feat: Add document scanner package

packages/paperless_document_scanner/ios/Classes/image_processor.cpp

@@ -0,0 +1,51 @@
+#include "image_processor.hpp"
+#include <opencv2/opencv.hpp>
+
+using namespace cv;
+
+Point2f computePoint(int p1, int p2)
+{
+    Point2f pt;
+    pt.x = p1;
+    pt.y = p2;
+    return pt;
+}
+
+Mat ImageProcessor::process_image(Mat img, float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4)
+{
+    cvtColor(img, img, COLOR_BGR2GRAY);
+    Mat dst = ImageProcessor::crop_and_transform(img, x1, y1, x2, y2, x3, y3, x4, y4);
+    adaptiveThreshold(dst, dst, 255, cv::ADAPTIVE_THRESH_MEAN_C, cv::THRESH_BINARY, 53, 10);
+
+    return dst;
+}
+
+Mat ImageProcessor::crop_and_transform(Mat img, float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4)
+{
+    float w1 = sqrt(pow(x4 - x3, 2) + pow(x4 - x3, 2));
+    float w2 = sqrt(pow(x2 - x1, 2) + pow(x2 - x1, 2));
+    float h1 = sqrt(pow(y2 - y4, 2) + pow(y2 - y4, 2));
+    float h2 = sqrt(pow(y1 - y3, 2) + pow(y1 - y3, 2));
+
+    float maxWidth = (w1 < w2) ? w1 : w2;
+    float maxHeight = (h1 < h2) ? h1 : h2;
+
+    Mat dst = Mat::zeros(maxHeight, maxWidth, CV_8UC1);
+
+    vector<Point2f> dst_pts;
+    vector<Point2f> img_pts;
+    dst_pts.push_back(Point(0, 0));
+    dst_pts.push_back(Point(maxWidth - 1, 0));
+    dst_pts.push_back(Point(0, maxHeight - 1));
+    dst_pts.push_back(Point(maxWidth - 1, maxHeight - 1));
+
+    img_pts.push_back(computePoint(x1, y1));
+    img_pts.push_back(computePoint(x2, y2));
+    img_pts.push_back(computePoint(x3, y3));
+    img_pts.push_back(computePoint(x4, y4));
+
+    Mat transformation_matrix = getPerspectiveTransform(img_pts, dst_pts);
+    warpPerspective(img, dst, transformation_matrix, dst.size());
+
+    return dst;
+}