我想在android中创建数字签名应用程序。它应该捕获用户签名并将其存储为图像。如果有人知道，请告诉我。
答案 0 :(得分：11)
尝试自定义视图而不是手势：
package com.example.myapp.gui.views;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
/**
* A simple view to capture a path traced onto the screen. Initially intended to be used to captures signatures.
*
* @author Andrew Crichton
* @version 0.1
*/
public class SignatureView extends View {
private Path mPath;
private Paint mPaint;
private Paint bgPaint = new Paint(Color.TRANSPARENT);
private Bitmap mBitmap;
private Canvas mCanvas;
private float curX, curY;
private static final int TOUCH_TOLERANCE = 4;
private static final int STROKE_WIDTH = 4;
public SignatureView(Context context) {
super(context);
init();
}
public SignatureView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public SignatureView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
setFocusable(true);
mPath = new Path();
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.WHITE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(STROKE_WIDTH);
}
public void setSigColor(int color) {
mPaint.setColor(color);
}
public void setSigColor(int a, int red, int green, int blue) {
mPaint.setARGB(a, red, green, blue);
}
public boolean clearSignature() {
if (mBitmap != null)
createFakeMotionEvents();
if (mCanvas != null) {
mCanvas.drawColor(Color.BLACK);
mCanvas.drawPaint(bgPaint);
mPath.reset();
invalidate();
}
else {
return false;
}
return true;
}
public Bitmap getImage() {
return this.mBitmap;
}
public void setImage(Bitmap bitmap) {
this.mBitmap = bitmap;
this.invalidate();
}
@Override
protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
int bitmapWidth = mBitmap != null ? mBitmap.getWidth() : 0;
int bitmapHeight = mBitmap != null ? mBitmap.getWidth() : 0;
if (bitmapWidth >= width && bitmapHeight >= height)
return;
if (bitmapWidth < width)
bitmapWidth = width;
if (bitmapHeight < height)
bitmapHeight = height;
Bitmap newBitmap = Bitmap.createBitmap(bitmapWidth, bitmapHeight, Bitmap.Config.ARGB_8888);
Canvas newCanvas = new Canvas();
newCanvas.setBitmap(newBitmap);
if (mBitmap != null)
newCanvas.drawBitmap(mBitmap, 0, 0, null);
mBitmap = newBitmap;
mCanvas = newCanvas;
}
private void createFakeMotionEvents() {
MotionEvent downEvent = MotionEvent.obtain(SystemClock.uptimeMillis(),SystemClock.uptimeMillis()+100, MotionEvent.ACTION_DOWN, 1f, 1f ,0);
MotionEvent upEvent = MotionEvent.obtain(SystemClock.uptimeMillis(),SystemClock.uptimeMillis()+100, MotionEvent.ACTION_UP, 1f, 1f ,0);
onTouchEvent(downEvent);
onTouchEvent(upEvent);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.BLACK);
canvas.drawBitmap(mBitmap, 0, 0, mPaint);
canvas.drawPath(mPath, mPaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touchDown(x, y);
break;
case MotionEvent.ACTION_MOVE:
touchMove(x, y);
break;
case MotionEvent.ACTION_UP:
touchUp();
break;
}
invalidate();
return true;
}
/**----------------------------------------------------------
* Private methods
**---------------------------------------------------------*/
private void touchDown(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
curX = x;
curY = y;
}
private void touchMove(float x, float y) {
float dx = Math.abs(x - curX);
float dy = Math.abs(y - curY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(curX, curY, (x + curX)/2, (y + curY)/2);
curX = x;
curY = y;
}
}
private void touchUp() {
mPath.lineTo(curX, curY);
if (mCanvas == null) {
mCanvas = new Canvas();
mCanvas.setBitmap(mBitmap);
}
mCanvas.drawPath(mPath, mPaint);
mPath.reset();
}
}
然后，在XML中使用此类：<com.example.myapp.gui.views.SignatureView .../>
要获取绘制的签名，请使用：Bitmap bmp = ((SignatureView)findViewById(R.id.signatureview)).getImage();
您最终可以使用以下代码保存位图：
public void saveBitmap(Bitmap bmp) {
try {
String root = Environment.getExternalStorageDirectory().getAbsolutePath() + "/";
String filepath = root + "signature.jpg";
FileOutputStream fos = new FileOutputStream(filepath);
bmp.compress(CompressFormat.JPEG, 100, fos);
fos.flush();
fos.close();
}
catch(Exception e) {
Log.e("Could not save", e.getMessage());
e.printStackTrace();
}
}
将签名作为signature.jpeg保存在SD卡的根目录中。对于写作部分，请确保在您的清单中具有该权限：<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
答案 1 :(得分：4)
希望此代码可以帮助您：）
esign_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<android.gesture.GestureOverlayView
android:id="@+id/signaturePad"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="5"
android:background="@android:color/white"
android:clickable="false"
android:eventsInterceptionEnabled="true"
android:fadeEnabled="false"
android:gestureColor="#0000ff"
android:gestureStrokeLengthThreshold="0.1"
android:gestureStrokeType="multiple"
android:longClickable="false"
android:orientation="vertical"
android:uncertainGestureColor="#000000"
android:splitMotionEvents="true"
android:fadeOffset="10000000">
</android.gesture.GestureOverlayView>
<RelativeLayout
android:id="@+id/rellay_esign_donebutton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingBottom="10dp"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:gravity="center"
>
<Button
android:id="@+id/DoneButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Done" />
<Button
android:id="@+id/ClearButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Clear" />
</LinearLayout>
</RelativeLayout>
</LinearLayout>
Esignature.java
public class Esignature extends Activity {
GestureOverlayView gestureView;
String path;
File file;
Bitmap bitmap;
public boolean gestureTouch=false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.esign_main);
Button donebutton = (Button) findViewById(R.id.DoneButton);
donebutton.setText("Done");
Button clearButton = (Button) findViewById(R.id.ClearButton);
clearButton.setText("Clear");
path=Environment.getExternalStorageDirectory()+"/signature.png";
file = new File(path);
file.delete();
gestureView = (GestureOverlayView) findViewById(R.id.signaturePad);
gestureView.setDrawingCacheEnabled(true);
gestureView.setAlwaysDrawnWithCacheEnabled(true);
gestureView.setHapticFeedbackEnabled(false);
gestureView.cancelLongPress();
gestureView.cancelClearAnimation();
gestureView.addOnGestureListener(new OnGestureListener() {
@Override
public void onGesture(GestureOverlayView arg0, MotionEvent arg1) {
// TODO Auto-generated method stub
}
@Override
public void onGestureCancelled(GestureOverlayView arg0,
MotionEvent arg1) {
// TODO Auto-generated method stub
}
@Override
public void onGestureEnded(GestureOverlayView arg0, MotionEvent arg1) {
// TODO Auto-generated method stub
}
@Override
public void onGestureStarted(GestureOverlayView arg0,
MotionEvent arg1) {
// TODO Auto-generated method stub
if (arg1.getAction()==MotionEvent.ACTION_MOVE){
gestureTouch=false;
}
else
{
gestureTouch=true;
}
}});
donebutton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
try {
bitmap = Bitmap.createBitmap(gestureView.getDrawingCache());
file.createNewFile();
FileOutputStream fos = new FileOutputStream(file);
fos = new FileOutputStream(file);
// compress to specified format (PNG), quality - which is
// ignored for PNG, and out stream
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
if(gestureTouch==false)
{
setResult(0);
finish();
}
else
{
setResult(1);
finish();
}
}
});
clearButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
gestureView.invalidate();
gestureView.clear(true);
gestureView.clearAnimation();
gestureView.cancelClearAnimation();
}
});
}
}
答案 2 :(得分：0)
这可以在Gestureoverlay的帮助下完成。这在APIDemos中得到了证明。以下链接必须有所帮助：
答案 3 :(得分：0)
对于白色背景的jpg文件：
gestureView.setDrawingCacheBackgroundColor(Color.WHITE);
和
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
使用Harshal Benake解决方案。
答案 4 :(得分：0)
感谢Harhal's answer，这是一种无需访问文件系统即可获取位图的方法。
是的，gestureView.buildDrawingCache() API已过时，但就我而言，这是一个更可接受的解决方案..而不是要求用户保存许可来仅支持整个应用这一功能。
// .. continuing from Harhal's code here:
donebutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
gestureView.buildDrawingCache();
bitmap = gestureView.getDrawingCache();
// set bitmap somewhere
// eg: mBinding.signature.setImageBitmap(bitmap);
}
catch (Exception e) {
e.printStackTrace();
}
// Activity Stuff ...
}
});
要重置视图，gestureView为我卡住了它加载的第一个位图。因此，似乎只是重新加载相同的片段是使所有内容完全重置的最简单方法。
下面是此操作的伪代码，因为每个人似乎对片段堆栈的管理方式不同。
clearButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Reload this fragment
// 1. Pop current fragment (current instance) from fragment stack
// 2. Set this same fragment again
}
});