bindbc-freetype 0.8.0

bindbc-freetype

This project provides both static and dynamic bindings to the FreeType library. They are @nogc and nothrow compatible can be compiled for compatibility with -betterC. This package is intended as a replacement of DerelictFT, which is not compatible with @nogc, nothrow, or -betterC.

Usage

By default, bindbc-freetype is configured to compile as a dynamic binding that is not -betterC compatible. The dynamic binding has no link-time dependency on the FreeType library, so the FreeType shared library must be manually loaded at runtime. When configured as a static binding, there is a link-time dependency on the FreeType library---either the static library or the appropriate file for linking with shared libraries on your platform (see below).

When using DUB to manage your project, the static binding can be enabled via a DUB subConfiguration statement in your project's package file. -betterC compatibility is also enabled via subconfigurations.

To use FreeType, add bindbc-freetype as a dependency to your project's package config file. For example, the following is configured to FreeType as a dynamic binding that is not -betterC compatible:

dub.json

dependencies {
    "bindbc-freetype": "~>0.1.0",
}

dub.sdl

dependency "bindbc-freetypee" version="~>0.1.0"

The dynamic binding

The dynamic binding requires no special configuration when using DUB to manage your project. There is no link-time dependency. At runtime, the FreeType shared library is required to be on the shared library search path of the user's system. On Windows, this is typically handled by distributing the FreeType DLL with your program. On other systems, it usually means the user must install the FreeType runtime library through a package manager.

To load the shared library, you need to call the loadFreeType function. This returns a member of the FTSupport enumeration (See the README for bindbc.loader for the error handling API):

• FTSupport.noLibrary indicating that the library failed to load (it couldn't be found)
• FTSupport.badLibrary indicating that one or more symbols in the library failed to load
• a member of FTSupport indicating a version number that matches the version of FreeType that bindbc-freetype was configured at compile-time to load. By default, that is FTSupport.ft26, but can be configured via a version identifier (see below). This value will match the global manifest constant, ftSupport.

import bindbc.freetype;

/*
This version attempts to load the FreeType shared library using well-known variations
of the library name for the host system.
*/
FTSupport ret = loadFreeType();
if(ret != ftSupport) {

    // Handle error. For most use cases, its reasonable to use the the error handling API in
    // bindbc-loader to retrieve error messages for logging and then abort. If necessary, it's
    // possible to determine the root cause via the return value:

    if(ret == FTSupport.noLibrary) {
        // FreeType shared library failed to load
    }
    else if(FTSupport.badLibrary) {
        // One or more symbols failed to load. The likely cause is that the
        // shared library is for a lower version than bindbc-freetype was configured
        // to load (via FT_26, FT_27, etc.)
    }
}
/*
This version attempts to load the FreeType library using a user-supplied file name.
Usually, the name and/or path used will be platform specific, as in this example
which attempts to load `freetype.dll` from the `libs` subdirectory, relative
to the executable, only on Windows.
*/
// version(Windows) loadFreeType("libs/freetype.dll")

By default, the bindbc-freetype binding is configured to compile to load FreeType 2.6. This ensures the widest level of compatibility at runtime. This behavior can be overridden via the -version compiler switch or the versions DUB directive with the desired FreeType version number. It is recommended that you always select the minimum version you require and no higher. In this example, the FreeType dynamic binding is compiled to support FreeType 2.7:

dub.json

"dependencies": {
    "bindbc-freetype": "~>0.1.0"
},
"versions": ["FT_27"]

dub.sdl

dependency "bindbc-freetype" version="~>0.1.0"
versions "FT_27"

With this example configuration, ftSupport == FTSupport.ft27. If FreeType 2.7 or later is installed on the user's system, loadFreeType will return FTSupport.ft27. If only FreeType 2.6 is installed, loadFreeType will return FTSupport.badLibrary. In this scenario, calling loadedFreeTypeVersion() will return a FTSupport member indicating which version of FreeType, if any, actually loaded. If a lower version was loaded, it's still possible to call functions from that version of FreeType, but any calls to functions from higher versions will result in a null pointer access. For this reason, it's recommended to always specify your required version of the FreeType library at compile time and abort when you receive a FTSupport.badLibrary return value from loadFreeType.

No matter which version was configured, the successfully loaded version can be obtained via a call to loadedFreeTypeVersion. It returns one of the following:

• FTSupport.noLibrary if loadFreeType returned FTSupport.noLibrary
• FTSupport.badLibrary if loadFreeType returned FTSupport.badLibrary and no version of FreeType successfully loaded
• a member of FTSupport indicating the version of FreeType that successfully loaded. When loadFreeType returns FTSupport.badLibrary, this will be a version number lower than that configured at compile time. Otherwise, it will be the same as the manifest constant ftSupport.

The function isFreeTypeLoaded returns true if any version of FreeType was successfully loaded and false otherwise.

Following are the supported versions of FreeType, the corresponding version IDs to pass to the compiler, and the corresponding FTSupport members.

Library & Version	Version ID	FTSupport Member
FreeType 2.6.4	Default	FTSupport.ft26
FreeType 2.7.1	FT_27	FTSupport.ft27
FreeType 2.8.1	FT_28	FTSupport.ft28
FreeType 2.9.1	FT_29	FTSupport.ft29
FreeType 2.10.0	FT_210	FTSupport.ft210

The static binding

The static binding has a link-time dependency on either the shared or the static FreeType library. On Windows, you can link with the static library or, to use the shared library (freetype.dll), with the import library. On other systems, you can link with either the static library or directly with the shared library. This requires the FreeType development package be installed on your system at compile time, either by compiling the FreeType source yourself, downloading the FreeType precompiled binaries for Windows, or installing via a system package manager. See the FreeType download page for details.

When linking with the static library, there is no runtime dependency on FreeType. When linking with the shared library (or the import library on Windows), the runtime dependency is the same as the dynamic binding, the difference being that the shared library is no longer loaded manually---loading is handled automatically by the system when the program is launched.

Enabling the static binding can be done in two ways.

Via the compiler's -version switch or DUB's versions directive

Pass the BindFT_Static version to the compiler and link with the appropriate library.

When using the compiler command line or a build system that doesn't support DUB, this is the only option. The -version=BindFT_Static option should be passed to the compiler when building your program. All of the required C libraries, as well as the bindbc-freetype and bindbc-loader static libraries must also be passed to the compiler on the command line or via your build system's configuration.

When using DUB, its versions directive is an option. For example, when using the static binding:

dub.json

"dependencies": {
    "bindbc-freetype": "~>0.1.0"
},
"versions": ["BindFT_Static"],
"libs": ["freetype"]

dub.sdl

dependency "bindbc-freetype" version="~>0.1.0"
versions "BindFT_Static"
libs "freetype"

Via DUB subconfigurations

Instead of using DUB's versions directive, a subConfiguration can be used. Enable the static subconfiguration for the bindbc-freetype dependency:

dub.json

"dependencies": {
    "bindbc-freetype": "~>0.1.0"
},
"subConfigurations": {
    "bindbc-freetype": "static"
},
"libs": ["freetype"]

dub.sdl

dependency "bindbc-freetype" version="~>0.1.0"
subConfiguration "bindbc-freetype" "static"
libs "freetype"

This has the benefit that it completely excludes from the build any source modules related to the dynamic binding, i.e. they will never be passed to the compiler.

betterC support

betterC support is enabled via the dynamicBC and staticBC subconfigurations, for dynamic and static bindings respectively. To enable the static binding with -betterC support:

dub.json

"dependencies": {
    "bindbc-freetype": "~>0.1.0"
},
"subConfigurations": {
    "bindbc-freetype": "staticBC"
},
"libs": ["freetype"]

dub.sdl

dependency "bindbc-freetype" version="~>0.1.0"
subConfiguration "bindbc-freetype" "staticBC"
libs "freetype"

When not using DUB to manage your project, first use DUB to compile the BindBC libraries with the dynamicBC or staticBC configuration, then pass -betterC to the compiler when building your project.