Skia-python：Skia 的 Python 封装

import skia

surface = skia.Surface(128, 128)

with surface as canvas:
    rect = skia.Rect(32, 32, 96, 96)
    paint = skia.Paint(
        Color=skia.ColorBLUE,
        Style=skia.Paint.kFill_Style
    )
    canvas.drawRect(rect, paint)

image = surface.makeImageSnapshot()
image.save('output.png', skia.kPNG)

import contextlib

import glfw
import skia
from OpenGL import GL

WIDTH, HEIGHT = 640, 480


@contextlib.contextmanager
def glfw_window():
    """
    创建 GLFW 窗口
    """
    # GLFW 必须首先调用 init 初始化
    if not glfw.init():
        raise RuntimeError('glfw.init() failed')
    # window_hint 用于设置 GLFW
    glfw.window_hint(glfw.STENCIL_BITS, 8)
    # 创建一个 GLFW 窗口
    window = glfw.create_window(640, 480, '', None, None)
    # 将 GLFW 窗口作为 OpenGL 的 Context
    # 后续的渲染，将都在这个窗口中进行
    glfw.make_context_current(window)
    # contextlib 返回创建好的窗口
    yield window
    # 窗口销毁操作
    glfw.terminate()

@contextlib.contextmanager
def skia_surface(window):
    # 通过 GrDirectContext 获取 GPU Backend 下的 Surafce
    context = skia.GrDirectContext.MakeGL()
    # 获取 GLFW 的尺寸
    (fb_width, fb_height) = glfw.get_framebuffer_size(window)
    # Skia GPU Backend 相关设置
    backend_render_target = skia.GrBackendRenderTarget(
        fb_width,
        fb_height,
        0,  # sampleCnt
        0,  # stencilBits
        skia.GrGLFramebufferInfo(0, GL.GL_RGBA8))
    # 传入 context、backend_render_target，得到 surface
    surface = skia.Surface.MakeFromBackendRenderTarget(
        context, 
        backend_render_target, 
        skia.kBottomLeft_GrSurfaceOrigin,
        skia.kRGBA_8888_ColorType, 
        skia.ColorSpace.MakeSRGB())
    assert surface is not None
    # 返回创建的 surface
    yield surface
    context.abandonContext()

# 创建窗口
with glfw_window() as window:
    GL.glClear(GL.GL_COLOR_BUFFER_BIT)
    # 创建 Skia GPU Backend Surafce
    with skia_surface(window) as surface:
        # 创建画布
        with surface as canvas:
            # 绘制图形
            canvas.drawCircle(100, 100, 40, skia.Paint(Color=skia.ColorGREEN))
        # 刷新
        surface.flushAndSubmit()
        # 上屏
        glfw.swap_buffers(window)

        # 窗口事件循环进入一个死循环，等待按下回车退出程序
        while (glfw.get_key(window, glfw.KEY_ESCAPE) != glfw.PRESS
            and not glfw.window_should_close(window)):
            glfw.wait_events()

sk_sp<GrDirectContext> GPUSurfaceGL::MakeGLContext(
    GPUSurfaceGLDelegate* delegate) {
  auto context_switch = delegate->GLContextMakeCurrent();

  const auto options =
      MakeDefaultContextOptions(ContextType::kRender, GrBackendApi::kOpenGL);

  auto context = GrDirectContext::MakeGL(delegate->GetGLInterface(), options);

  context->setResourceCacheLimit(kGrCacheMaxByteSize);

  PersistentCache::GetCacheForProcess()->PrecompileKnownSkSLs(context.get());

  return context;
}

#!/usr/bin/env bash

# depot_tools 是 Google 的源码管理工具
# 该工程内置了一份，导出 PATH 地址
export PATH=${PWD}/depot_tools:$PATH

EXTRA_CFLAGS=""

# uname -m 返回的是系统架构，x86 电脑返回的是 x86_64
# 安装 ninja 构建工具
if [[ $(uname -m) == "aarch64" ]]; then
    # 如果是 ARM 架构，从源中安装 ninja
    # Install ninja for aarch64
    yum -y install epel-release && \
        yum repolist && \
        yum install -y ninja-build && \
        ln -s ninja-build /usr/bin/ninja &&
        mv depot_tools/ninja depot_tools/ninja.bak
fi

# 安装构建所需的工具
# Install system dependencies
yum install -y \
    fontconfig-devel \
    mesa-libGL-devel \
    xorg-x11-server-Xvfb \
    mesa-dri-drivers && \
    yum clean all && \
    rm -rf /var/cache/yum

# Build gn
export CC=gcc
export CXX=g++
export AR=ar
export CFLAGS="-Wno-deprecated-copy"
export LDFLAGS="-lrt"

# 这一步是编译 gn 工具
# gn 用于执行代码配置，相当于 configure
git clone https://gn.googlesource.com/gn && \
    cd gn && \
    git checkout 981f46c64d1456d2083b1a2fa1367e753e0cdc1b && \
    python build/gen.py && \
    ninja -C out gn && \
    cd ..

# Build skia
# skia 代码是一个 submodule
# 需要打入几个 patch
# git-sync-deps：调整依赖源路径
# 执行 git-sync-deps：拉取依赖
# make_data_assembly：适配 Python3
# libjpeg-arm.patch：补充了一些源文件
# 最后通过 gn 生成配置
# 配置完成后通过 ninja 执行真正的构建
cd skia && \
    patch -p1 < ../patch/git-sync-deps.patch && \
    python tools/git-sync-deps && \
    patch -p1 < ../patch/make_data_assembly.patch && \
    patch -p1 < ../patch/libjpeg-arm.patch && \
    cp -f ../gn/out/gn bin/gn && \
    bin/gn gen out/Release --args="
is_official_build=true
skia_enable_tools=true
skia_use_system_libjpeg_turbo=false
skia_use_system_libwebp=false
skia_use_system_libpng=false
skia_use_system_icu=false
skia_use_system_harfbuzz=false
extra_cflags_cc=[\"-frtti\"]
extra_ldflags=[\"-lrt\"]
" && \
    ninja -C out/Release skia skia.h experimental_svg_model && \
    cd ..

    DEFINE_MACROS = [
        ('VERSION_INFO', __version__),
        ('SK_GL', ''),
    ]
    LIBRARIES = [
        'dl',
        'fontconfig',
        'freetype',
        'GL',
    ]
    EXTRA_OBJECTS = list(
        glob.glob(
            os.path.join(
                SKIA_OUT_PATH,
                'obj',
                'experimental',
                'svg',
                'model',
                '*.o',
            )
        )
    ) + [os.path.join(SKIA_OUT_PATH, 'libskia.a')]
    EXTRA_COMPILE_ARGS = [
        '-std=c++14',
        '-fvisibility=hidden',
        '-Wno-attributes',
        '-fdata-sections',
        '-ffunction-sections',
    ]
    EXTRA_LINK_ARGS = [
        '-Wl,--gc-sections',
        '-s',
        '-O3',
    ]

extension = Extension(
    'skia',
    sources=list(glob.glob(os.path.join('src', 'skia', '*.cpp'))),
    include_dirs=[
        # Path to pybind11 headers
        get_pybind_include(),
        get_pybind_include(user=True),
        SKIA_PATH,
        os.path.join(SKIA_OUT_PATH, 'gen'),
    ],
    define_macros=DEFINE_MACROS,
    libraries=LIBRARIES,
    extra_objects=EXTRA_OBJECTS,
    extra_compile_args=EXTRA_COMPILE_ARGS,
    extra_link_args=EXTRA_LINK_ARGS,
    depends=[os.path.join('src', 'skia', 'common.h')],
    language='c++',
)