前段时间项目用到了电子签证。

刚开始听到产品的需求就是一个大写的懵逼。

后来详谈才知道是在手机上签名而已。

在网上查了下。

基本实现就是自定义view ，然后重写触摸事件。实现写字的功能。

然后实现view映射成图片。

基本实现很简单。需要注意的是 一定一定要在XML文件中把自定义控件的背景设置一个颜色。否则保存的图片是一个黑板。

下面贴一下自定义VIEW的代码。

public class SignatureView extends View {

private static final float STROKE_WIDTH = 5f;

/** Need to track this so the dirty region can accommodate the stroke. **/

private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;

private Paint paint = new Paint();

private Path path = new Path();

/**

* Optimizes painting by invalidating the smallest possible area.

*/

private float lastTouchX;

private float lastTouchY;

private final RectF dirtyRect = new RectF();

public SignatureView(Context context, AttributeSet attrs) {

super(context, attrs);

paint.setAntiAlias(true);

paint.setColor(Color.BLACK);

paint.setStyle(Paint.Style.STROKE);

paint.setStrokeJoin(Paint.Join.ROUND);

paint.setStrokeWidth(STROKE_WIDTH);

}

/**

* Erases the signature.

*/

public void clear() {

path.reset();

// Repaints the entire view.

invalidate();

}

@Override

protected void onDraw(Canvas canvas) {

canvas.drawPath(path, paint);

}

@Override

public boolean onTouchEvent(MotionEvent event) {

float eventX = event.getX();

float eventY = event.getY();

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:

path.moveTo(eventX, eventY);

lastTouchX = eventX;

lastTouchY = eventY;

// There is no end point yet, so don't waste cycles invalidating.

return true;

case MotionEvent.ACTION_MOVE:

case MotionEvent.ACTION_UP:

// Start tracking the dirty region.

resetDirtyRect(eventX, eventY);

// When the hardware tracks events faster than they are delivered, the

// event will contain a history of those skipped points.

int historySize = event.getHistorySize();

for (int i = 0; i < historySize; i++) {

float historicalX = event.getHistoricalX(i);

float historicalY = event.getHistoricalY(i);

expandDirtyRect(historicalX, historicalY);

path.lineTo(historicalX, historicalY);

}

// After replaying history, connect the line to the touch point.

path.lineTo(eventX, eventY);

break;

default:

// debug("Ignored touch event: " + event.toString());

return false;

}

// Include half the stroke width to avoid clipping.

invalidate(

(int) (dirtyRect.left - HALF_STROKE_WIDTH),

(int) (dirtyRect.top - HALF_STROKE_WIDTH),

(int) (dirtyRect.right + HALF_STROKE_WIDTH),

(int) (dirtyRect.bottom + HALF_STROKE_WIDTH));

lastTouchX = eventX;

lastTouchY = eventY;

return true;

}

/**

* Called when replaying history to ensure the dirty region includes all

* points.

*/

private void expandDirtyRect(float historicalX, float historicalY) {

if (historicalX < dirtyRect.left) {

dirtyRect.left = historicalX;

} else if (historicalX > dirtyRect.right) {

dirtyRect.right = historicalX;

}

if (historicalY < dirtyRect.top) {

dirtyRect.top = historicalY;

} else if (historicalY > dirtyRect.bottom) {

dirtyRect.bottom = historicalY;

}

}

/**

* Resets the dirty region when the motion event occurs.

*/

private void resetDirtyRect(float eventX, float eventY) {

// The lastTouchX and lastTouchY were set when the ACTION_DOWN

// motion event occurred.

dirtyRect.left = Math.min(lastTouchX, eventX);

dirtyRect.right = Math.max(lastTouchX, eventX);

dirtyRect.top = Math.min(lastTouchY, eventY);

dirtyRect.bottom = Math.max(lastTouchY, eventY);

}

}

下面贴上使用的代码

1.将view映射成图片

public Bitmap createViewBitmap(View v) {

Bitmap bitmap = Bitmap.createBitmap(v.getWidth(), v.getHeight(),

Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(bitmap);

v.draw(canvas);

return bitmap;

}

2.然后保存，或者上传服务器就好。

OK 搞定！！