ImageFilter.blur default tile mode automatic selection.

The ui.ImageFilter.blur's default tile mode is now automatically selected by the backend. Previously TileMode.clamp was used unless a different tile mode was specified. Now, the default is null and specifies automatic selection unless a specific tile mode is specified.

ImageFilter.blur's tile mode specifies what happens to edge pixels for the applied filter. There are four options:

• TileMode.clamp (the previous default)
• Tilemode.repeated
• TileMode.mirror
• TileMode.decal

Previously, if the behavior wasn't specified, ImageFilter defaulted to clamp mode. This sometimes surprised developers as it didn't always match expectations.

As of this change, the filter automatically selects the following tile modes based on context:

• decal with save layers and when applied to individual shape draws (such as with drawRect and drawPath).
• mirror with backdrop filters.
• clamp for drawImage.

Only blur image filters that don't specify an explicit tile mode are impacted by this change.

We believe that the new defaults are generally better and would recommend removing any specified blur tile modes.

Code before migration:

final filter = ui.ImageFilter.blur(sigmaX: 4, sigmaY: 4, tileMode: TileMode.decal);

Code after migration:

final filter = ui.ImageFilter.blur(sigmaX: 4, sigmaY: 4);

Landed in version: 3.28.0-0.1.pre
In stable release: 3.29

API documentation:

• ImageFilter
• TileMode

Relevant issues:

• Issue #154935
• Issue #110318
• Issue #157693

Relevant PRs:

• Change default TileMode for blur ImageFilter objects to null