An exhaustive BMP Loader, MIT-licensed, implemented for c++11
This BMP loader library decodes Windows BMP files encoded according to BMP format versions 1 up to 5, as well as the specific OS/2 1.x and OS/2 2.x BMP (BitMaP) and BA (Bitmap multi images Array) file formats.
It nevertheless currently does not decode JPEG and PNG encoded images that are embedded in BMP files, nor does it decode images embedding Windows color profiles.
The genesis of this project is the initial creation of another library that needed to be associated with an external library for loading BMP images under the MIT license or from the public domain, free of rights, to associate them with icons.
Unfortunately, no such library has been found under this type of license that would provide for the decoding of all the different standardized formats of BMP images.
The CppBMPLoader library therefore fills this gap by offering the only loading of BMP images in all the forms that this image format allows and under the permissive MIT license. It will also meet many other needs when one sees the number of questions asked on this topic on the Internet and the number of BMPLoader libraries already existing, but apparently incomplete, that can be found on GitHub, programmed in c++ or in other programming languages.
Initially, only a c++11 version of the library code is offerred.
The c++11 version of CppBMPLoader has been compiled with c++14 standard as provided by Visual Studio 2022. Meanwhile, it does not use any c++14 specificities but only c++11 ones. While having been compiled and validated with a c++14 compiler it should as well be compilable with a c++11 compiler.
All released code has been validated. For this purpose, we used the great BMP Suite Image List provided by Jason Summers - see also https://entropymine.com/jason/bmpsuite/ and we augmented it with images we created by our own for the version 1 of Windows BMP format (lacking in Jason's suite) and with OS/2 BA files that we either created from scratch or downloaded from the Web, extracted from some original ISO images of OS/2.
The API of CppBMPLoader is documented in documentation.md.
Shortly speeking, this API offers a templated class BMPImage<> for the loading of BMP images content and classes and functions to extract and load all images from a BA file or just the one of them that best fits dimensions, colors and/or resolutions criterias.
Many error cases and warnings are detected by CppBMPLoader. Errors are always fatal. Execution stops on any encountered error. Warnings do not stop your application and are accumulated along the processing of BMP and BA files. You get access to the error code and to a list of warning codes as well to the associated messages at will, since they are attached to the faulty BMP images.
For those of you who are the most motivated for deeply diving into this library code, please notice that no implementation documentation is provided for CppBMPLoader.
The design decision made for its first implementation has been to factorize as much code as possible. This was a tremendous decision when at bugs fixing time: each bug had to be fixed in one and only one place. This was also a very deceptive decision about the final readability of the code. It might be that a further version of libray CppBMPLoader will embed c++20 or even c++23 code. Should this happen, a full refactoring would then happen. Duplicating the already debugged code, to provide a single clear class for each type of object and for each format version that is internally managed by the library, would eventually enhance the readiness of the code. So, wait and see.
Meanwhile, experienced c++ developers should get no trouble in understanding
the directories tree structure and the code itself as well, which is
commented everywhere it seemed to be useful.
See directories cpp-14 or cpp-20 and enjoy!