Android OpenCV4.7 开发环境配置

1、下载OpenCV的Android包并解压缩。

下载：https://opencv.org/releases/

2、创建Android应用或者在现有应用中，导入OpenCV模块。

// Import module: Menu -> “File” -> “New” -> “Module” -> “Import Gradle project”:
// Source directory: select this “sdk” directory
// Module name: “:opencv”

3、修改导入的opencv4.7模块的build.gradle，使compileSdkVersion、minSdkVersion、targetSdkVersion与app的build.gradle中的一致。

4、加入依赖（Dependency）。

打开app的build.gradle，可以看到依赖已经被添加进去。

5、在使用OpenCV的Activity中，加入测试代码。

package com.test;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.navigation.fragment.NavHostFragment;

import com.test.databinding.FragmentFirstBinding;

import org.opencv.android.OpenCVLoader;
import org.opencv.android.Utils;
import org.opencv.core.Mat;
import org.opencv.imgproc.Imgproc;

public class FirstFragment extends Fragment {

    private FragmentFirstBinding binding;

    @Override
    public View onCreateView(
            LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState
    ) {

        binding = FragmentFirstBinding.inflate(inflater, container, false);
        return binding.getRoot();

    }

    public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        ImageView iv;
        iv = view.findViewById(R.id.img_logo);

        boolean success = OpenCVLoader.initDebug();
        if (success) {
            Toast.makeText(getActivity(), "加载 OpenCV Libraries 成功", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(getActivity(), "加载 OpenCV Libraries 失败", Toast.LENGTH_SHORT).show();
        }

        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon);
        Mat src = new Mat();
        Mat dst = new Mat();
        Utils.bitmapToMat(bitmap, src);
        Imgproc.cvtColor(src,dst, Imgproc.COLOR_BGR2GRAY);
        Utils.matToBitmap(dst, bitmap);
        iv.setImageBitmap(bitmap);
        src.release();
        dst.release();

        binding.buttonFirst.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavHostFragment.findNavController(FirstFragment.this)
                        .navigate(R.id.action_FirstFragment_to_SecondFragment);
            }
        });
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }

}

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