Hello everyone, I am learning Android recently and would like to share some of the results I have learned~~~
Go directly to the code:
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
public class PhotoTakeActivity extends AppCompatActivity {
private boolean isPreview = false;//Whether it is in preview state, false means not in preview state
private Camera camera; //Define a camera object
private Button bt1; //Photo button
private Button bt2;//Preview button
//------------------------------------------------Add watermark
Bitmap realBitmap;//The real photo after synthesis
TextView textView;//used to display location information
String str0;//Save the location information, the text to be added to the photo, that is, the watermark
String str1;//Save the location information, the text to be added to the photo, that is, the watermark
String str2;//Save the location information, the text to be added to the photo, that is, the watermark
String str3;//Save the location information, the text to be added to the photo, that is, the watermark
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_takephotos);
bt1 = findViewById(R.id.bt1); //Photo button
bt2 = findViewById(R.id.bt2);//Preview button
textView = findViewById(R.id.textView);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);//Set full screen display
if (!android.os.Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
Toast.makeText(this, "Please install SD card", Toast.LENGTH_LONG).show();
}//Determine whether the mobile phone has an SD card installed
//Location
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
//Code for permission checking
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED & amp; & amp; ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,//Specify the provider of GPS positioning
1000,//Interval time
1,//position interval is 1 meter
new LocationListener() {//Listen to whether the GPS positioning information changes
@Override
public void onLocationChanged(Location location) {//Method called when GPS positioning information changes
}
public void onStatusChanged(String provider, int status, Bundle extras) {//Method called when the GPS positioning status changes
}
public void onProviderEnabled(String provider) {//Called when the positioning provider starts
}
public void onProviderDisabled(String provider) {//Triggered when the positioning provider is closed
throw new RuntimeException("Stub!");
}
}
);
//Get the latest positioning information
Location location = locationManager.getLastKnownLocation((LocationManager.GPS_PROVIDER));
locationUpdates(location);//Pass the latest location information to this method
//Open the camera and preview
SurfaceView surfaceView = (SurfaceView) findViewById(R.id.surfaceview); //Used to display camera preview
SurfaceHolder surfaceHolder = surfaceView.getHolder();//Get SurfaceHolder
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//Set SurfaceView to maintain its own buffer
bt2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (!isPreview)//It is now a non-preview state
{
camera = Camera.open();//Open the camera
isPreview = true; //Set to preview state
}
try {
camera.setPreviewDisplay(surfaceHolder);//Set the SurfaceView used to display the preview
Camera.Parameters parameters = camera.getParameters();//Get camera parameters
parameters.setPictureFormat(PixelFormat.JPEG);//Set the picture to a JPG picture
parameters.set("jpeg-quality", 80);//Set the quality of the picture
camera.setParameters(parameters);//Reset camera parameters
camera.startPreview();//Start preview
camera.autoFocus(null);//Set auto focus
} catch (IOException e) {
throw new RuntimeException(e);
}
}
});
//Get the photo button to implement the photo function
bt1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (camera != null) {
camera.takePicture(null, null, jpeg); // Take pictures
}
}
});
}
//Get the latitude and longitude
public void locationUpdates(Location location) {
if (location != null)//location is used to obtain location information
{
StringBuilder stringBuilder = new StringBuilder();//Create a string builder to record positioning information
stringBuilder.append("Your location is:\\
");
stringBuilder.append("Longitude:");
stringBuilder.append(location.getLongitude());
stringBuilder.append("\\
Dimension:");
stringBuilder.append(location.getLatitude());
stringBuilder.append("\\
Altitude:");
stringBuilder.append(location.getAltitude());
str0 = "Your location is:";
str1 = "Longitude:" + location.getLongitude();
str2 = "Latitude:" + location.getLatitude();
str3 = "Altitude:" + location.getAltitude();
textView.setText(stringBuilder.toString());//Display on the page
} else {
textView.setText("No GPS information obtained");
}
}
//Camera
final Camera.PictureCallback jpeg = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] bytes, Camera camera) {
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);//Create a bitmap based on the data obtained from the photo
camera.stopPreview();//Stop preview
isPreview = false; //Set to non-preview state
realBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(realBitmap);
Paint paint = new Paint();
paint.setColor(Color.YELLOW);
paint.setTextSize(90);
paint.setAntiAlias(true);
canvas.drawBitmap(bitmap, 0, 0, null);
canvas.save();
Canvas canvas1 = new Canvas(realBitmap);
canvas1.drawText(str0, realBitmap.getWidth() / 2, realBitmap.getHeight() / 2, paint);
canvas1.drawText(str1, realBitmap.getWidth() / 2, realBitmap.getHeight() / 2 + 100, paint);
canvas1.drawText(str2, realBitmap.getWidth() / 2, realBitmap.getHeight() / 2 + 200, paint);
canvas1.drawText(str3, realBitmap.getWidth() / 2, realBitmap.getHeight() / 2 + 300, paint);
canvas1.save();
//Get the location where photos are saved in the SD card
File appDir = new File(Environment.getExternalStorageDirectory(), "/DCIM/Camera/");
if (!appDir.exists()) {
appDir.mkdir(); //Create the directory if it does not exist
}
String fileName = System.currentTimeMillis() + ".jpg";//Set the current system time to the photo name
File file = new File(appDir, fileName);//Create file object
try {//Save the captured picture
FileOutputStream fos = new FileOutputStream(file);//Create a file output stream object
realBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);//Compress the image content into JPEG format and output it to the output stream
//bitmap.compress(Bitmap.CompressFormat.JPEG,100,fos);//Compress the image content into JPEG format and output it to the output stream
fos.flush();//Write all the data in the buffer to the output stream
fos.close();//Close the file output stream object
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
//Insert the photo into the system gallery
try {
MediaStore.Images.Media.insertImage(PhotoTakeActivity.this.getContentResolver(), file.getAbsolutePath(), fileName, null);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
//Final notification gallery update
PhotoTakeActivity.this.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + "")));
Toast.makeText(PhotoTakeActivity.this, "Save photos to:" + file, Toast.LENGTH_LONG).show();
resetCamera();//Reset camera preview
}
};
private void resetCamera() {
if (!isPreview) {
camera.startPreview();//Start preview
isPreview = true;
}
}
protected void onPause() {
super.onPause();
//Stop preview and release camera resources
if (camera != null) {
camera.stopPreview();//Stop preview
camera.release();//Release resources
}
}
}
Finally, let’s summarize the pitfalls I encountered: (1) If the drawing coordinates passed in by Bitmap’s drawText method are (0,0), the watermark will definitely not be displayed because it is drawn elsewhere, so to be conservative, If you set the coordinates to half the width and height of the Bitmap and draw it, you will definitely be able to see it. (2) Bitmap must be created through the Bitmap.createBitmap() method in order for the pixels to be changeable. Only Bitmaps with changeable pixels can be passed into the Canvas object.