Add switch to DXT1 encoder to select block mode (With alpha/Without a…

…lpha)

Tests/test_file_vtf.py

@@ -63,7 +63,7 @@ def test_get_mipmap_count(size: Tuple[int, int], expected_count: int):
     ],
 )
 def test_get_texture_size(
-    pixel_format: VtfPF, size: Tuple[int, int], expected_size: int
+        pixel_format: VtfPF, size: Tuple[int, int], expected_size: int
 ):
     assert _get_texture_size(pixel_format, *size) == expected_size
 
@@ -72,17 +72,18 @@ def test_get_texture_size(
     ("etalon_path", "file_path", "expected_mode", "epsilon"),
     [
         ("Tests/images/vtf_i8.png", "Tests/images/vtf_i8.vtf", "L", 0.0),
-        ("Tests/images/vtf_a8.png", "Tests/images/vtf_a8.vtf", "L", 0.0),
+        ("Tests/images/vtf_a8.png", "Tests/images/vtf_a8.vtf", "RGBA", 0.0),
         ("Tests/images/vtf_ia88.png", "Tests/images/vtf_ia88.vtf", "LA", 0.0),
         ("Tests/images/vtf_uv88.png", "Tests/images/vtf_uv88.vtf", "RGB", 0.0),
         ("Tests/images/vtf_rgb888.png", "Tests/images/vtf_rgb888.vtf", "RGB", 0.0),
         ("Tests/images/vtf_bgr888.png", "Tests/images/vtf_bgr888.vtf", "RGB", 0.0),
         ("Tests/images/vtf_dxt1.png", "Tests/images/vtf_dxt1.vtf", "RGBA", 3.0),
+        ("Tests/images/vtf_dxt1A.png", "Tests/images/vtf_dxt1A.vtf", "RGBA", 8.0),
         ("Tests/images/vtf_rgba8888.png", "Tests/images/vtf_rgba8888.vtf", "RGBA", 0),
     ],
 )
-def test_vtf_loading(
-    etalon_path: str, file_path: str, expected_mode: str, epsilon: float
+def test_vtf_read(
+        etalon_path: str, file_path: str, expected_mode: str, epsilon: float
 ):
     e = Image.open(etalon_path)
     f = Image.open(file_path)
@@ -92,3 +93,32 @@ def test_vtf_loading(
         assert_image_equal(e, f)
     else:
         assert_image_similar(e, f, epsilon)
+
+
+@pytest.mark.parametrize(
+    ("pixel_format", "file_path", "expected_mode", "epsilon"),
+    [
+        (VtfPF.I8, "Tests/images/vtf_i8.png", "L", 0.0),
+        (VtfPF.A8, "Tests/images/vtf_a8.png", "RGBA", 0.0),
+        (VtfPF.IA88, "Tests/images/vtf_ia88.png", "LA", 0.0),
+        (VtfPF.UV88, "Tests/images/vtf_uv88.png", "RGB", 0.0),
+        (VtfPF.RGB888, "Tests/images/vtf_rgb888.png", "RGB", 0.0),
+        (VtfPF.BGR888, "Tests/images/vtf_bgr888.png", "RGB", 0.0),
+        (VtfPF.DXT1, "Tests/images/vtf_dxt1.png", "RGBA", 3.0),
+        (VtfPF.DXT1_ONEBITALPHA, "Tests/images/vtf_dxt1A.png", "RGBA", 8.0),
+        (VtfPF.RGBA8888, "Tests/images/vtf_rgba8888.png", "RGBA", 0),
+    ],
+)
+def test_vtf_save(pixel_format: VtfPF, file_path: str,
+                  expected_mode: str, epsilon: float, tmp_path):
+    f: Image.Image = Image.open(file_path)
+    out = (tmp_path / "tmp.vtf").as_posix()
+    f.save(out, pixel_format=pixel_format)
+    if pixel_format == VtfPF.DXT1:
+        f = f.convert("RGBA")
+    e = Image.open(out)
+    assert e.mode == expected_mode
+    if epsilon == 0:
+        assert_image_equal(e, f)
+    else:
+        assert_image_similar(e, f, epsilon)

src/PIL/VtfImagePlugin.py

@@ -76,29 +76,29 @@ class VtfPF(IntEnum):
     ABGR8888 = 1
     RGB888 = 2
     BGR888 = 3
-    RGB565 = 4
+    # RGB565 = 4
     I8 = 5
     IA88 = 6
-    P8 = 7
+    # P8 = 7
     A8 = 8
-    RGB888_BLUESCREEN = 9
-    BGR888_BLUESCREEN = 10
+    # RGB888_BLUESCREEN = 9
+    # BGR888_BLUESCREEN = 10
     ARGB8888 = 11
     BGRA8888 = 12
     DXT1 = 13
     DXT3 = 14
     DXT5 = 15
     BGRX8888 = 16
-    BGR565 = 17
-    BGRX5551 = 18
-    BGRA4444 = 19
+    # BGR565 = 17
+    # BGRX5551 = 18
+    # BGRA4444 = 19
     DXT1_ONEBITALPHA = 20
-    BGRA5551 = 21
+    # BGRA5551 = 21
     UV88 = 22
-    UVWQ8888 = 23
-    RGBA16161616F = 24
-    RGBA16161616 = 25
-    UVLX8888 = 26
+    # UVWQ8888 = 23
+    # RGBA16161616F = 24
+    # RGBA16161616 = 25
+    # UVLX8888 = 26
 
 
 VTFHeader = NamedTuple(
@@ -125,26 +125,8 @@ class VtfPF(IntEnum):
         ("resource_count", int),
     ],
 )
-RGB_FORMATS = (
-    VtfPF.DXT1,
-    VtfPF.RGB888,
-    VtfPF.BGR888,
-    VtfPF.UV88,
-)
-RGBA_FORMATS = (
-    VtfPF.DXT1_ONEBITALPHA,
-    VtfPF.DXT3,
-    VtfPF.DXT5,
-    VtfPF.RGBA8888,
-)
-L_FORMATS = (
-    VtfPF.A8,
-    VtfPF.I8,
-)
-LA_FORMATS = (VtfPF.IA88,)
 
 BLOCK_COMPRESSED = (VtfPF.DXT1, VtfPF.DXT1_ONEBITALPHA, VtfPF.DXT3, VtfPF.DXT5)
-SUPPORTED_FORMATS = RGBA_FORMATS + RGB_FORMATS + LA_FORMATS + L_FORMATS
 HEADER_V70 = "<I2HI2H4x3f4xfIbI2b"
 HEADER_V72 = "<I2HI2H4x3f4xfIbI2bH"
 HEADER_V73 = "<I2HI2H4x3f4xfIbI2bH3xI8x"
@@ -153,22 +135,13 @@ class VtfPF(IntEnum):
 def _get_texture_size(pixel_format: VtfPF, width, height):
     if pixel_format in (VtfPF.DXT1, VtfPF.DXT1_ONEBITALPHA):
         return width * height // 2
-    elif (
-        pixel_format
-        in (
-            VtfPF.DXT3,
-            VtfPF.DXT5,
-        )
-        + L_FORMATS
-    ):
+    elif pixel_format in (VtfPF.DXT3, VtfPF.DXT5):
         return width * height
-    elif pixel_format == VtfPF.UV88:
-        return width * height * 2
-    elif pixel_format in LA_FORMATS:
+    elif pixel_format in (VtfPF.A8, VtfPF.I8,):
+        return width * height
+    elif pixel_format in (VtfPF.UV88, VtfPF.IA88):
         return width * height * 2
-    elif pixel_format == VtfPF.RGB888:
-        return width * height * 3
-    elif pixel_format == VtfPF.BGR888:
+    elif pixel_format in (VtfPF.RGB888, VtfPF.BGR888):
         return width * height * 3
     elif pixel_format == VtfPF.RGBA8888:
         return width * height * 4
@@ -190,36 +163,28 @@ def _write_image(fp: BufferedIOBase, im: Image.Image, pixel_format: VtfPF):
     if pixel_format == VtfPF.DXT1:
         encoder = "bcn"
         encoder_args = (1, "DXT1")
-        im = im.convert("RGB")
+        im = im.convert("RGBA")
     elif pixel_format == VtfPF.DXT1_ONEBITALPHA:
         encoder = "bcn"
         encoder_args = (1, "DXT1A")
-        im = im.convert("RGBA")
     elif pixel_format == VtfPF.DXT3:
         encoder = "bcn"
         encoder_args = (3, "DXT3")
-        im = im.convert("RGBA")
     elif pixel_format == VtfPF.DXT5:
         encoder = "bcn"
         encoder_args = (5, "DXT5")
-        im = im.convert("RGBA")
     elif pixel_format == VtfPF.RGB888:
         encoder = "raw"
         encoder_args = ("RGB", 0, 0)
-        im = im.convert("RGB")
     elif pixel_format == VtfPF.BGR888:
         encoder = "raw"
         encoder_args = ("BGR", 0, 0)
-        im = im.convert("RGB")
     elif pixel_format == VtfPF.RGBA8888:
         encoder = "raw"
         encoder_args = ("RGBA", 0, 0)
-        im = im.convert("RGBA")
     elif pixel_format == VtfPF.A8:
         encoder = "raw"
-        encoder_args = ("L", 0, 0)
-        *_, a = im.split()
-        im = Image.merge("L", (a,))
+        encoder_args = ("A", 0, 0)
     elif pixel_format == VtfPF.I8:
         encoder = "raw"
         encoder_args = ("L", 0, 0)
@@ -240,7 +205,7 @@ def _write_image(fp: BufferedIOBase, im: Image.Image, pixel_format: VtfPF):
 
 def _closest_power(x):
     possible_results = round(log(x, 2)), ceil(log(x, 2))
-    return 2 ** min(possible_results, key=lambda z: abs(x - 2**z))
+    return 2 ** min(possible_results, key=lambda z: abs(x - 2 ** z))
 
 
 class VtfImageFile(ImageFile.ImageFile):
@@ -281,15 +246,14 @@ def _open(self):
         # flags = CompiledVtfFlags(header.flags)
         pixel_format = VtfPF(header.pixel_format)
         low_format = VtfPF(header.low_pixel_format)
-        if pixel_format == VtfPF.DXT1:  # Special case for DXT1
+        if pixel_format in (VtfPF.DXT1_ONEBITALPHA, VtfPF.DXT1, VtfPF.DXT3, VtfPF.DXT5,
+                            VtfPF.RGBA8888, VtfPF.BGRA8888,VtfPF.A8):
             self.mode = "RGBA"
-        elif pixel_format in RGB_FORMATS:
+        elif pixel_format in (VtfPF.RGB888, VtfPF.BGR888, VtfPF.UV88):
             self.mode = "RGB"
-        elif pixel_format in RGBA_FORMATS:
-            self.mode = "RGBA"
-        elif pixel_format in L_FORMATS:
+        elif pixel_format == VtfPF.I8:
             self.mode = "L"
-        elif pixel_format in LA_FORMATS:
+        elif pixel_format == VtfPF.IA88:
             self.mode = "LA"
         else:
             raise VTFException(f"Unsupported VTF pixel format: {pixel_format}")
@@ -311,19 +275,21 @@ def _open(self):
             tile = ("bcn", (0, 0) + self.size, data_start, (2, "DXT3"))
         elif pixel_format == VtfPF.DXT5:
             tile = ("bcn", (0, 0) + self.size, data_start, (3, "DXT5"))
-        elif pixel_format in (VtfPF.RGBA8888,):
+        elif pixel_format == VtfPF.RGBA8888:
             tile = ("raw", (0, 0) + self.size, data_start, ("RGBA", 0, 1))
-        elif pixel_format in (VtfPF.RGB888,):
+        elif pixel_format == VtfPF.RGB888:
             tile = ("raw", (0, 0) + self.size, data_start, ("RGB", 0, 1))
-        elif pixel_format in (VtfPF.BGR888,):
+        elif pixel_format == VtfPF.BGR888:
             tile = ("raw", (0, 0) + self.size, data_start, ("BGR", 0, 1))
-        elif pixel_format in (VtfPF.BGRA8888,):
+        elif pixel_format == VtfPF.BGRA8888:
             tile = ("raw", (0, 0) + self.size, data_start, ("BGRA", 0, 1))
-        elif pixel_format in (VtfPF.UV88,):
+        elif pixel_format == VtfPF.UV88:
             tile = ("raw", (0, 0) + self.size, data_start, ("RG", 0, 1))
-        elif pixel_format in L_FORMATS:
+        elif pixel_format == VtfPF.I8:
             tile = ("raw", (0, 0) + self.size, data_start, ("L", 0, 1))
-        elif pixel_format in LA_FORMATS:
+        elif pixel_format == VtfPF.A8:
+            tile = ("raw", (0, 0) + self.size, data_start, ("A", 0, 1))
+        elif pixel_format == VtfPF.IA88:
             tile = ("raw", (0, 0) + self.size, data_start, ("LA", 0, 1))
         else:
             raise VTFException(f"Unsupported VTF pixel format: {pixel_format}")
@@ -343,15 +309,12 @@ def _save(im, fp, filename):
 
     if pixel_format == VtfPF.DXT1_ONEBITALPHA:
         flags |= CompiledVtfFlags.ONEBITALPHA
-    elif pixel_format == VtfPF.A8:
-        flags |= CompiledVtfFlags.EIGHTBITALPHA
-    elif pixel_format in RGBA_FORMATS + LA_FORMATS:
+    elif pixel_format in (VtfPF.DXT3, VtfPF.DXT5,
+                          VtfPF.RGBA8888, VtfPF.BGRA8888,
+                          VtfPF.A8, VtfPF.IA88):
         flags |= CompiledVtfFlags.EIGHTBITALPHA
-    elif pixel_format in RGB_FORMATS + L_FORMATS:
-        pass
     else:
-        raise VTFException("Unhandled case")
-
+        pass
     im = im.resize((_closest_power(im.width), _closest_power(im.height)))
     width, height = im.size
 

src/libImaging/BcnEncode.c

@@ -111,7 +111,7 @@ get_closest_color_index(const UINT16 *colors, UINT16 color) {
         if (error == 0) {
             return color_id;
         }
-        if (error < color_error) {
+        if (error <= color_error) {
             color_error = error;
             lowest_id = color_id;
         }
@@ -122,10 +122,10 @@ get_closest_color_index(const UINT16 *colors, UINT16 color) {
 int
 encode_bc1(Imaging im, ImagingCodecState state, UINT8 *buf, int bytes) {
     UINT8 *dst = buf;
-    UINT8 no_alpha = 0;
+    UINT8 alpha = 0;
     INT32 block_index;
-    if (strcmp(((BCNSTATE *)state->context)->pixel_format, "DXT1A") != 0) {
-        no_alpha = 1;
+    if (strcmp(((BCNSTATE *)state->context)->pixel_format, "DXT1A") == 0) {
+        alpha = 1;
     }
     INT32 block_count = (im->xsize * im->ysize) / 16;
     if (block_count * sizeof(bc1_color) > bytes) {
@@ -143,6 +143,7 @@ encode_bc1(Imaging im, ImagingCodecState state, UINT8 *buf, int bytes) {
         UINT16 unique_colors[16];
         UINT8 color_frequency[16];
         UINT8 opaque[16];
+        UINT8 local_alpha = 0;
         memset(all_colors, 0, sizeof(all_colors));
         memset(unique_colors, 0, sizeof(unique_colors));
         memset(color_frequency, 0, sizeof(color_frequency));
@@ -157,7 +158,8 @@ encode_bc1(Imaging im, ImagingCodecState state, UINT8 *buf, int bytes) {
                 UINT8 b = im->image[y][x * im->pixelsize + 0];
                 UINT8 a = im->image[y][x * im->pixelsize + 3];
                 UINT16 color = PACK_SHORT_565(r, g, b);
-                opaque[bx + by * 4] = a >= 127;
+                opaque[bx + by * 4] = a >= 128;
+                local_alpha |= a <= 128;
                 all_colors[bx + by * 4] = color;
 
                 UINT8 new_color = 1;
@@ -179,28 +181,34 @@ encode_bc1(Imaging im, ImagingCodecState state, UINT8 *buf, int bytes) {
 
         UINT16 c0 = 0, c1 = 0;
         pick_2_major_colors(unique_colors, color_frequency, unique_count, &c0, &c1);
-        if (c0 < c1 && no_alpha) {
-            SWAP(UINT16, c0, c1);
+        if (alpha && local_alpha) {
+            if (c0 > c1) {
+                SWAP(UINT16, c0, c1);
+            }
+        } else {
+            if (c0 < c1) {
+                SWAP(UINT16, c0, c1);
+            }
         }
 
         UINT16 palette[4] = {c0, c1, 0, 0};
-        if (no_alpha) {
-            palette[2] = rgb565_lerp(c0, c1, 2, 1);
-            palette[3] = rgb565_lerp(c0, c1, 1, 2);
-        } else {
+        if (alpha && local_alpha) {
             palette[2] = rgb565_lerp(c0, c1, 1, 1);
             palette[3] = 0;
+        } else {
+            palette[2] = rgb565_lerp(c0, c1, 2, 1);
+            palette[3] = rgb565_lerp(c0, c1, 1, 2);
         }
         bc1_color block = {0};
         block.c0 = c0;
         block.c1 = c1;
         UINT32 color_id;
         for (color_id = 0; color_id < 16; ++color_id) {
             UINT8 bc_color_id;
-            if (opaque[color_id] || no_alpha) {
-                bc_color_id = get_closest_color_index(palette, all_colors[color_id]);
-            } else {
+            if ((alpha && local_alpha) && !opaque[color_id]) {
                 bc_color_id = 3;
+            } else {
+                bc_color_id = get_closest_color_index(palette, all_colors[color_id]);
             }
             SET_BITS(block.lut, color_id * 2, 2, bc_color_id);
         }