android 电子签名 手写签名 功能实现
【摘要】
android 电子签名 手写签名 功能实现
这个手写的效果 就是一个 重写的的自定义的view 代码如下：
package com.example.hand.views; import java.util.ArrayList;import java.util.List; import a...
android 电子签名 手写签名 功能实现
这个手写的效果 就是一个 重写的的自定义的view 代码如下：
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package com.example.hand.views;
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import java.util.ArrayList;
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import java.util.List;
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import android.content.Context;
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import android.content.res.Resources;
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import android.content.res.TypedArray;
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import android.graphics.Bitmap;
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import android.graphics.Canvas;
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import android.graphics.Color;
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import android.graphics.Matrix;
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import android.graphics.Paint;
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import android.graphics.Path;
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import android.graphics.RectF;
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import android.util.AttributeSet;
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import android.util.DisplayMetrics;
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import android.view.MotionEvent;
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import android.view.View;
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import com.example.hand.R;
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import com.example.hand.utils.Bezier;
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import com.example.hand.utils.ControlTimedPoints;
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import com.example.hand.utils.TimedPoint;
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public class SignatureView extends View {
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// View state
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private List<TimedPoint> mPoints;
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private boolean mIsEmpty;
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private float mLastTouchX;
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private float mLastTouchY;
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private float mLastVelocity;
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private float mLastWidth;
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private RectF mDirtyRect;
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// Configurable parameters
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private int mMinWidth;
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private int mMaxWidth;
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private float mVelocityFilterWeight;
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private OnSignedListener mOnSignedListener;
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private Paint mPaint = new Paint();
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private Path mPath = new Path();
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private Bitmap mSignatureBitmap = null;
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private Canvas mSignatureBitmapCanvas = null;
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public SignatureView(Context context, AttributeSet attrs) {
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super(context, attrs);
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TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.SignatureView, 0, 0);
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// Configurable parameters
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try {
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mMinWidth = a.getDimensionPixelSize(R.styleable.SignatureView_minWidth, convertDpToPx(3));
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mMaxWidth = a.getDimensionPixelSize(R.styleable.SignatureView_maxWidth, convertDpToPx(7));
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mVelocityFilterWeight = a.getFloat(R.styleable.SignatureView_velocityFilterWeight, 0.9f);
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mPaint.setColor(a.getColor(R.styleable.SignatureView_penColor, Color.BLACK));
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} finally {
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a.recycle();
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}
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// Fixed parameters
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mPaint.setAntiAlias(true);
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mPaint.setStyle(Paint.Style.STROKE);
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mPaint.setStrokeCap(Paint.Cap.ROUND);
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mPaint.setStrokeJoin(Paint.Join.ROUND);
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// Dirty rectangle to update only the changed portion of the view
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mDirtyRect = new RectF();
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clear();
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}
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/**
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* Set the pen color from a given resource. If the resource is not found,
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* {@link android.graphics.Color#BLACK} is assumed.
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*
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* @param colorRes
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* the color resource.
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*/
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public void setPenColorRes(int colorRes) {
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try {
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setPenColor(getResources().getColor(colorRes));
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} catch (Resources.NotFoundException ex) {
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setPenColor(getResources().getColor(Color.BLACK));
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}
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}
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/**
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* Set the pen color from a given color.
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*
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* @param color
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* the color.
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*/
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public void setPenColor(int color) {
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mPaint.setColor(color);
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}
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/**
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* Set the minimum width of the stroke in pixel.
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*
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* @param minWidth
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* the width in dp.
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*/
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public void setMinWidth(float minWidth) {
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mMinWidth = convertDpToPx(minWidth);
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}
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/**
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* Set the maximum width of the stroke in pixel.
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*
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* @param maxWidth
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* the width in dp.
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*/
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public void setMaxWidth(float maxWidth) {
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mMaxWidth = convertDpToPx(maxWidth);
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}
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/**
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* Set the velocity filter weight.
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*
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* @param velocityFilterWeight
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* the weight.
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*/
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public void setVelocityFilterWeight(float velocityFilterWeight) {
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mVelocityFilterWeight = velocityFilterWeight;
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}
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public void clear() {
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mPoints = new ArrayList<TimedPoint>();
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mLastVelocity = 0;
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mLastWidth = (mMinWidth + mMaxWidth) / 2;
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mPath.reset();
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if (mSignatureBitmap != null) {
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mSignatureBitmap = null;
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ensureSignatureBitmap();
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}
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setIsEmpty(true);
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invalidate();
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}
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@Override
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public boolean onTouchEvent(MotionEvent event) {
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if (!isEnabled())
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return false;
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float eventX = event.getX();
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float eventY = event.getY();
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switch (event.getAction()) {
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case MotionEvent.ACTION_DOWN:
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getParent().requestDisallowInterceptTouchEvent(true);
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mPoints.clear();
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mPath.moveTo(eventX, eventY);
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mLastTouchX = eventX;
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mLastTouchY = eventY;
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addPoint(new TimedPoint(eventX, eventY));
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case MotionEvent.ACTION_MOVE:
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resetDirtyRect(eventX, eventY);
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addPoint(new TimedPoint(eventX, eventY));
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break;
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case MotionEvent.ACTION_UP:
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resetDirtyRect(eventX, eventY);
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addPoint(new TimedPoint(eventX, eventY));
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getParent().requestDisallowInterceptTouchEvent(true);
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setIsEmpty(false);
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break;
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default:
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return false;
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}
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// invalidate();
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invalidate((int) (mDirtyRect.left - mMaxWidth), (int) (mDirtyRect.top - mMaxWidth),
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(int) (mDirtyRect.right + mMaxWidth), (int) (mDirtyRect.bottom + mMaxWidth));
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return true;
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}
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@Override
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protected void onDraw(Canvas canvas) {
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if (mSignatureBitmap != null) {
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canvas.drawBitmap(mSignatureBitmap, 0, 0, mPaint);
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}
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}
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public void setOnSignedListener(OnSignedListener listener) {
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mOnSignedListener = listener;
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}
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public boolean isEmpty() {
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return mIsEmpty;
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}
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public Bitmap getSignatureBitmap() {
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Bitmap originalBitmap = getTransparentSignatureBitmap();
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Bitmap whiteBgBitmap = Bitmap.createBitmap(originalBitmap.getWidth(), originalBitmap.getHeight(),
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Bitmap.Config.ARGB_8888);
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Canvas canvas = new Canvas(whiteBgBitmap);
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canvas.drawColor(Color.WHITE);
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canvas.drawBitmap(originalBitmap, 0, 0, null);
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return whiteBgBitmap;
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}
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public void setSignatureBitmap(Bitmap signature) {
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clear();
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ensureSignatureBitmap();
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RectF tempSrc = new RectF();
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RectF tempDst = new RectF();
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int dWidth = signature.getWidth();
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int dHeight = signature.getHeight();
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int vWidth = getWidth();
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int vHeight = getHeight();
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// Generate the required transform.
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tempSrc.set(0, 0, dWidth, dHeight);
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tempDst.set(0, 0, vWidth, vHeight);
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Matrix drawMatrix = new Matrix();
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drawMatrix.setRectToRect(tempSrc, tempDst, Matrix.ScaleToFit.CENTER);
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Canvas canvas = new Canvas(mSignatureBitmap);
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canvas.drawBitmap(signature, drawMatrix, null);
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setIsEmpty(false);
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invalidate();
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}
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public Bitmap getTransparentSignatureBitmap() {
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ensureSignatureBitmap();
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return mSignatureBitmap;
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}
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public Bitmap getTransparentSignatureBitmap(boolean trimBlankSpace) {
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if (!trimBlankSpace) {
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return getTransparentSignatureBitmap();
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}
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ensureSignatureBitmap();
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int imgHeight = mSignatureBitmap.getHeight();
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int imgWidth = mSignatureBitmap.getWidth();
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int backgroundColor = Color.TRANSPARENT;
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int xMin = Integer.MAX_VALUE, xMax = Integer.MIN_VALUE, yMin = Integer.MAX_VALUE, yMax = Integer.MIN_VALUE;
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boolean foundPixel = false;
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// Find xMin
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for (int x = 0; x < imgWidth; x++) {
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boolean stop = false;
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for (int y = 0; y < imgHeight; y++) {
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if (mSignatureBitmap.getPixel(x, y) != backgroundColor) {
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xMin = x;
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stop = true;
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foundPixel = true;
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break;
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}
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}
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if (stop)
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break;
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}
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// Image is empty...
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if (!foundPixel)
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return null;
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// Find yMin
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for (int y = 0; y < imgHeight; y++) {
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boolean stop = false;
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for (int x = xMin; x < imgWidth; x++) {
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if (mSignatureBitmap.getPixel(x, y) != backgroundColor) {
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yMin = y;
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stop = true;
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break;
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}
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}
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if (stop)
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break;
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}
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// Find xMax
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for (int x = imgWidth - 1; x >= xMin; x--) {
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boolean stop = false;
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for (int y = yMin; y < imgHeight; y++) {
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if (mSignatureBitmap.getPixel(x, y) != backgroundColor) {
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xMax = x;
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stop = true;
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break;
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}
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}
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if (stop)
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break;
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}
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// Find yMax
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for (int y = imgHeight - 1; y >= yMin; y--) {
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boolean stop = false;
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for (int x = xMin; x <= xMax; x++) {
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if (mSignatureBitmap.getPixel(x, y) != backgroundColor) {
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yMax = y;
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stop = true;
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break;
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}
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}
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if (stop)
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break;
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}
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return Bitmap.createBitmap(mSignatureBitmap, xMin, yMin, xMax - xMin, yMax - yMin);
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}
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private void addPoint(TimedPoint newPoint) {
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mPoints.add(newPoint);
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if (mPoints.size() > 2) {
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// To reduce the initial lag make it work with 3 mPoints
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// by copying the first point to the beginning.
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if (mPoints.size() == 3)
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mPoints.add(0, mPoints.get(0));
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ControlTimedPoints tmp = calculateCurveControlPoints(mPoints.get(0), mPoints.get(1), mPoints.get(2));
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TimedPoint c2 = tmp.c2;
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tmp = calculateCurveControlPoints(mPoints.get(1), mPoints.get(2), mPoints.get(3));
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TimedPoint c3 = tmp.c1;
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Bezier curve = new Bezier(mPoints.get(1), c2, c3, mPoints.get(2));
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TimedPoint startPoint = curve.startPoint;
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TimedPoint endPoint = curve.endPoint;
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float velocity = endPoint.velocityFrom(startPoint);
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velocity = Float.isNaN(velocity) ? 0.0f : velocity;
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velocity = mVelocityFilterWeight * velocity + (1 - mVelocityFilterWeight) * mLastVelocity;
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// The new width is a function of the velocity. Higher velocities
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// correspond to thinner strokes.
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float newWidth = strokeWidth(velocity);
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// The Bezier's width starts out as last curve's final width, and
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// gradually changes to the stroke width just calculated. The new
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// width calculation is based on the velocity between the Bezier's
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// start and end mPoints.
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addBezier(curve, mLastWidth, newWidth);
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mLastVelocity = velocity;
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mLastWidth = newWidth;
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// Remove the first element from the list,
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// so that we always have no more than 4 mPoints in mPoints array.
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mPoints.remove(0);
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}
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}
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private void addBezier(Bezier curve, float startWidth, float endWidth) {
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ensureSignatureBitmap();
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float originalWidth = mPaint.getStrokeWidth();
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float widthDelta = endWidth - startWidth;
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float drawSteps = (float) Math.floor(curve.length());
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for (int i = 0; i < drawSteps; i++) {
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// Calculate the Bezier (x, y) coordinate for this step.
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float t = ((float) i) / drawSteps;
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float tt = t * t;
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float ttt = tt * t;
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float u = 1 - t;
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float uu = u * u;
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float uuu = uu * u;
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float x = uuu * curve.startPoint.x;
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x += 3 * uu * t * curve.control1.x;
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x += 3 * u * tt * curve.control2.x;
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x += ttt * curve.endPoint.x;
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float y = uuu * curve.startPoint.y;
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y += 3 * uu * t * curve.control1.y;
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y += 3 * u * tt * curve.control2.y;
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y += ttt * curve.endPoint.y;
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// Set the incremental stroke width and draw.
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mPaint.setStrokeWidth(startWidth + ttt * widthDelta);
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mSignatureBitmapCanvas.drawPoint(x, y, mPaint);
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expandDirtyRect(x, y);
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}
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mPaint.setStrokeWidth(originalWidth);
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}
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private ControlTimedPoints calculateCurveControlPoints(TimedPoint s1, TimedPoint s2, TimedPoint s3) {
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float dx1 = s1.x - s2.x;
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float dy1 = s1.y - s2.y;
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float dx2 = s2.x - s3.x;
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float dy2 = s2.y - s3.y;
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TimedPoint m1 = new TimedPoint((s1.x + s2.x) / 2.0f, (s1.y + s2.y) / 2.0f);
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TimedPoint m2 = new TimedPoint((s2.x + s3.x) / 2.0f, (s2.y + s3.y) / 2.0f);
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float l1 = (float) Math.sqrt(dx1 * dx1 + dy1 * dy1);
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float l2 = (float) Math.sqrt(dx2 * dx2 + dy2 * dy2);
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float dxm = (m1.x - m2.x);
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float dym = (m1.y - m2.y);
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float k = l2 / (l1 + l2);
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TimedPoint cm = new TimedPoint(m2.x + dxm * k, m2.y + dym * k);
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float tx = s2.x - cm.x;
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float ty = s2.y - cm.y;
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return new ControlTimedPoints(new TimedPoint(m1.x + tx, m1.y + ty), new TimedPoint(m2.x + tx, m2.y + ty));
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}
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private float strokeWidth(float velocity) {
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return Math.max(mMaxWidth / (velocity + 1), mMinWidth);
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}
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/**
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* Called when replaying history to ensure the dirty region includes all
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* mPoints.
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*
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* @param historicalX
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* the previous x coordinate.
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* @param historicalY
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* the previous y coordinate.
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*/
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private void expandDirtyRect(float historicalX, float historicalY) {
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if (historicalX < mDirtyRect.left) {
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mDirtyRect.left = historicalX;
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} else if (historicalX > mDirtyRect.right) {
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mDirtyRect.right = historicalX;
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}
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if (historicalY < mDirtyRect.top) {
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mDirtyRect.top = historicalY;
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} else if (historicalY > mDirtyRect.bottom) {
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mDirtyRect.bottom = historicalY;
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}
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}
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/**
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* Resets the dirty region when the motion event occurs.
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*
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* @param eventX
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* the event x coordinate.
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* @param eventY
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* the event y coordinate.
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*/
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private void resetDirtyRect(float eventX, float eventY) {
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// The mLastTouchX and mLastTouchY were set when the ACTION_DOWN motion
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// event occurred.
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mDirtyRect.left = Math.min(mLastTouchX, eventX);
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mDirtyRect.right = Math.max(mLastTouchX, eventX);
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mDirtyRect.top = Math.min(mLastTouchY, eventY);
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mDirtyRect.bottom = Math.max(mLastTouchY, eventY);
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}
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private void setIsEmpty(boolean newValue) {
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mIsEmpty = newValue;
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if (mOnSignedListener != null) {
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if (mIsEmpty) {
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mOnSignedListener.onClear();
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} else {
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mOnSignedListener.onSigned();
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}
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}
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}
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private void ensureSignatureBitmap() {
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if (mSignatureBitmap == null) {
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mSignatureBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
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mSignatureBitmapCanvas = new Canvas(mSignatureBitmap);
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}
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}
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private int convertDpToPx(float dp) {
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return Math.round(dp * (getResources().getDisplayMetrics().xdpi / DisplayMetrics.DENSITY_DEFAULT));
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}
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public interface OnSignedListener {
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public void onSigned();
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public void onClear();
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}
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}
最后我集成到项目里面的效果图 如上图
如果大家有其他问题 欢迎加入我的qq群讨论 开发一群：454430053开发二群：537532956
文章来源: wukong.blog.csdn.net，作者：再见孙悟空_，版权归原作者所有，如需转载，请联系作者。
原文链接：wukong.blog.csdn.net/article/details/77993757
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