最近有一个电子合同的需求 需要用户手写签字 保存签名图片 

先上图

主要实现自定义View

public class GestureSignatureView extends View {

private static final String TAG = "GestureSignatureView";private Path mPath;//绘制路径private Paint mPaint;// 绘制画笔private Canvas mCanvas;//背景画布private Bitmap mMBitmap;//背景bitmapprivate boolean isTouchedSignature = false;//是否签名public GestureSignatureView(Context context) {this(context, null);}public GestureSignatureView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public GestureSignatureView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);initPaint();}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);Log.d(TAG, "onMeasure: 测量的宽高：" + getMeasuredWidth() + "-----------" + getMeasuredHeight());}@Overrideprotected void onLayout(boolean changed, int left, int top, int right, int bottom) {super.onLayout(changed, left, top, right, bottom);mMBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);mCanvas = new Canvas(mMBitmap);mCanvas.drawColor(Color.TRANSPARENT);mCanvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));isTouchedSignature = false;}private void initPaint() {mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mPaint.setColor(Color.BLACK);mPaint.setStrokeWidth(10.0f);mPaint.setStrokeCap(Paint.Cap.ROUND);mPaint.setStyle(Paint.Style.STROKE);mPaint.setStrokeJoin(Paint.Join.ROUND);mPaint.setDither(true);mPath = new Path();}@Overrideprotected void onDraw(Canvas canvas) {canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));canvas.drawBitmap(mMBitmap, 0, 0, mPaint);// 通过画布绘制多点形成的图形canvas.drawPath(mPath, mPaint);}private float[] downPoint = new float[2];private float[] previousPoint = new float[2];@Overridepublic boolean onTouchEvent(MotionEvent event) {downPoint[0] = event.getX();downPoint[1] = event.getY();switch (event.getAction()) {case MotionEvent.ACTION_DOWN:previousPoint[0] = downPoint[0];previousPoint[1] = downPoint[1];mPath.moveTo(downPoint[0], downPoint[1]);break;case MotionEvent.ACTION_MOVE:float dX = Math.abs(downPoint[0] - previousPoint[0]);float dY = Math.abs(downPoint[1] - previousPoint[1]);// 两点之间的距离大于等于3时，生成贝塞尔绘制曲线if (dX >= 3 || dY >= 3) {// 设置贝塞尔曲线的操作点为起点和终点的一半float cX = (downPoint[0] + previousPoint[0]) / 2;float cY = (downPoint[1] + previousPoint[1]) / 2;// 二次贝塞尔，实现平滑曲线；previousX, previousY为操作点，cX, cY为终点mPath.quadTo(previousPoint[0], previousPoint[1], cX, cY);// 第二次执行时，第一次结束调用的坐标值将作为第二次调用的初始坐标值previousPoint[0] = downPoint[0];previousPoint[1] = downPoint[1];}
//                float moveCurrentX = downPoint[0];
//                float moveCurrentY = downPoint[1];
//                mPath.quadTo(moveCurrentX, moveCurrentY, downPoint[0], downPoint[1]);break;case MotionEvent.ACTION_UP:mCanvas.drawPath(mPath, mPaint);mPath.reset();break;}invalidate();return true;}// 缩放public static Bitmap resizeImage(Bitmap bitmap, int width, int height) {int originWidth = bitmap.getWidth();int originHeight = bitmap.getHeight();float scaleWidth = ((float) width) / originWidth;float scaleHeight = ((float) height) / originHeight;Matrix matrix = new Matrix();matrix.postScale(scaleWidth, scaleHeight);Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0, originWidth,originHeight, matrix, true);return resizedBitmap;}public Bitmap getPaintBitmap() {return resizeImage(mMBitmap, 320, 480);}public void clear() {if (mCanvas != null) {isTouchedSignature = false;mPath.reset();mCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);invalidate();}}/*** 保存画板** @param path 保存到路劲*/public void save(String path) throws IOException {save(path, false, 0);}/*** 保存画板** @param path       保存到路劲* @param clearBlank 是否清楚空白区域* @param blank      边缘空白区域*/public void save(String path, boolean clearBlank, int blank) throws IOException {Bitmap bitmap = mMBitmap;//BitmapUtil.createScaledBitmapByHeight(srcBitmap, 300);//  压缩图片if (clearBlank) {bitmap = clearBlank(mMBitmap, blank);}Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(newBitmap);canvas.drawColor(Color.WHITE);canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));canvas.drawBitmap(bitmap, 0, 0, null);ByteArrayOutputStream bos = new ByteArrayOutputStream();newBitmap.compress(Bitmap.CompressFormat.JPEG, 100, bos);byte[] buffer = bos.toByteArray();if (buffer != null) {File file = new File(path);if (file.exists()) {file.delete();}OutputStream outputStream = new FileOutputStream(file);outputStream.write(buffer);outputStream.close();scanMediaFile(file);}}/*** 是否有签名** @return*/public boolean getTouched() {return isTouchedSignature;}/*** 逐行扫描 清楚边界空白。** @param bp* @param blank 边距留多少个像素* @return*/private Bitmap clearBlank(Bitmap bp, int blank) {int HEIGHT = bp.getHeight();int WIDTH = bp.getWidth();int top = 0, left = 0, right = 0, bottom = 0;int[] pixs = new int[WIDTH];boolean isStop;for (int y = 0; y < HEIGHT; y++) {bp.getPixels(pixs, 0, WIDTH, 0, y, WIDTH, 1);isStop = false;for (int pix : pixs) {if (pix != Color.TRANSPARENT) {top = y;isStop = true;break;}}if (isStop) {break;}}for (int y = HEIGHT - 1; y >= 0; y--) {bp.getPixels(pixs, 0, WIDTH, 0, y, WIDTH, 1);isStop = false;for (int pix : pixs) {if (pix != Color.TRANSPARENT) {bottom = y;isStop = true;break;}}if (isStop) {break;}}pixs = new int[HEIGHT];for (int x = 0; x < WIDTH; x++) {bp.getPixels(pixs, 0, 1, x, 0, 1, HEIGHT);isStop = false;for (int pix : pixs) {if (pix != Color.TRANSPARENT) {left = x;isStop = true;break;}}if (isStop) {break;}}for (int x = WIDTH - 1; x > 0; x--) {bp.getPixels(pixs, 0, 1, x, 0, 1, HEIGHT);isStop = false;for (int pix : pixs) {if (pix != Color.TRANSPARENT) {right = x;isStop = true;break;}}if (isStop) {break;}}if (blank < 0) {blank = 0;}left = left - blank > 0 ? left - blank : 0;top = top - blank > 0 ? top - blank : 0;right = right + blank > WIDTH - 1 ? WIDTH - 1 : right + blank;bottom = bottom + blank > HEIGHT - 1 ? HEIGHT - 1 : bottom + blank;return Bitmap.createBitmap(bp, left, top, right - left, bottom - top);}private void scanMediaFile(File photo) {Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);Uri contentUri = Uri.fromFile(photo);mediaScanIntent.setData(contentUri);getContext().sendBroadcast(mediaScanIntent);}

}

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