native opengl

github：hrydgard/native

https://github.com/hrydgard/native

http://www.henrikrydgard.com/

native、png、opengl （libPng）

#ifndef OPENGL_IMAGE_PARSEPNGFILE_H#define OPENGL_IMAGE_PARSEPNGFILE_H#include "common.h"#include <android/asset_manager.h>#include <android/asset_manager_jni.h>class ParsePngFile{public:    ParsePngFile(AAssetManager *assetManager,const char *filePath);    bool parse();    void glPngTexImage2D(int target, int level);    int getWidth();    int getHeight();    bool hasAlpha();    ~ParsePngFile();private:    char * pngData;    bool _hasAlpha;    int _width, _height;    std::string pngDataString;};#endif //OPENGL_IMAGE_PARSEPNGFILE_H

#include "ParsePngFile.h"#include <GLES2/gl2.h>#include <png.h>#include <istream>#include <fstream>#include <sstream>#include <vector>ParsePngFile::ParsePngFile(AAssetManager *assetManager,const char *filePath) {    std::vector<char> buffer;    AAsset * asset = AAssetManager_open(assetManager,filePath, AASSET_MODE_UNKNOWN);    if (asset) {        int size = AAsset_getLength(asset);        buffer.resize(size);        AAsset_read(asset, &buffer[0], size);        AAsset_close(asset);        for (int i = 0; i < buffer.size(); i++) {            pngDataString += buffer[i];        }        std::vector<char>().swap(buffer);    }}void readFileCallback(png_structp png_ptr, png_bytep destination, png_size_t bytesToRead){    png_voidp io_ptr = png_get_io_ptr( png_ptr );    if( io_ptr == 0 )    {        return;    }    png_voidp a = png_get_io_ptr(png_ptr);    //Cast the pointer to std::istream* and read 'bytesToRead' bytes into 'destination'    ((std::istream*)a)->read((char*)destination, bytesToRead);}bool ParsePngFile::parse() {    std::istringstream pngDataStream(pngDataString);    const int PNG_SIG_BYTES = 8;    char pngSignature[PNG_SIG_BYTES];    pngDataStream.read(pngSignature, PNG_SIG_BYTES * sizeof(char));    if(!png_check_sig( (png_bytep)pngSignature, PNG_SIG_BYTES) )    {        return false;    }    /**     * Create and initialize the png_struct     * with the desired error handler     * functions.  If you want to use the     * default stderr and longjump method,     * you can supply NULL for the last     * three parameters.  We also supply the     * the compiler header file version, so     * that we know if the application     * was compiled with a compatible version     * of the library.  REQUIRED     */    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);    if (png_ptr == NULL)    {        return false;    }    /**     * Allocate/initialize the memory     * for image information.  REQUIRED. */    png_infop info_ptr = png_create_info_struct(png_ptr);    if (info_ptr == NULL)    {        png_destroy_read_struct(&png_ptr, NULL, NULL);        return false;    }    /**     * Set error handling if you are     * using the setjmp/longjmp method     * (this is the normal method of     * doing things with libpng).     * REQUIRED unless you  set up     * your own error handlers in     * the png_create_read_struct()     * earlier.     */    if (setjmp(png_jmpbuf(png_ptr))) {        /* Free all of the memory associated         * with the png_ptr and info_ptr */        png_destroy_read_struct(&png_ptr, &info_ptr, NULL);        return false;    }    /**     * Set custom input stream READER / handler     */    png_set_read_fn( png_ptr, (void*)&pngDataStream, readFileCallback );    /* If we have already     * read some of the signature */    png_set_sig_bytes( png_ptr, 8 );    png_read_info( png_ptr, info_ptr);    int  _depth;    int color_type, interlace_type;    png_get_IHDR( png_ptr, info_ptr, (png_uint_32*)&_width, (png_uint_32*)&_height, &_depth, &color_type, &interlace_type, NULL, NULL );    switch(color_type)    {        case PNG_COLOR_TYPE_RGB:            _hasAlpha = false;            break;        case PNG_COLOR_TYPE_RGBA:            _hasAlpha = true;            break;        default:            return false;    }    png_size_t cols = png_get_rowbytes(png_ptr, info_ptr);    png_bytepp row_pp = new png_bytep[_height];    pngData= new char[ cols * _height ];    for( int i = 0; i < _height; ++i )    {        // note that png is ordered top to        // bottom, but OpenGL expect it bottom to top        // so the order or swapped        row_pp[i] = (png_bytep)&((char *)pngData)[ i * cols ];    }    png_read_image( png_ptr, row_pp );    png_read_end( png_ptr, info_ptr );    png_destroy_read_struct( &png_ptr, &info_ptr, 0 );    delete [] row_pp;    return true;}void ParsePngFile::glPngTexImage2D(int target, int level) {   if(pngData != NULL){       glTexImage2D(target, level, _hasAlpha ? GL_RGBA : GL_RGB, _width, _height, 0, _hasAlpha ? GL_RGBA : GL_RGB, GL_UNSIGNED_BYTE, pngData);   }}int ParsePngFile::getWidth() { return _width; }int ParsePngFile::getHeight() { return _height; }bool ParsePngFile::hasAlpha() { return _hasAlpha; }ParsePngFile::~ParsePngFile() {    if(pngData != NULL){        delete [] pngData;        pngData = NULL;    }}