097625de52
When wxImage is rescaled with wxIMAGE_QUALITY_BILINEAR, wxIMAGE_QUALITY_BICUBIC or wxIMAGE_QUALITY_BOX_AVERAGE algorithm then for proper interpolation there is necessary to uniformly (linearly) map entire pixel range in the new image to the entire pixel range in the current image, i.e. pixels positions (integer values) in range [0..newDim-1] has to be mapped to "virtual" pixel positions (not necessary integer values) exactly in the range [0..oldDim-1]. [0..oldDim-1] range of target mapping is required because for proper interpolation every "virtual" pixel has to be located between two physical pixels in the current image. Thus scaling ratio used to find corresponding pixels in the current image should be (oldDim-1)/(newDim-1) and not oldDim/newDim (which is used now). When image is e.g. upsampled oldDim/newDim ratio then some new rightmost/botommost pixels are mapped to old pixels > (oldDim-1) and their values are improperly interpolated (in the current implementation their positions are just truncated to (oldDim-1) to bypass the problem and upsampled image looks like it was shifted left/up). The larger scaling ratio the effect is more visible. Note: Because reference images used currently in the unit tests were created with improper scaling there is necessary to upload new reference images created with fixed scaling. Closes #17594
About
wxWidgets is a free and open source cross-platform C++ framework for writing advanced GUI applications using native controls.
wxWidgets allows you to write native-looking GUI applications for all the major desktop platforms and also helps with abstracting the differences in the non-GUI aspects between them. It is free for the use in both open source and commercial applications, comes with the full, easy to read and modify, source and extensive documentation and a collection of more than a hundred examples. You can learn more about wxWidgets at https://www.wxwidgets.org/ and read its documentation online at http://docs.wxwidgets.org/
Platforms
wxWidgets currently supports the following primary platforms:
- Windows XP, Vista, 7, 8 and 10 (32/64 bits).
- Most Unix variants using the GTK+ toolkit (version 2.6 or newer or 3.x).
- OS X (10.7 or newer) using Cocoa (32/64 bits).
Most popular C++ compilers are supported including but not limited to:
- Microsoft Visual C++ 2003 or later (up to 2015).
- g++ 3.4 or later, including MinGW/MinGW-64/TDM under Windows.
- Clang under OS X and Linux.
- Intel icc compiler.
- Oracle (ex-Sun) aCC.
Licence
wxWidgets licence is a modified version of LGPL explicitly allowing not distributing the sources of an application using the library even in the case of static linking.
Further information
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wxwidgets) - Please report bugs at http://trac.wxwidgets.org/newticket
We would also gladly welcome your contributions.
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The wxWidgets Team.