Question

我正在开发Android应用程序。在我的项目中，我有一个关于签名捕获的任务，即用户应将他/她的签名保留在移动设备的屏幕上，并且一次保存按钮单击签名必须存储在数据库中。我搜索并找到了一些链接，但我仍然没有找到确切的解决方案。我也试过TouchPaint.java，但在那里我找不到布局的xml文件。你能用一些示例代码向我们建议吗？我会感激你的....

Answer 1

以下是Has AlTaiar的C＃签名视图的Java版本，花了一些时间让它正常工作

public class CaptureSignatureView extends View {

    private Bitmap _Bitmap;
    private Canvas _Canvas;
    private Path _Path;
    private Paint _BitmapPaint;
    private Paint _paint;
    private float _mX;
    private float _mY;
    private float TouchTolerance = 4;
    private float LineThickness = 4;

    public CaptureSignatureView(Context context, AttributeSet attr) {
        super(context, attr);
        _Path = new Path();
        _BitmapPaint = new Paint(Paint.DITHER_FLAG);
        _paint = new Paint();
        _paint.setAntiAlias(true);
        _paint.setDither(true);
        _paint.setColor(Color.argb(255, 0, 0, 0));
        _paint.setStyle(Paint.Style.STROKE);
        _paint.setStrokeJoin(Paint.Join.ROUND);
        _paint.setStrokeCap(Paint.Cap.ROUND);
        _paint.setStrokeWidth(LineThickness);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        _Bitmap = Bitmap.createBitmap(w, (h > 0 ? h : ((View) this.getParent()).getHeight()), Bitmap.Config.ARGB_8888);
        _Canvas = new Canvas(_Bitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.WHITE);
        canvas.drawBitmap(_Bitmap, 0, 0, _BitmapPaint);
        canvas.drawPath(_Path, _paint);
    }

    private void TouchStart(float x, float y) {
        _Path.reset();
        _Path.moveTo(x, y);
        _mX = x;
        _mY = y;
    }

    private void TouchMove(float x, float y) {
        float dx = Math.abs(x - _mX);
        float dy = Math.abs(y - _mY);

        if (dx >= TouchTolerance || dy >= TouchTolerance) {
            _Path.quadTo(_mX, _mY, (x + _mX) / 2, (y + _mY) / 2);
            _mX = x;
            _mY = y;
        }
    }

    private void TouchUp() {
        if (!_Path.isEmpty()) {
            _Path.lineTo(_mX, _mY);
            _Canvas.drawPath(_Path, _paint);
        } else {
            _Canvas.drawPoint(_mX, _mY, _paint);
        }

        _Path.reset();
    }

    @Override
    public boolean onTouchEvent(MotionEvent e) {
        super.onTouchEvent(e);
        float x = e.getX();
        float y = e.getY();

        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN:
                TouchStart(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                TouchMove(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                TouchUp();
                invalidate();
                break;
        }

        return true;
    }

    public void ClearCanvas() {
        _Canvas.drawColor(Color.WHITE);
        invalidate();
    }

    public byte[] getBytes() {
        Bitmap b = getBitmap();

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        b.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();
    }

    public Bitmap getBitmap() {
        View v = (View) this.getParent();
        Bitmap b = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(b);
        v.layout(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
        v.draw(c);

        return b;
    }
}

我尝试过Rob Croll的建议，这个建议效果很好，但它很直率，使得签名不像人类。如果你知道我的意思：P

以下是在空线性布局上附加视图的方法

LinearLayout mContent = (LinearLayout) findViewById(R.id.linearLayout);
CaptureSignatureView mSig = new CaptureSignatureView(this, null);
mContent.addView(mSig, LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

以下是如何获取签名的字节或位图

byte[] signature = mSig.getBytes();
Bitmap signature = mSig.getBitmap();

Answer 2

对于寻找解决方案的任何人，您都可以在http://www.mysamplecode.com/2011/11/android-capture-signature-using-canvas.html

找到解决方案

它实际上将签名写入文件，但它很容易改变并写入数据库。

Answer 3

您可能需要手势构建器。

我认为这个链接。

http://android-developers.blogspot.com/2009/10/gestures-on-android-16.html

对您有用。如果你需要再次检查签名。

<强>更新

你在谈论这个吗？

http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/TouchPaint.html

然后此示例不使用xml 。它具有内部类（MyView）

的视图

Answer 4

我知道这是一个老问题，但我需要实现自己的视图来捕获签名，因为我使用的是MonoForAndroid（C＃而不是Java）。所以我在这里添加我的View代码以防有人需要它。

using System;
using Android.Content;
using Android.Graphics;
using Android.Views;

namespace MyApp.Views
{
    public class CaptureSignatureView : View
    {
        public CaptureSignatureView(Context c, SignatureData signatureData) : base(c)
        {
            SignatureData = signatureData;
            _Path = new Path();
            _BitmapPaint = new Paint(PaintFlags.Dither);
            _paint = new Paint
            {
                AntiAlias = true,
                Dither = true,
                Color = Color.Argb(255, 0, 0, 0)
            };
            _paint.SetStyle(Paint.Style.Stroke);
            _paint.StrokeJoin = Paint.Join.Round;
            _paint.StrokeCap = Paint.Cap.Round;
            _paint.StrokeWidth = 8;
        }

        protected override void OnSizeChanged(int w, int h, int oldw, int oldh)
        {
            base.OnSizeChanged(w, h, oldw, oldh);
            _Bitmap = Bitmap.CreateBitmap(w, (h > 0 ? h : ((View)this.Parent).Height), Bitmap.Config.Argb8888);
            _Canvas = new Canvas(_Bitmap);
        }

        protected override void OnDraw(Canvas canvas)
        {
            canvas.DrawColor(Color.White);
            canvas.DrawBitmap(_Bitmap, 0, 0, _BitmapPaint);
            canvas.DrawPath(_Path, _paint);
        }

        private float _mX, _mY;
        private const float TouchTolerance = 4;

        private void TouchStart(float x, float y)
        {
            _Path.Reset();
            _Path.MoveTo(x, y);
            _mX = x;
            _mY = y;
            SignatureData.AddPoint(SignatureState.Start, (int)x, (int)y);
        }

        private void TouchMove(float x, float y)
        {
            float dx = Math.Abs(x - _mX);
            float dy = Math.Abs(y - _mY);

            if (dx >= TouchTolerance || dy >= TouchTolerance)
            {
                _Path.QuadTo(_mX, _mY, (x + _mX) / 2, (y + _mY) / 2);
                SignatureData.AddPoint(SignatureState.Move, (int)x, (int)y);
                _mX = x;
                _mY = y;
            }
        }

        private void TouchUp()
        {
            if (!_Path.IsEmpty)
            {
                _Path.LineTo(_mX, _mY);
                _Canvas.DrawPath(_Path, _paint);
            }
            else
            {
                _Canvas.DrawPoint(_mX, _mY, _paint);
            }
            SignatureData.AddPoint(SignatureState.End, (int)_mX, (int)_mY);

            _Path.Reset();
        }

        public override bool OnTouchEvent(MotionEvent e)
        {
            var x = e.GetX();
            var y = e.GetY();

            switch (e.Action)
            {
                case MotionEventActions.Down:
                    TouchStart(x, y);
                    Invalidate();
                    break;
                case MotionEventActions.Move:
                    TouchMove(x, y);
                    Invalidate();
                    break;
                case MotionEventActions.Up:
                    TouchUp();
                    Invalidate();
                    break;
            }
            return true;
        }

        public void ClearCanvas()
        {
            _Canvas.DrawColor(Color.White);
            Invalidate();
        }

        public Bitmap CanvasBitmap()
        {
            return _Bitmap;
        }

        public void Clear()
        {
            ClearCanvas();
            SignatureData = new SignatureData();
        }

        #region Implementation

        private Bitmap _Bitmap;
        private Canvas _Canvas;
        private readonly Path _Path;
        private readonly Paint _BitmapPaint;
        private readonly Paint _paint;
        public  SignatureData SignatureData;

        #endregion
    }

}

另外，我有一个blog post here，详细介绍了如何捕获签名。基本上你可以用两种不同的方式做到这一点。您可以使用签名捕获视图作为图像，然后保存该位图（并将其发送到服务器）。或者你可以捕获一个二维点阵列，并以你想要的任何方式重建签名。

Android签名捕获

4 个答案: