Ignore the alternateSpace and tintTransform

As a reasonable compromise in my eyes this new patch
now also checks the alternate colorspace, and if this
is DeviceGray in case of a separation colorspace with
name black this patch treats is as if it is really a
DeviceGray and so ignore tintTransform and alternate
colorspace just in this case when using getGray() and getRGB().

Bug #92381

poppler/GfxState.cc

@@ -18,7 +18,7 @@
 // Copyright (C) 2006, 2010 Carlos Garcia Campos <carlosgc@gnome.org>
 // Copyright (C) 2006-2015 Albert Astals Cid <aacid@kde.org>
 // Copyright (C) 2009, 2012 Koji Otani <sho@bbr.jp>
-// Copyright (C) 2009, 2011-2014 Thomas Freitag <Thomas.Freitag@alfa.de>
+// Copyright (C) 2009, 2011-2015 Thomas Freitag <Thomas.Freitag@alfa.de>
 // Copyright (C) 2009 Christian Persch <chpe@gnome.org>
 // Copyright (C) 2010 Paweł Wiejacha <pawel.wiejacha@gmail.com>
 // Copyright (C) 2010 Christian Feuersänger <cfeuersaenger@googlemail.com>
@@ -2864,12 +2864,16 @@ void GfxSeparationColorSpace::getGray(GfxColor *color, GfxGray *gray) {
   GfxColor color2;
   int i;
 
-  x = colToDbl(color->c[0]);
-  func->transform(&x, c);
-  for (i = 0; i < alt->getNComps(); ++i) {
-    color2.c[i] = dblToCol(c[i]);
+  if (alt->getMode() == csDeviceGray && name->cmp("Black") == 0) {
+    *gray = clip01(gfxColorComp1 - color->c[0]);
+  } else {
+    x = colToDbl(color->c[0]);
+    func->transform(&x, c);
+    for (i = 0; i < alt->getNComps(); ++i) {
+      color2.c[i] = dblToCol(c[i]);
+    }
+    alt->getGray(&color2, gray);
   }
-  alt->getGray(&color2, gray);
 }
 
 void GfxSeparationColorSpace::getRGB(GfxColor *color, GfxRGB *rgb) {
@@ -2878,12 +2882,18 @@ void GfxSeparationColorSpace::getRGB(GfxColor *color, GfxRGB *rgb) {
   GfxColor color2;
   int i;
 
-  x = colToDbl(color->c[0]);
-  func->transform(&x, c);
-  for (i = 0; i < alt->getNComps(); ++i) {
-    color2.c[i] = dblToCol(c[i]);
+  if (alt->getMode() == csDeviceGray && name->cmp("Black") == 0) {
+    rgb->r = clip01(gfxColorComp1 - color->c[0]);
+    rgb->g = clip01(gfxColorComp1 - color->c[0]);
+    rgb->b = clip01(gfxColorComp1 - color->c[0]);
+  } else {
+    x = colToDbl(color->c[0]);
+    func->transform(&x, c);
+    for (i = 0; i < alt->getNComps(); ++i) {
+      color2.c[i] = dblToCol(c[i]);
+    }
+    alt->getRGB(&color2, rgb);
   }
-  alt->getRGB(&color2, rgb);
 }
 
 void GfxSeparationColorSpace::getCMYK(GfxColor *color, GfxCMYK *cmyk) {
@@ -2892,12 +2902,34 @@ void GfxSeparationColorSpace::getCMYK(GfxColor *color, GfxCMYK *cmyk) {
   GfxColor color2;
   int i;
 
-  x = colToDbl(color->c[0]);
-  func->transform(&x, c);
-  for (i = 0; i < alt->getNComps(); ++i) {
-    color2.c[i] = dblToCol(c[i]);
+  if (name->cmp("Black") == 0) {
+    cmyk->c = 0;
+    cmyk->m = 0;
+    cmyk->y = 0;
+    cmyk->k = color->c[0];
+  } else if (name->cmp("Cyan") == 0) {
+    cmyk->c = color->c[0];
+    cmyk->m = 0;
+    cmyk->y = 0;
+    cmyk->k = 0;
+  } else if (name->cmp("Magenta") == 0) {
+    cmyk->c = 0;
+    cmyk->m = color->c[0];
+    cmyk->y = 0;
+    cmyk->k = 0;
+  } else if (name->cmp("Yellow") == 0) {
+    cmyk->c = 0;
+    cmyk->m = 0;
+    cmyk->y = color->c[0];
+    cmyk->k = 0;
+  } else {
+    x = colToDbl(color->c[0]);
+    func->transform(&x, c);
+    for (i = 0; i < alt->getNComps(); ++i) {
+      color2.c[i] = dblToCol(c[i]);
+    }
+    alt->getCMYK(&color2, cmyk);
   }
-  alt->getCMYK(&color2, cmyk);
 }
 
 void GfxSeparationColorSpace::getDeviceN(GfxColor *color, GfxColor *deviceN) {