I have a series example of "Something about processing images in Android", but have show how to save the result bitmap to SD Card. This example modify from one of the example "Detect touch and free draw on Bitmap", add the function to save the result bitmap to External Storage, with file name "test.jpg".
layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
android:orientation="vertical"
tools:context="com.blogspot.android_er.androiddrawbitmap.MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:autoLink="web"
android:text="http://android-er.blogspot.com/"
android:textStyle="bold" />
<Button
android:id="@+id/loadimage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Load Image" />
<Button
android:id="@+id/saveimage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Save Image" />
<ImageView
android:id="@+id/result"
android:scaleType="centerInside"
android:adjustViewBounds="true"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@android:color/background_dark" />
</LinearLayout>
MainActivity.java
package com.blogspot.android_er.androiddrawbitmap;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
public class MainActivity extends AppCompatActivity {
Button btnLoadImage, btnSaveImage;
ImageView imageResult;
final int RQS_IMAGE1 = 1;
Uri source;
Bitmap bitmapMaster;
Canvas canvasMaster;
int prvX, prvY;
Paint paintDraw;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnLoadImage = (Button)findViewById(R.id.loadimage);
btnSaveImage = (Button)findViewById(R.id.saveimage);
imageResult = (ImageView)findViewById(R.id.result);
paintDraw = new Paint();
paintDraw.setStyle(Paint.Style.FILL);
paintDraw.setColor(Color.WHITE);
paintDraw.setStrokeWidth(10);
btnLoadImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Intent intent = new Intent(Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, RQS_IMAGE1);
}
});
btnSaveImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(bitmapMaster != null){
saveBitmap(bitmapMaster);
}
}
});
imageResult.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
int x = (int) event.getX();
int y = (int) event.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
prvX = x;
prvY = y;
drawOnProjectedBitMap((ImageView) v, bitmapMaster, prvX, prvY, x, y);
break;
case MotionEvent.ACTION_MOVE:
drawOnProjectedBitMap((ImageView) v, bitmapMaster, prvX, prvY, x, y);
prvX = x;
prvY = y;
break;
case MotionEvent.ACTION_UP:
drawOnProjectedBitMap((ImageView) v, bitmapMaster, prvX, prvY, x, y);
break;
}
/*
* Return 'true' to indicate that the event have been consumed.
* If auto-generated 'false', your code can detect ACTION_DOWN only,
* cannot detect ACTION_MOVE and ACTION_UP.
*/
return true;
}
});
}
/*
Project position on ImageView to position on Bitmap draw on it
*/
private void drawOnProjectedBitMap(ImageView iv, Bitmap bm,
float x0, float y0, float x, float y){
if(x<0 || y<0 || x > iv.getWidth() || y > iv.getHeight()){
//outside ImageView
return;
}else{
float ratioWidth = (float)bm.getWidth()/(float)iv.getWidth();
float ratioHeight = (float)bm.getHeight()/(float)iv.getHeight();
canvasMaster.drawLine(
x0 * ratioWidth,
y0 * ratioHeight,
x * ratioWidth,
y * ratioHeight,
paintDraw);
imageResult.invalidate();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Bitmap tempBitmap;
if(resultCode == RESULT_OK){
switch (requestCode){
case RQS_IMAGE1:
source = data.getData();
try {
//tempBitmap is Immutable bitmap,
//cannot be passed to Canvas constructor
tempBitmap = BitmapFactory.decodeStream(
getContentResolver().openInputStream(source));
Bitmap.Config config;
if(tempBitmap.getConfig() != null){
config = tempBitmap.getConfig();
}else{
config = Bitmap.Config.ARGB_8888;
}
//bitmapMaster is Mutable bitmap
bitmapMaster = Bitmap.createBitmap(
tempBitmap.getWidth(),
tempBitmap.getHeight(),
config);
canvasMaster = new Canvas(bitmapMaster);
canvasMaster.drawBitmap(tempBitmap, 0, 0, null);
imageResult.setImageBitmap(bitmapMaster);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
}
}
private void saveBitmap(Bitmap bm){
File file = Environment.getExternalStorageDirectory();
File newFile = new File(file, "test.jpg");
try {
FileOutputStream fileOutputStream = new FileOutputStream(newFile);
bm.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
fileOutputStream.flush();
fileOutputStream.close();
Toast.makeText(MainActivity.this,
"Save Bitmap: " + fileOutputStream.toString(),
Toast.LENGTH_LONG).show();
} catch (FileNotFoundException e) {
e.printStackTrace();
Toast.makeText(MainActivity.this,
"Something wrong: " + e.getMessage(),
Toast.LENGTH_LONG).show();
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(MainActivity.this,
"Something wrong: " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
}
}
"android.permission.WRITE_EXTERNAL_STORAGE" is needed in AndroidManifest.xml. Also I add android:largeHeap="true" to require more heap for the app. But if you have a really big image, it still will closed, caused by Out Of Memory!
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.blogspot.android_er.androiddrawbitmap">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:largeHeap="true"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
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more: Something about processing images in Android
