flycast/newdc/android/utils.cpp

#include <EGL/egl.h>
#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
extern "C" {
#include "deps/libpng/png.h"
}
#include "types.h"
#include "deps/libzip/zip.h"

#define TEXTURE_LOAD_ERROR 0

//Taken from http://en.wikibooks.org/wiki/OpenGL_Programming/Intermediate/Textures
/** loadTexture
 *   loads a png file into an opengl texture object, using cstdio , libpng, and opengl.
 *
 *   \param filename : the png file to be loaded
 *   \param width : width of png, to be updated as a side effect of this function
 *   \param height : height of png, to be updated as a side effect of this function
 *
 *   \return GLuint : an opengl texture id.  Will be 0 if there is a major error,
 *           should be validated by the client of this function.
 *
 */
zip_file* file;

zip* APKArchive;
void setAPK (const char* apkPath) {
  LOGI("Loading APK %s", apkPath);
  APKArchive = zip_open(apkPath, 0, NULL);
  if (APKArchive == NULL) {
    LOGE("Error loading APK");
    return;
  }

  //Just for debug, print APK contents
  int numFiles = zip_get_num_files(APKArchive);
  for (int i=0; i<numFiles; i++) {
    const char* name = zip_get_name(APKArchive, i, 0);
    if (name == NULL) {
      LOGE("Error reading zip file name at index %i : %s", zip_strerror(APKArchive));
      return;
    }
    LOGI("File %i : %s\n", i, name);
  }
}

void png_zip_read(png_structp png_ptr, png_bytep data, png_size_t length) {
  zip_fread(file, data, length);
}

GLuint loadTextureFromPNG(const char* filename, int &width, int &height) {
  file = zip_fopen(APKArchive, filename, 0);
  if (!file) {
    LOGE("Error opening %s from APK", filename);
    return TEXTURE_LOAD_ERROR;
  }

  //header for testing if it is a png
  png_byte header[8];

  //read the header
  zip_fread(file, header, 8);

  //test if png
  int is_png = !png_sig_cmp(header, 0, 8);
  if (!is_png) {
    zip_fclose(file);
    LOGE("Not a png file : %s", filename);
    return TEXTURE_LOAD_ERROR;
  }

  //create png struct
  png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
      NULL, NULL);
  if (!png_ptr) {
    zip_fclose(file);
    LOGE("Unable to create png struct : %s", filename);
    return (TEXTURE_LOAD_ERROR);
  }

  //create png info struct
  png_infop info_ptr = png_create_info_struct(png_ptr);
  if (!info_ptr) {
    png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
    LOGE("Unable to create png info : %s", filename);
    zip_fclose(file);
    return (TEXTURE_LOAD_ERROR);
  }

  //create png info struct
  png_infop end_info = png_create_info_struct(png_ptr);
  if (!end_info) {
    png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
    LOGE("Unable to create png end info : %s", filename);
    zip_fclose(file);
    return (TEXTURE_LOAD_ERROR);
  }

  //png error stuff, not sure libpng man suggests this.
  if (setjmp(png_jmpbuf(png_ptr))) {
    zip_fclose(file);
    LOGE("Error during setjmp : %s", filename);
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
    return (TEXTURE_LOAD_ERROR);
  }

  //init png reading
  //png_init_io(png_ptr, fp);
  png_set_read_fn(png_ptr, NULL, png_zip_read);

  //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,
      NULL, NULL, NULL);

  //update width and height based on png info
  width = twidth;
  height = theight;

  // 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
  png_byte *image_data = new png_byte[rowbytes * height];
  if (!image_data) {
    //clean up memory and close stuff
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
    LOGE("Unable to allocate image_data while loading %s ", filename);
    zip_fclose(file);
    return TEXTURE_LOAD_ERROR;
  }

  //row_pointers is for pointing to image_data for reading the png with libpng
  png_bytep *row_pointers = new png_bytep[height];
  if (!row_pointers) {
    //clean up memory and close stuff
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
    delete[] image_data;
    LOGE("Unable to allocate row_pointer while loading %s ", filename);
    zip_fclose(file);
    return TEXTURE_LOAD_ERROR;
  }
  // set the individual row_pointers to point at the correct offsets of image_data
  for (int i = 0; i < height; ++i)
    row_pointers[height - 1 - i] = image_data + i * rowbytes;

  //read the png into image_data through row_pointers
  png_read_image(png_ptr, row_pointers);

  //Now generate the OpenGL texture object
  GLuint texture;
  glGenTextures(1, &texture);
  glBindTexture(GL_TEXTURE_2D, texture);
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA,
      GL_UNSIGNED_BYTE, (GLvoid*) image_data);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

  //clean up memory and close stuff
  png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
  delete[] image_data;
  delete[] row_pointers;
  zip_fclose(file);

  return texture;
}