# Rotate Bitmap

, 27 Aug 2013
 Rate this:
Rotate bitmap

## Introduction

Today, I will guide a snippet code to create a new bitmap by rotating an original bitmap by using Canvas.

Besides that, if you want to cut bitmap, please refer to this tip. And if you want to combine many bitmaps into one, please refer to this tip.

## Using the Code

To rotate bitmap by using canvas, focus on the function below:

`public void drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint) `

The main point to rotate is `matrix`, with method:

`matrix.postRotate(angle, x, y);  `
• `angle`: the angle will be rotated
• `x,y`: the coordinate of anchor point to rotate on

With the above explanation, to rotate bitmap with anchor point as center, anchor point will be `(bitmap.width/2, bitmap.height/2)`.

```private Bitmap rotateBitmap(float angle) {
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.original);
Bitmap rotateBitmap = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(rotateBitmap);
Matrix matrix = new Matrix();
matrix.postRotate(angle, bitmap.getWidth() / 2, bitmap.getHeight() / 2);
canvas.drawBitmap(bitmap, matrix, null);
return rotateBitmap;
}  ```

And rotate bitmap with anchor point is (left, top), anchor point will be (0, 0)

```private Bitmap rotate(Bitmap bitmap, float angle) {
Bitmap rotateBitmap = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(rotateBitmap);
Matrix matrix = new Matrix();
matrix.postRotate(angle, 0, 0);
canvas.drawBitmap(bitmap, matrix, new Paint());
return rotateBitmap;
}```

## History

• 2013-08-27: Created
• 2013-08-27: Updated to clear more about the anchor point, following the comment from users
• 2013-08-28: Changed the link name to download source code

## About the Author

Vietnam
I'm Java developer.
I started Java web coding from 2007 to 2010. After that, I began to develop Android from 2010 to now.
In my thinking, sharing and connecting is the best way to develop.
I would like to study more via yours comments and would like to have relationship with more developers in the world.

## Comments and Discussions

 First Prev Next
 My vote of 1 Andre Luiz V Sanches 27-Aug-13 3:00
 Re: My vote of 1 huyletran 27-Aug-13 3:37
 Last Visit: 31-Dec-99 18:00     Last Update: 31-Aug-14 21:44 Refresh 1

General    News    Suggestion    Question    Bug    Answer    Joke    Rant    Admin

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Mobile
Web03 | 2.8.140827.1 | Last Updated 27 Aug 2013
Article Copyright 2013 by huyletran