# Solution to Challenge: Saving State and Rotating Box

#1

I took some idea from previous posts and selected the code that’s shorter and easier to read.

Box.java

``````import android.graphics.PointF;

public class Box {
private PointF mOrigin;
private PointF mCurrent;
private PointF mPointerOrigin;
private float  angle;

public Box(PointF origin){
mOrigin = origin;
mCurrent = origin;
}

public PointF getPointerOrigin() {
return mPointerOrigin;
}

public void setPointerOrigin(PointF pointerOrigin) {
mPointerOrigin = pointerOrigin;
}

public float getAngle() {
return angle;
}

public void setAngle(float angle) {
this.angle = angle;
}

public PointF getCurrent(){
return mCurrent;
}

public void setCurrent(PointF current){
mCurrent=current;
}

public PointF getOrigin() {
return mOrigin;
}
}
``````

BoxDrawingView.Java

``````import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PointF;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

import java.util.ArrayList;
import java.util.List;
import java.util.jar.Attributes;

public class BoxDrawingView extends View {
private static final String TAG = "BoxDrawingView";
private Box mCurrentBox;
private List<Box> mBoxen = new ArrayList<>();
private Paint mBoxPaint;
private Paint mBackgroundPaint;

public BoxDrawingView(Context context) {
this(context,null);
}

public BoxDrawingView(Context context, AttributeSet attrs){
super(context, attrs);

mBoxPaint = new Paint();
mBoxPaint.setColor(0x22ff0000);

mBackgroundPaint = new Paint();
mBackgroundPaint.setColor(0xfff8efe0);
}

@Override
public boolean onTouchEvent(MotionEvent event) {

PointF touchPoint  = null;
PointF touchPoint2 = null;
for (int i=0;i<event.getPointerCount();i++) {
if(event.getPointerId(i)==0)
touchPoint = new PointF(event.getX(i), event.getY(i));
if(event.getPointerId(i)==1)
touchPoint2 = new PointF(event.getX(i), event.getY(i));
}

case MotionEvent.ACTION_DOWN:
mCurrentBox = new Box(touchPoint);
break;
case MotionEvent.ACTION_POINTER_DOWN:
mCurrentBox.setPointerOrigin(touchPoint2);
break;
case MotionEvent.ACTION_MOVE:
if(touchPoint  != null )
mCurrentBox.setCurrent(touchPoint);
if(touchPoint2 != null ) {
PointF boxOrigin     = mCurrentBox.getOrigin();
PointF pointerOrigin = mCurrentBox.getPointerOrigin();
float angle2 = (float) Math.atan2(touchPoint2.y   - boxOrigin.y, touchPoint2.x   - boxOrigin.x);
float angle1 = (float) Math.atan2(pointerOrigin.y - boxOrigin.y, pointerOrigin.x - boxOrigin.x);
float calculatedAngle = (float) Math.toDegrees(angle2 - angle1);
if (calculatedAngle < 0) calculatedAngle += 360;
mCurrentBox.setAngle(calculatedAngle);
Log.d(TAG, "Set Box Angle " + calculatedAngle);
}
invalidate();
break;
case MotionEvent.ACTION_UP:
Log.d(TAG, "Finger UP Box Set");
mCurrentBox = null;
break;
case MotionEvent.ACTION_CANCEL:
Log.d(TAG, "Action Cancel Box Set");
mCurrentBox = null;
break;
}

return true;
}

@Override
protected void onDraw(Canvas canvas) {
canvas.drawPaint(mBackgroundPaint);

for(Box box:mBoxen){
float left   = Math.min(box.getOrigin().x,box.getCurrent().x);
float right  = Math.max(box.getOrigin().x,box.getCurrent().x);
float top    = Math.min(box.getOrigin().y,box.getCurrent().y);
float bottom = Math.max(box.getOrigin().y,box.getCurrent().y);

float angle = box.getAngle();
float px = (box.getOrigin().x+box.getCurrent().x)/2;
float py = (box.getOrigin().y+box.getCurrent().y)/2;
canvas.save();
canvas.rotate(angle, px, py);
canvas.drawRect(left, top, right, bottom, mBoxPaint);
canvas.restore();
}
}

@Override
public Parcelable onSaveInstanceState() {
Log.d(TAG,"Saving Instance State");
Parcelable superState = super.onSaveInstanceState();
SavedState ss = new SavedState(superState);
ss.mBoxList = mBoxen;

return ss;
}

@Override
public void onRestoreInstanceState(Parcelable state) {

SavedState ss = (SavedState) state;
super.onRestoreInstanceState(ss.getSuperState());
Log.d(TAG,"Restoring Instance State");
mBoxen = ss.mBoxList;
}

private static class SavedState extends BaseSavedState {
private List<Box> mBoxList ;

public SavedState(Parcelable superState) {
super(superState);
Log.d(TAG,"Saving parcelable");
}
}
}
``````

fragment_drag_and_draw.xml

``````<com.shaodw_wxh.www.draganddraw.BoxDrawingView
xmlns:android = "http://schemas.android.com/apk/res/android"
android:id="@+id/box_drawing_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>``````