[Android]libpng的编译与使用
16lz
2021-12-04
库地址
https://github.com/julienr/libpng-android
设置NDK环境变量
将NDK目录加入PATH变量：
C:\Users\xx\AppData\Local\Android\Sdk\ndk\20.0.5594570\
静态库
修改Android.mk文件
#LOCAL_SHARED_LIBRARIES := -lzLOCAL_EXPORT_LDLIBS := -lzLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/.#include $(BUILD_SHARED_LIBRARY)include $(BUILD_STATIC_LIBRARY)动态库
修改Android.mk文件
#LOCAL_SHARED_LIBRARIES := -lz#LOCAL_EXPORT_LDLIBS := -lzLOCAL_LDLIBS := -lz LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/.include $(BUILD_SHARED_LIBRARY)#include $(BUILD_STATIC_LIBRARY)编译命令
ndk-build NDK_PROJECT_PATH=./libpng库使用
从内存中读取png图片数据，解码为RGBA格式的raw数据
glPngReader.h
//// Created by Jinzhu on 2019/9/7.//#ifndef OPENGLES_GLPNGREADER_H#define OPENGLES_GLPNGREADER_H#ifdef __cplusplusextern "C" {#endif#include #include #include #include struct glPngReader { uint8_t *m_raw_data; size_t m_raw_size; size_t m_raw_offset; int m_width; int m_height; int m_color_type; int m_pixel_depth; int m_status; uint8_t *m_pixel_data;};void glPngReader_Create(struct glPngReader *pngReader, uint8_t *raw_data, size_t raw_size);void glPngReader_Destory(struct glPngReader *pngReader);uint8_t *glPngReader_GetPixelData(struct glPngReader *pngReader);int glPngReader_GetWidth(struct glPngReader *pngReader);int glPngReader_GetHeight(struct glPngReader *pngReader);#ifdef __cplusplus};#endif#endif //OPENGLES_GLPNGREADER_H glPngReader.c
//// Created by Jinzhu on 2019/9/7.//#include #ifdef __cplusplusextern "C" {#endif#include "glPngReader.h"#include #include #include #include #include #define LOG_TAG "PNGREADER-LIB"#define ALOGE(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)void glPngReader_ReadCallback(png_structp png_ptr, png_bytep data, png_size_t length) { struct glPngReader *pThis = (struct glPngReader *) png_get_io_ptr(png_ptr); if (pThis != NULL) { if (pThis->m_raw_offset + length <= pThis->m_raw_size) { memcpy(data, pThis->m_raw_data + pThis->m_raw_offset, length); pThis->m_raw_offset += length; } else { ALOGE("the length is illegal."); } }}void glPngReader_ReadImage(struct glPngReader *pngReader) { png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); if (png_ptr == NULL) { ALOGE("load libpng error,png_ptr = NULL."); pngReader->m_status = 0; return; } png_infop info_ptr = png_create_info_struct(png_ptr); if (info_ptr == NULL) { png_destroy_read_struct(&png_ptr, NULL, NULL); ALOGE("load libpng error,info_ptr = NULL."); pngReader->m_status = 0; return; } if (setjmp(png_jmpbuf(png_ptr))) { png_destroy_read_struct(&png_ptr, &info_ptr, NULL); ALOGE("libpng process error."); pngReader->m_status = 0; return; } png_set_read_fn(png_ptr, pngReader, glPngReader_ReadCallback); png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_EXPAND, NULL); pngReader->m_width = info_ptr->width; pngReader->m_height = info_ptr->height; pngReader->m_color_type = info_ptr->color_type; pngReader->m_pixel_depth = info_ptr->pixel_depth; if ((pngReader->m_color_type != PNG_COLOR_TYPE_RGB && pngReader->m_color_type != PNG_COLOR_TYPE_RGB_ALPHA) && pngReader->m_pixel_depth == 8) { ALOGE("image format error."); pngReader->m_status = 0; png_destroy_read_struct(&png_ptr, &info_ptr, NULL); return; } if (pngReader->m_pixel_data != NULL) { free(pngReader->m_pixel_data); pngReader->m_pixel_data = NULL; } pngReader->m_pixel_data = (uint8_t *) malloc(pngReader->m_width * pngReader->m_height * 4); png_bytep *row_pointers = png_get_rows(png_ptr, info_ptr); if (pngReader->m_color_type == PNG_COLOR_TYPE_RGB) { int pos = 0; for (int row = 0; row < pngReader->m_height; ++row) { for (int col = 0; col < (3 * pngReader->m_width); col += 3) { pngReader->m_pixel_data[pos++] = row_pointers[row][col + 0];//RED pngReader->m_pixel_data[pos++] = row_pointers[row][col + 1];//GREEN pngReader->m_pixel_data[pos++] = row_pointers[row][col + 2];//BLUE pngReader->m_pixel_data[pos++] = 255;//ALPHA } } pngReader->m_status = 1; } else if (pngReader->m_color_type == PNG_COLOR_TYPE_RGB_ALPHA) { int pos = 0; for (int row = 0; row < pngReader->m_height; ++row) { for (int col = 0; col < (4 * pngReader->m_width); col += 4) { pngReader->m_pixel_data[pos++] = row_pointers[row][col + 0];//RED pngReader->m_pixel_data[pos++] = row_pointers[row][col + 1];//GREEN pngReader->m_pixel_data[pos++] = row_pointers[row][col + 2];//BLUE pngReader->m_pixel_data[pos++] = row_pointers[row][col + 3];//ALPHA } } pngReader->m_status = 1; } else { pngReader->m_status = 0; } png_destroy_read_struct(&png_ptr, &info_ptr, NULL);}void glPngReader_Create(struct glPngReader *pngReader, uint8_t *raw_data, size_t raw_size) { pngReader->m_raw_data = raw_data; pngReader->m_raw_size = raw_size; pngReader->m_raw_offset = 0; pngReader->m_width = 0; pngReader->m_height = 0; pngReader->m_color_type = PNG_TRANSFORM_STRIP_ALPHA; pngReader->m_pixel_depth = 8; pngReader->m_status = 0; pngReader->m_pixel_data = NULL; glPngReader_ReadImage(pngReader);}void glPngReader_Destory(struct glPngReader *pngReader) { if (pngReader->m_pixel_data != NULL) { free(pngReader->m_pixel_data); pngReader->m_pixel_data = NULL; }}uint8_t *glPngReader_GetPixelData(struct glPngReader *pngReader) { return pngReader->m_pixel_data; }int glPngReader_GetWidth(struct glPngReader *pngReader) { return pngReader->m_width; }int glPngReader_GetHeight(struct glPngReader *pngReader) { return pngReader->m_height; }#ifdef __cplusplus};#endif 更多相关文章
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