Align fastdeploy prediction precision with yolov5 (#11)

* Align fastdeploy prediction precision with yolov5

* Change name of Sort function to SortDetectionResult

* Add stride max_wh is_mini_pad property in __init__.py and unify format of getting image width and length

* Change mergesort.cc to sort_det_res.cc

fastdeploy/vision/utils/sort_det_res.cc

@@ -0,0 +1,77 @@
+// Copyright (c) 2022 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.
+
+#include "fastdeploy/vision/utils/utils.h"
+
+namespace fastdeploy {
+namespace vision {
+namespace utils {
+
+void Merge(DetectionResult* result, size_t low, size_t mid, size_t high) {
+  std::vector<std::array<float, 4>>& boxes = result->boxes;
+  std::vector<float>& scores = result->scores;
+  std::vector<int32_t>& label_ids = result->label_ids;
+  std::vector<std::array<float, 4>> temp_boxes(boxes);
+  std::vector<float> temp_scores(scores);
+  std::vector<int32_t> temp_label_ids(label_ids);
+  size_t i = low;
+  size_t j = mid + 1;
+  size_t k = i;
+  for (; i <= mid && j <= high; k++) {
+    if (temp_scores[i] >= temp_scores[j]) {
+      scores[k] = temp_scores[i];
+      label_ids[k] = temp_label_ids[i];
+      boxes[k] = temp_boxes[i];
+      i++;
+    } else {
+      scores[k] = temp_scores[j];
+      label_ids[k] = temp_label_ids[j];
+      boxes[k] = temp_boxes[j];
+      j++;
+    }
+  }
+  while (i <= mid) {
+    scores[k] = temp_scores[i];
+    label_ids[k] = temp_label_ids[i];
+    boxes[k] = temp_boxes[i];
+    k++;
+    i++;
+  }
+  while (j <= high) {
+    scores[k] = temp_scores[j];
+    label_ids[k] = temp_label_ids[j];
+    boxes[k] = temp_boxes[j];
+    k++;
+    j++;
+  }
+}
+
+void MergeSort(DetectionResult* result, size_t low, size_t high) {
+  if (low < high) {
+    size_t mid = (high - low) / 2 + low;
+    MergeSort(result, low, mid);
+    MergeSort(result, mid + 1, high);
+    Merge(result, low, mid, high);
+  }
+}
+
+void SortDetectionResult(DetectionResult* result) {
+  size_t low = 0;
+  size_t high = result->scores.size() - 1;
+  MergeSort(result, low, high);
+}
+
+}  // namespace utils
+}  // namespace vision
+}  // namespace fastdeploy