Add preliminary hooks for reading out png data...

IO/ImageFile.cpp

@@ -63,6 +63,23 @@ EImageFileFormat ImageFile::DetectFileFormat(const char *filename) {
 }
 
 bool ImageFile::LoadImage(const unsigned char *rawImageData) {
+
+  ImageLoader *loader = NULL;
+  switch(m_FileFormat) {
+
+#ifdef PNG_FOUND
+    case eFileFormat_PNG:
+      {
+	loader = new ImageLoaderPNG(rawImageData);
+      }
+      break;
+#endif // PNG_FOUND
+
+    default:
+      fprintf(stderr, "Unable to load image: unknown file format.\n");
+      break;
+  }
+
   return false;
 }
 

IO/ImageLoader.h.in

@@ -10,25 +10,56 @@ enum EImageFileFormat {
 class ImageLoader {
 
  protected:
-  int m_RedChannelPrecision;
+
+  unsigned int m_Width;
+  unsigned int m_Height;
+
+  unsigned int m_RedChannelPrecision;
   unsigned char *m_RedData;
 
-  int m_GreenChannelPrecision;
+  unsigned int m_GreenChannelPrecision;
   unsigned char *m_GreenData;
-
-  int m_BlueChannelPrecision;
-  unsigned char *m_BlueData;
   
-  int m_AlphaChannelPrecision;
+  unsigned int m_BlueChannelPrecision;
+  unsigned char *m_BlueData;
+ 
+  unsigned int m_AlphaChannelPrecision;
   unsigned char *m_AlphaData;
 
   const unsigned char *const m_RawData;
 
-  ImageLoader(const unsigned char *rawData);
-  virtual ~ImageLoader();
+  ImageLoader(const unsigned char *rawData) : m_RawData(rawData)
+  , m_Width(0), m_Height(0)
+  , m_RedChannelPrecision(0), m_RedData(0)
+  , m_GreenChannelPrecision(0), m_GreenData(0)
+  , m_BlueChannelPrecision(0), m_BlueData(0)
+  , m_AlphaChannelPrecision(0), m_AlphaData(0)
+    { }
+
+  virtual ~ImageLoader() {
+    if(m_RedData) {
+      delete [] m_RedData;
+      m_RedData = 0;
+    }
+
+    if(m_GreenData) {
+      delete [] m_GreenData;
+      m_GreenData = 0;
+    }
+
+    if(m_BlueData) {
+      delete [] m_BlueData;
+      m_BlueData = 0;
+    }
+
+    if(m_AlphaData) {
+      delete [] m_AlphaData;
+      m_AlphaData = 0;
+    }
+  }
 
  public:
-  virtual void ReadData() = 0;
+  virtual bool ReadData() = 0;
 
   int GetRedChannelPrecision() const { return m_RedChannelPrecision; }
   unsigned char * GetRedPixelData() const { return m_RedData; }

IO/ImageLoaderPNG.cpp

@@ -1,7 +1,22 @@
 #include "ImageLoaderPNG.h"
 
+#include <stdio.h>
+#include <assert.h>
+
 #include <png.h>
 
+class PNGStreamReader {
+public:
+  static void ReadDataFromStream(
+    png_structp png_ptr, 
+    png_bytep outBytes, 
+    png_size_t byteCountToRead
+  ) {
+
+    
+  }
+};
+
 ImageLoaderPNG::ImageLoaderPNG(const unsigned char *rawData) 
   : ImageLoader(rawData)
 {
@@ -10,5 +25,167 @@ ImageLoaderPNG::ImageLoaderPNG(const unsigned char *rawData)
 ImageLoaderPNG::~ImageLoaderPNG() {
 }
 
-void ImageLoaderPNG::ReadData() {
+static void ReportError(const char *msg) {
+  fprintf(stderr, "ERROR: ImageLoaderPNG -- %s\n", msg);
+}
+
+bool ImageLoaderPNG::ReadData() {
+  
+  const int kNumSigBytesToRead = 8;
+  if(!png_sig_cmp(m_RawData, 0, kNumSigBytesToRead)) {
+    ReportError("Incorrect PNG signature");
+    return false;
+  }
+
+  png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+  if(!png_ptr) {
+    ReportError("Could not create read struct");
+    return false;
+  }
+
+  png_infop info_ptr = png_create_info_struct(png_ptr);
+  if(!info_ptr) {
+    ReportError("Could not create info struct");
+    png_destroy_read_struct(&png_ptr, NULL, NULL);
+    return false;
+  }
+
+  // Read from our buffer, not a file pointer...
+  png_set_read_fn(png_ptr, this, PNGStreamReader::ReadDataFromStream);
+
+  // Make sure to tell libpng how many bytes we've read...
+  png_set_sig_bytes(png_ptr, kNumSigBytesToRead);
+
+  png_read_info(png_ptr, info_ptr);
+
+  int bitDepth = 0;
+  int colorType = -1;
+
+  if( 1 != png_get_IHDR(png_ptr, info_ptr, 
+      &m_Width, &m_Height, 
+      &bitDepth, &colorType, 
+      NULL, NULL, NULL) 
+  ) {
+    ReportError("Could not read PNG header");
+    png_destroy_read_struct(&png_ptr, NULL, NULL);
+    return false;
+  }
+
+  if(bitDepth != 8) {
+    ReportError("Only 8-bit images currently supported.");
+    png_destroy_read_struct(&png_ptr, NULL, NULL);
+    return false;
+  }
+
+  const int numPixels = m_Width * m_Height;
+  unsigned int bpr = png_get_rowbytes(png_ptr, info_ptr);
+  png_bytep rowData = new png_byte[bpr];
+
+  switch(colorType) {
+  default:
+  case PNG_COLOR_TYPE_PALETTE:
+    ReportError("PNG color type unsupported");
+    png_destroy_read_struct(&png_ptr, NULL, NULL);
+    return false;
+
+  case PNG_COLOR_TYPE_GRAY: {
+      m_RedChannelPrecision = bitDepth;
+      m_RedData = new unsigned char[numPixels];
+
+      for(int i = 0; i < m_Height; i++) {
+	
+	png_read_row(png_ptr, rowData, NULL);
+
+	unsigned int rowOffset = i * m_Height;
+	
+	unsigned int byteIdx = 0;
+	for(int j = 0; j < m_Width; j++) {
+
+	}
+
+	assert(byteIdx == bpr);
+      }
+    }
+    break;
+
+  case PNG_COLOR_TYPE_RGB:
+      m_RedChannelPrecision = bitDepth;
+      m_RedData = new unsigned char[numPixels];
+      m_GreenChannelPrecision = bitDepth;
+      m_GreenData = new unsigned char[numPixels];
+      m_BlueChannelPrecision = bitDepth;
+      m_BlueData = new unsigned char[numPixels];
+
+      for(int i = 0; i < m_Height; i++) {
+	
+	png_read_row(png_ptr, rowData, NULL);
+
+	unsigned int rowOffset = i * m_Height;
+	
+	unsigned int byteIdx = 0;
+	for(int j = 0; j < m_Width; j++) {
+ 	  m_RedData[rowOffset + j] = rowData[byteIdx++];
+	  m_GreenData[rowOffset + j] = rowData[byteIdx++];
+	  m_BlueData[rowOffset + j] = rowData[byteIdx++];
+	}
+
+	assert(byteIdx == bpr);
+      }
+    break;
+
+  case PNG_COLOR_TYPE_RGB_ALPHA:
+      m_RedChannelPrecision = bitDepth;
+      m_RedData = new unsigned char[numPixels];
+      m_GreenChannelPrecision = bitDepth;
+      m_GreenData = new unsigned char[numPixels];
+      m_BlueChannelPrecision = bitDepth;
+      m_BlueData = new unsigned char[numPixels];
+      m_AlphaChannelPrecision = bitDepth;
+      m_AlphaData = new unsigned char[numPixels];
+
+      for(int i = 0; i < m_Height; i++) {
+	
+	png_read_row(png_ptr, rowData, NULL);
+
+	unsigned int rowOffset = i * m_Height;
+	
+	unsigned int byteIdx = 0;
+	for(int j = 0; j < m_Width; j++) {
+ 	  m_RedData[rowOffset + j] = rowData[byteIdx++];
+	  m_GreenData[rowOffset + j] = rowData[byteIdx++];
+	  m_BlueData[rowOffset + j] = rowData[byteIdx++];
+	  m_AlphaData[rowOffset + j] = rowData[byteIdx++];
+	}
+
+	assert(byteIdx == bpr);
+      }
+    break;
+
+  case PNG_COLOR_TYPE_GRAY_ALPHA:
+      m_RedChannelPrecision = bitDepth;
+      m_RedData = new unsigned char[numPixels];
+      m_AlphaChannelPrecision = bitDepth;
+      m_AlphaData = new unsigned char[numPixels];
+
+      for(int i = 0; i < m_Height; i++) {
+	
+	png_read_row(png_ptr, rowData, NULL);
+
+	unsigned int rowOffset = i * m_Height;
+	
+	unsigned int byteIdx = 0;
+	for(int j = 0; j < m_Width; j++) {
+ 	  m_RedData[rowOffset + j] = rowData[byteIdx++];
+	  m_AlphaData[rowOffset + j] = rowData[byteIdx++];
+	}
+
+	assert(byteIdx == bpr);
+      }
+    break;
+  }
+
+  // Cleanup
+  delete [] rowData;
+  png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+  return true;
 }

IO/ImageLoaderPNG.h

@@ -8,7 +8,11 @@ class ImageLoaderPNG : public ImageLoader {
   ImageLoaderPNG(const unsigned char *rawData);
   virtual ~ImageLoaderPNG();
 
-  virtual void ReadData();
+  virtual bool ReadData();
+
+private:
+  unsigned int m_StreamPosition;
+  friend class PNGStreamReader;
 };
 
 #endif // _IMAGE_LOADER_H_