func setupDecoderOptions(dinfo *C.struct_jpeg_decompress_struct, opt *DecoderOptions) {
tw, th := opt.ScaleTarget.Dx(), opt.ScaleTarget.Dy()
if tw > 0 && th > 0 {
var scaleFactor int
for scaleFactor = 1; scaleFactor <= 8; scaleFactor++ {
if ((scaleFactor*int(dinfo.image_width)+7)/8) >= tw &&
((scaleFactor*int(dinfo.image_height)+7)/8) >= th {
break
}
}
if scaleFactor < 8 {
dinfo.scale_num = C.uint(scaleFactor)
dinfo.scale_denom = 8
}
}
dinfo.dct_method = C.J_DCT_METHOD(opt.DCTMethod)
if opt.DisableFancyUpsampling {
dinfo.do_fancy_upsampling = C.FALSE
} else {
dinfo.do_fancy_upsampling = C.TRUE
}
if opt.DisableBlockSmoothing {
dinfo.do_block_smoothing = C.FALSE
} else {
dinfo.do_block_smoothing = C.TRUE
}
}
func setupEncoderOptions(cinfo *C.struct_jpeg_compress_struct, opt *EncoderOptions) {
C.jpeg_set_quality(cinfo, C.int(opt.Quality), C.TRUE)
if opt.OptimizeCoding {
cinfo.optimize_coding = C.TRUE
} else {
cinfo.optimize_coding = C.FALSE
}
cinfo.dct_method = C.J_DCT_METHOD(opt.DCTMethod)
}