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我正在开发 android 绘画签名应用程序，它可以灵活地清除绘画并将画布保存为位图图像。我在这个应用程序中遇到了一个问题，每当我想将画布保存为位图时，我都需要检查签名是否足够长。如果签名太短，我必须要求用户再次签名。以下是我的代码： 这里面有两个类。

指绘活动

public class FingerPaintActivity extends Activity implements OnClickListener{

private Button clearBtn, saveBtn;

private View myView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    myView = findViewById(R.id.myView);

    clearBtn = (Button) findViewById(R.id.clearBtn);
    clearBtn.setOnClickListener(this);

    saveBtn = (Button) findViewById(R.id.submitBtn);
    saveBtn.setOnClickListener(this);

}

@Override
public void onClick(View v) {

    if (v == clearBtn) {

        MyView.clearCanvas();
        myView.invalidate();
        myView.refreshDrawableState();

    } else {

        myView.setDrawingCacheEnabled(true);

        myView.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
        myView.layout(0, 0, myView.getWidth(), myView.getHeight());
        myView.buildDrawingCache(true);
        Bitmap bm = Bitmap.createBitmap(myView.getDrawingCache());
        myView.setDrawingCacheEnabled(false);
        if (bm != null) {
            try {
                String path = Environment.getExternalStorageDirectory().toString();
                OutputStream fOut = null;
                File file = new File(path, "screentest.jpg");
                fOut = new FileOutputStream(file);
                bm.compress(Bitmap.CompressFormat.JPEG, 85, fOut);
                fOut.flush();
                fOut.close();
                Log.e("ImagePath", "Image Path : " + MediaStore.Images.Media.insertImage( getContentResolver(), file.getAbsolutePath(), file.getName(), file.getName()));

                sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"+ Environment.getExternalStorageDirectory())));
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}
}

这是第二类：MyView

public class MyView extends View {

// private static final float MINP = 0.25f;
// private static final float MAXP = 0.75f;

private Bitmap mBitmap;
private static Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
private Paint mPaint;

public MyView(Context c) {
    super(c);

}

public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);

    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(Color.BLACK);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(6);
    mBitmap = Bitmap.createBitmap(320, 480, Bitmap.Config.ARGB_8888);
    mCanvas = new Canvas(mBitmap);
    mPath = new Path();
    mBitmapPaint = new Paint(Paint.DITHER_FLAG);
}

public MyView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
}

@Override
protected void onDraw(Canvas canvas) {

    canvas.drawColor(0xFFAAAAAA);

    canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

    canvas.drawPath(mPath, mPaint);
}

private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;

private void touch_start(float x, float y) {
    mPath.reset();
    mPath.moveTo(x, y);
    mX = x;
    mY = y;
}

private void touch_move(float x, float y) {
    float dx = Math.abs(x - mX);
    float dy = Math.abs(y - mY);
    if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
        mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
        mX = x;
        mY = y;
    }
}

private void touch_up() {
    mPath.lineTo(mX, mY);
    // commit the path to our offscreen
    mCanvas.drawPath(mPath, mPaint);
    // kill this so we don't double draw
    mPath.reset();
}

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

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        touch_start(x, y);
        invalidate();
        break;
    case MotionEvent.ACTION_MOVE:
        touch_move(x, y);
        invalidate();
        break;
    case MotionEvent.ACTION_UP:
        touch_up();
        invalidate();
        break;
    }
    return true;
}

public static void clearCanvas() {
    Paint paint = new Paint();
    paint.setXfermode(new PorterDuffXfermode(Mode.CLEAR));
    mCanvas.drawPaint(paint);
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC));

}

}

我面临的唯一问题是在保存签名时，我必须在保存之前检查位图或画布或绘画的大小。我不知道要检查哪一个如果有人有想法请帮助我。

4

1 回答 1

1

一种简单的方法是将触摸坐标之间的距离相加，并且仅在总和大于某个阈值时才接受签名。

因此，保持在 touch_move() 中绘制的总距离的运行总和

mTotal += Math.sqrt(Math.pow(dx, 2) + Math.pow(dy, 2));

然后稍后

if(mTotal >= MINIMUM_SIGNATURE_LENGTH)
{
    acceptSignature();
}
于 2012-05-23T18:48:08.713 回答