ImageProcess/native_vision/ios/Classes/doc_cropper.cpp

#include "native_structs.h"
#include "opencv2/core/types_c.h"
#include "opencv2/core/core_c.h"
#include <opencv2/opencv.hpp>
//#include <opencv2/imgproc/imgproc.hpp>
//#include <algorithm>

static void captureDoc(std::vector<cv::Point> &points, cv::Mat &input, cv::Mat &output)
{
    assert(points.size() == 4);
    cv::Point ptTopLeft = points[0];
    cv::Point ptTopRight = points[1];
    cv::Point ptBottomLeft = points[2];
    cv::Point ptBottomRight = points[3];
    float w1 = sqrt(pow(ptBottomRight.x - ptBottomLeft.x, 2) + pow(ptBottomRight.x - ptBottomLeft.x, 2));
    float w2 = sqrt(pow(ptTopRight.x - ptTopLeft.x, 2) + pow(ptTopRight.x - ptTopLeft.x, 2));

    float h1 = sqrt(pow(ptTopRight.y - ptBottomRight.y, 2) + pow(ptTopRight.y - ptBottomRight.y, 2));
    float h2 = sqrt(pow(ptTopLeft.y - ptBottomLeft.y, 2) + pow(ptTopLeft.y - ptBottomLeft.y, 2));

    float maxWidth = (w1 < w2) ? w1 : w2;
    float maxHeight = (h1 < h2) ? h1 : h2;

    cv::Point2f src[4], dst[4];
    src[0].x = ptTopLeft.x;
    src[0].y = ptTopLeft.y;
    src[1].x = ptTopRight.x;
    src[1].y = ptTopRight.y;
    src[2].x = ptBottomRight.x;
    src[2].y = ptBottomRight.y;
    src[3].x = ptBottomLeft.x;
    src[3].y = ptBottomLeft.y;

    dst[0].x = 0;
    dst[0].y = 0;
    dst[1].x = maxWidth - 1;
    dst[1].y = 0;
    dst[2].x = maxWidth - 1;
    dst[2].y = maxHeight - 1;
    dst[3].x = 0;
    dst[3].y = maxHeight - 1;

    cv::Mat undistorted = cv::Mat(cvSize(maxWidth, maxHeight), CV_8UC4);
    cv::warpPerspective(input, undistorted, cv::getPerspectiveTransform(src, dst), cvSize(maxWidth, maxHeight));
    output = undistorted;
    undistorted.release();
}

extern "C" __attribute__((visibility("default"))) __attribute__((used))
bool native_doc_crop(const char *imgPath, const char *outPath, CoordinateArray *coordList) {
    int len = coordList->length;
    std::vector<cv::Point> points(len);
    cv::Mat input = cv::imread(imgPath), croppedImg;
    auto width = input.size().width;
    auto height = input.size().height;
    for (int i = 0; i < len; i++) {
        points[i].x = coordList->coordsPtr[i].x * width;
        points[i].y = coordList->coordsPtr[i].y * height;
    }
    captureDoc(points, input, croppedImg);
    auto ret = imwrite(outPath, croppedImg);
    return ret;
}