Combine image readers in class Fl_Image_Reader

This new class is explicitly internal and undocumented. We can
rename and/or redefine or extend it as we need.

This work is based on Matt's recent update with separate internal
classes BMPReader and GIFReader which have been replaced by
Fl_Image_Reader.

5 files changed, 41 insertions, 260 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 08eb9194f..9db3dc421 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -46,6 +46,7 @@ set (CPPFILES
   Fl_Group.cxx
   Fl_Help_View.cxx
   Fl_Image.cxx
+  Fl_Image_Reader.cxx
   Fl_Image_Surface.cxx
   Fl_Input.cxx
   Fl_Input_.cxx
diff --git a/src/Fl_BMP_Image.cxx b/src/Fl_BMP_Image.cxx
index b2faf2de9..da869f5a6 100644
--- a/src/Fl_BMP_Image.cxx
+++ b/src/Fl_BMP_Image.cxx
@@ -1,8 +1,9 @@
 //
 // "$Id$"
 //
-// Fl_BMP_Image routines.
+// Fl_BMP_Image class for the Fast Light Tool Kit (FLTK).
 //
+// Copyright 2011-2020 by Bill Spitzak and others.
 // Copyright 1997-2010 by Easy Software Products.
 // Image support by Matthias Melcher, Copyright 2000-2009.
 //
@@ -10,15 +11,11 @@
 // the file "COPYING" which should have been included with this file.  If this
 // file is missing or damaged, see the license at:
 //
-//     http://www.fltk.org/COPYING.php
+//     https://www.fltk.org/COPYING.php
 //
 // Please report all bugs and problems on the following page:
 //
-//     http://www.fltk.org/str.php
-//
-// Contents:
-//
-//   Fl_BMP_Image::Fl_BMP_Image() - Load a BMP image file.
+//     https://www.fltk.org/str.php
 //
 
 //
@@ -26,12 +23,12 @@
 //
 
 #include <FL/Fl_BMP_Image.H>
+#include "Fl_Image_Reader.h"
 #include <FL/fl_utf8.h>
 #include <FL/Fl.H>
 #include <stdio.h>
 #include <stdlib.h>
 
-
 //
 // BMP definitions...
 //
@@ -44,135 +41,8 @@
 #endif // !BI_RGB
 
 
-//
-// Local reader class...
-//
-
-/*
- This class reads data chunks from a file or from memory in LSB-first
- byte order.
- 
- TODO: GIFReader and BMPReader are very similar and should be combined to avoid
- code duplication.
- */
-class BMPReader
-{
-public:
-  // Create the reader.
-  BMPReader() :
-  pIsFile(0), pIsData(0),
-  pFile(0L), pData(0L), pStart(0L),
-  pName(0L)
-  { }
-  // Initialize the reader to access the file system, filename is copied
-  // and stored.
-  int open(const char *filename) {
-    if (!filename)
-      return -1;
-    pName = strdup(filename);
-    if ( (pFile = fl_fopen(filename, "rb")) == NULL ) {
-      return -1;
-    }
-    pIsFile = 1;
-    return 0;
-  }
-  // Initialize the reader for memory access, name is copied and stored
-  int open(const char *imagename, const unsigned char *data) {
-    if (imagename)
-      pName = strdup(imagename);
-    if (data) {
-      pStart = pData = data;
-      pIsData = 1;
-      return 0;
-    } else {
-      return -1;
-    }
-  }
-  // Close and destroy the reader
-  ~BMPReader() {
-    if (pIsFile && pFile) {
-      fclose(pFile);
-    }
-    if (pName)
-      ::free(pName);
-  }
-  // Read a single byte form memory or a file
-  uchar read_byte() {
-    if (pIsFile) {
-      return getc(pFile);
-    } else if (pIsData) {
-      return *pData++;
-    } else {
-      return 0;
-    }
-  }
-  // Read a 16-bit unsigned integer, LSB-first
-  unsigned short read_word() {
-    unsigned char b0, b1;  // Bytes from file
-    if (pIsFile) {
-      b0 = (uchar)getc(pFile);
-      b1 = (uchar)getc(pFile);
-      return ((b1 << 8) | b0);
-    } else if (pIsData) {
-      b0 = *pData++;
-      b1 = *pData++;
-      return ((b1 << 8) | b0);
-    } else {
-      return 0;
-    }
-  }
-  // Read a 32-bit unsigned integer, LSB-first
-  unsigned int read_dword() {
-    unsigned char b0, b1, b2, b3;  // Bytes from file
-    if (pIsFile) {
-      b0 = (uchar)getc(pFile);
-      b1 = (uchar)getc(pFile);
-      b2 = (uchar)getc(pFile);
-      b3 = (uchar)getc(pFile);
-      return ((((((b3 << 8) | b2) << 8) | b1) << 8) | b0);
-    } else if (pIsData) {
-      b0 = *pData++;
-      b1 = *pData++;
-      b2 = *pData++;
-      b3 = *pData++;
-      return ((((((b3 << 8) | b2) << 8) | b1) << 8) | b0);
-    } else {
-      return 0;
-    }
-  }
-  // Read a 32-bit signed integer, LSB-first
-  int read_long() {
-    return (int)read_dword();
-  };
-  // Move the current read position to a byte offset fro the beginning of the
-  // file or the original start address in memory
-  void seek(unsigned int n) {
-    if (pIsFile) {
-      fseek(pFile, n , SEEK_SET);
-    } else if (pIsData) {
-      pData = pStart + n;
-    }
-  }
-  // return the name or filename for this reader
-  const char *name() { return pName; }
-private:
-  // open() sets this if we read form a file
-  char pIsFile;
-  // open() sets this if we read form memory
-  char pIsData;
-  // a pointer to the opened file
-  FILE *pFile;
-  // a pointer to the current byte in memory
-  const unsigned char *pData;
-  // a pointer to the start of the image data
-  const unsigned char *pStart;
-  // a copy of the name associated with this reader
-  char *pName;
-};
-
-
 /**
- \brief The constructor loads the named BMP image from the given bmp filename.
+ \brief This constructor loads the named BMP image from the given BMP filename.
 
  The destructor frees all memory and server resources that are used by
  the image.
@@ -189,11 +59,11 @@ private:
 Fl_BMP_Image::Fl_BMP_Image(const char *filename) // I - File to read
 : Fl_RGB_Image(0,0,0)
 {
-  BMPReader f;
-  if (f.open(filename)==-1) {
+  Fl_Image_Reader rdr;
+  if (rdr.open(filename) == -1) {
     ld(ERR_FILE_ACCESS);
   } else {
-    load_bmp_(f);
+    load_bmp_(rdr);
   }
 }
 
@@ -201,12 +71,12 @@ Fl_BMP_Image::Fl_BMP_Image(const char *filename) // I - File to read
  \brief Read a BMP image from memory.
 
  Construct an image from a block of memory inside the application. Fluid offers
- "binary Data" chunks as a great way to add image data into the C++ source code.
+ "binary data" chunks as a great way to add image data into the C++ source code.
  imagename can be NULL. If a name is given, the image is added to the list of
  shared images and will be available by that name.
 
  Use Fl_Image::fail() to check if Fl_BMP_Image failed to load. fail() returns
- ERR_FILE_ACCESS if the file could not be opened or read, ERR_FORMAT if the
+ ERR_FILE_ACCESS if the image could not be read from memory, ERR_FORMAT if the
  BMP format could not be decoded, and ERR_NO_IMAGE if the image could not
  be loaded for another reason.
 
@@ -219,20 +89,20 @@ Fl_BMP_Image::Fl_BMP_Image(const char *filename) // I - File to read
 Fl_BMP_Image::Fl_BMP_Image(const char *imagename, const unsigned char *data)
 : Fl_RGB_Image(0,0,0)
 {
-  BMPReader d;
-  if (d.open(imagename, data)==-1) {
+  Fl_Image_Reader rdr;
+  if (rdr.open(imagename, data) == -1) {
     ld(ERR_FILE_ACCESS);
   } else {
-    load_bmp_(d);
+    load_bmp_(rdr);
   }
 }
 
 /*
  This method reads BMP image data and creates an RGB or RGBA image. The BMP
  format supports only 1 bit for alpha. To avoid code duplication, we use
- a BMPReader that reads data from either a file or from memory.
+ an Fl_Image_Reader that reads data from either a file or from memory.
  */
-void Fl_BMP_Image::load_bmp_(class BMPReader &rdr)
+void Fl_BMP_Image::load_bmp_(Fl_Image_Reader &rdr)
 {
   int     info_size,    // Size of info header
           depth,        // Depth of image (bits)
@@ -584,7 +454,7 @@ void Fl_BMP_Image::load_bmp_(class BMPReader &rdr)
         break;
     }
   }
-  
+
   if (havemask) {
     for (y = h() - 1; y >= 0; y --) {
       ptr = (uchar *)array + y * w() * d() + 3;
diff --git a/src/Fl_GIF_Image.cxx b/src/Fl_GIF_Image.cxx
index 4054eac77..9036b6f6f 100644
--- a/src/Fl_GIF_Image.cxx
+++ b/src/Fl_GIF_Image.cxx
@@ -3,7 +3,7 @@
 //
 // Fl_GIF_Image routines.
 //
-// Copyright 1997-2019 by Bill Spitzak and others.
+// Copyright 1997-2020 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -15,9 +15,6 @@
 //
 //     http://www.fltk.org/str.php
 //
-// Contents:
-//
-//
 
 //
 // Reference: GIF89a Specification (links valid as of Jan 05, 2019):
@@ -35,11 +32,13 @@
 
 #include <FL/Fl.H>
 #include <FL/Fl_GIF_Image.H>
-#include <stdio.h>
-#include <stdlib.h>
+#include "Fl_Image_Reader.h"
 #include <FL/fl_utf8.h>
 #include "flstring.h"
 
+#include <stdio.h>
+#include <stdlib.h>
+
 // Read a .gif file and convert it to a "xpm" format (actually my
 // modified one with compressed colormaps).
 
@@ -75,100 +74,6 @@
  *                     (415) 336-1080
  */
 
-typedef unsigned char uchar;
-
-//
-// Local reader class...
-//
-
-/*
- This class reads data chunks from a file or from memory in LSB-first
- byte order.
-
- TODO: GIFReader and BMPReader are very similar and should be combined to avoid
-       code duplication.
- */
-class GIFReader
-{
-public:
-  // Create the reader.
-  GIFReader() :
-  pIsFile(0), pIsData(0),
-  pFile(0L), pData(0L),
-  pName(0L)
-  { }
-  // Initialize the reader to access the file system, filename is copied
-  // and stored.
-  int open(const char *filename) {
-    if (!filename)
-      return -1;
-    pName = strdup(filename);
-    if ( (pFile = fl_fopen(filename, "rb")) == NULL ) {
-      return -1;
-    }
-    pIsFile = 1;
-    return 0;
-  }
-  // Initialize the reader for memory access, name is copied and stored
-  int open(const char *imagename, const unsigned char *data) {
-    if (imagename)
-      pName = strdup(imagename);
-    if (data) {
-      pData = data;
-      pIsData = 1;
-      return 0;
-    } else {
-      return -1;
-    }
-  }
-  // Close and destroy the reader
-  ~GIFReader() {
-    if (pIsFile && pFile) {
-      fclose(pFile);
-    }
-    if (pName)
-      ::free(pName);
-  }
-  // Read a single byte form memory or a file
-  uchar read_byte() {
-    if (pIsFile) {
-      return getc(pFile);
-    } else if (pIsData) {
-      return *pData++;
-    } else {
-      return 0;
-    }
-  }
-  // Read a 16-bit unsigned integer, LSB-first
-  unsigned short read_word() {
-    unsigned char b0, b1;  // Bytes from file
-    if (pIsFile) {
-      b0 = (uchar)getc(pFile);
-      b1 = (uchar)getc(pFile);
-      return ((b1 << 8) | b0);
-    } else if (pIsData) {
-      b0 = *pData++;
-      b1 = *pData++;
-      return ((b1 << 8) | b0);
-    } else {
-      return 0;
-    }
-  }
-  // return the name or filename for this reader
-  const char *name() { return pName; }
-private:
-  // open() sets this if we read form a file
-  char pIsFile;
-  // open() sets this if we read form memory
-  char pIsData;
-  // a pointer to the opened file
-  FILE *pFile;
-  // a pointer to the current byte in memory
-  const unsigned char *pData;
-  // a copy of the name associated with this reader
-  char *pName;
-};
-
 
 /**
  \brief The constructor loads the named GIF image.
@@ -191,12 +96,12 @@ private:
 Fl_GIF_Image::Fl_GIF_Image(const char *filename) :
   Fl_Pixmap((char *const*)0)
 {
-  GIFReader f;
-  if (f.open(filename)==-1) {
+  Fl_Image_Reader rdr;
+  if (rdr.open(filename) == -1) {
     Fl::error("Fl_GIF_Image: Unable to open %s!", filename);
     ld(ERR_FILE_ACCESS);
   } else {
-    load_gif_(f);
+    load_gif_(rdr);
   }
 }
 
@@ -222,24 +127,24 @@ Fl_GIF_Image::Fl_GIF_Image(const char *filename) :
 
  \see Fl_GIF_Image::Fl_GIF_Image(const char *filename)
  \see Fl_Shared_Image
- */
+*/
 Fl_GIF_Image::Fl_GIF_Image(const char *imagename, const unsigned char *data) :
   Fl_Pixmap((char *const*)0)
 {
-  GIFReader d;
-  if (d.open(imagename, data)==-1) {
+  Fl_Image_Reader rdr;
+  if (rdr.open(imagename, data)==-1) {
     ld(ERR_FILE_ACCESS);
   } else {
-    load_gif_(d);
+    load_gif_(rdr);
   }
 }
 
 /*
  This method reads GIF image data and creates an RGB or RGBA image. The GIF
  format supports only 1 bit for alpha. To avoid code duplication, we use
- a GIFReader that reads data from either a file or from memory.
- */
-void Fl_GIF_Image::load_gif_(GIFReader &rdr)
+ an Fl_Image_Reader that reads data from either a file or from memory.
+*/
+void Fl_GIF_Image::load_gif_(Fl_Image_Reader &rdr)
 {
   char **new_data;	// Data array
 
@@ -343,7 +248,7 @@ void Fl_GIF_Image::load_gif_(GIFReader &rdr)
     }
 
     // skip the data:
-    while (blocklen>0) {while (blocklen--) {ch = rdr.read_byte();} blocklen=rdr.read_byte();}
+    while (blocklen>0) {while (blocklen--) {ch = rdr.read_byte();} blocklen = rdr.read_byte();}
   }
 
   if (BitsPerPixel >= CodeSize)
@@ -402,7 +307,7 @@ void Fl_GIF_Image::load_gif_(GIFReader &rdr)
     /* Fetch the next code from the raster data stream.  The codes can be
      * any length from 3 to 12 bits, packed into 8-bit bytes, so we have to
      * maintain our location as a pointer and a bit offset.
-     * In addition, gif adds totally useless and annoying block counts
+     * In addition, GIF adds totally useless and annoying block counts
      * that must be correctly skipped over. */
     int CurCode = thisbyte;
     if (frombit+CodeSize > 7) {
diff --git a/src/Makefile b/src/Makefile
index 57891d332..597ff03fb 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -3,7 +3,7 @@
 #
 # Library Makefile for the Fast Light Tool Kit (FLTK).
 #
-# Copyright 1998-2018 by Bill Spitzak and others.
+# Copyright 1998-2020 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -48,6 +48,7 @@ CPPFILES = \
 	Fl_Group.cxx \
 	Fl_Help_View.cxx \
 	Fl_Image.cxx \
+	Fl_Image_Reader.cxx \
 	Fl_Image_Surface.cxx \
 	Fl_Input.cxx \
 	Fl_Input_.cxx \
diff --git a/src/makedepend b/src/makedepend
index 8198618cc..7a01c834e 100644
--- a/src/makedepend
+++ b/src/makedepend
@@ -61,6 +61,7 @@ Fl_BMP_Image.o: ../FL/abi-version.h
 Fl_BMP_Image.o: ../FL/fl_types.h
 Fl_BMP_Image.o: ../FL/fl_utf8.h
 Fl_BMP_Image.o: ../FL/platform_types.h
+Fl_BMP_Image.o: Fl_Image_Reader.h
 Fl_Bitmap.o: ../FL/Enumerations.H
 Fl_Bitmap.o: ../FL/Fl.H
 Fl_Bitmap.o: ../FL/Fl_Bitmap.H
@@ -466,6 +467,7 @@ Fl_GIF_Image.o: ../FL/fl_types.h
 Fl_GIF_Image.o: ../FL/fl_utf8.h
 Fl_GIF_Image.o: ../FL/platform_types.h
 Fl_GIF_Image.o: ../config.h
+Fl_GIF_Image.o: Fl_Image_Reader.h
 Fl_GIF_Image.o: flstring.h
 Fl_Gl_Choice.o: ../FL/Enumerations.H
 Fl_Gl_Choice.o: ../FL/Fl.H
@@ -672,6 +674,8 @@ Fl_Image.o: ../FL/platform_types.h
 Fl_Image.o: ../config.h
 Fl_Image.o: config_lib.h
 Fl_Image.o: flstring.h
+Fl_Image_Reader.o: ../FL/fl_utf8.h
+Fl_Image_Reader.o: Fl_Image_Reader.h
 Fl_Image_Surface.o: ../FL/Enumerations.H
 Fl_Image_Surface.o: ../FL/Fl.H
 Fl_Image_Surface.o: ../FL/Fl_Bitmap.H