JDK的代码：抱怨FreeType的斜体不好用，自行处理

Posted 2022-03-26 柳鲲鹏

　　昨天整合OpenJDK8到泰山JDK8，发现freetypeScaler.c有所改动。实际上这个文件已经被泰山JDK改得面目全非。吾当时还有点奇怪，这个文件应该不会改，怎么这次改动了呢？仔细对比了代码，发现其中一段很有意思：

// values used by FreeType (as of version 2.10.1) for italics transformation matrix in FT_GlyphSlot_Oblique
#define FT_MATRIX_ONE        0x10000
#define FT_MATRIX_OBLIQUE_XY 0x0366A

static void setupTransform(FT_Matrix* target, FTScalerContext *context) 
    FT_Matrix* transform = &context->transform;
    if (context->doItalize) 
        // we cannot use FT_GlyphSlot_Oblique as it doesn't work well with arbitrary transforms,
        // so we add corresponding shear transform to the requested glyph transformation
        target->xx = FT_MATRIX_ONE;
        target->xy = FT_MATRIX_OBLIQUE_XY;
        target->yx = 0;
        target->yy = FT_MATRIX_ONE;
        FT_Matrix_Multiply(transform, target);
     else 
        target->xx = transform->xx;
        target->xy = transform->xy;
        target->yx = transform->yx;
        target->yy = transform->yy;
    

　　这意思就是：FreeType对于任意变形的斜体支持不好，所以我们不得不自行处理。

　　任意变形的斜体？某些情况下泰山OFFICE也会遇到，需要进行专门研究。