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If pasting an image onto itself at a lower position, copy from bottom #8882

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Merged
hugovk merged 2 commits into from
Oct 15, 2025
Merged

If pasting an image onto itself at a lower position, copy from bottom #8882

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79f834e
If pasting an image onto itself at a lower position, copy from bottom
radarhere Apr 11, 2025
81fa4e1
If pasting image to self at lower position with mask, copy from bottom
radarhere Apr 11, 2025
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15 changes: 15 additions & 0 deletions Tests/test_image_paste.py
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,21 @@ def test_image_solid(self, mode: str) -> None:
im = im.crop((12, 23, im2.width + 12, im2.height + 23))
assert_image_equal(im, im2)

@pytest.mark.parametrize("y", [10, -10])
@pytest.mark.parametrize("mode", ["L", "RGB"])
@pytest.mark.parametrize("mask_mode", ["", "1", "L", "LA", "RGBa"])
def test_image_self(self, y: int, mode: str, mask_mode: str) -> None:
im = getattr(self, "gradient_" + mode)
mask = Image.new(mask_mode, im.size, 0xFFFFFFFF) if mask_mode else None

im_self = im.copy()
im_self.paste(im_self, (0, y), mask)

im_copy = im.copy()
im_copy.paste(im_copy.copy(), (0, y), mask)

assert_image_equal(im_self, im_copy)

@pytest.mark.parametrize("mode", ["RGBA", "RGB", "L"])
def test_image_mask_1(self, mode: str) -> None:
im = Image.new(mode, (200, 200), "white")
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45 changes: 30 additions & 15 deletions src/libImaging/Paste.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,18 @@

#include "Imaging.h"

#define PREPARE_PASTE_LOOP() \
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@hugovk hugovk Oct 10, 2025

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Can this be a function instead?

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@radarhere radarhere Oct 11, 2025

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radarhere@be8209e is what would be required. I don't think it's as neat, but let me know if you disagree.

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@hugovk hugovk Oct 15, 2025

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OK, let's go with this PR version.

int y, y_end, offset; \
if (imOut == imIn && dy > sy) { \
y = ysize - 1; \
y_end = -1; \
offset = -1; \
} else { \
y = 0; \
y_end = ysize; \
offset = 1; \
}

static inline void
paste(
Imaging imOut,
Expand All @@ -37,14 +49,13 @@
) {
/* paste opaque region */

int y;

dx *= pixelsize;
sx *= pixelsize;

xsize *= pixelsize;

for (y = 0; y < ysize; y++) {
PREPARE_PASTE_LOOP();

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for (; y != y_end; y += offset) {
memcpy(imOut->image[y + dy] + dx, imIn->image[y + sy] + sx, xsize);
}
}
Expand All @@ -64,12 +75,13 @@
) {
/* paste with mode "1" mask */

int x, y;
int x;

PREPARE_PASTE_LOOP();

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if (imOut->image8) {
int in_i16 = strncmp(imIn->mode, "I;16", 4) == 0;
int out_i16 = strncmp(imOut->mode, "I;16", 4) == 0;
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = imOut->image8[y + dy] + dx;
if (out_i16) {
out += dx;
Expand Down Expand Up @@ -97,7 +109,7 @@
}

} else {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
INT32 *out = imOut->image32[y + dy] + dx;
INT32 *in = imIn->image32[y + sy] + sx;
UINT8 *mask = imMask->image8[y + sy] + sx;
Expand Down Expand Up @@ -126,11 +138,12 @@
) {
/* paste with mode "L" matte */

int x, y;
int x;
unsigned int tmp1;

PREPARE_PASTE_LOOP();

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if (imOut->image8) {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = imOut->image8[y + dy] + dx;
UINT8 *in = imIn->image8[y + sy] + sx;
UINT8 *mask = imMask->image8[y + sy] + sx;
Expand All @@ -141,7 +154,7 @@
}

} else {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = (UINT8 *)(imOut->image32[y + dy] + dx);
UINT8 *in = (UINT8 *)(imIn->image32[y + sy] + sx);
UINT8 *mask = (UINT8 *)(imMask->image8[y + sy] + sx);
Expand Down Expand Up @@ -174,11 +187,12 @@
) {
/* paste with mode "RGBA" matte */

int x, y;
int x;
unsigned int tmp1;

PREPARE_PASTE_LOOP();

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if (imOut->image8) {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = imOut->image8[y + dy] + dx;
UINT8 *in = imIn->image8[y + sy] + sx;
UINT8 *mask = (UINT8 *)imMask->image[y + sy] + sx * 4 + 3;
Expand All @@ -189,7 +203,7 @@
}

} else {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = (UINT8 *)(imOut->image32[y + dy] + dx);
UINT8 *in = (UINT8 *)(imIn->image32[y + sy] + sx);
UINT8 *mask = (UINT8 *)(imMask->image32[y + sy] + sx);
Expand Down Expand Up @@ -222,11 +236,12 @@
) {
/* paste with mode "RGBa" matte */

int x, y;
int x;
unsigned int tmp1;

PREPARE_PASTE_LOOP();

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if (imOut->image8) {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = imOut->image8[y + dy] + dx;
UINT8 *in = imIn->image8[y + sy] + sx;
UINT8 *mask = (UINT8 *)imMask->image[y + sy] + sx * 4 + 3;
Expand All @@ -237,7 +252,7 @@
}

} else {
for (y = 0; y < ysize; y++) {
for (; y != y_end; y += offset) {
UINT8 *out = (UINT8 *)(imOut->image32[y + dy] + dx);
UINT8 *in = (UINT8 *)(imIn->image32[y + sy] + sx);
UINT8 *mask = (UINT8 *)(imMask->image32[y + sy] + sx);
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