Sunday, July 18, 2010

Rotate bitmap image, using Matrix

Here Rotating function is going to be added on the last exercise "Scale bitmap image, using Matrix". It's a SeekBar on the screen to change the degree to rotate the bitmap, by using of Matrix.postRotate().

Rotate bitmap image, using Matrix

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Spinner
android:id="@+id/scale"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<SeekBar
android:id="@+id/rotate"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="5px"
android:max="360"
android:progress="0"
/>
<ImageView
android:id="@+id/imageview"
android:layout_gravity="center"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="center"
/>
</LinearLayout>


AndroidBitmap.java

package com.exercise.AndroidBitmap;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.Spinner;

public class AndroidBitmap extends Activity {

private final String imageInSD = "/sdcard/er.PNG";

ImageView myImageView;
Spinner spinnerScale;
SeekBar seekbarRotate;

private static final String[] strScale
= {"0.2x", "0.5x", "1.0x", "2.0x", "5.0x"};
private static final Float[] floatScale
= {0.2F, 0.5F, 1F, 2F, 5F};
private final int defaultSpinnerScaleSelection = 2;

private ArrayAdapter<String> adapterScale;

private float curScale = 1F;
private float curRotate = 0F;

Bitmap bitmap;
int bmpWidth, bmpHeight;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

myImageView = (ImageView)findViewById(R.id.imageview);

spinnerScale = (Spinner)findViewById(R.id.scale);
seekbarRotate = (SeekBar)findViewById(R.id.rotate);

adapterScale = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, strScale);
adapterScale.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerScale.setAdapter(adapterScale);
spinnerScale.setSelection(defaultSpinnerScaleSelection);
curScale = floatScale[defaultSpinnerScaleSelection];

bitmap = BitmapFactory.decodeFile(imageInSD);
bmpWidth = bitmap.getWidth();
bmpHeight = bitmap.getHeight();

drawMatrix();

spinnerScale.setOnItemSelectedListener(spinnerScaleOnItemSelectedListener);
seekbarRotate.setOnSeekBarChangeListener(seekbarRotateSeekBarChangeListener);

}

private void drawMatrix(){

Matrix matrix = new Matrix();
matrix.postScale(curScale, curScale);
matrix.postRotate(curRotate);

Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0, bmpWidth, bmpHeight, matrix, true);
myImageView.setImageBitmap(resizedBitmap);

}

private SeekBar.OnSeekBarChangeListener seekbarRotateSeekBarChangeListener
= new SeekBar.OnSeekBarChangeListener(){

@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// TODO Auto-generated method stub
curRotate = (float)progress;
drawMatrix();
}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub

}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub

}};

private Spinner.OnItemSelectedListener spinnerScaleOnItemSelectedListener
= new Spinner.OnItemSelectedListener(){

@Override
public void onItemSelected(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
// TODO Auto-generated method stub
curScale = floatScale[arg2];
drawMatrix();
}

@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
spinnerScale.setSelection(defaultSpinnerScaleSelection);
curScale = floatScale[defaultSpinnerScaleSelection];
}};
}



Download the files.

next: Skew bitmap image, using Matrix

3 comments:

Vipin said...

Nice example...
But can you help me on how to crop an image.

davender said...
This comment has been removed by the author.
davender said...

This Work only when we have Width And Height of ImageView fill_parent.
If we change them its rotation does not remain fine.