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[flutter_svg] Update README with an example to scale images #10547

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[flutter_svg] Update README with an example to scale images #10547

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20 changes: 19 additions & 1 deletion third_party/packages/flutter_svg/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,25 @@ import 'dart:ui' as ui;
canvas.drawPicture(pictureInfo.picture);

// Or convert the picture to an image:
final ui.Image image = await pictureInfo.picture.toImage(width, height);
ui.Image image = await pictureInfo.picture.toImage(width, height);

// Or convert the picture to a scaled image:
const double targetWidth = 512;
const double targetHeight = 512;
final pictureRecorder = ui.PictureRecorder();
canvas = Canvas(
pictureRecorder,
Rect.fromPoints(Offset.zero, const Offset(targetWidth, targetHeight)),
);
canvas.scale(
targetWidth / pictureInfo.size.width,
targetHeight / pictureInfo.size.height,
);
canvas.drawPicture(pictureInfo.picture);
image = await pictureRecorder.endRecording().toImage(
targetWidth.ceil(),
targetHeight.ceil(),
);
Comment on lines +125 to +143
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@gemini-code-assist gemini-code-assist bot Dec 1, 2025

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medium

Assigning a value to image and then immediately reassigning it can be confusing in an example, as it might suggest to users that both steps are necessary. To make it clearer that creating an unscaled image and a scaled image are alternative operations, I suggest commenting out the first assignment. This also allows you to use final for the image variable, which is good practice.

Suggested change
ui.Image image = await pictureInfo.picture.toImage(width, height);
// Or convert the picture to a scaled image:
const double targetWidth = 512;
const double targetHeight = 512;
final pictureRecorder = ui.PictureRecorder();
canvas = Canvas(
pictureRecorder,
Rect.fromPoints(Offset.zero, const Offset(targetWidth, targetHeight)),
);
canvas.scale(
targetWidth / pictureInfo.size.width,
targetHeight / pictureInfo.size.height,
);
canvas.drawPicture(pictureInfo.picture);
image = await pictureRecorder.endRecording().toImage(
targetWidth.ceil(),
targetHeight.ceil(),
);
// To create an unscaled image, you can do:
// final ui.Image image = await pictureInfo.picture.toImage(width, height);
// Or convert the picture to a scaled image:
const double targetWidth = 512;
const double targetHeight = 512;
final pictureRecorder = ui.PictureRecorder();
canvas = Canvas(
pictureRecorder,
Rect.fromPoints(Offset.zero, const Offset(targetWidth, targetHeight)),
);
canvas.scale(
targetWidth / pictureInfo.size.width,
targetHeight / pictureInfo.size.height,
);
canvas.drawPicture(pictureInfo.picture);
final ui.Image image = await pictureRecorder.endRecording().toImage(
targetWidth.ceil(),
targetHeight.ceil(),
);


pictureInfo.picture.dispose();
```
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22 changes: 20 additions & 2 deletions third_party/packages/flutter_svg/example/lib/readme_excerpts.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ Widget loadPrecompiledAsset() {

/// Demonstrates converting SVG to another type.
Future<ui.Image> convertSvgOutput() async {
final canvas = Canvas(ui.PictureRecorder());
var canvas = Canvas(ui.PictureRecorder());
const width = 100;
const height = 100;

Expand All @@ -94,7 +94,25 @@ Future<ui.Image> convertSvgOutput() async {
canvas.drawPicture(pictureInfo.picture);

// Or convert the picture to an image:
final ui.Image image = await pictureInfo.picture.toImage(width, height);
ui.Image image = await pictureInfo.picture.toImage(width, height);

// Or convert the picture to a scaled image:
const double targetWidth = 512;
const double targetHeight = 512;
final pictureRecorder = ui.PictureRecorder();
canvas = Canvas(
pictureRecorder,
Rect.fromPoints(Offset.zero, const Offset(targetWidth, targetHeight)),
);
canvas.scale(
targetWidth / pictureInfo.size.width,
targetHeight / pictureInfo.size.height,
);
canvas.drawPicture(pictureInfo.picture);
image = await pictureRecorder.endRecording().toImage(
targetWidth.ceil(),
targetHeight.ceil(),
);
Comment on lines +97 to +115
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@gemini-code-assist gemini-code-assist bot Dec 1, 2025

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medium

Assigning a value to image and then immediately reassigning it can be confusing in an example, as it might suggest to users that both steps are necessary. To make it clearer that creating an unscaled image and a scaled image are alternative operations, I suggest commenting out the first assignment. This also allows you to use final for the image variable, which is good practice.

Suggested change
ui.Image image = await pictureInfo.picture.toImage(width, height);
// Or convert the picture to a scaled image:
const double targetWidth = 512;
const double targetHeight = 512;
final pictureRecorder = ui.PictureRecorder();
canvas = Canvas(
pictureRecorder,
Rect.fromPoints(Offset.zero, const Offset(targetWidth, targetHeight)),
);
canvas.scale(
targetWidth / pictureInfo.size.width,
targetHeight / pictureInfo.size.height,
);
canvas.drawPicture(pictureInfo.picture);
image = await pictureRecorder.endRecording().toImage(
targetWidth.ceil(),
targetHeight.ceil(),
);
// To create an unscaled image, you can do:
// final ui.Image image = await pictureInfo.picture.toImage(width, height);
// Or convert the picture to a scaled image:
const double targetWidth = 512;
const double targetHeight = 512;
final pictureRecorder = ui.PictureRecorder();
canvas = Canvas(
pictureRecorder,
Rect.fromPoints(Offset.zero, const Offset(targetWidth, targetHeight)),
);
canvas.scale(
targetWidth / pictureInfo.size.width,
targetHeight / pictureInfo.size.height,
);
canvas.drawPicture(pictureInfo.picture);
final ui.Image image = await pictureRecorder.endRecording().toImage(
targetWidth.ceil(),
targetHeight.ceil(),
);


pictureInfo.picture.dispose();
// #enddocregion OutputConversion
Expand Down