C API

Global C API functions exported as extern "C" (C API).

We do not document these functions as they are called from C++ wrappers, which are documented and should be used as a reference. The most important thing in using C API is to understand how lifetime of objects is managed.

Each type that requires initialization provides Init and Reset functions. These functions are called by C++ constructors and destructors on C++ side and must be used the same way by C users. Although these functions return BLResult it's guaranteed the result is always BL_SUCCESS - the return value is only provided for consistency and possible tail calling.

The following example should illustrate how Init and Reset works:

blImageInit(&img);
blImageCreate(&img, 128, 128, BL_FORMAT_PRGB32);
blImageReset(&img);

Some init functions may provide shortcuts for the most used scenarios that merge initialization and resource allocation into a single function.

blImageInitAs(&img, 128, 128, BL_FORMAT_PRGB32);
blImageReset(&img);

It's worth knowing that default initialization in Blend2D costs nothing and no resources are allocated, thus initialization never fails and in theory default initialized objects don't have to be reset as they don't hold any data (however never do that in practice). Resetting always resets the object into its default initialized form, so you can reuse such object afterwards (after reset it's still properly initialized) or consider it destroyed.

The following example should explain how init/reset works:

// Now image is default constructed/initialized. if you did just this and
// abandon it then no resources will be leaked as default construction is
// not allocating any resources nor increasing any reference counters.
blImageInit(&img);
// Now image will have to dynamically allocate some memory to store pixel
// data. If this succeeds the image will have to be reset to destroy the
// data it holds.
BLResult result = blImageCreate(&img, 128, 128, BL_FORMAT_PRGB32);
if (result != BL_SUCCESS) {
// If function fails it should behave like it was never called, so `img`
// would still be default initialized in this case. this means that you
// don't have to reset it explicitly although the C++ API would do it in
// image destructor.
return result;
}
// Resetting image would destroy its data and make it default constructed.
blImageReset(&img);
// You can still use the image after it has been reset as the data it holds
// is still valid, but the image is of course empty.
printf("%d", blImageEquals(&img, &img));

BLArray

Array functionality is provided by BLArrayCore in C-API and wrapped by BLArray template in C++ API.

C API users must call either generic functions with Item suffix or correct specialized functions in case of typed arrays. For example if you create a BLArray<uint32_t> in C then you can only modify it through functions that have either U32 or Item suffix. Arrays of signed types are treated as arrays of unsigned types at API level as there is no difference between them from implementation perspective.

BLContext

Rendering functionality is provided by BLContextCore in C-API and wrapped by BLContext in C++ API.

BLFile

File read/write functionality is provided by BLFileCore in C-API and wrapped by BLFile in C++ API.

BLFileSystem

Filesystem API is provided by functions prefixed with blFileSystem and wrapped by BLFileSystem namespace in C++ API.

BLFont

Font functionality is provided by BLFontCore in C-API and wrapped by BLFont in C++ API.

BLFontData

Font-data functionality is provided by BLFontDataCore in C-API and wrapped by BLFontData in C++ API.

BLFontFace

Font-face functionality is provided by BLFontFaceCore in C-API and wrapped by BLFontFace in C++ API.

BLFontLoader

Font loading functionality is provided by BLFontLoaderCore in C-API and wrapped by BLFontLoader in C++ API.

BLFormat

BLGlyphBuffer

Glyph-buffer functionality is provided by BLGlyphBufferCore in C-API and wrapped by BLGlyphBuffer in C++ API.

BLGradient

Gradient container is provided by BLGradientCore in C-API and wrapped by BLGradient in C++ API.

BLImage

Image container is provided by BLImageCore in C-API and wrapped by BLImage in C++ API.

BLImageCodec

Image codec functionality is provided by BLImageCodecCore in C-API and wrapped by BLImageCodec in C++ API.

BLImageDecoder

Image decoder functionality is provided by BLImageDecoderCore in C-API and wrapped by BLImageDecoder in C++ API.

BLImageEncoder

Image encoder functionality is provided by BLImageEncoderCore in C-API and wrapped by BLImageEncoder in C++ API.

BLMatrix2D

Matrix functionality is provided by BLMatrix2D, C++ API adds methods to the struct when compiling in C++ mode.

BLPath

2D path functionality is provided by BLPathCore in C-API and wrapped by BLPath in C++ API.

BLPattern

Pattern functionality is provided by BLPatternCore in C-API and wrapped by BLPattern in C++ API.

BLPixelConverter

Pixel conversion functionality is provided by BLPixelConverterCore in C-API and wrapped by BLPixelConverter in C++ API.

BLRandom

BLRegion

2D region functionality is provided by BLRegionCore in C-API and wrapped by BLRegion in C++ API.

BLRuntime

Blend2D runtime functions are provided either as a C-API or wrapped by BLRuntime namespace in C++ API.

BLString

String contanter is provided by BLStringCore in C-API and wrapped by BLString in C++ API.

BLStrokeOptions

Stroke options are provided by BLStrokeOptionsCore in C-API and wrapped by BLStrokeOptions in C++ API.

BLVariant

Variant C-API can be used on any object compatible with Blend2D Impl, at the moment only BLStrokeOptionsCore and BLGlyphBufferCore are not compatible, all others are.