在android中如何在imageview上画线

Question

在我的应用程序中，我想在ImageView上画一条线。当我触摸它时，我想用手指写一条线。这是我的要求。为此，我谷歌了很多次，并休耕了贝娄链接：

如何在Android上的ImageView中画一条线？。

在我的活动中，我创建了MyImageView类的对象，在我的OnTouchListener中重写了onTouch（）方法，在MotionEvent.action_down:switch case中，我编写了update（）方法。我得到了这个错误：“new View.OnTouchListener（）{}类型的方法update（）是未定义的”。所以请任何人建议我如何这样做。谢谢您的帮助。

这是我的代码：imageView.setonTouchListener（new view.onTouchListener（）{

@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub

ImageView view = (ImageView) v;
view.setScaleType(ImageView.ScaleType.MATRIX);
float scale;

switch (event.getAction() & MotionEvent.ACTION_MASK) 
{
case MotionEvent.ACTION_DOWN:   // first finger down only
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
og.d(TAG, "mode=DRAG"); // write to LogCat
mode1 = DRAG1;
if(checkPencil){
//update();
}
break;

case MotionEvent.ACTION_UP: // first finger lifted

case MotionEvent.ACTION_POINTER_UP: // second finger lifted

mode1 = NONE1;
Log.d(TAG, "mode1=NONE1");
break;
case MotionEvent.ACTION_MOVE:
if (mode1 == DRAG1) 
{ 
if(check){                                                                                                                                   matrix.set(savedMatrix);                                                             matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the   transformation in the matrix  of points
}
} 
else if (mode1 == ZOOM1) 
{ 
if(check){
Log.e("if elseeeeeee","dfgrtgytey");
// pinch zooming
float newDist = spacing(event);
Log.d(TAG, "newDist=" + newDist);
if (newDist > 5f) 
{
                                                             matrix.set(savedMatrix);
scale = newDist / oldDist; // setting the scaling of the
                                                                                          // matrix...if scale > 1 means
                                                                                        // zoom in...if scale < 1 means
                                                                                        // zoom out
                                                                matrix.postScale(scale, scale, mid.x, mid.y);

}
// its for rotation..
if (lastEvent!=null){
newRot = rotation(event); 
//if (Constant.TRACE) Log.d("Degreeeeeeeeeee", "newRot="+(newRot));
float r = newRot-d;                                                               matrix.postRotate(r, view.getMeasuredWidth()/2, view.getMeasuredHeight()/2);  
}
}
}
break;
//rotation..
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 10f) {                                                          savedMatrix.set(matrix);
midPoint(mid, event);
mode1 = ZOOM1;
Log.d(TAG, "mode=ZOOM")
}
lastEvent = new float[4];
lastEvent[0] = event.getX(0);
lastEvent[1] = event.getX(1);
lastEvent[2] = event.getY(0);
lastEvent[3] = event.getY(1);
d = rotation(event);
break;

}//switch

view.setImageMatrix(matrix); // display the transformation on screen

return true; // indicate event was handled

}
});

在我的应用程序中，拖动图像、旋转图像和缩放图像一切都正常工作。我的要求是当我单击按钮时，绘图功能将正常工作。这就是我在此块中编写更新方法的原因：“If（checkPencil）{//update（）；}。但它不工作。

Answer 1

Canvas c = null;
c = mSurfaceHolder.lockCanvas();
imageview.line(canvas);

mSurfaceHolder.unlockCanvasAndPost(c);

public void line(Canvas draw){
// set the layout parameters
// get the background image as ImageView
// Use the gesture Overlay concept. 
}