Skia基础运用（Ubuntu环境下使用BUILD.gn）

1.拉取代码

git clone https://skia.googlesource.com/skia
python tools/git-sync-deps
// 这一步可能会出现部分错误，再次执行直到成功
// 这里面拉取完三方库之后会拉取node，linux等压缩包，从google下载

上面执行完，代码就完全拿到了

2.生成ninja

gn gen out/default
// 如果要导出compile_commands.json, 加入--export-compile-commands
// 可以用导出的文件加上clangd和clang配一波智能提示

3.增加自己的demo

skia
├── demo├── BUILD.gn└── main.cpp
└── out

增加demo代码如下

#include "include/codec/SkEncodedImageFormat.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkPaint.h"
#include "include/core/SkRect.h"
#include "include/core/SkStream.h"
#include "include/core/SkTextBlob.h"
#include "include/core/SkTypeface.h"
#include "include/encode/SkJpegEncoder.h"
#include "src/core/SkDevice.h"
#include "src/encode/SkImageEncoderFns.h"
const char* pText = "Hello world!";
int main() {SkBitmap bitmap;SkImageInfo ii = SkImageInfo::Make(480, 320, kBGRA_8888_SkColorType, kPremul_SkAlphaType);bitmap.allocPixels(ii, ii.minRowBytes());SkPaint paint;paint.setStyle(SkPaint::kStroke_Style);paint.setColor(0xff1f78b4);paint.setStrokeWidth(8);bitmap.allocPixels();SkCanvas canvas(bitmap);canvas.clear(0xFF000000);  // 背景为透明色{SkRect rc;rc.fLeft = 123;rc.fTop = 0;rc.fRight = 222;rc.fBottom = 50;canvas.drawOval(rc, paint);}{paint.setColor(SK_ColorYELLOW);canvas.drawCircle(100, 100, 50, paint);}SkFILEWStream stream("./1bc.jpg");SkJpegEncoder::Encode(&stream, bitmap.pixmap(), {});return 0;
}

接下来增加同级目录下的BUILD.gn

import("//gn/skia.gni")
skia_executable("demo") {sources = ["main.cpp"]deps = ["../.:skia"]
}

目前还识别不到新增的demo编译目标，需要在总工程目录中增加如下内容

group("gdemo") {deps = ["//demo:demo"]
}

再生成一遍ninja，或者先弄第三步再执行第二步

5.执行编译

ninja -C out/demo demo

待执行编译之后，out/demo中会得到名字为demo的可执行文件，执行，得到生成的jpeg图片，这样我们就能愉快的学习源码了

我绘制文字貌似有问题，之后再写