Remove unused ImagingConvertInPlace

Tests/test_image_putalpha.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import pytest
+
 from PIL import Image
 
 
@@ -39,6 +41,9 @@ def test_promote() -> None:
     assert im.mode == "RGBA"
     assert im.getpixel((0, 0)) == (1, 2, 3, 4)
 
+    with pytest.raises(ValueError, match="image has wrong mode"):
+        im.im.setalpha()
+
 
 def test_readonly() -> None:
     im = Image.new("RGB", (1, 1), (1, 2, 3))

src/PIL/Image.py

@@ -2044,19 +2044,19 @@ def putalpha(self, alpha: Image | int) -> None:
 
         self._ensure_mutable()
 
-        if self.mode not in ("LA", "PA", "RGBA"):
-            # attempt to promote self to a matching alpha mode
+        if self.mode in ("RGB", "RGBX"):
+            # promote self to RGBA
+            self.im.setalpha()
+            self._mode = "RGBA"
+        elif self.mode not in ("LA", "PA", "RGBA"):
             try:
+                # do things the hard way
                 mode = getmodebase(self.mode) + "A"
-                try:
-                    self.im.setmode(mode)
-                except (AttributeError, ValueError) as e:
-                    # do things the hard way
-                    im = self.im.convert(mode)
-                    if im.mode not in ("LA", "PA", "RGBA"):
-                        msg = "alpha channel could not be added"
-                        raise ValueError(msg) from e  # sanity check
-                    self.im = im
+                im = self.im.convert(mode)
+                if im.mode not in ("LA", "PA", "RGBA"):
+                    msg = "alpha channel could not be added"
+                    raise ValueError(msg)  # sanity check
+                self.im = im
                 self._mode = self.im.mode
             except KeyError as e:
                 msg = "illegal image mode"

src/_imaging.c

@@ -2052,45 +2052,16 @@ _reduce(ImagingObject *self, PyObject *args) {
     return PyImagingNew(imOut);
 }
 
-static int
-isRGB(const ModeID mode) {
-    return mode == IMAGING_MODE_RGB || mode == IMAGING_MODE_RGBA ||
-           mode == IMAGING_MODE_RGBX;
-}
-
 static PyObject *
-im_setmode(ImagingObject *self, PyObject *args) {
+im_setalpha(ImagingObject *self, PyObject *args) {
     /* attempt to modify the mode of an image in place */
-
-    Imaging im;
-
-    char *mode_name;
-    Py_ssize_t modelen;
-    if (!PyArg_ParseTuple(args, "s#:setmode", &mode_name, &modelen)) {
-        return NULL;
-    }
-
-    const ModeID mode = findModeID(mode_name);
-
-    im = self->image;
-
-    /* move all logic in here to the libImaging primitive */
-
-    if (im->mode == mode) {
-        ; /* same mode; always succeeds */
-    } else if (isRGB(im->mode) && isRGB(mode)) {
-        /* color to color */
-        im->mode = mode;
-        im->bands = modelen;
-        if (mode == IMAGING_MODE_RGBA) {
-            (void)ImagingFillBand(im, 3, 255);
-        }
-    } else {
-        /* trying doing an in-place conversion */
-        if (!ImagingConvertInPlace(im, mode)) {
-            return NULL;
-        }
+    Imaging im = self->image;
+    if (im->mode != IMAGING_MODE_RGB && im->mode != IMAGING_MODE_RGBX) {
+        return ImagingError_ModeError();
     }
+    im->mode = IMAGING_MODE_RGBA;
+    im->bands = 4;
+    (void)ImagingFillBand(im, 3, 255);
 
     if (self->access) {
         ImagingAccessDelete(im, self->access);
@@ -3739,7 +3710,7 @@ static struct PyMethodDef methods[] = {
     {"split", (PyCFunction)_split, METH_NOARGS},
     {"fillband", (PyCFunction)_fillband, METH_VARARGS},
 
-    {"setmode", (PyCFunction)im_setmode, METH_VARARGS},
+    {"setalpha", (PyCFunction)im_setalpha, METH_NOARGS},
 
     {"getpalette", (PyCFunction)_getpalette, METH_VARARGS},
     {"getpalettemode", (PyCFunction)_getpalettemode, METH_NOARGS},

src/libImaging/Convert.c

@@ -1734,27 +1734,3 @@ ImagingConvertTransparent(Imaging imIn, const ModeID mode, int r, int g, int b)
 
     return imOut;
 }
-
-Imaging
-ImagingConvertInPlace(Imaging imIn, const ModeID mode) {
-    ImagingSectionCookie cookie;
-    ImagingShuffler convert;
-    int y;
-
-    /* limited support for inplace conversion */
-    if (imIn->mode == IMAGING_MODE_L && mode == IMAGING_MODE_1) {
-        convert = l2bit;
-    } else if (imIn->mode == IMAGING_MODE_1 && mode == IMAGING_MODE_L) {
-        convert = bit2l;
-    } else {
-        return ImagingError_ModeError();
-    }
-
-    ImagingSectionEnter(&cookie);
-    for (y = 0; y < imIn->ysize; y++) {
-        (*convert)((UINT8 *)imIn->image[y], (UINT8 *)imIn->image[y], imIn->xsize);
-    }
-    ImagingSectionLeave(&cookie);
-
-    return imIn;
-}

src/libImaging/Imaging.h

@@ -305,8 +305,6 @@ ImagingCopy(Imaging im);
 extern Imaging
 ImagingConvert(Imaging im, ModeID mode, ImagingPalette palette, int dither);
 extern Imaging
-ImagingConvertInPlace(Imaging im, ModeID mode);
-extern Imaging
 ImagingConvertMatrix(Imaging im, ModeID mode, const float m[12]);
 extern Imaging
 ImagingConvertTransparent(Imaging im, ModeID mode, int r, int g, int b);