我正试图在vs2013中使用libpng 1.2.10读取一个png文件 . 我下载了最新的zlib并编译了pnglib,效果很好 . 现在我正在尝试加载文件:
int *w = &width;
int *h = &height;
const char* name = file.c_str();
FILE *png_file = fopen(name, "rb");
if (!png_file)
{
std::cerr << "Could not open " + file << std::endl;
return;
}
unsigned char header[PNG_SIG_BYTES];
fread(header, 1, PNG_SIG_BYTES, png_file);
if (png_sig_cmp(header, 0, PNG_SIG_BYTES))
{
std::cerr << "PNG signature fail " + file << std::endl;
return;
}
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if(png_ptr == NULL)
{
std::cerr << "PNG read fail " + file << std::endl;
return;
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if(!info_ptr)
{
std::cerr << "PNG info fail " + file << std::endl;
return;
}
png_infop end_info = png_create_info_struct(png_ptr);
if(!end_info)
{
std::cerr << "PNG info end fail " + file << std::endl;
return;
}
if (setjmp(png_jmpbuf(png_ptr)))
{
std::cerr << "PNG setjmp fail " + file << std::endl;
return;
}
png_init_io(png_ptr, png_file);
png_set_sig_bytes(png_ptr, PNG_SIG_BYTES);
png_read_info(png_ptr, info_ptr);
*w = png_get_image_width(png_ptr, info_ptr);
*h = png_get_image_height(png_ptr, info_ptr);
png_uint_32 bit_depth, color_type;
bit_depth = png_get_bit_depth(png_ptr, info_ptr);
color_type = png_get_color_type(png_ptr, info_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
{
std::cerr << "Grayscale PNG not supported " + file << std::endl;
return;
}
if (bit_depth == 16)
png_set_strip_16(png_ptr);
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png_ptr);
else if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
png_set_gray_to_rgb(png_ptr);
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(png_ptr);
else
png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
png_read_update_info(png_ptr, info_ptr);
png_uint_32 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
png_uint_32 numbytes = rowbytes*(height);
png_byte* pixels = (png_byte*)malloc(numbytes);
png_byte** row_ptrs = (png_byte**)malloc((height)* sizeof(png_byte*));
int i;
for (i = 0; i<height; i++)
row_ptrs[i] = pixels + (height - 1 - i)*rowbytes;
png_read_image(png_ptr, row_ptrs);
free(row_ptrs);
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
fclose(png_file);
//return (char *)pixels;
Create(*w, *h, 4, pixels, GL_UNSIGNED_BYTE);
不幸的是我得到了
SimpleShader.exe中0x77D78E19(ntdll.dll)的未处理异常:0xC0000005:访问冲突写入位置0x00000014 .
在线上
png_read_info(png_ptr, info_ptr);
特别是错误发生在这里:
#ifdef PNG_STDIO_SUPPORTED
/* This is the function that does the actual reading of data. If you are
* not reading from a standard C stream, you should create a replacement
* read_data function and use it at run time with png_set_read_fn(), rather
* than changing the library.
*/
void PNGCBAPI
png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
png_size_t check;
if (png_ptr == NULL)
return;
/* fread() returns 0 on error, so it is OK to store this in a png_size_t
* instead of an int, which is what fread() actually returns.
*/
check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr)); // <---------- ERROR HERE
if (check != length)
png_error(png_ptr, "Read Error");
}
#endif
可能是什么问题呢?
编辑:好的,当我在发布模式下编译libpng和我的项目时,它不会崩溃 . 我需要在调试模式下运行我的项目...
1 回答
这是由libpng和项目之间的编译器设置不匹配引起的 . 特别是运行时库设置,它必须在libpng和您的项目中都是 Multi-threaded DLL (/MD) . 自述文件指出:
避免崩溃和保留调试可能性的最简单方法是复制项目中的“Release”配置并更改一些属性,以便在Visual Studio中轻松调试 . 这是怎么做的:
单击项目上的RMB - >属性 - >配置管理器 - >展开活动解决方案配置,然后单击 . 从Release中选择一个新名称和复制设置 .
现在在项目设置中,选择新创建的配置并更改以下属性:
C / C - >常规 - > Debug Information Format :用于编辑和继续的程序数据库(/ ZI)
C / C - >优化 - > Optimization :禁用(/ Od), Whole Program Optimization :否
那是必要的_1512771 . 您还可以禁用链接器优化(引用和COMDAT折叠),启用最小重建等 .
就是这样,祝你好运!