title: Android: digital signature using Bezier
body: <p><img src="https://i.stack.imgur.com/kZrzQ.jpg" alt="enter image description here"><br>
  I am trying two draw digital signature using Bezier as show in above image.when i touch and try to draw line then the result is dot line but not getting continuous line.
  Simple signature done by using <a href="http://corner.squareup.com/2010/07/smooth-signatures.html" rel="nofollow noreferrer">simple signature</a>
  but I want to create more a smooth curve using Bezier with touch pressure.
  <a href="http://corner.squareup.com/2012/07/smoother-signatures.html" rel="nofollow noreferrer">tried with this link</a></p>
  
  <p><strong>SignatureViewDemo.java</strong></p>
  
  <pre><code>    public class SignatureViewDemo extends View {
          private int color = Color.BLACK;
          private Bitmap m_Bitmap;
          private final Paint m_BorderPaint;
          private Canvas m_Canvas;
          private Point m_CropBotRight;
          private Point m_CropTopLeft;
          private float m_CurrentX;
          private float m_CurrentY;
          private final float m_DesiredDash;
          private float m_LastWidth = 6.5F;
          private Paint m_PenPaint;
          private int m_PointIndex = 0;
          private ArrayList&lt;Point&gt; m_Points = new ArrayList&lt;Point&gt;();
          private final float m_StrokeWidth;
          boolean m_Empty;
  
  
  
      public SignatureViewDemo(Context paramContext) {
  
          this(paramContext, null);
      }
  
      public SignatureViewDemo(Context paramContext,
              AttributeSet paramAttributeSet) {
          this(paramContext, paramAttributeSet, 0);
      }
  
      public SignatureViewDemo(Context paramContext,
              AttributeSet paramAttributeSet, int paramInt) {
          super(paramContext, paramAttributeSet, paramInt);
          setFocusable(true);
          this.m_PenPaint = new Paint();
          this.m_PenPaint.setAntiAlias(true);
          this.m_PenPaint.setColor(Color.BLACK);
          this.m_PenPaint.setStrokeWidth(5.0F);
          this.m_PenPaint.setStrokeJoin(Paint.Join.ROUND);
          this.m_PenPaint.setStrokeCap(Paint.Cap.ROUND);
          this.m_CurrentY = (0.0F / 0.0F);
          this.m_CurrentX = (0.0F / 0.0F);
          this.m_StrokeWidth = 5.0F;
          this.m_DesiredDash = 10.0F;
          this.m_BorderPaint = new Paint();
          this.m_BorderPaint.setColor(Color.BLACK);
          this.m_BorderPaint.setStyle(Paint.Style.STROKE);
          this.m_BorderPaint.setStrokeWidth(this.m_StrokeWidth);
      }
  
      public void addBezier(Bezier paramBezier, float paramFloat1,
              float paramFloat2) {
          if (this.m_Bitmap == null) {
              this.m_Bitmap = Bitmap.createBitmap(getWidth(), getHeight(),
                      Bitmap.Config.ARGB_8888);
              this.m_Canvas = new Canvas(this.m_Bitmap);
          }
          paramBezier.draw(this.m_Canvas, this.m_PenPaint, paramFloat1,
                  paramFloat2);
      }
  
      public void addPoint(Point paramPoint) {
          if ((paramPoint.getX() &lt; this.m_CropTopLeft.getX())
                  &amp;&amp; (paramPoint.getX() &gt;= 0.0F))
              this.m_CropTopLeft.setX(paramPoint.getX());
          if ((paramPoint.getY() &lt; this.m_CropTopLeft.getY())
                  &amp;&amp; (paramPoint.getY() &gt;= 0.0F))
              this.m_CropTopLeft.setY(paramPoint.getY());
          if ((paramPoint.getX() &gt; this.m_CropBotRight.getX())
                  &amp;&amp; (paramPoint.getX() &lt;= this.m_Canvas.getWidth()))
              this.m_CropBotRight.setX(paramPoint.getX());
          if ((paramPoint.getY() &gt; this.m_CropBotRight.getY())
                  &amp;&amp; (paramPoint.getY() &lt;= this.m_Canvas.getHeight()))
              this.m_CropBotRight.setY(paramPoint.getY());
          this.m_Points.add(paramPoint);
          drawPoints();
      }
  
      // public void clear() {
      // if (this.m_Canvas == null)
      // this.m_Canvas.drawColor(0, PorterDuff.Mode.CLEAR);
      // invalidate();
      // // return;
      // }
  
      public void clear() {
          if (this.m_Canvas == null)
              return;
          while (m_Empty) {
              m_Canvas.drawColor(0, PorterDuff.Mode.CLEAR);
              m_Empty = true;
              invalidate();
              return;
          }
      }
  
      public void drawBitmap(Bitmap paramBitmap) {
          clear();
          if ((paramBitmap != null) &amp;&amp; (this.m_Canvas != null)
                  &amp;&amp; (this.m_Canvas.getWidth() != 0)
                  &amp;&amp; (this.m_Canvas.getHeight() != 0)) {
              Matrix localMatrix = new Matrix();
              localMatrix.setRectToRect(
                      new RectF(0.0F, 0.0F, paramBitmap.getWidth(), paramBitmap
                              .getHeight()),
                      new RectF(0.0F, 0.0F, this.m_Canvas.getWidth(),
                              this.m_Canvas.getHeight()),
                      Matrix.ScaleToFit.CENTER);
              this.m_Canvas.drawBitmap(paramBitmap, localMatrix, null);
              m_Empty = false;
          }
          invalidate();
      }
  
      public void drawPoints() {
          if ((m_Points.size() &gt;= 4)
                  &amp;&amp; (4 + this.m_PointIndex &lt;= this.m_Points.size())) {
              Point localPoint1 = (Point) this.m_Points.get(this.m_PointIndex);
              Point localPoint2 = (Point) this.m_Points
                      .get(1 + this.m_PointIndex);
              Point localPoint3 = (Point) this.m_Points
                      .get(2 + this.m_PointIndex);
              Point localPoint4 = (Point) this.m_Points
                      .get(3 + this.m_PointIndex);
              Bezier localBezier = new Bezier(localPoint1, localPoint2,
                      localPoint3, localPoint4);
              localBezier.setColor(Color.GREEN);
              float f = strokeWidth(8.0F / localPoint4.velocityFrom(localPoint1));
              addBezier(localBezier, this.m_LastWidth, f);
              invalidate();
              this.m_LastWidth = f;
              this.m_PointIndex = (3 + this.m_PointIndex);
              m_Empty = false;
          }
      }
  
      public boolean isEmpty() {
          return m_Empty;
      }
  
      public Bitmap getBitmap() {
          return this.m_Bitmap;
      }
  
      public int getColor() {
          return this.color;
      }
  
      protected void onDraw(Canvas paramCanvas) {
          if (this.m_Bitmap != null)
              paramCanvas.drawBitmap(this.m_Bitmap, 0.0F, 0.0F, null);
      }
  
      protected void onMeasure(int paramInt1, int paramInt2) {
          int i = View.MeasureSpec.getSize(paramInt1);
          int j = View.MeasureSpec.getSize(paramInt2);
          this.m_CropTopLeft = new Point(i, j);
          this.m_CropBotRight = new Point(0.0F, 0.0F);
          setMeasuredDimension(i, j);
      }
  
      protected void onSizeChanged(int paramInt1, int paramInt2, int paramInt3,
              int paramInt4) {
          Bitmap localBitmap = Bitmap.createBitmap(paramInt1, paramInt2,
                  Bitmap.Config.ARGB_8888);
          this.m_Canvas = new Canvas(localBitmap);
          float f1 = 2.0F * (this.m_Canvas.getWidth() + this.m_Canvas.getHeight() - 2.0F * this.m_StrokeWidth);
          float f2 = f1
                  * this.m_DesiredDash
                  / (Math.round(f1 / (4.0F * this.m_DesiredDash)) * (4.0F * this.m_DesiredDash));
          Paint localPaint = this.m_BorderPaint;
          float[] arrayOfFloat = new float[2];
          arrayOfFloat[0] = f2;
          arrayOfFloat[1] = f2;
          localPaint.setPathEffect(new DashPathEffect(arrayOfFloat, f2 / 2.0F));
          clear();
          if (this.m_Bitmap != null) {
              Rect localRect = new Rect(0, 0, this.m_Canvas.getWidth(),
                      this.m_Canvas.getHeight());
              this.m_Canvas.drawBitmap(this.m_Bitmap, null, localRect, null);
              m_Empty = false;
          }
          this.m_Bitmap = localBitmap;
      }
  
      public boolean onTouchEvent(MotionEvent paramMotionEvent) {
          int i = 0xFF &amp; paramMotionEvent.getAction();
          if (i == 0) {
              this.m_CurrentX = paramMotionEvent.getX();
              this.m_CurrentY = paramMotionEvent.getY();
              addPoint(new Point(this.m_CurrentX, this.m_CurrentY,
                      paramMotionEvent.getEventTime()));
              getParent().requestDisallowInterceptTouchEvent(true);
          }
          // while (m_Empty) {
          if ((i == 1) || (i == 3)) {
              this.m_CurrentY = (0.0F / 0.0F);
              this.m_CurrentX = (0.0F / 0.0F);
              this.m_Points.clear();
              this.m_PointIndex = 0;
              getParent().requestDisallowInterceptTouchEvent(false);
          }
          // if ((this.m_Points.size() &lt; 4) || (4 + this.m_PointIndex &gt;
          // this.m_Points.size()))
          // while (1 + this.m_PointIndex &lt;= this.m_Points.size())
          drawPoints();
          if ((i == 2) || (i == 1)) {
              for (int j = 0; j &lt; paramMotionEvent.getHistorySize(); j++)
                  addPoint(new Point(paramMotionEvent.getHistoricalX(j),
                          paramMotionEvent.getHistoricalY(j),
                          paramMotionEvent.getHistoricalEventTime(j)));
              addPoint(new Point(paramMotionEvent.getX(),
                      paramMotionEvent.getY(), paramMotionEvent.getEventTime()));
  
          }
          // }
          return true;
      }
  
      public void setColor(int paramInt) {
          this.color = Color.BLACK;
      }
  
      public Point getCropBotRight() {
          return this.m_CropBotRight;
      }
  
      public Point getCropTopLeft() {
          return this.m_CropTopLeft;
      }
  
      // public float strokeWidth(float paramFloat) {
      // if (paramFloat &gt; 11.0F)
      // paramFloat = 10.0F;
      // if (paramFloat &lt; 5.0F)
      // paramFloat = 6.0F;
      // return paramFloat;
      // }
  
      public float strokeWidth(float paramFloat) {
          if (paramFloat &gt; 11.0F)
              paramFloat = 10.0F;
          while (m_Empty) {
              if (paramFloat &lt; 5.0F)
                  paramFloat = 6.0F;
              return paramFloat;
          }
          return paramFloat;
      }
  
  }
  </code></pre>
  
  <p><strong>Point.java</strong></p>
  
  <pre><code>    private long time;
      private float x;
      private float y;
  
      public Point(float paramFloat1, float paramFloat2) {
          this.x = paramFloat1;
          this.y = paramFloat2;
      }
  
      public Point(float paramFloat1, float paramFloat2, long paramLong) {
          this.x = paramFloat1;
          this.y = paramFloat2;
          this.time = paramLong;
      }
  
      protected float distanceTo(Point paramPoint) {
          float f1 = this.x - paramPoint.getX();
          float f2 = this.y - paramPoint.getY();
          return FloatMath.sqrt(f1 * f1 + f2 * f2);
      }
  
      public long getTime() {
          return this.time;
      }
  
      public float getX() {
          return this.x;
      }
  
      public float getY() {
          return this.y;
      }
  
      public void setX(float paramFloat) {
          this.x = paramFloat;
      }
  
      public void setY(float paramFloat) {
          this.y = paramFloat;
      }
  
      public float velocityFrom(Point paramPoint) {
              return distanceTo(paramPoint) / (this.time - paramPoint.time);
      }
  }
  </code></pre>
  
  <p><strong>Bezier.java</strong></p>
  
  <pre><code>public class Bezier {
  private Point controlPointOne;
  private Point controlPointTwo;
  private int drawSteps;
  private Point endPoint;
  private int mColor;
  private Point startPoint;
  
  public Bezier() {
  }
  
  public Bezier(Point paramPoint1, Point paramPoint2, Point paramPoint3,
          Point paramPoint4) {
      this.startPoint = paramPoint1;
      this.controlPointOne = paramPoint2;
      this.controlPointTwo = paramPoint3;
      this.endPoint = paramPoint4;
      this.drawSteps = ((int) (paramPoint1.distanceTo(paramPoint2)
              + paramPoint2.distanceTo(paramPoint3) + paramPoint3
              .distanceTo(paramPoint4)));
  }
  
  public void draw(Canvas paramCanvas, Paint paramPaint, float paramFloat1,
          float paramFloat2) {
      float f1 = paramFloat2 - paramFloat1;
      for (int i = 0; i &lt; this.drawSteps; i++) {
          float f2 = i / this.drawSteps;
          float f3 = f2 * f2;
          float f4 = f3 * f2;
          float f5 = 1.0F - f2;
          float f6 = f5 * f5;
          float f7 = f6 * f5;
          float f8 = f7 * this.startPoint.getX() + f2 * (3.0F * f6)
                  * this.controlPointOne.getX() + f3 * (3.0F * f5)
                  * this.controlPointTwo.getX() + f4 * this.endPoint.getX();
          float f9 = f7 * this.startPoint.getY() + f2 * (3.0F * f6)
                  * this.controlPointOne.getY() + f3 * (3.0F * f5)
                  * this.controlPointTwo.getY() + f4 * this.endPoint.getY();
          paramPaint.setColor(getColor());
          paramPaint.setStrokeWidth(paramFloat1 + f4 * f1);
          paramCanvas.drawPoint(f8, f9, paramPaint);
      }
  }
  
  public int getColor() {
      return this.mColor;
  }
  
  public Point getControlPointOne() {
      return this.controlPointOne;
  }
  
  public Point getControlPointTwo() {
      return this.controlPointTwo;
  }
  
  public int getDrawSteps() {
      return this.drawSteps;
  }
  
  public Point getEndPoint() {
      return this.endPoint;
  }
  
  public Point getStartPoint() {
      return this.startPoint;
  }
  
  public void setColor(int paramInt) {
      this.mColor = Color.BLACK;
  }
  
  public void setControlPointOne(Point paramPoint) {
      this.controlPointOne = paramPoint;
  }
  
  public void setControlPointTwo(Point paramPoint) {
      this.controlPointTwo = paramPoint;
  }
  
  public void setDrawSteps(int paramInt) {
      this.drawSteps = paramInt;
  }
  
  public void setEndPoint(Point paramPoint) {
      this.endPoint = paramPoint;
  }
  
  public void setStartPoint(Point paramPoint) {
      this.startPoint = paramPoint;
  }
  </code></pre>
  
  <p>}</p>