From d4e88b87a3dbc3e584bda0854afec1813a0578e8 Mon Sep 17 00:00:00 2001
From: Adrian Johnson <ajohnson@redneon.com>
Date: Sun, 18 Aug 2013 16:08:02 +0930
Subject: [PATCH 2/5] Change PNGWriter monochrome format to be 8 pixels/byte

to be consistent with TiffWriter and NetPBMWriter
---
 goo/PNGWriter.cc        |  4 ----
 goo/PNGWriter.h         |  2 +-
 utils/HtmlOutputDev.cc  | 31 +++++++++++++++++++------------
 utils/ImageOutputDev.cc |  9 ++++++---
 utils/pdftocairo.cc     |  2 +-
 5 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/goo/PNGWriter.cc b/goo/PNGWriter.cc
index b775600..4370f28 100644
--- a/goo/PNGWriter.cc
+++ b/goo/PNGWriter.cc
@@ -147,10 +147,6 @@ bool PNGWriter::init(FILE *f, int width, int height, int hDPI, int vDPI)
     return false;
   }
 
-  // pack 1 pixel/byte rows into 8 pixels/byte
-  if (priv->format == MONOCHROME)
-    png_set_packing(priv->png_ptr);
-
   return true;
 }
 
diff --git a/goo/PNGWriter.h b/goo/PNGWriter.h
index ac8f95a..64b8833 100644
--- a/goo/PNGWriter.h
+++ b/goo/PNGWriter.h
@@ -31,7 +31,7 @@ public:
   /* RGB        - 3 bytes/pixel
    * RGBA       - 4 bytes/pixel
    * GRAY       - 1 byte/pixel
-   * MONOCHROME - 1 byte/pixel. PNGWriter will bitpack to 8 pixels/byte
+   * MONOCHROME - 8 pixels/byte
    */
   enum Format { RGB, RGBA, GRAY, MONOCHROME };
 
diff --git a/utils/HtmlOutputDev.cc b/utils/HtmlOutputDev.cc
index 7926674..3926178 100644
--- a/utils/HtmlOutputDev.cc
+++ b/utils/HtmlOutputDev.cc
@@ -1413,32 +1413,39 @@ void HtmlOutputDev::drawPngImage(GfxState *state, Stream *str, int width, int he
     delete imgStr;
   }
   else { // isMask == true
-    ImageStream *imgStr = new ImageStream(str, width, 1, 1);
-    imgStr->reset();
+    int size = (width + 7)/8;
+
+    // PDF masks use 0 = draw current color, 1 = leave unchanged.
+    // We invert this to provide the standard interpretation of alpha
+    // (0 = transparent, 1 = opaque). If the colorMap already inverts
+    // the mask we leave the data unchanged.
+    int invert_bits = 0xff;
+    if (colorMap) {
+      GfxGray gray;
+      Guchar zero = 0;
+      colorMap->getGray(&zero, &gray);
+      if (colToByte(gray) == 0)
+        invert_bits = 0x00;
+    }
 
-    Guchar *png_row = (Guchar *)gmalloc( width );
+    str->reset();
+    Guchar *png_row = (Guchar *)gmalloc(size);
 
     for (int ri = 0; ri < height; ++ri)
     {
-      // read the row of the mask
-      Guchar *bit_row = imgStr->getLine();
-
-      // invert for PNG
-      for(int i = 0; i < width; i++)
-        png_row[i] = bit_row[i] ? 0xff : 0x00;
+      for(int i = 0; i < size; i++)
+        png_row[i] = str->getChar() ^ invert_bits;
 
       if (!writer->writeRow( &png_row ))
       {
         error(errIO, -1, "Failed to write into PNG '%s'", fName->getCString());
         delete writer;
         fclose(f1);
-        delete imgStr;
         gfree(png_row);
         return;
       }
     }
-    imgStr->close();
-    delete imgStr;
+    str->close();
     gfree(png_row);
   }
 
diff --git a/utils/ImageOutputDev.cc b/utils/ImageOutputDev.cc
index 897c116..bd8dc35 100644
--- a/utils/ImageOutputDev.cc
+++ b/utils/ImageOutputDev.cc
@@ -309,7 +309,7 @@ void ImageOutputDev::writeImageFile(ImgWriter *writer, ImageFormat format, const
   GfxRGB rgb;
   GfxGray gray;
   Guchar zero = 0;
-  int invert_bits = 0xff;
+  int invert_bits;
 
   setFilename(ext);
   ++imgNum;
@@ -335,8 +335,11 @@ void ImageOutputDev::writeImageFile(ImgWriter *writer, ImageFormat format, const
 
   row = (unsigned char *) gmallocn(width, sizeof(unsigned int));
 
-  // if 0 comes out as 0 in the color map, the we _flip_ stream bits
-  // otherwise we pass through stream bits unmolested
+  // PDF masks use 0 = draw current color, 1 = leave unchanged.
+  // We invert this to provide the standard interpretation of alpha
+  // (0 = transparent, 1 = opaque). If the colorMap already inverts
+  // the mask we leave the data unchanged.
+  invert_bits = 0xff;
   if (colorMap) {
     colorMap->getGray(&zero, &gray);
     if (colToByte(gray) == 0)
diff --git a/utils/pdftocairo.cc b/utils/pdftocairo.cc
index 192d295..841c388 100644
--- a/utils/pdftocairo.cc
+++ b/utils/pdftocairo.cc
@@ -370,7 +370,7 @@ void writePageImage(GooString *filename)
 	int b = (*pixel & 0x000000ff) >>  0;
 	// an arbitrary integer approximation of .3*r + .59*g + .11*b
 	int y = (r*19661+g*38666+b*7209 + 32829)>>16;
-        if (tiff && mono) {
+        if (mono) {
           if (bit == 7)
             *rowp = 0;
           if (y > 127)
-- 
1.8.1.2