bindbc-sdl 2.0.0-prerelease.4

NOTICE: All future pull requests for SDL2 support should be in the SDL2 branch, as ~master is now moving towards supporting SDL3 exclusively.

NOTICE: SDL 3.2.0 has not been officially released yet. This documentation is being written as if it is. SDL 3.1.X will not be supported after 3.2.0 releases.

Based on this commit, tagged preview-3.1.6.

<h1 align="center" width="100%">

<img alt="BindBC-SDL logo" width="50%" src="https://raw.githubusercontent.com/BindBC/bindbc-branding/master/logo_wide_sdl.png"/>

</h1>

This project provides a set of both static and dynamic bindings to SDL (Simple DirectMedia Layer) and its official extension libraries. They are compatible with @nogc and nothrow, and can be compiled with BetterC compatibility.

| Table of Contents | |-------------------| |License| |SDL documentation| |Quickstart guide| |Binding-specific changes| |Configurations| |Library versions| |Special platforms|

License

BindBC-SDL—as well as every other binding in the BindBC project—is licensed under the Boost Software License.

Bear in mind that you still need to abide by SDL's license, and the licenses of any SDL_* libraries that you use through these bindings.

SDL documentation

This readme describes how to use BindBC-SDL, not SDL itself. BindBC-SDL is a direct D binding to the SDL3 API, so any existing SDL 3documentation and tutorials can be adapted with only minor modifications.

• The SDL Wiki has official documentation of the SDL API. It also has a list of tutorials, although most still deal with SDL2 at present.
• Layers All The Way Down has a broad explanation of rendering and SDL3's GPU API.
• How to migrate from SDL 2.0.
• Lazy Foo' Productions' SDL3 tutorials are aimed at C++ programmers, and give a good overview of the SDL3 API.

[!NOTE]\ The bindings for SDL_atomics.h have not been thoroughly tested. If the SDL_atomics binding causes trouble and you don't need to use it, you can supply the version identifier SDL_No_Atomics and the module's contents will not be compiled. If it's causing trouble and you need it, please report an issue.

Quickstart guide

To use BindBC-SDL in your dub project, add it to the list of dependencies in your dub configuration file. The easiest way is by running dub add bindbc-sdl in your project folder. The result should look like this:

Example dub.json

"dependencies": {
	"bindbc-sdl": "~>2.0",
},

Example dub.sdl

dependency "bindbc-sdl" version="~>2.0"

By default, BindBC-SDL is configured to compile as a dynamic binding that is not BetterC-compatible. If you prefer static bindings or need BetterC compatibility, they can be enabled via subConfigurations in your dub configuration file. For configuration naming & more details, see Configurations.

Example dub.json

"subConfigurations": {
	"bindbc-sdl": "staticBC",
},

Example dub.sdl

subConfiguration "bindbc-sdl" "staticBC"

If you need to use the SDL_* libraries, or versions of SDL newer than 3.2.0, then you will have to add the appropriate version identifiers to versions in your dub configuration. For a list of library version identifiers, see Library versions.

If you're using static bindings, then you will also need to add the name of each library you're using to libs.

Example dub.json

"versions": [
	"SDL_3_4", "SDL_Net_3_0",
],
"libs": [
	"SDL3", "SDL3_net",
],

Example dub.sdl

versions "SDL_3_4" "SDL_Net_3_0"
libs "SDL3" "SDL3_net"

If you're using static bindings: import bindbc.sdl in your code, and then you can use all of SDL just like you would in C. That's it!

import bindbc.sdl;

void main(){
	SDL_Init(SDL_INIT_VIDEO);
	
	//etc.
	
	SDL_Quit();
}

If you're using dynamic bindings: you need to load each library you need with the appropriate load function.

For most use cases, it's best to use BindBC-Loader's error handling API to see if there were any errors while loading the libraries. This information can be written to a log file before aborting the program.

The load function will also return a member of the LoadMsg enum, which can be used for debugging:

• noLibrary means the library couldn't be found.
• badLibrary means there was an error while loading the library.
• success means that the library was loaded without any errors.

You should also check that the desired minimum version of the library was loaded. You can do this using:

• SDL_GetVersion() for SDL.
• IMG_Linked_Version() for SDL_image.
• Mix_Linked_Version() for SDL_mixer.
• SDLNet_Linked_Version() for SDL_net.
• TTF_Linked_Version() for SDL_ttf.

Here's a simple example using only the load function's return value:

import bindbc.sdl;
import bindbc.loader;

/*
This code attempts to load the SDL shared library using
well-known variations of the library name for the host system.
*/
LoadMsg ret = loadSDL();
if(ret != LoadMsg.success){
	/*
	Error handling. For most use cases, it's best to use 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 == LoadMsg.noLibrary){
		//The SDL shared library failed to load
	}else if(ret == LoadMsg.badLibrary){
		/*
		One or more symbols failed to load. The likely cause is that
		the shared library is for a lower version than BindBC-SDL was
		configured to load.
		*/
	}
}

/*
This code attempts to load the SDL 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 `sdl3.dll` from the `libs` subdirectory,
relative to the executable, only on Windows.
*/
version(Windows) loadSDL("libs/sdl3.dll");

The error handling API in BindBC-Loader can be used to log error messages:

import bindbc.sdl;

/*
Import the sharedlib module for error handling. Assigning an alias ensures that the
function names do not conflict with other public APIs. This isn't strictly necessary,
but the API names are common enough that they could appear in other packages.
*/
import loader = bindbc.loader.sharedlib;

bool loadLib(){
	LoadMsg ret = loadSDL();
	if(ret != LoadMsg.success){
		//Log the error info
		foreach(info; loader.errors){
			/*
			A hypothetical logging function. Note that `info.error` and
			`info.message` are null-terminated `const(char)*`, not `string`.
			*/
			logError(info.error, info.message);
		}
		
		//Optionally construct a user-friendly error message for the user
		string msg;
		if(ret == LoadMsg.noLibrary){
			msg = "This application requires the SDL library.";
		}else{
			SDL_version version_;
			SDL_GetVersion(&version_);
			msg = "Your SDL version is too low: "~
				itoa(version_.major)~"."~
				itoa(version_.minor)~"."~
				itoa(version_.patch)~
				". Please upgrade to 3.5.0+.";
		}
		//A hypothetical message box function
		showMessageBox(msg);
		return false;
	}
	return true;
}

Binding-specific changes

Enums are available both in their original C-style UPPER_SNAKE_CASE form, and as the D-style PascalCase.camelCase. Both variants are enabled by default, but can be selectively chosen using the version identifiers SDL_C_Enums_Only or SDL_D_Enums_Only respectively.

[!NOTE]\ The version identifiers BindBC_C_Enums_Only and BindBC_D_Enums_Only can be used to configure all of the applicable official BindBC packages used in your program. Package-specific version identifiers override this.

camelCased variants are available for struct fields using snake_case or lowercase.

Configurations

BindBC-SDL has the following configurations:

┌	DRuntime	BetterC
Dynamic	dynamic	dynamicBC
Static	static	staticBC

For projects that don't use dub, if BindBC-SDL is compiled for static bindings then the version identifier BindSDL_Static must be passed to your compiler when building your project.

[!NOTE]\ The version identifier BindBC_Static can be used to configure all of the official BindBC packages used in your program. (i.e. those maintained in the BindBC GitHub organisation) Some third-party BindBC packages may support it as well.

Dynamic bindings

The dynamic bindings have no link-time dependency on the SDL libraries, so the SDL shared libraries must be manually loaded at runtime from the shared library search path of the user's system. On Windows, this is typically handled by distributing the SDL DLLs with your program. On other systems, it usually means installing the SDL shared libraries through a package manager.

It is recommended that you always select the minimum version you require and no higher. If a lower version is loaded then it's still possible to call functions available in that lower version, but any calls to functions from versions between that version and the one you configured will result in a null pointer access. For example, if you configured SDL to 3.6.0 (SDL_3_6) but loaded SDL 3.2.0 at runtime, then any function pointers from 3.6.0 and 3.4.0 will be null. For this reason, it's recommended to always specify your required version of the SDL library at compile time and unconditionally abort when you receive an LoadMsg.badLibrary return value from loadSDL (or equivalent).

The function isSDLLoaded returns true if any version of the shared library has been loaded and false if not. unloadSDL can be used to unload a successfully loaded shared library. The SDL_* libraries provide similar functions: isSDLImageLoaded, unloadSDLImage, etc.

Static bindings

Static bindings do not require static linking. The static bindings have a link-time dependency on either the shared or static SDL libraries and any satellite SDL libraries the program uses. On Windows, you can link with the static libraries or, to use the DLLs, the import libraries. On other systems, you can link with either the static libraries or directly with the shared libraries.

When linking with the shared (or import) libraries, there is a runtime dependency on the shared library just as there is when using the dynamic bindings. The difference is that the shared libraries are no longer loaded manually—loading is handled automatically by the system when the program is launched. Attempting to call loadSDL with the static bindings enabled will result in a compilation error.

Static linking requires the SDL development packages be installed on your system. The SDL releases page provides development packages for Windows and macOS. You can also install them via your system's package manager. For example, on Debian-based Linux distributions sudo apt install libsdl3-dev will install both the development and runtime packages.

When linking with the static libraries, there is no runtime dependency on SDL. The SDL homepage does not distribute pre-compiled static libraries. If you decide to obtain static libraries from another source (usually by compiling them yourself) you will also need to ensure that you link with all of SDL's link-time dependencies (such as the OpenGL library and system API libraries).

Library Versions

These are the supported versions of each SDL_* library, along with the corresponding version identifiers to add to your dub configuration or pass to the compiler.

[!NOTE]\ If you have SDL_THREAD_SAFETY_ANALYSIS support enabled in SDL, you may use version identifier SDL_ThreadSafetyAnalysis.

[!NOTE]\ It is necessary to specify only a single version identifier per library. For example, SDL_Image_3_0 by itself will activate the SDL_image binding.

[!NOTE]\ All even-numbered SDL/SDL_* versions are releases, while all odd-numbered versions are pre-releases—which are not for general use and are therefore not supported by BindBC-SDL.

<details>

<summary><h3>SDL versions</h3></summary>

Version	Version identifier
3.2.0	(none; default)

</details>

<details><summary><h3>SDL_image versions</h3></summary>

Version	Version identifier	Public API changed
3.0.0	SDL_Image_3_0

</details>

<details><summary><h3>SDL_mixer versions</h3></summary>

Version	Version identifier	Public API changed
3.0.0	SDL_Mixer_3_0

</details>

<details><summary><h3>SDL_net versions</h3></summary>

Version	Version identifier	Public API changed
3.0.0	SDL_Net_3_0

</details>

<details><summary><h3>SDL_ttf versions</h3></summary>

Version	Version identifier	Public API changed
3.0.0	SDL_TTF_3_0

</details>

Special platforms

Some platforms do not have pre-defined versions in D, meaning that BindBC-SDL has to use custom version identifiers for them. If you intend to compile for any of these platforms, please add the corresponding version identifier(s) in your dub recipe's versions list, or supply them directly to the compiler.

[!NOTE]\ If you're building on Wayland and you have X11 support disabled in SDL, please add version identifier SDL_NoX11.

Platform	Version identifier
Nintendo 3DS	_3DS
Microsoft Game Development Kit	GDK
Sony Vita	Vita
Sony PSP	PSP

Gesture API

TODO: expand this section

SDL_Gesture enables sdl.gesture from this commit.

Entry points

It is recommended that you read this first: README-main-functions.md

For convenience, sdl.main (equivalent to SDL_main.h) is imported by default. However, in BindBC-SDL having your entry point replaced by sdl.main is opt-in rather than opt-out. See more information below.

Replacing the main entry point

If you want SDL to replace your entry point, you will have to wrap your main function's parameter names & body in a mixin of makeSDLMain. Doing so is the equivalent of using #include <SDL3/SDL_main.h> in C without defining SDL_MAIN_NOIMPL.

enum dynLoadSDL = q{
	LoadMsg ret = loadSDL();
	if(ret != LoadMsg.success){
		import core.stdc.stdio, bindbc.loader;
		foreach(error; bindbc.loader.errors){
			printf("%s\n", error.message);
		}
	}};
mixin(makeSDLMain(q{argC}, q{argV}, dynLoadSDL, dynLoadSDL~q{
	import core.stdc.stdio;
	foreach(argument; argV[0..argC]){
		printf("%s\n", argument);
	}
	return 0;
}));

[!IMPORTANT]\ makeSDLMain's third argument (dynLoad) specifies what code to load SDL (and handle loading errors) when using the dynamic bindings. It can be left blank as long as you ONLY use the static bindings. This code will be prepended to your main function in cases where SDL does not override it.

[!WARNING]\ When using this feature, your provided main function will always be extern(C) nothrow, take (int, char**) as its parameters, and must return int. Having an extern(C) main means that you need to handle some tasks (e.g. runtime initialisation & termination) that are normally taken care of for you by D's runtime. See the extern(C) main spec.

Callback entry points

If you want to use the callback entry points (or 'main callbacks'), then you also need to use version identifier SDL_MainUseCallbacks. When using callback functions, only the dynLoad parameter of makeSDLMain is used. As a side-effect, this means that you can safely write code in your main body that depends on SDL_MainUseCallbacks not being in-use.

Here's an example that initialises & terminates DRuntime, and has basic exception handling.

import core.runtime, core.stdc.stdio;

mixin(makeSDLMain(dynLoad: q{
	LoadMsg ret = loadSDL();
	if(ret != LoadMsg.success){
		import core.stdc.stdio, bindbc.loader;
		foreach(error; bindbc.loader.errors){
			printf("%s\n", error.message);
		}
	}})); //makeSDLMain's parameters are optional

version SDL_MainUseCallbacks{
	extern(C) SDL_AppResult SDL_AppInit(void** state, int argC, char** argV) nothrow{
		try{
			if(!rt_init()) return SDL_AppResult.failure;
		}catch(Exception ex){
			return SDL_AppResult.failure;
		}
		return SDL_AppResult.continue_;
	}
	
	extern(C) SDL_AppResult SDL_AppIterate(void* state) nothrow{
		try{
			/*
			Put your code that can throw exceptions here!
			*/
		}catch(Throwable t){
			void sink(in char[] buf) scope nothrow{
				fwrite(buf.ptr, char.sizeof, buf.length, stderr);
			}
			do{
				try t.toString(&sink);
				catch(Exception) return SDL_AppResult.failure;
			}while((t = t.next) !is null);
			printf("\n");
			return SDL_AppResult.failure;
		}
		return SDL_AppResult.success;
	}
	
	extern(C) SDL_AppResult SDL_AppEvent(void* state, SDL_Event* event) nothrow => SDL_AppResult.continue_;
	
	extern(C) void SDL_AppQuit(void*, SDL_AppResult result) nothrow{
		try rt_term();
		catch(Exception ex){}
	}
}

[!NOTE]\ This example code does NOT support unittests, and doesn't run any module constructors/destructors. Look at how DRuntime implements these features if you need them in your project.