Add WebP advanced options

[ikait]

Added more WebP convert options below.
https://github.com/webmproject/libwebp/blob/main/src/enc/config_enc.c

[pdknsk]

- pic.use_argb = !!opt->lossless;
+ pic.use_argb = !!opt->lossless || config.preprocessing > 0;

Works well otherwise. (A few additional options have been added since.)

[pdknsk]

I've updated the patch with the newest options.

diff --git a/PIL/WebPImagePlugin.py b/PIL/WebPImagePlugin.py
index bb06928..44ea7c2 100644
--- a/PIL/WebPImagePlugin.py
+++ b/PIL/WebPImagePlugin.py
@@ -74,6 +74,9 @@ def _save(im, fp, filename):
     emulate_jpeg_size = im.encoderinfo.get("emulate_jpeg_size", False)
     thread_level = im.encoderinfo.get("thread_level", 0)
     low_memory = im.encoderinfo.get("low_memory", False)
+    exact = im.encoderinfo.get("exact", False)
+    near_lossless = im.encoderinfo.get("near_lossless", 100) # 0-100
+    use_sharp_yuv = im.encoderinfo.get("use_sharp_yuv", False)
 
     data = _webp.WebPEncode(
         im.tobytes(),
@@ -103,7 +106,10 @@ def _save(im, fp, filename):
         partition_limit,
         emulate_jpeg_size,
         thread_level,
-        low_memory
+        low_memory,
+        exact,
+        near_lossless,
+        use_sharp_yuv,
     )
     if data is None:
         raise IOError("cannot write file as WEBP (encoder returned None)")
diff --git a/_webp.c b/_webp.c
index 54bd2bf..92738d2 100644
--- a/_webp.c
+++ b/_webp.c
@@ -36,6 +36,9 @@ struct option {
     int emulate_jpeg_size;
     int thread_level;
     int low_memory;
+    int exact;
+    int near_lossless;
+    int use_sharp_yuv;
 } opt;
 
 int getSizeAfterEncode(struct option *opt, uint8_t** rgb, uint8_t** output, int is_rgba) {
@@ -62,14 +65,20 @@ int getSizeAfterEncode(struct option *opt, uint8_t** rgb, uint8_t** output, int
         config.emulate_jpeg_size = opt->emulate_jpeg_size;
         config.thread_level = opt->thread_level;
         config.low_memory = opt->low_memory;
+        config.exact = opt->exact;
+        config.near_lossless = opt->near_lossless;
+        config.use_sharp_yuv = opt->use_sharp_yuv;
     }
 
+    if (config.near_lossless < 100)
+        config.lossless = 1;
+
     WebPPicture pic;
     WebPPictureInit(&pic);
 
     WebPMemoryWriter wrt;
     WebPMemoryWriterInit(&wrt);
-    pic.use_argb = !!opt->lossless;
+    pic.use_argb = !!config.lossless || config.preprocessing > 0 || !!config.use_sharp_yuv;
     pic.writer = WebPMemoryWrite;
     pic.custom_ptr = &wrt;
     pic.width = opt->width;
@@ -99,7 +108,7 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
     Py_ssize_t exif_size;
     size_t ret_size;
 
-    if (!PyArg_ParseTuple(args, "s#iiifss#s#iiifiiiiiiiiiiiiiiii",
+    if (!PyArg_ParseTuple(args, "s#iiifss#s#iiifiiiiiiiiiiiiiiiiiii",
                 (char**)&rgb, &size,
                 &opt.width, &opt.height, &opt.lossless,
                 &opt.quality,
@@ -111,7 +120,8 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
                 &opt.autofilter,
                 &opt.alpha_compression, &opt.alpha_filtering, &opt.alpha_quality,
                 &opt.pass, &opt.preprocessing, &opt.partitions, &opt.partition_limit,
-                &opt.emulate_jpeg_size, &opt.thread_level, &opt.low_memory
+                &opt.emulate_jpeg_size, &opt.thread_level, &opt.low_memory,
+                &opt.exact, &opt.near_lossless, &opt.use_sharp_yuv
                 )) {
         Py_RETURN_NONE;
     }

[wiredfool]

We still need testing and documentation on this, as that's (at least a portion) of what's been blocking this PR.

[Efreak]

Has anyone applied this to a more recent version of PIL? I'd like to make use of this with something more recent, but rebasing has conflicts, some of which don't seem related to this PR (probably an issue with my git config there, but it also takes a ridiculously long time to rebase due to the number of commits since).

Specifically, I would like: sharp_yuv, method (I think this has since been added), filter, passes, emulate_jpeg.