Android Scale View

Scale is an android application to measure things with excellent UI which makes you feel like you are working with a scale, which has not measurement limit.
A scale is shown, user can scroll it and select any reading according to one’s weight or height etc.
Scale
Create a class Scale.java and extend this class with View class. All logics will be done in overide method onDraw(Canvas canvas) of view class, ehere we pla with the canvas to draw scale.

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.view.View;

import java.text.DecimalFormat;

/** * Created by Sanjay on 30/6/16. */

public class Scale extends View {


    private String TAG = "Scale";



    private int pxPerMM = 20;
    int width, height;
    float startingPoint = 0;

    private Paint rulerPaint, textPaint;
    private int endPoint;
    private int scaleLineSmall;
    private int scaleLineMedium;
    private int scaleLineLarge;
    private int textStartPoint;

    private Rect rect;
    private OnScaleUpdate scaleUpdate;

    private int startCm = 0;
    private int maxCm = 100;
    private String unit = " cm";

    public Scale(Context context) {
        super(context);
        if (!isInEditMode()) {
            init();
        }
    }

    public Scale(Context context, AttributeSet foo) {
        super(context, foo);
        if (!isInEditMode()) {
            init();
        }
    }

    private void init() {
        rect = new Rect();

        rulerPaint = new Paint();
        rulerPaint.setStyle(Paint.Style.STROKE);
        rulerPaint.setStrokeWidth(0);
        rulerPaint.setAntiAlias(false);
        rulerPaint.setColor(Color.WHITE);

        textPaint = new TextPaint();
        textPaint.setStyle(Paint.Style.FILL);
        textPaint.setStrokeWidth(0);
        textPaint.setAntiAlias(true);
        textPaint.setTextSize(getResources().getDimension(R.dimen.txt_size));
        textPaint.setColor(Color.WHITE);

        scaleLineSmall = (int) getResources()

                                 .getDimension(R.dimen.scale_line_small);
        scaleLineMedium = (int) getResources()

                                 .getDimension(R.dimen.scale_line_medium);
        scaleLineLarge = (int) getResources()

                                 .getDimension(R.dimen.scale_line_large);
        textStartPoint = (int) getResources()

                                 .getDimension(R.dimen.text_start_point);

    }

    @Override    

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        setMeasuredDimension(widthMeasureSpec, 

                                (int) ((maxCm - startCm) * 10 * pxPerMM));

    }

    @Override    

    public void onSizeChanged(int w, int h, int oldW, int oldH) {
        width = w;
        height = h;
        endPoint = width;

    }

    @Override    

    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        startingPoint = 0;

        for (int i = (startCm *10)+1; i < (maxCm * 10); ++i) {
            startingPoint = startingPoint + pxPerMM;
            int size = (i % 10 == 0) ? scaleLineLarge : (i % 5 == 0) ? 

                                              scaleLineMedium : scaleLineSmall;
            canvas.drawLine(endPoint - size, startingPoint, endPoint, 

                                              startingPoint, rulerPaint);
            if (i % 10 == 0) {
                canvas.drawText((i / 10) + unit, endPoint - textStartPoint, 

                                              startingPoint + 8, textPaint);
            }
        }

        canvas.getClipBounds(rect);
        float h = ((rect.bottom - rect.top) / 2);
        float selected = (rect.top + h) / (pxPerMM * 10) + startCm;
        selected = Float.parseFloat(

                         new DecimalFormat("#####.#").format(selected));

        if (scaleUpdate != null) {
            scaleUpdate.onScaleSelected(selected);
        }
    }


    public void setScaleUpdate(OnScaleUpdate l) {
        scaleUpdate = l;
    }

    public void setMaxCm(int maxCm) {
        this.maxCm = maxCm;
    }

    public void setStartCm(int startCm){
        this.startCm = startCm;
    }

    public void setUnit(String unit){
        this.unit = unit;
    }

    public void setPxPerMM(int pxPerMM) {
        this.pxPerMM = pxPerMM;
    }

}

Use Scale.java class in your xml to create the view like

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout 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:orientation="horizontal"    

    tools:context="com.aubergine.scale.MainActivity">

    <ScrollView        

        android:id="@+id/scroll"        

        android:layout_width="wrap_content"        

        android:layout_height="match_parent"        

        android:fadingEdge="none"        

        android:scrollbars="none">

        <com.aubergine.scale.Scale            

            android:id="@+id/scale"            

            android:layout_width="100dp"            

            android:layout_height="match_parent"            

            android:background="#c2c2c2" />
    </ScrollView>

    <ImageView        

            android:layout_width="60dp"        

            android:layout_height="60dp"        

            android:layout_centerVertical="true"        

            android:layout_marginLeft="-20dp"        

            android:src="@drawable/select_height" />

    <TextView        

            android:id="@+id/tv_result"        

            android:layout_width="wrap_content"        

            android:layout_height="wrap_content"        

            android:layout_centerVertical="true"        

            android:layout_marginLeft="10dp"        

            android:layout_toRightOf="@+id/scroll"        

            android:padding="5dp"        

            android:text="----cm"        

            android:textSize="20dp" />

</RelativeLayout>

MainActivity class

public class MainActivity extends AppCompatActivity {

    @Override    
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Scale scale = (Scale)findViewById(R.id.scale);
        final TextView tvResult = (TextView)findViewById(R.id.tv_result);
        scale.setStartCm(21);
        scale.setPxPerMM(50);
        scale.setScaleUpdate(new OnScaleUpdate() {
            @Override            
            public void onScaleSelected(float result) {
                tvResult.setText(result + " cm");
            }
        });
    }
}

Thats all!
A scale will be shown and you can select any reading just by scrolling it.

Full code is here.