Android 画板小工具demo

package com.swy.signdemo; import android.Manifest; import android.app.AlertDialog; import android.content.Intent; import android.content.pm.PackageManager; import android.graphics.Bitmap; import android.graphics.Color; import android.net.Uri; import android.os.Build; import android.os.Bundle; import android.os.Environment; import android.provider.Settings; import android.util.Log; import android.view.View; import android.view.Window; import android.view.WindowManager; import android.widget.Toast; import androidx.appcompat.app.AppCompatActivity; import androidx.core.app.ActivityCompat; import com.swy.signdemo.databinding.ActivityMainBinding; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; public class MainActivity extends AppCompatActivity { private ActivityMainBinding binding; private AlertDialog dialog; private static final int REQUEST_EXTERNAL_STORAGE = 1; private static String[] PERMISSIONS_STORAGE = { Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE }; private boolean havePermission = false; private PickColorWindow pickColorWindow; private ColorData currentColor = new ColorData("#000000"); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); binding = ActivityMainBinding.inflate(getLayoutInflater()); Window window = getWindow(); window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS); window.setStatusBarColor(Color.TRANSPARENT); // 设置状态栏颜色为透明 window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN); setContentView(binding.getRoot()); binding.pickColor.setOnClickListener(v -> { showColorPickerDialog(); }); binding.clearButton.setOnClickListener(v -> { binding.signatureView.clear(); }); binding.saveButton.setOnClickListener(v -> { if (havePermission) { saveBitmap(binding.signatureView.getSignatureBitmap()); } else { checkPermission(); } }); } private void saveBitmap(Bitmap bitmap) { // 获取外部存储目录 String folderName = Environment.DIRECTORY_PICTURES; File file = new File(Environment.getExternalStoragePublicDirectory(folderName), "signature.png"); try { if (file.exists()) { file.delete(); } // 创建目录（如果不存在） file.getParentFile().mkdirs(); // 尝试创建文件 if (file.createNewFile()) { OutputStream os = new FileOutputStream(file); bitmap.compress(Bitmap.CompressFormat.PNG, 100, os); // 保存为PNG格式 os.close(); // 发送广播通知相册刷新 sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.fromFile(file))); Toast.makeText(MainActivity.this, "保存成功", Toast.LENGTH_SHORT).show(); } } catch (IOException e) { e.printStackTrace(); } } private void showColorPickerDialog() { if (pickColorWindow != null) { pickColorWindow.dismiss(); pickColorWindow = null; } pickColorWindow = new PickColorWindow(this, currentColor, (ColorData color) -> { currentColor = color; binding.signatureView.setColor(Color.parseColor(currentColor.getColorValue())); binding.viewColor.setBackgroundColor(Color.parseColor(currentColor.getColorValue())); }); pickColorWindow.showAsDropDown(binding.getRoot()); } private void checkPermission() { //检查权限（NEED_PERMISSION）是否被授权 PackageManager.PERMISSION_GRANTED表示同意授权 if (Build.VERSION.SDK_INT >= 30) { if (!Environment.isExternalStorageManager()) { if (dialog != null) { dialog.dismiss(); dialog = null; } dialog = new AlertDialog.Builder(this) .setTitle("提示")//设置标题 .setMessage("请开启文件访问权限，否则无法正常使用本应用！") .setNegativeButton("取消", (dialog, i) -> dialog.dismiss()) .setPositiveButton("确定", (dialog, which) -> { dialog.dismiss(); Intent intent = new Intent(Settings.ACTION_MANAGE_ALL_FILES_ACCESS_PERMISSION); startActivity(intent); }).create(); dialog.show(); } else { havePermission = true; saveBitmap(binding.signatureView.getSignatureBitmap()); Log.i("swyLog", "Android 11以上，当前已有权限"); } } else { if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) { if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) { //申请权限 if (dialog != null) { dialog.dismiss(); dialog = null; } dialog = new AlertDialog.Builder(this) .setTitle("提示")//设置标题 .setMessage("请开启文件访问权限，否则无法正常使用本应用！") .setPositiveButton("确定", (dialog, which) -> { dialog.dismiss(); ActivityCompat.requestPermissions(MainActivity.this, PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE); }).create(); dialog.show(); } else { havePermission = true; saveBitmap(binding.signatureView.getSignatureBitmap()); Log.i("swyLog", "Android 6.0以上，11以下，当前已有权限"); } } else { havePermission = true; saveBitmap(binding.signatureView.getSignatureBitmap()); Log.i("swyLog", "Android 6.0以下，已获取权限"); } } } @Override public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) { super.onRequestPermissionsResult(requestCode, permissions, grantResults); switch (requestCode) { case REQUEST_EXTERNAL_STORAGE: { if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { havePermission = true; saveBitmap(binding.signatureView.getSignatureBitmap()); Toast.makeText(this, "授权成功！", Toast.LENGTH_SHORT).show(); } else { havePermission = false; Toast.makeText(this, "授权被拒绝！", Toast.LENGTH_SHORT).show(); } return; } } } }