if they use at least 128KB more than required.<topic_end>
<topic_start>Fixing images
Wherever possible, the best way to fix this problem is resizing
the image asset file so it’s smaller.If this isn’t possible, you can use the cacheHeight and cacheWidth
parameters on the Image constructor:
<code_start>class ResizedImage extends StatelessWidget {
const ResizedImage({super.key});
@override
Widget build(BuildContext context) {
return Image.asset(
'dash.png',
cacheHeight: 213,
cacheWidth: 392,
);
}
}<code_end>
This makes the engine decode this image at the specified size,
and reduces memory usage (decoding and storage is still more expensive
than if the image asset itself was shrunk).
The image is rendered to the constraints of the layout or width and height
regardless of these parameters.This property can also be set in code:
<code_start>void showOversizedImages() {
debugInvertOversizedImages = true;
}<code_end>
<topic_end>
<topic_start>More information
You can learn more at the following link:<topic_end>
<topic_start>
Details Tree
Select the Widget Details Tree tab to display the details tree for the
selected widget. From here, you can gather useful information about a
widget’s properties, render object, and children.<topic_end>
<topic_start>
Track widget creation
Part of the functionality of the Flutter inspector is based on
instrumenting the application code in order to better understand
the source locations where widgets are created. The source
instrumentation allows the Flutter inspector to present the
widget tree in a manner similar to how the UI was defined
in your source code. Without it, the tree of nodes in the
widget tree are much deeper, and it can be more difficult to
understand how the runtime widget hierarchy corresponds to
your application’s UI.You can disable this feature by passing --no-track-widget-creation to
the flutter run command.Here are examples of what your widget tree might look like
with and without track widget creation enabled.Track widget creation enabled (default):Track widget creation disabled (not recommended):This feature prevents otherwise-identical const Widgets from
being considered equal in debug builds. For more details, see
the discussion on common problems when debugging.<topic_end>
<topic_start>
Inspector settings
<topic_end>
<topic_start>
Enable hover inspection
Hovering over any widget displays its properties and values.Toggling this value enables or disables the hover inspection functionality.<topic_end>