android – 如何在点之间画一条线,拉这些点？

概述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(10,10,90,10,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… 这是如何完成的.假设你有点,使这些全局： PointF topLeft = new PointF(10 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 *** 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：

@OverrIDepublic 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.

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