Patch committed upstream
https://bitbucket.org/libgd/gd-libgd/commits/a79232c5fa692c3b6e3f5bc95ecfc455424c3f54?at=master

Downloaded from Gentoo
https://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/media-libs/gd/files/gd-2.1.1-webp.patch?revision=1.1&view=markup

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>

---
https://bugs.gentoo.org/545956

From a79232c5fa692c3b6e3f5bc95ecfc455424c3f54 Mon Sep 17 00:00:00 2001
From: Pierre Joye <pierre.php@gmail.com>
Date: Tue, 20 Jan 2015 04:55:11 +0100
Subject: [PATCH] fix #129, drop VPX usage in favor of libwebp

---
 configure.ac          |  80 +++++------------
 src/gd_webp.c         | 231 +++++++++++++++++++++-----------------------------
 tests/Makefile.am     |   2 +-
 tests/webp/bug00111.c |   2 +-
 4 files changed, 122 insertions(+), 193 deletions(-)

diff --git a/configure.ac b/configure.ac
index 1024a3a..8923186 100644
--- a/configure.ac
+++ b/configure.ac
@@ -317,63 +317,6 @@ if test "$with_xpm" != no; then
 fi
 AM_CONDITIONAL([HAVE_LIBXPM], test "$with_xpm" = yes)
 
-dnl check for libvpx by default
-AC_ARG_WITH(vpx,dnl
-[  --with-vpx=DIR         where to find the vpx library])
-
-case $with_vpx in
-no) ;;
-yes|"")
-  PKG_CHECK_MODULES([LIBVPX], vpx, [with_vpx=yes],
-  [
-    PKG_CHECK_MODULES([LIBVPX], libvpx, [with_vpx=yes],
-    [
-      if test "$with_vpx" = yes; then
-        AC_MSG_ERROR([VPX support requested, but not found])
-      fi
-      with_vpx=no
-    ])
-  ])
-  ;;
-*)
-  save_LIBS="$LIBS"
-  save_CPPFLAGS="$CPPFLAGS"
-
-  if test -d "$with_vpx"; then
-    LIBVPX_CFLAGS="-I$with_vpx/include"
-    LIBVPX_LIBS="-L$with_vpx/lib -lvpx"
-  fi
-
-  CPPFLAGS="$CPPFLAGS $LIBVPX_CFLAGS"
-  LIBS="$LIBS $LIBVPX_LIBS"
-
-  AC_CHECK_LIB(vpx,vpx_codec_destroy,
-    [
-      if test -z "$LIBVPX_LIBS"; then
-        LIBVPX_LIBS="-lvpx"
-      fi
-      with_vpx=yes
-    ],[
-      if test "$with_vpx" != ""; then
-        AC_MSG_ERROR([vpx support requested, but not found])
-      else
-        with_vpx=no
-      fi
-    ])
-
-  CPPFLAGS="$save_CPPFLAGS"
-  LIBS="$save_LIBS"
-  ;;
-esac
-
-if test "$with_vpx" != no; then
-  CPPFLAGS="$CPPFLAGS $LIBVPX_CFLAGS"
-  LIBS="$LIBS $LIBVPX_LIBS"
-  FEATURES="GD_VPX $FEATURES"
-  AC_DEFINE(HAVE_LIBVPX, 1, [ Define if you have the VPX library. ])
-fi
-AM_CONDITIONAL([HAVE_LIBVPX], test "$with_vpx" = yes)
-
 dnl check for libtiff by default
 AC_ARG_WITH(tiff,dnl
 [  --with-tiff=DIR         where to find the TIFF library])
@@ -437,6 +380,27 @@ if test "$mingw_cv_win32_host" = yes; then
 AC_DEFINE([BGDWIN32], [], [Define is you are building for Win32 API])
 fi
 
+
+dnl check for libwebp by default
+AC_ARG_WITH(webp,dnl
+[  --with-webp=DIR         where to find the webp library],
+  [if test -d "$withval"; then
+     LDFLAGS="$LDFLAGS -L$withval/lib"
+     CFLAGS="$CFLAGS -I$withval/include"
+   fi],
+  withval=yes)
+
+if test "$withval" != no; then
+  AC_CHECK_LIB(webp,WebPGetInfo,
+    [LIBS="-lwebp $LIBS" 
+     FEATURES="GD_WEBP $FEATURES"
+     AC_DEFINE(HAVE_LIBWEBP, 1, [ Define if you have the webp library. ])])
+     with_webp=yes
+else
+  with_webp=no
+fi
+AM_CONDITIONAL([HAVE_LIBWEBP], test "$with_webp" = yes)
+
 dnl report configuration
 AC_MSG_RESULT([
 ** Configuration summary for $PACKAGE $VERSION:
@@ -444,7 +408,7 @@ AC_MSG_RESULT([
    Support for Zlib:                 $with_zlib
    Support for PNG library:          $with_png
    Support for JPEG library:         $ac_cv_lib_jpeg_jpeg_set_defaults
-   Support for VPX library:          $with_vpx
+   Support for WebP library:         $with_webp
    Support for TIFF library:         $with_tiff
    Support for Freetype 2.x library: $with_freetype
    Support for Fontconfig library:   $with_fontconfig
diff --git a/src/gd_webp.c b/src/gd_webp.c
index a3ae1ac..c44bd80 100644
--- a/src/gd_webp.c
+++ b/src/gd_webp.c
@@ -2,33 +2,21 @@
 #include "config.h"
 #endif /* HAVE_CONFIG_H */
 
+
+#ifdef HAVE_LIBWEBP
 #include <stdio.h>
 #include <math.h>
 #include <string.h>
 #include <stdlib.h>
 #include "gd.h"
 #include "gd_errors.h"
-
-#ifdef HAVE_LIBVPX
-#include "webpimg.h"
 #include "gdhelpers.h"
+#include "webp/decode.h"
+#include "webp/encode.h"
 
-extern void gd_YUV420toRGBA(uint8* Y,
-				  uint8* U,
-				  uint8* V,
-				  gdImagePtr im);
-
-extern void gd_RGBAToYUV420(gdImagePtr im2,
-				  uint8* Y,
-				  uint8* U,
-				  uint8* V);
-
-const char * gdWebpGetVersionString()
-{
-	return "not defined";
-}
+#define GD_WEBP_ALLOC_STEP (4*1024)
 
-BGD_DECLARE(gdImagePtr) gdImageCreateFromWebp (FILE * inFile)
+gdImagePtr gdImageCreateFromWebp (FILE * inFile)
 {
 	gdImagePtr im;
 	gdIOCtx *in = gdNewFileCtx(inFile);
@@ -38,42 +26,16 @@ BGD_DECLARE(gdImagePtr) gdImageCreateFromWebp (FILE * inFile)
 	return im;
 }
 
-BGD_DECLARE(gdImagePtr) gdImageCreateFromWebpPtr (int size, void *data)
+gdImagePtr gdImageCreateFromWebpCtx (gdIOCtx * infile)
 {
-	int	width, height, ret;
- 	unsigned char   *Y = NULL;
-	unsigned char   *U = NULL;
-	unsigned char   *V = NULL;
-	gdImagePtr im;
-
-	ret = WebPDecode(data, size, &Y, &U, &V, &width, &height);
-	if (ret != webp_success) {
-		if (Y) free(Y);
-		if (U) free(U);
-		if (V) free(V);
-		gd_error("WebP decode: fail to decode input data");
-		return NULL;
-	}
-	im = gdImageCreateTrueColor(width, height);
-	if (!im) {
-		return NULL;
-	}
-	gd_YUV420toRGBA(Y, U, V, im);
-	return im;
-}
-
-#define GD_WEBP_ALLOC_STEP (4*1024)
-
-BGD_DECLARE(gdImagePtr) gdImageCreateFromWebpCtx (gdIOCtx * infile)
-{
-	int	width, height, ret;
-	unsigned char   *filedata = NULL;
+	int    width, height;
+	uint8_t   *filedata = NULL;
+	uint8_t    *argb = NULL;
 	unsigned char   *read, *temp;
-	unsigned char   *Y = NULL;
-	unsigned char   *U = NULL;
-	unsigned char   *V = NULL;
 	size_t size = 0, n;
 	gdImagePtr im;
+	int x, y;
+	uint8_t *p;
 
 	do {
 		temp = gdRealloc(filedata, size+GD_WEBP_ALLOC_STEP);
@@ -89,23 +51,97 @@ BGD_DECLARE(gdImagePtr) gdImageCreateFromWebpCtx (gdIOCtx * infile)
 		}
 
 		n = gdGetBuf(read, GD_WEBP_ALLOC_STEP, infile);
-		size += n;
-	} while (n>0);
+		if (n>0 && n!=EOF) {
+			size += n;
+		}
+	} while (n>0 && n!=EOF);
 
-	ret = WebPDecode(filedata, size, &Y, &U, &V, &width, &height);
-	gdFree(filedata);
-	if (ret != webp_success) {
-		if (Y) free(Y);
-		if (U) free(U);
-		if (V) free(V);
-		gd_error("WebP decode: fail to decode input data");
+	if (WebPGetInfo(filedata,size, &width, &height) == 0) {
+		gd_error("gd-webp cannot get webp info");
 		return NULL;
 	}
+
 	im = gdImageCreateTrueColor(width, height);
-	gd_YUV420toRGBA(Y, U, V, im);
+	if (!im) {
+		return NULL;
+	}
+	argb = WebPDecodeARGB(filedata, size, &width, &height);
+	if (!argb) {
+		gd_error("gd-webp cannot allocate temporary buffer");
+		gdFree(argb);
+		return NULL;
+	}
+	for (y = 0, p = argb;  y < height; y++) {
+		for (x = 0; x < width; x++) {
+			register uint8_t a = gdAlphaMax - (*(p++) >> 1);
+			register uint8_t r = *(p++);
+			register uint8_t g = *(p++);
+			register uint8_t b = *(p++);
+			im->tpixels[y][x] = gdTrueColorAlpha(r, g, b, a);
+		}
+	}
+	gdFree(filedata);
+	free(argb);
+	im->saveAlphaFlag = 1;
 	return im;
 }
 
+void gdImageWebpCtx (gdImagePtr im, gdIOCtx * outfile, int quantization)
+{
+	uint8_t *argb;
+	int x, y;
+	uint8_t *p;
+	uint8_t *out;
+	size_t out_size;
+
+	if (im == NULL) {
+		return;
+	}
+
+	if (!gdImageTrueColor(im)) {
+		gd_error("Paletter image not supported by webp");
+		return;
+	}
+
+	if (quantization == -1) {
+		quantization = 80;
+	}
+
+	argb = (uint8_t *)gdMalloc(gdImageSX(im) * 4 * gdImageSY(im));
+	if (!argb) {
+		return;
+	}
+	p = argb;
+	for (y = 0; y < gdImageSY(im); y++) {
+		for (x = 0; x < gdImageSX(im); x++) {
+			register int c;
+			register char a;
+			c = im->tpixels[y][x];
+			a = gdTrueColorGetAlpha(c);
+			if (a == 127) {
+				a = 0;
+			} else {
+				a = 255 - ((a << 1) + (a >> 6));
+			}
+			*(p++) = gdTrueColorGetRed(c);
+			*(p++) = gdTrueColorGetGreen(c);
+			*(p++) = gdTrueColorGetBlue(c); 
+			*(p++) = a;
+		}
+	}
+	out_size = WebPEncodeRGBA(argb, gdImageSX(im), gdImageSY(im), gdImageSX(im) * 4, quantization, &out);
+	printf("outsize: %i\n", out_size);
+	if (out_size == 0) {
+		gd_error("gd-webp encoding failed");
+		goto freeargb;
+	}
+	gdPutBuf(out, out_size, outfile);
+	free(out);
+
+freeargb:
+	gdFree(argb);
+}
+
 BGD_DECLARE(void) gdImageWebpEx (gdImagePtr im, FILE * outFile, int quantization)
 {
 	gdIOCtx *out = gdNewFileCtx(outFile);
@@ -116,7 +152,7 @@ BGD_DECLARE(void) gdImageWebpEx (gdImagePtr im, FILE * outFile, int quantization
 BGD_DECLARE(void) gdImageWebp (gdImagePtr im, FILE * outFile)
 {
 	gdIOCtx *out = gdNewFileCtx(outFile);
-  	gdImageWebpCtx(im, out, -1);
+	gdImageWebpCtx(im, out, -1);
 	out->gd_free(out);
 }
 
@@ -140,75 +176,4 @@ BGD_DECLARE(void *) gdImageWebpPtrEx (gdImagePtr im, int *size, int quantization
 	out->gd_free(out);
 	return rv;
 }
-
-/*
- * Maps normalized QP (quality) to VP8 QP
- */
-int mapQualityToVP8QP(int quality) {
-#define MIN_QUALITY 0
-#define MAX_QUALITY 100
-#define MIN_VP8QP 1
-#define MAX_VP8QP 63
-	const float scale = MAX_VP8QP - MIN_VP8QP;
-	const float vp8qp =
-	scale * (MAX_QUALITY - quality) / (MAX_QUALITY - MIN_QUALITY) + MIN_VP8QP;
-	if (quality < MIN_QUALITY || quality > MAX_QUALITY) {
-		gd_error("Wrong quality value %d.", quality);
-		return -1;
-	}
-
-	return (int)(vp8qp + 0.5);
-}
-
-/* This routine is based in part on code from Dale Lutz (Safe Software Inc.)
- *  and in part on demo code from Chapter 15 of "PNG: The Definitive Guide"
- *  (http://www.cdrom.com/pub/png/pngbook.html).
- */
-BGD_DECLARE(void) gdImageWebpCtx (gdImagePtr im, gdIOCtx * outfile, int quantization)
-{
-	int width = im->sx;
-	int height = im->sy;
-
-	int  yuv_width, yuv_height, yuv_nbytes, ret;
-	int vp8_quality;
-	unsigned char *Y = NULL,
-				  *U = NULL,
-				  *V = NULL;
-	unsigned char *filedata = NULL;
-
-	/* Conversion to Y,U,V buffer */
-	yuv_width = (width + 1) >> 1;
-	yuv_height = (height + 1) >> 1;
-	yuv_nbytes = width * height + 2 * yuv_width * yuv_height;
-
-	if ((Y = (unsigned char *)gdCalloc(yuv_nbytes, sizeof(unsigned char))) == NULL) {
-		gd_error("gd-webp error: cannot allocate Y buffer");
-		return;
-	}
-	if (quantization == -1) {
-		quantization = 80;
-	}
-	vp8_quality = mapQualityToVP8QP(quantization);
-
-	U = Y + width * height;
-	V = U + yuv_width * yuv_height;
-	gd_RGBAToYUV420(im, Y, U, V);
-
-	/* Encode Y,U,V and write data to file */
-	ret = WebPEncode(Y, U, V, width, height, width, yuv_width, yuv_height, yuv_width,
-					 vp8_quality, &filedata, &yuv_nbytes, NULL);
-	gdFree(Y);
-
-	if (ret != webp_success) {
-		if (filedata) {
-			free(filedata);
-		}
-		gd_error("gd-webp error: WebP Encoder failed");
-		return;
-	}
-
-	gdPutBuf (filedata, yuv_nbytes, outfile);
-	free(filedata);
-}
-
-#endif /* HAVE_LIBVPX */
+#endif /* HAVE_LIBWEBP */
-- 
2.3.5