如何画点之间的线拉的点？ [英] How to draw a lines between points and pull those points?
问题描述
我要画上观点之间的界线，再拉这些点高达希望的位置，甚至形状会发生变化。
I want to draw the lines between points on the view, and then pull those points upto desired positions even the shape will change.
我知道如何绘制两点之间的连线 canvas.drawLine（10，10，90，10，油漆）; 通过使用这个我可以绘制的线条点。
i know how to draw the line between two points canvas.drawLine(10, 10, 90, 10, paint); by using this i can draw the lines between points.
修改：我在这里附上图片解释清楚，从保罗的回答现在我能够得出点之间的线路，还有的拉分的问题..
EDIT : here i am attaching image for clear explanation, from Paul answer now i am able to draw the lines between points, still have the problem of pulling points...
推荐答案
下面是它是如何做。假设你有你的观点，使这些全球性：
Here's how it's done. Suppose you have your points, make these global:
PointF topLeft = new PointF(10,10);
PointF topRight = new PointF(90,10);
PointF bottomLeft = new PointF(10,90);
PointF bottomRight = new PointF(90,90);
您需要做的是让每个点周围一RectF。该RectF越大，更大的触摸区域的点。
What you need to do is make a RectF around each point. The bigger the RectF, the bigger the touch area for the point is.
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正在做的onTouch。一个int值的角落被触动，另外四个是标识符的角落。
Define some globals to keep track of what the user is doing in onTouch. One int is the corner being touched, and the other four are identifiers for the corners.
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，在你的onTouch活动，您可以检查这一点你的用户是在接触这样的：
Now, in your onTouch event, you can check which point your user is touching in like this:
@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;
}
}
这样做是让周围的点的矩形。想象一下，在图片周围的点来绘制框。这些都是由矩形对象创建的触摸板。的矩形的尺寸是由sizeOfRect设置。在的onTouchEvent，它检查每个矩形对象，以确定用户的触摸是在矩形内，信令一个用户试图触摸该点。
What this does is make a rectangle around your point. Imagine drawing boxes around your points in the picture. These are the "touch pads" created by the Rect objects. The size of the rectangle is set by sizeOfRect. In the onTouchEvent, it checks each rectangle object to see if the user's touch is inside the rectangle, signaling an the user trying to touch that point.
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