Lazy loading of icons, theme for faster app startup#6043
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FeodorFitsner merged 12 commits intomainfrom Jan 21, 2026
Merged
Lazy loading of icons, theme for faster app startup#6043FeodorFitsner merged 12 commits intomainfrom
FeodorFitsner merged 12 commits intomainfrom
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Removed direct imports of Icons and CupertinoIcons from __init__.py and added dynamic attribute access via __getattr__. Updated Dropdown to set default icons in before_update instead of as class attributes. Fixed import of IconData in time_picker.py to use the correct module.
Updated the icon generation script to output both .pyi stubs and JSON files for Material and Cupertino icons. Replaced hardcoded icon values in cupertino_icons.py with dynamic loading from JSON, and added package data configuration in pyproject.toml to include new icon resources.
Moved theme-related imports in __init__.py to dynamic attribute access via __getattr__, reducing upfront imports and improving modularity. Updated type hints in base_page.py and container.py to use TYPE_CHECKING for Theme, ensuring proper type checking without runtime imports.
Introduced a random() method to both CupertinoIcons and Icons proxies, allowing selection of a random icon with optional exclusion and weighting. Also refactored internal value caching and removed unnecessary time measurement from Material icons.
Deleted .github/scripts/templates/cupertino_icons.py and material_icons.py as they are no longer needed. Minor formatting changes in Dart icon lists and updates to Python icon JSON and type stub files for Cupertino and Material icons.
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Sorry @FeodorFitsner, your pull request is larger than the review limit of 150000 diff characters
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Pull request overview
This pull request implements lazy loading of icons and theme modules to improve app startup performance. The changes defer the import of large icon datasets and theme configurations until they are actually needed.
Changes:
- Introduced lazy loading pattern for icons in dropdown component using
before_update()hook - Applied TYPE_CHECKING pattern to avoid circular imports for Theme references in container and base_page
- Added JSON data files for Material and Cupertino icons for runtime loading
- Created stub files (.pyi) for type hints without runtime overhead
- Updated package configuration to include JSON and stub files
- Configured pre-commit hooks to exclude generated files
Reviewed changes
Copilot reviewed 19 out of 23 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| sdk/python/pyproject.toml | Added ruff exclusion for .github directory |
| sdk/python/packages/flet/src/flet/controls/material/time_picker.py | Changed IconData import to use icon_data module instead of material.icons |
| sdk/python/packages/flet/src/flet/controls/material/icons.json | Added Material icons JSON data (new file with icon mappings) |
| sdk/python/packages/flet/src/flet/controls/material/dropdown.py | Implemented lazy loading of Icons in before_update() method |
| sdk/python/packages/flet/src/flet/controls/material/container.py | Applied TYPE_CHECKING pattern for Theme imports |
| sdk/python/packages/flet/src/flet/controls/cupertino/cupertino_icons.pyi | Added type stub file for Cupertino icons |
| sdk/python/packages/flet/src/flet/controls/base_page.py | Applied TYPE_CHECKING pattern for Theme imports |
| sdk/python/packages/flet/pyproject.toml | Added package data configuration for JSON and stub files |
| sdk/python/.pre-commit-config.yaml | Added exclusion patterns for .github directory |
| client/windows/flutter/generated_plugins.cmake | Added flutter_secure_storage_windows plugin |
| client/linux/flutter/generated_plugins.cmake | Added flutter_secure_storage_linux plugin |
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sdk/python/packages/flet/src/flet/controls/cupertino/cupertino_icons.pyi
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Updated cupertino_icons.pyi and material_icons.pyi templates to remove inheritance from IconData and related class arguments, making the classes plain containers for IconData attributes. Also fixed formatting in Dart icon lists and updated JSON icon files for Python SDK.
ndonkoHenri
approved these changes
Jan 21, 2026
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lgtm
So, the below changes are always to be applied, right?
- Theme -> "Theme"
- icons import in before_update()
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New failing test btw: https://github.com/flet-dev/flet/actions/runs/21192744715/job/60962467504?pr=6043 |
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Author
Looks like, yeah. Both are heavy things to be imported without necessity. |
Deleted the before_update method that set default trailing icons in the Dropdown control. This change may be part of a refactor to handle icon defaults elsewhere or to simplify the control's logic.
Changed the GitHub Actions runner from macos-15 to macos-26 for the macOS integration tests workflow to use a newer macOS environment.
Updated the PyPI cleanup script to target version 0.81.0.dev and include flet-secure-storage. Added a delay in the test_responsive_row.py custom breakpoint test to improve test stability.
Corrected references in the Image control docstrings from 'placeholder' to 'placeholder_src'. Simplified ResponsiveRow docstrings by removing unsupported alignment notes and the clean() method. Fixed a docstring reference in LayoutControl from 'LayoutControl' to 'Control' for the opacity property.
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