How to rotate Canvas in Android

In this android programming source code example, we are going to rotate Canvas in Android.

You can copy and adopt this source code example to your android project without reinventing the wheel.

Below is a step by step source code to rotate Canvas in Android.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relativeLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <RelativeLayout
        android:id="@+id/canvas"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/rotate"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent"
        android:textColor="#ffffff"
        android:layout_alignParentBottom="true"
        android:text="Rotate"/>

</RelativeLayout>

MainActivity.java

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;


public class CanvasActivity15 extends AppCompatActivity {
    private RelativeLayout view;
    private Button rotate;
    private canvas15 customcanvas;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_canvas15);
        view = (RelativeLayout) findViewById(R.id.canvas);
        rotate = (Button) findViewById(R.id.rotate);
        customcanvas = new canvas15(CanvasActivity15.this, null);
        view.addView(customcanvas);
        rotate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                customcanvas.rotateCanvas();
            }
        });
    }

    public static class canvas15 extends View {
        private Paint paint;
        private Canvas mcanvas;
        private boolean cc = false;
        public canvas15(Context context, AttributeSet attributeSet){
            super(context, attributeSet);
            paint = new Paint();
            paint.setColor(getResources().getColor(R.color.colorAccent));
            paint.setStrokeWidth(10);
            paint.setStyle(Paint.Style.STROKE);
        }

        @Override
        protected void onDraw(Canvas canvas){
            super.onDraw(canvas);
            mcanvas = canvas;
            if(cc){
                mcanvas.save();
                mcanvas.rotate(25, mcanvas.getWidth()/2, mcanvas.getHeight()/2);
                mcanvas.drawRect(50,50,200,200, paint);
                mcanvas.restore();
            }else{
                mcanvas.drawRect(50,50,200,200, paint);
                cc = false;
            }
        }

        public void rotateCanvas(){
            cc = true;
            invalidate();
        }
    }
}

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