ensure that the defined interpolation method is used by the generic scaling functions

Author: pierrejoye

ext/gd/libgd/gd_interpolation.c

@@ -1063,13 +1063,15 @@ gdImagePtr gdImageScaleTwoPass(const gdImagePtr src, const unsigned int src_widt
 	if (tmp_im == NULL) {
 		return NULL;
 	}
+	gdImageSetInterpolationMethod(tmp_im, src->interpolation_id);
 	_gdScaleHoriz(src, src_width, src_height, tmp_im, new_width, src_height);
 
 	dst = gdImageCreateTrueColor(new_width, new_height);
 	if (dst == NULL) {
 		gdFree(tmp_im);
 		return NULL;
 	}
+	gdImageSetInterpolationMethod(dst, src->interpolation_id);
 	_gdScaleVert(tmp_im, new_width, src_height, dst, new_width, new_height);
 	gdFree(tmp_im);
 
@@ -1084,8 +1086,9 @@ gdImagePtr Scale(const gdImagePtr src, const unsigned int src_width, const unsig
 	if (tmp_im == NULL) {
 		return NULL;
 	}
-	_gdScaleHoriz(src, src_width, src_height, tmp_im, new_width, src_height);
+	gdImageSetInterpolationMethod(tmp_im, src->interpolation_id);
 
+	_gdScaleHoriz(src, src_width, src_height, tmp_im, new_width, src_height);
 	_gdScaleVert(tmp_im, new_width, src_height, dst, new_width, new_height);
 
 	gdFree(tmp_im);