Add Image.alpha_composite

This commit is contained in:
Tom Payne 2012-12-04 16:44:26 +01:00
parent 4a10a363e4
commit e414c66070
5 changed files with 127 additions and 2 deletions

View File

@ -1980,6 +1980,21 @@ def open(fp, mode="r"):
#
# Image processing.
##
# Alpha composites im2 over im1.
#
# @param im1 The first image.
# @param im2 The second image. Must have the same mode and size as
# the first image.
# @return An Image object.
def alpha_composite(im1, im2):
"Alpha composite im2 over im1."
im1.load()
im2.load()
return im1._new(core.alpha_composite(im1.im, im2.im))
##
# Creates a new image by interpolating between two input images, using
# a constant alpha.

View File

@ -694,6 +694,20 @@ _open_ppm(PyObject* self, PyObject* args)
return PyImagingNew(ImagingOpenPPM(filename));
}
static PyObject*
_alpha_composite(ImagingObject* self, PyObject* args)
{
ImagingObject* imagep1;
ImagingObject* imagep2;
if (!PyArg_ParseTuple(args, "O!O!",
&Imaging_Type, &imagep1,
&Imaging_Type, &imagep2))
return NULL;
return PyImagingNew(ImagingAlphaComposite(imagep1->image, imagep2->image));
}
static PyObject*
_blend(ImagingObject* self, PyObject* args)
{
@ -3152,6 +3166,7 @@ extern PyObject* PyImaging_MapBuffer(PyObject* self, PyObject* args);
static PyMethodDef functions[] = {
/* Object factories */
{"alpha_composite", (PyCFunction)_alpha_composite, 1},
{"blend", (PyCFunction)_blend, 1},
{"fill", (PyCFunction)_fill, 1},
{"new", (PyCFunction)_new, 1},

View File

@ -0,0 +1,94 @@
/*
* The Python Imaging Library
* $Id$
*
* Alpha composite imSrc over imDst.
* http://en.wikipedia.org/wiki/Alpha_compositing
*
* See the README file for details on usage and redistribution.
*/
#include "Imaging.h"
Imaging
ImagingAlphaComposite(Imaging imDst, Imaging imSrc)
{
Imaging imOut;
int x, y;
float dstR, dstG, dstB, dstA;
float srcR, srcG, srcB, srcA;
float outR, outG, outB, outA;
/* Check arguments */
if (!imDst || !imSrc ||
strcmp(imDst->mode, "RGBA") ||
imDst->type != IMAGING_TYPE_UINT8 ||
imDst->bands != 4)
return ImagingError_ModeError();
if (strcmp(imDst->mode, imSrc->mode) ||
imDst->type != imSrc->type ||
imDst->bands != imSrc->bands ||
imDst->xsize != imSrc->xsize ||
imDst->ysize != imSrc->ysize)
return ImagingError_Mismatch();
imOut = ImagingNew(imDst->mode, imDst->xsize, imDst->ysize);
if (!imOut)
return NULL;
ImagingCopyInfo(imOut, imDst);
for (y = 0; y < imDst->ysize; y++) {
UINT8* dst = (UINT8*) imDst->image[y];
UINT8* src = (UINT8*) imSrc->image[y];
UINT8* out = (UINT8*) imOut->image[y];
for (x = 0; x < imDst->linesize; x += 4) {
dstR = dst[x + 0] / 255.0;
dstG = dst[x + 1] / 255.0;
dstB = dst[x + 2] / 255.0;
dstA = dst[x + 3] / 255.0;
srcR = src[x + 0] / 255.0;
srcG = src[x + 1] / 255.0;
srcB = src[x + 2] / 255.0;
srcA = src[x + 3] / 255.0;
if (dstA == 1.0) {
outR = srcR * srcA + dstR * (1.0 - srcA);
outG = srcG * srcA + dstG * (1.0 - srcA);
outB = srcB * srcA + dstB * (1.0 - srcA);
outA = 1.0;
} else if (srcA == 0.0) {
outR = dstR;
outG = dstG;
outB = dstB;
outA = dstA;
} else {
outA = srcA + dstA * (1.0 - srcA);
if (outA == 0.0) {
outR = 0.0;
outG = 0.0;
outB = 0.0;
} else {
outR = (srcR * srcA + dstR * dstA * (1.0 - srcA)) / outA;
outG = (srcG * srcA + dstG * dstA * (1.0 - srcA)) / outA;
outB = (srcB * srcA + dstB * dstA * (1.0 - srcA)) / outA;
}
}
out[x + 0] = (UINT8) (255.0 * outR);
out[x + 1] = (UINT8) (255.0 * outG);
out[x + 2] = (UINT8) (255.0 * outB);
out[x + 3] = (UINT8) (255.0 * outA);
}
}
return imOut;
}

View File

@ -239,6 +239,7 @@ typedef int (*ImagingTransformFilter)(void* out, Imaging im,
/* Image Manipulation Methods */
/* -------------------------- */
extern Imaging ImagingAlphaComposite(Imaging imIn1, Imaging imIn2);
extern Imaging ImagingBlend(Imaging imIn1, Imaging imIn2, float alpha);
extern Imaging ImagingCopy(Imaging im);
extern Imaging ImagingConvert(Imaging im, const char* mode, ImagingPalette palette, int dither);

View File

@ -15,8 +15,8 @@ _IMAGING = (
)
_LIB_IMAGING = (
"Access", "Antialias", "Bands", "BitDecode", "Blend", "Chops",
"Convert", "ConvertYCbCr", "Copy", "Crc32", "Crop", "Dib", "Draw",
"Access", "AlphaComposite", "Antialias", "Bands", "BitDecode", "Blend",
"Chops", "Convert", "ConvertYCbCr", "Copy", "Crc32", "Crop", "Dib", "Draw",
"Effects", "EpsEncode", "File", "Fill", "Filter", "FliDecode",
"Geometry", "GetBBox", "GifDecode", "GifEncode", "HexDecode",
"Histo", "JpegDecode", "JpegEncode", "LzwDecode", "Matrix",