void SkBaseDevice::drawTextRSXform(const void* text, size_t len, const SkRSXform xform[], const SkPaint& paint) { CountTextProc proc = nullptr; switch (paint.getTextEncoding()) { case SkPaint::kUTF8_TextEncoding: proc = SkUTF8_CountUTF8Bytes; break; case SkPaint::kUTF16_TextEncoding: proc = count_utf16; break; case SkPaint::kUTF32_TextEncoding: proc = return_4; break; case SkPaint::kGlyphID_TextEncoding: proc = return_2; break; } SkPaint localPaint(paint); SkShader* shader = paint.getShader(); SkMatrix localM, currM; const void* stopText = (const char*)text + len; while ((const char*)text < (const char*)stopText) { localM.setRSXform(*xform++); currM.setConcat(this->ctm(), localM); SkAutoDeviceCTMRestore adc(this, currM); // We want to rotate each glyph by the rsxform, but we don't want to rotate "space" // (i.e. the shader that cares about the ctm) so we have to undo our little ctm trick // with a localmatrixshader so that the shader draws as if there was no change to the ctm. if (shader) { SkMatrix inverse; if (localM.invert(&inverse)) { localPaint.setShader(shader->makeWithLocalMatrix(inverse)); } else { localPaint.setShader(nullptr); // can't handle this xform } } int subLen = proc((const char*)text); this->drawText(text, subLen, 0, 0, localPaint); text = (const char*)text + subLen; } }