Initial commit.

Framework/external/embree/tutorials/common/image/png.cpp

@@ -0,0 +1,135 @@
+// Copyright 2009-2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#ifdef EMBREE_TUTORIALS_LIBPNG
+
+#include "image.h"
+
+#include <iostream>
+#include <cstring>
+#include <cstdio>
+#include <png.h>
+
+namespace embree
+{
+  struct AutoCloseFile
+  {
+    FILE* file;
+    AutoCloseFile (FILE* file) : file(file) {}
+    ~AutoCloseFile () { if (file) fclose(file); }
+  };
+
+  /*! read PNG file from disk */
+  Ref<Image> loadPNG(const FileName& fileName)
+  {
+    size_t width, height;
+
+    //header for testing if it is a png
+    png_byte header[8];
+ 
+    //open file as binary
+    FILE* fp = fopen(fileName.c_str(), "rb");
+    if (!fp) THROW_RUNTIME_ERROR("cannot open file "+fileName.str());
+    //ON_SCOPE_EXIT(fclose(fp));
+    AutoCloseFile close_file(fp);
+
+    //read the header
+    if (fread(header, 1, 8, fp) != 8)
+      THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
+
+    //test if png
+    int is_png = !png_sig_cmp(header, 0, 8);
+    if (!is_png)
+      THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
+
+    //create png struct
+    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+    if (!png_ptr) THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
+    ON_SCOPE_EXIT(png_destroy_read_struct(&png_ptr, (png_infopp) nullptr, (png_infopp) nullptr));
+    
+    //create png info struct
+    png_infop info_ptr = png_create_info_struct(png_ptr);
+    if (!info_ptr)
+      THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
+ 
+    //create png info struct
+    png_infop end_info = png_create_info_struct(png_ptr);
+    if (!end_info) 
+      THROW_RUNTIME_ERROR("invalid PNG file "+fileName.str());
+ 
+    //png error stuff, not sure libpng man suggests this.
+    //if (setjmp(png_jmpbuf(png_ptr))) {
+    ///  return (TEXTURE_LOAD_ERROR);
+    //}
+ 
+    //init png reading
+    png_init_io(png_ptr, fp);
+ 
+    //let libpng know you already read the first 8 bytes
+    png_set_sig_bytes(png_ptr, 8);
+ 
+    // read all the info up to the image data
+    png_read_info(png_ptr, info_ptr);
+ 
+    //variables to pass to get info
+    int bit_depth, color_type;
+    png_uint_32 twidth, theight;
+ 
+    // get info about png
+    png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
+                 nullptr, nullptr, nullptr);
+ 
+    //update width and height based on png info
+    width = twidth;
+    height = theight;
+    
+    Ref<Image> img = new Image4uc(width,height,fileName);
+
+    // Update the png info struct.
+    png_read_update_info(png_ptr, info_ptr);
+ 
+    // Row size in bytes.
+    int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+
+    // Allocate the image_data as a big block, to be given to opengl
+    std::vector<png_byte> data(rowbytes * height);
+ 
+    // row_pointers is for pointing to image_data for reading the png with libpng
+    std::vector<png_bytep> row_pointers(height);
+
+    // set the individual row_pointers to point at the correct offsets of image_data
+    for (size_t i = 0; i < height; ++i)
+      row_pointers[i] = (unsigned char*) &data[i * rowbytes];
+ 
+    // read the png into image_data through row_pointers
+    png_read_image(png_ptr, row_pointers.data());
+  
+    if (color_type == PNG_COLOR_TYPE_RGB && bit_depth == 8)
+    {
+      for (size_t y=0;y<height;y++)
+        for (size_t x=0;x<width;x++)
+        {
+          unsigned char* texel = data.data() + (y * width + x) * 3;
+          Color4 c( (float)texel[0] * 1.0f/255.0f, (float)texel[1] * 1.0f/255.0f, (float)texel[2] * 1.0f/255.0f, 0.0f );
+          img.ptr->set(x,y,c);
+        }
+    }
+    else if (color_type == PNG_COLOR_TYPE_RGBA && bit_depth == 8)
+    {
+      for (size_t y=0;y<height;y++)
+        for (size_t x=0;x<width;x++)
+        {
+          unsigned char *texel = data.data() + (y * width + x) * 4;
+          Color4 c( (float)texel[0] * 1.0f/255.0f, (float)texel[1] * 1.0f/255.0f, (float)texel[2] * 1.0f/255.0f, (float)texel[3] * 1.0f/255.0f );
+          img.ptr->set(x,y,c);
+        }
+    }
+    else
+      THROW_RUNTIME_ERROR("invalid color type in PNG file "+fileName.str());
+      
+    return img;
+  }
+}
+
+#endif
+