utils.h

// Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <cstring>
#ifdef _WIN32
#include <filesystem>
#else
#include <dirent.h>
#include <sys/types.h>
#endif

namespace PaddleSolution {
    namespace utils {
        enum SCALE_TYPE{
	    UNPADDING,
	    RANGE_SCALING
	};
        inline std::string path_join(const std::string& dir, const std::string& path) {
            std::string seperator = "/";
            #ifdef _WIN32
            seperator = "\\";
            #endif
            return dir + seperator + path;
        }
        #ifndef _WIN32
        // scan a directory and get all files with input extensions
        inline std::vector<std::string> get_directory_images(const std::string& path, const std::string& exts)
        {
            std::vector<std::string> imgs;
            struct dirent *entry;
            DIR *dir = opendir(path.c_str());
            if (dir == NULL) {
                closedir(dir);
                return imgs;
            }

            while ((entry = readdir(dir)) != NULL) {
                std::string item = entry->d_name;
                auto ext = strrchr(entry->d_name, '.');
                if (!ext || std::string(ext) == "." || std::string(ext) == "..") {
                    continue;
                }
                if (exts.find(ext) != std::string::npos) {
                    imgs.push_back(path_join(path, entry->d_name));
                }
            }
	    sort(imgs.begin(), imgs.end());
            return imgs;
        }
        #else
        // scan a directory and get all files with input extensions
        inline std::vector<std::string> get_directory_images(const std::string& path, const std::string& exts)
        {
            std::vector<std::string> imgs;
            for (const auto& item : std::experimental::filesystem::directory_iterator(path)) {
                auto suffix = item.path().extension().string();
                if (exts.find(suffix) != std::string::npos && suffix.size() > 0) {
                    auto fullname = path_join(path, item.path().filename().string());
                    imgs.push_back(item.path().string());
                }
            }
	    sort(imgs.begin(), imgs.end());
            return imgs;
        }
        #endif
	
	inline int scaling(int resize_type, int &w, int &h, int new_w, int new_h, int target_size, int max_size, float &im_scale_ratio)
	{
	    if(w <= 0 || h <= 0 || new_w <= 0 || new_h <= 0){
		return -1;
	    }
	    switch(resize_type) {
	        case SCALE_TYPE::UNPADDING:
		    {
		        w = new_w;
		        h = new_h;
		        im_scale_ratio=0;
		    }
		    break;
		case SCALE_TYPE::RANGE_SCALING:
		    {
                        int im_max_size = std::max(w, h);
                        int im_min_size = std::min(w, h);                        
			float scale_ratio= static_cast<float>(target_size) / static_cast<float>(im_min_size);
                        if(max_size > 0) {
                            if(round(scale_ratio * im_max_size) > max_size) {
			        scale_ratio = static_cast<float>(max_size) / static_cast<float>(im_max_size);
			    }
			}
			w = round(scale_ratio * static_cast<float>(w));
			h = round(scale_ratio * static_cast<float>(h));
			im_scale_ratio = scale_ratio;
		    }
		    break;
		default :
                    {
			std::cout << "Can't support this type of scaling strategy." << std::endl;
			std::cout << "Throw exception at file " << __FILE__ << " on line " << __LINE__ << std::endl;
			throw 0;
		    }
		    break;
	    }
	    return 0;
	}
    }
}