[FEATURE] more informative building instructions (for Windows)

[mgood7123]

To build SkiaSharp on Windows:

this requires ~50GB for installation/setup
and an additional 44GB for building natives and bindings/views

building is recommended on EXTERNAL HARD-DRIVE if free space on internal hdd is small

install VS 2022
install specified https://github.com/mono/SkiaSharp/wiki/Building-SkiaSharp for 2022

NOTE: MSVC v143 - VS 2019 C++ build tools (x86/64, ARM, and ARM64) are required for the UWP natives to build

NOTE: Xamarin SDKs are required to build libs (SkiaSharp bindings)

IMPORTANT: the following files require re-targeting

native/uwp/libHarfBuzzSharp/libHarfBuzzSharp.sln

native/uwp/SkiaSharp.Views.Interop.UWP/SkiaSharp.Views.Interop.UWP.sln

native/windows/libHarfBuzzSharp/libHarfBuzzSharp.sln

open each solution, select Retarget solution and then select Update to v143 and then select ok

~25GB for components installation

Windows 10 SDK (10.0.10240) can be obtained from https://go.microsoft.com/fwlink/p/?LinkId=619296
Windows 10 SDK (10.0.16299.91) can be obtained from https://go.microsoft.com/fwlink/p/?linkid=864422

Android NDK is not available in VS component selection

install Android NDK 21 from https://github.com/android/ndk/wiki/Unsupported-Downloads#r21e

Android NDK 22 restructures the following root paths, which are not yet adapted to this build system

   * platforms
   * sources/cxx-stl
   * sysroot
   * toolchains (with the exception of toolchains/llvm)

   In general this change should only affect build system maintainers, or those
   using build systems that are not up to date. ndk-build and the CMake
   toolchain users are unaffected, and neither are
   `make_standalone_toolchain.py` users (though that script has been unnecessary
   since r19).

go to System > Advanced System Settings > Environment Variables
add the following

name:  ANDROID_SDK_ROOT
value: C:\Program Files (x86)\Android\android-sdk

the above is where VS installs the sdk to

name:  ANDROID_NDK_ROOT
value: C:\Users\small\Downloads\android-ndk-r21

(replace "small" with your username)

restart your machine to apply the above changes to system environmental variables

open and replace ./scripts/install-android-platform.ps1 with the following content

Param(
    [string] $API
)

$ErrorActionPreference = 'Stop'

$sdk = "$env:ANDROID_SDK_ROOT"

$apiPath = "$sdk/platforms/android-$API/android.jar"
if (Test-Path $apiPath) {
    Write-Host "Android API level $API was already installed."
    exit 0
}

$latest = "$sdk/cmdline-tools/latest"
if (-not (Test-Path $latest)) {
    $versions = Get-ChildItem ("$sdk/cmdline-tools")
    $latest = "$sdk/cmdline-tools/" + ($versions | Select-Object -Last 1)[0]
}

if (-not $IsMacOS -and -not $IsLinux) {
    $ext = ".bat"
}

$sdkmanager = "$latest/bin/sdkmanager$ext"

Set-Content -Value "y" -Path "yes.txt"
try {
    if ($IsMacOS -or $IsLinux) {
        sh -c "`"$sdkmanager`" `"platforms\;android-$API`" < yes.txt"
    } else {
        cmd /c "`"$sdkmanager`" `"platforms;android-$API`" < yes.txt"
    }
} finally {
    Remove-Item "yes.txt"
}

exit $LASTEXITCODE

next execute the following in an admin powershell

./scripts/install-android-platform.ps1 29

execute the following in non-admin powershell

# note you will need to execute ./scripts/install-tizen.ps1
# multiple times due to bugs in waiting for process to finish
./scripts/install-tizen.ps1 # install tizen studio
# dont execute the next line until the above is done installing tizen studio

# note you will need to execute ./scripts/install-tizen.ps1
# multiple times due to bugs in waiting for process to finish
./scripts/install-tizen.ps1 # install packages from tizen studio package manager
# dont execute the next line until the above is done installing packages from tizen studio package manager

# note you will need to execute ./scripts/install-tizen.ps1
# multiple times due to bugs in waiting for process to finish
./scripts/install-tizen.ps1 # patch llvm in tizen
./scripts/install-llvm.ps1 # windows llvm
./scripts/install-gtk.ps1
./scrips/install-maui.ps1
./scrips/install-mono.ps1
dotnet workload install android ios tvos macos maccatalyst wasm-tools maui --source https://api.nuget.org/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-runtime-bd261ea4/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-emsdk-52e9452f-3/nuget/v3/index.json

add the following to cake/msbuild.cake

find

        if (!string.IsNullOrEmpty(MSBUILD_EXE)) {
            c.ToolPath = MSBUILD_EXE;
        } else if (IsRunningOnWindows() && !string.IsNullOrEmpty(VS_INSTALL)) {
            c.ToolPath = ((DirectoryPath)VS_INSTALL).CombineWithFilePath("MSBuild/Current/Bin/MSBuild.exe");
        }

and replace it with

        if (!string.IsNullOrEmpty(MSBUILD_EXE)) {
            c.ToolPath = MSBUILD_EXE;
        } else if (IsRunningOnWindows()) {
            if (!string.IsNullOrEmpty(VS_INSTALL)) {
                c.ToolPath = ((DirectoryPath)VS_INSTALL).CombineWithFilePath("MSBuild/Current/Bin/MSBuild.exe");
            } else {
                // check for msbuild 17, this is required to build .net 6 projects (non-natives)
                // VS 2022 is in preview
                // check VS 2022 Community when it comes out of preview
                bool vs2022Cexists = DirectoryExists("C:/Program Files/Microsoft Visual Studio/2022/Community");
                bool vs2022Pexists = DirectoryExists("C:/Program Files/Microsoft Visual Studio/2022/Preview");
                if (!vs2022Pexists && !vs2022Cexists) {
                    throw new Exception("Visual Studio 2022 Preview or Community is required");
                }
                if (vs2022Pexists) {
                    c.ToolPath = "C:/Program Files/Microsoft Visual Studio/2022/Preview/MSBuild/Current/Bin/MSBuild.exe";
                }
                if (vs2022Cexists) {
                    c.ToolPath = "C:/Program Files/Microsoft Visual Studio/2022/Community/MSBuild/Current/Bin/MSBuild.exe";
                }
            }
        }

next, we can begin building

we will assume K:\ is location of SkiaSharp git repo and the repo has been cloned into SkiaSharp

first we need to grab all external libs needed to pack the nuget

dotnet cake --target=externals-download

any native builds will be built over the top of these

build/windows/skia.so -> out/native/windows/skia.so # overwrites downloaded native/windows/skia.so

when building on a different platform the above will need to be done to retain changes to native libs

Windows natives/windows/skia.so -> K:\skia.so
OSX download natives
OSX K:\skia.so -> natives/windows/skia.so // for windows

next we build

the nugets (WITH NATIVE BUILDING) can be built via

cd K:\SkiaSharp\
dotnet tool restore

if ($?) {
	dotnet run --project=utils/SkiaSharpGenerator/SkiaSharpGenerator.csproj -- generate --config binding/libSkiaSharp.json --skia externals/skia --output binding/Binding/SkiaApi.generated.cs
	if ($?) {
		dotnet run --project=utils/SkiaSharpGenerator/SkiaSharpGenerator.csproj -- verify --config binding/libSkiaSharp.json --skia externals/skia
		if ($?) {
			dotnet cake --target=nuget --buildall=true
		}
	}
}

this is useful if you want to build the natives (and then build C# bindings to be able to test) (when modifying native code)

the nugets (WITHOUT NATIVE BUILDING) can be built via

cd K:\SkiaSharp\
dotnet tool restore

if ($?) {
	dotnet run --project=utils/SkiaSharpGenerator/SkiaSharpGenerator.csproj -- generate --config binding/libSkiaSharp.json --skia externals/skia --output binding/Binding/SkiaApi.generated.cs
	if ($?) {
		dotnet run --project=utils/SkiaSharpGenerator/SkiaSharpGenerator.csproj -- verify --config binding/libSkiaSharp.json --skia externals/skia
		if ($?) {
			dotnet cake --target=nuget --buildall=true --skipexternals=all
		}
	}
}

this is useful if you want to build the C# bindings only (when your modifying the C# code)

[mgood7123]

i feel like this should be pinned somewhere?