Added DXT5 saving

Author: radarhere

Tests/test_file_dds.py

@@ -398,21 +398,48 @@ def test_save(mode: str, test_file: str, tmp_path: Path) -> None:
 
 
 def test_save_dxt1(tmp_path: Path) -> None:
+    # RGB
     out = str(tmp_path / "temp.dds")
     with Image.open(TEST_FILE_DXT1) as im:
         im.convert("RGB").save(out, pixel_format="DXT1")
     assert_image_similar_tofile(im, out, 1.84)
 
+    # RGBA
     im_alpha = im.copy()
     im_alpha.putpixel((0, 0), (0, 0, 0, 0))
     im_alpha.save(out, pixel_format="DXT1")
     with Image.open(out) as reloaded:
         assert reloaded.getpixel((0, 0)) == (0, 0, 0, 0)
 
+    # L
     im_l = im.convert("L")
     im_l.save(out, pixel_format="DXT1")
-    assert_image_similar_tofile(im_l.convert("RGBA"), out, 9.25)
+    assert_image_similar_tofile(im_l.convert("RGBA"), out, 6.07)
 
+    # LA
     im_alpha.convert("LA").save(out, pixel_format="DXT1")
     with Image.open(out) as reloaded:
         assert reloaded.getpixel((0, 0)) == (0, 0, 0, 0)
+
+
+def test_save_dxt5(tmp_path: Path) -> None:
+    # RGB
+    out = str(tmp_path / "temp.dds")
+    with Image.open(TEST_FILE_DXT1) as im:
+        im.convert("RGB").save(out, pixel_format="DXT5")
+    assert_image_similar_tofile(im, out, 1.84)
+
+    # RGBA
+    with Image.open(TEST_FILE_DXT5) as im_rgba:
+        im_rgba.save(out, pixel_format="DXT5")
+    assert_image_similar_tofile(im_rgba, out, 3.69)
+
+    # L
+    im_l = im.convert("L")
+    im_l.save(out, pixel_format="DXT5")
+    assert_image_similar_tofile(im_l.convert("RGBA"), out, 6.07)
+
+    # LA
+    im_la = im_rgba.convert("LA")
+    im_la.save(out, pixel_format="DXT5")
+    assert_image_similar_tofile(im_la.convert("RGBA"), out, 8.32)

src/PIL/DdsImagePlugin.py

@@ -520,23 +520,31 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
 
     flags = DDSD.CAPS | DDSD.HEIGHT | DDSD.WIDTH | DDSD.PIXELFORMAT
     bitcount = len(im.getbands()) * 8
-    raw = im.encoderinfo.get("pixel_format") != "DXT1"
-    if raw:
+    pixel_format = im.encoderinfo.get("pixel_format")
+    if pixel_format in ("DXT1", "DXT5"):
+        codec_name = "bcn"
+        flags |= DDSD.LINEARSIZE
+        pitch = (im.width + 3) * 4
+        args = pixel_format
+        rgba_mask = [0, 0, 0, 0]
+        pixel_flags = DDPF.FOURCC
+        fourcc = D3DFMT.DXT1 if pixel_format == "DXT1" else D3DFMT.DXT5
+    else:
         codec_name = "raw"
         flags |= DDSD.PITCH
         pitch = (im.width * bitcount + 7) // 8
 
         alpha = im.mode[-1] == "A"
         if im.mode[0] == "L":
             pixel_flags = DDPF.LUMINANCE
-            rawmode = im.mode
+            args = im.mode
             if alpha:
                 rgba_mask = [0x000000FF, 0x000000FF, 0x000000FF]
             else:
                 rgba_mask = [0xFF000000, 0xFF000000, 0xFF000000]
         else:
             pixel_flags = DDPF.RGB
-            rawmode = im.mode[::-1]
+            args = im.mode[::-1]
             rgba_mask = [0x00FF0000, 0x0000FF00, 0x000000FF]
 
             if alpha:
@@ -546,15 +554,7 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
             pixel_flags |= DDPF.ALPHAPIXELS
         rgba_mask.append(0xFF000000 if alpha else 0)
 
-        fourcc = 0
-    else:
-        codec_name = "bcn"
-        flags |= DDSD.LINEARSIZE
-        pitch = (im.width + 3) * 4
-        rawmode = None
-        rgba_mask = [0, 0, 0, 0]
-        pixel_flags = DDPF.FOURCC
-        fourcc = D3DFMT.DXT1
+        fourcc = D3DFMT.UNKNOWN
     fp.write(
         o32(DDS_MAGIC)
         + struct.pack(
@@ -573,7 +573,7 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
         + struct.pack("<4I", *rgba_mask)  # dwRGBABitMask
         + struct.pack("<5I", DDSCAPS.TEXTURE, 0, 0, 0, 0)
     )
-    ImageFile._save(im, fp, [ImageFile._Tile(codec_name, (0, 0) + im.size, 0, rawmode)])
+    ImageFile._save(im, fp, [ImageFile._Tile(codec_name, (0, 0) + im.size, 0, args)])
 
 
 def _accept(prefix: bytes) -> bool:

src/encode.c

@@ -27,6 +27,7 @@
 
 #include "thirdparty/pythoncapi_compat.h"
 #include "libImaging/Imaging.h"
+#include "libImaging/Bcn.h"
 #include "libImaging/Gif.h"
 
 #ifdef HAVE_UNISTD_H
@@ -358,13 +359,21 @@ PyObject *
 PyImaging_BcnEncoderNew(PyObject *self, PyObject *args) {
     ImagingEncoderObject *encoder;
 
-    encoder = PyImaging_EncoderNew(0);
+    char *mode;
+    char *pixel_format;
+    if (!PyArg_ParseTuple(args, "ss", &mode, &pixel_format)) {
+        return NULL;
+    }
+
+    encoder = PyImaging_EncoderNew(sizeof(BCNSTATE));
     if (encoder == NULL) {
         return NULL;
     }
 
     encoder->encode = ImagingBcnEncode;
 
+    ((BCNSTATE *)encoder->state.context)->pixel_format = pixel_format;
+
     return (PyObject *)encoder;
 }