我想在视图上的点之间画线,然后将这些点拉到所需的位置,即使形状也会改变.
我知道如何绘制两点之间的线canvas.drawLine(10,10,90,paint);通过使用这个我可以绘制点之间的线.
编辑：在这里我附上图片,以清楚解释,从保罗回答现在我可以绘制点之间的线,仍然有拉点的问题…
解决方法
这是如何完成的.假设你有点,使这些全局：
PointF topLeft = new PointF(10,10); PointF topRight = new PointF(90,10); PointF bottomLeft = new PointF(10,90); PointF bottomRight = new PointF(90,90);
你需要做的是在每个点周围做一个RectF. RectF越大,触摸面积就越大.
float sizeOfRect = 5f; RectF topLeftTouchArea = new RectF(topLeft.x - sizeOfRect,topLeft.y - sizeOfRect,topLeft.x + sizeOfRect,topLeft.y + sizeOfRect); //Do this for the other points too
定义一些全局变量来跟踪用户在onTouch中的操作.一个int是被触摸的角落,另外四个是角落的标识符.
private final int NONE = -1,TOUCH_TOP_LEFT = 0,TOUCH_TOP_RIGHT = 1,TOUCH_BOT_LEFT = 2,TOUCH_BOT_RIGHT = 3; int currentTouch = NONE;
现在,在您的onTouch事件中,您可以检查用户感兴趣的点,如下所示：
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
//The user just put their finger down.
//We check to see which corner the user is touching
//And set our global,currentTouch,to the appropriate constant.
case MotionEvent.ACTION_DOWN:
if (topLeftTouchArea.contains(event.getX(),event.getY()) {
currentTouch = TOUCH_TOP_LEFT;
} else if (topRightTouchArea.contains(event.getX(),event.getY()) {
currentTouch = TOUCH_TOP_RIGHT;
} else if (botLeftTouchArea.contains(event.getX(),event.getY()) {
currentTouch = TOUCH_BOT_LEFT;
} else if (botRightTouchArea.contains(event.getX(),event.getY()) {
currentTouch = TOUCH_BOT_RIGHT;
} else {
return false; //Return false if user touches none of the corners
}
return true; //Return true if the user touches one of the corners
//Now we know which corner the user is touching.
//When the user moves their finger,we update the point to the user position and invalidate.
case MotionEvent.ACTION_MOVE:
switch (currentTouch) {
case TOUCH_TOP_LEFT:
topLeft.x = event.getX();
topLeft.y = event.getY();
//The bottom left x position has to move with the top left corner
bottomLeft.x = topLeft.x;
//The top right y position has to move with the top left corner
topRight.y = topLeft.y;
invalidate();
return true;
case TOUCH_TOP_RIGHT:
topRight.x = event.getX();
topRight.y = event.getY();
//The top left y position has to move with the top right corner
topLeft.y = topRight.y;
//The bottom right x position has to move with the top right corner
bottomRight.x = topRight.x;
invalidate();
return true;
case TOUCH_BOT_LEFT:
bottomLeft.x = event.getX();
bottomLeft.y = event.getY();
bottomRight.y = bottomLeft.y;
topLeft.x = bottomLeft.x;
invalidate();
return true;
case TOUCH_BOT_RIGHT:
bottomRight.x = event.getX();
bottomRight.y = event.getY();
topRight.x = bottomRight.x;
bottomLeft.y = bottomRight.y;
invalidate();
return true;
}
//We returned true for all of the above cases,because we used the event
return false; //If currentTouch is none of the above cases,return false
//Here the user lifts up their finger.
//We update the points one last time,and set currentTouch to NONE.
case MotionEvent.ACTION_UP:
switch (currentTouch) {
case TOUCH_TOP_LEFT:
topLeft.x = event.getX();
topLeft.y = event.getY();
//The bottom left x position has to move with the top left corner
bottomLeft.x = topLeft.x;
//The top right y position has to move with the top left corner
topRight.y = topLeft.y;
invalidate();
currentTouch = NONE;
return true;
case TOUCH_TOP_RIGHT:
topRight.x = event.getX();
topRight.y = event.getY();
//The top left y position has to move with the top right corner
topLeft.y = topRight.y;
//The bottom right x position has to move with the top right corner
bottomRight.x = topRight.x;
invalidate();
currentTouch = NONE;
return true;
case TOUCH_BOT_LEFT:
bottomLeft.x = event.getX();
bottomLeft.y = event.getY();
bottomRight.y = bottomLeft.y;
topLeft.x = bottomLeft.x;
invalidate();
currentTouch = NONE;
return true;
case TOUCH_BOT_RIGHT:
bottomRight.x = event.getX();
bottomRight.y = event.getY();
topRight.x = bottomRight.x;
bottomLeft.y = bottomRight.y;
invalidate();
currentTouch = NONE;
return true;
}
return false;
}
}
这是做一个围绕你的点的矩形.想像一下在图片周围的绘图框.这些是由Rect对象创建的“触摸板”.矩形的大小由sizeOfRect设置.在onTouchEvent中,它检查每个矩形对象以查看用户的触摸是否在矩形内,从而指示用户尝试触摸该点.
