Roundup of the Recent Changes

Posted on October 30, 2021

A quick overview of the recent changes and improvements in wxWidgets: since 3.1.5, quite a few things have happened and this post provides a summary of the last 6 months.

The most important one is the addition of wxBitmapBundle class class, which allows to provide several versions of the same bitmap, including the default (used at 100% DPI, i.e. without DPI scaling at all) and high-resolution one (used at 200% DPI scaling) as well as more variants for the intermediate scaling factors, if necessary, and let wxWidgets automatically select the best version to use and switch between them if the DPI scaling changes, as it happens when moving the window between displays using different DPI. Note that the new API is 100% backwards-compatible with the existing one, i.e. all the existing code will continue to work and if you provide just a single bitmap, it will be upscaled to the expected size, just as before. But now you can also easily provide your own high resolution version to avoid the bitmaps in your application looking blurry in high DPI. This already works today with wxButton (and all the derived classes), wxStaticBitmap and wxToolBar and all the other classes using bitmaps will support the new API in wx 3.1.6.

Moreover, as a side-effect of this work, it is now possible to use SVG images everywhere where wxBitmap is used with wxBitmapBundle::FromSVG(), thanks to Nano SVG library integration.

The next big addition to the API is the wxUILocale class, which provides a new and more flexible way to get locale-specific information than the old wxLocale. Notably, the new class doesn’t rely on the – quite naive, in retrospect – assumption that the standard C setlocale() function actually works, which allows it to work correctly under the recent macOS, where C locale cannot be used at all, due to bugs in Apple code. It also uses BCP 47-like identifiers for the locale instead of wxLanguage enum, which allows it to cover all the languages supported by the OS and not just those known to wxWidgets, and provides a new CompareString() function which compares strings using language-specific rules. It is recommended to use this class rather than wxLocale in all new code, especially for applications targeting macOS, as using the old class results in a bad bug under macOS 10.15 or newer.

Other new features include:

• Add support for using native spell checking in wxTextCtrl.
• Add XRC handler for wxStyledTextCtrl.
• Implement support for undo/redo for wxTextCtrl in wxOSX.
• Add wxImage::Change{Saturation,Brightness,HSV,Lightness}().
• Add wxKeyEvent::IsAutoRepeat().
• Add wxSpinCtrl::GetTextValue().

There have a few updates for the new compiler versions and other modernizations:

• wxWidgets headers have been updated to not produce any warnings when compiling in C++20 mode with gcc 11 and clang 12.
• MSVS 2022 is now supported.
• Variadic functions such as wxPrintf() and wxLogXXX() now support std::string_view arguments too.
• wxMSW uses (quite old) Winsock 2 by default rather than the (absolutely ancient) Winsock 1.

A few optimizations as well:

• wxMBConv was significantly sped up under Unix systems.
• Creating standard system fonts is now much faster in wxOSX.

And other than that, there were all the usual minor improvements and bug fixes:

• wxMediaCtrl in wxGTK now works when using Wayland too.
• Fix key event generation in wxDataViewCtrl.
• Improve handling printer settings in wxMSW and wxGTK.
• Fix mouse events when using touch events in wxGTK.
• Fix wxDC::Blit() when using RTL layout in wxMSW.
• Improve wxSpinCtrlDouble significant digits handling.
• Several bug fixes in the long-neglected wxUniv port.

That’s all for this “brief” summary, please don’t hesitate to try the new features and let us know if you have any questions about them or if you find any problems, so that they could be fixed before the upcoming 3.2.0 release.

Thanks in advance!

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