Skia最新“编译”，绘制中文字符串，加载PNG、BMP图片等资料的整理。

“编译”Skia

国内不适合自己编译。Github 有不止一个自动构建的SKIA二进制build，涵盖多个操作系统，可直接取而用之。

推荐大名鼎鼎的JetBrains维护的仓库，地址是 https://github.com/JetBrains/skia-build。含静态库与头文件。release静态库解压出来180MB，debug解压出来一两个G。推荐直接用release版本的。

绘制中文字符串

直接用Skia的SkString就可以，无需多次转换。如果显示方框，那说明字体不对，要设置宋体。

auto pFace = SkTypeface::MakeFromName("宋体", SkFontStyle::Normal());
SkFont font;
font.setTypeface(pFace);

SkString string("加载图片 #");

canvas->drawString(string, 1, 28, font, textpaint);

完整代码见文末的demo

加载并显示PNG图片等

百度“Skia绘制图片”出来的结果大多已经过时。

最新方法，要用 SkCodec::MakeFromData 解析二进制流，得到SkCodec 与 SkImageInfo，中SkImageInfo包括图片尺寸信息，然后再解码为 SkBitmap。

    DWORD fileLength;
    char* memFile;
    ... 加载文件到 memFile数组中
 
 
    sk_sp data = SkData::MakeWithoutCopy(memFile, fileLength);
    auto codec = SkCodec::MakeFromData(data);
    if (!codec) {
        LogIs(2, "FAILED DECODING FILE!");
    }
    
    SkImageInfo codecInfo = codec->getInfo();
    
    auto alphaType = codecInfo.isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
    
    auto decodeInfo = SkImageInfo::Make(codecInfo.width()
        , codecInfo.height()
        , kN32_SkColorType, alphaType);

    SkBitmap* skBitmap = new SkBitmap();

    char* pixels = new char[codecInfo.width()*codecInfo.height()*32];

    skBitmap->setInfo(decodeInfo, codecInfo.width()*32);


    skBitmap->setPixels(pixels);

    auto decodeResult = codec->getPixels(decodeInfo
        , pixels
        , codecInfo.width()*32);

decodeResult 等于零代表成功，其他可能的数值：

    /**
     *  Error codes for various SkCodec methods.
     */
    enum Result {
        /**
         *  General return value for success.
         */
        kSuccess, 0
        /**
         *  The input is incomplete. A partial image was generated.
         */
        kIncompleteInput, 1
        /**
         *  Like kIncompleteInput, except the input had an error.
         *
         *  If returned from an incremental decode, decoding cannot continue,
         *  even with more data.
         */
        kErrorInInput, 2
        /**
         *  The generator cannot convert to match the request, ignoring
         *  dimensions.
         */
        kInvalidConversion, 3
        /**
         *  The generator cannot scale to requested size.
         */
        kInvalidScale, 4
        /**
         *  Parameters (besides info) are invalid. e.g. NULL pixels, rowBytes
         *  too small, etc.
         */
        kInvalidParameters, 5
        /**
         *  The input did not contain a valid image.
         */
        kInvalidInput, 6
        /**
         *  Fulfilling this request requires rewinding the input, which is not
         *  supported for this input.
         */
        kCouldNotRewind, 7
        /**
         *  An internal error, such as OOM.
         */
        kInternalError, 8
        /**
         *  This method is not implemented by this codec.
         *  FIXME: Perhaps this should be kUnsupported?
         */
        kUnimplemented, 9
    };

完整 Demo 代码 | 我的Skia测试盒子

运行：

参考资料：《调用Skia内置位图编解码器的坑点》