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Monday, 19 August 2013

Draw text on bitmap using Canvas.drawText()

06:47
Example to draw text on bitmap using Canvas.drawText() method.

Draw text on bitmap using Canvas.drawText()


package com.example.androiddrawtextonbitmap;

import java.io.FileNotFoundException;

import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
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.graphics.Bitmap.Config;
import android.graphics.Paint.Style;
import android.graphics.Rect;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

Button btnLoadImage1;
TextView textSource1;
EditText editTextCaption;
Button btnProcessing;
ImageView imageResult;

final int RQS_IMAGE1 = 1;

Uri source1;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

btnLoadImage1 = (Button)findViewById(R.id.loadimage1);
textSource1 = (TextView)findViewById(R.id.sourceuri1);
editTextCaption = (EditText)findViewById(R.id.caption);
btnProcessing = (Button)findViewById(R.id.processing);
imageResult = (ImageView)findViewById(R.id.result);

btnLoadImage1.setOnClickListener(new 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);
}});

btnProcessing.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {

if(source1 != null){
Bitmap processedBitmap = ProcessingBitmap();
if(processedBitmap != null){
imageResult.setImageBitmap(processedBitmap);
Toast.makeText(getApplicationContext(),
"Done",
Toast.LENGTH_LONG).show();
}else{
Toast.makeText(getApplicationContext(),
"Something wrong in processing!",
Toast.LENGTH_LONG).show();
}
}else{
Toast.makeText(getApplicationContext(),
"Select both image!",
Toast.LENGTH_LONG).show();
}

}});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == RESULT_OK){
switch (requestCode){
case RQS_IMAGE1:
source1 = data.getData();
textSource1.setText(source1.toString());
break;
}
}
}

private Bitmap ProcessingBitmap(){
Bitmap bm1 = null;
Bitmap newBitmap = null;

try {
bm1 = BitmapFactory.decodeStream(
getContentResolver().openInputStream(source1));

Config config = bm1.getConfig();
if(config == null){
config = Bitmap.Config.ARGB_8888;
}

newBitmap = Bitmap.createBitmap(bm1.getWidth(), bm1.getHeight(), config);
Canvas newCanvas = new Canvas(newBitmap);

newCanvas.drawBitmap(bm1, 0, 0, null);

String captionString = editTextCaption.getText().toString();
if(captionString != null){

Paint paintText = new Paint(Paint.ANTI_ALIAS_FLAG);
paintText.setColor(Color.BLUE);
paintText.setTextSize(50);
paintText.setStyle(Style.FILL);
paintText.setShadowLayer(10f, 10f, 10f, Color.BLACK);

Rect rectText = new Rect();
paintText.getTextBounds(captionString, 0, captionString.length(), rectText);

newCanvas.drawText(captionString,
0, rectText.height(), paintText);

Toast.makeText(getApplicationContext(),
"drawText: " + captionString,
Toast.LENGTH_LONG).show();

}else{
Toast.makeText(getApplicationContext(),
"caption empty!",
Toast.LENGTH_LONG).show();
}

} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

return newBitmap;
}

}


Layout
<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context=".MainActivity" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="http://android-er.blogspot.com/"
android:textStyle="bold"
android:layout_gravity="center_horizontal"
android:autoLink="web" />

<Button
android:id="@+id/loadimage1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Load Image 1" />
<TextView
android:id="@+id/sourceuri1"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/caption"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/processing"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Draw text on Bitmap" />
<ImageView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="match_parent" />

</LinearLayout>


download filesDownload the files.

If you simple want to display TextView over ImageView only, refer to next exercise.


more: Something about processing images in Android

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