【发布时间】：2014-10-16 14:45:40
【问题描述】：
在我在两个不同矩形上的 2 个固定点之间画线后，我需要旋转它们。问题是我的线没有更新，它保持在相同的 x1、y1、x2、y2 上。如何画线跟随这个矩形？
如果你们有任何示例代码或可以提供帮助的东西，那就太好了！ 谢谢！
我认为我不需要 OnValidateUpdate 来解决这个问题。 这是我演示此问题的示例代码：
我要绘制的对象：
public class Object {
private int xPos;
private int yPos;
private int width;
private int height;
float xDistance = 0f;
float yDistance = 0f;
double angleToTurn = 0.0;
Matrix matrix = new Matrix();
private Rect rect;
private Paint paint;
private Point point;
Paint p = null;
public Object(int xPos, int yPos){
this.xPos = xPos;
this.yPos = yPos;
this.width = 300;
this.height = 100;
matrix = new Matrix();
rect = new Rect(xPos,yPos,xPos + width,yPos + height);
paint = new Paint();
paint.setStyle(Style.FILL);
paint.setColor(Color.BLUE);
p = new Paint();
p.setStyle(Style.FILL);
p.setStrokeWidth(15);
p.setColor(Color.BLACK);
point = new Point(this.getxPos(), this.getyPos()+this.getHeight());
}
public void rotate(float xEvent, float yEvent){
xDistance = xEvent - this.xPos;
yDistance = yEvent - this.yPos;
int angleToTurn = ((int)Math.toDegrees(Math.atan2(yDistance, xDistance)));
matrix.setRotate((int)(angleToTurn),xPos,yPos + height/2);
}
public void draw(Canvas c){
c.save();
c.setMatrix(matrix);
c.drawRect(rect, paint);
c.drawPoint(point.x,point.y,p);
c.restore();
}
public Point getPoint() {
return point;
}
public void setPoint(Point point) {
this.point = point;
}
public Matrix getMatrix() {
return matrix;
}
public void setMatrix(Matrix matrix) {
this.matrix = matrix;
}
public int getxPos() {
return xPos;
}
public void setxPos(int xPos) {
this.xPos = xPos;
}
public int getyPos() {
return yPos;
}
public void setyPos(int yPos) {
this.yPos = yPos;
}
public int getWidth() {
return width;
}
public void setWidth(int width) {
this.width = width;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
我在其中绘制 2 个矩形的 GameView 类：
public class GameView extends SurfaceView implements SurfaceHolder.Callback{
private SurfaceHolder surfaceHolder;
private GameloopThread gameloopThread;
float downx,downy,upx,upy;
private Object object,object1;
Line line;
public GameView(Context context) {
super(context);
gameloopThread = new GameloopThread(this);
surfaceHolder = getHolder();
surfaceHolder.addCallback(this);
object = new Object(500,500);
object1 = new Object(800,700);
line = new Line(object.getPoint(),object1.getPoint());
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
Canvas canvas = surfaceHolder.lockCanvas();
onDraw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
gameloopThread.setRunning(true);
gameloopThread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
gameloopThread.setRunning(false);
while(retry){
try {
gameloopThread.join();
retry=false;
}catch(InterruptedException e){
}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {
}
@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouchEvent( MotionEvent event) {
float x = 0f,y=0f;
if(event.getAction() == MotionEvent.ACTION_DOWN){
downx = event.getX();
downy = event.getY();
}
if (event.getAction() == MotionEvent.ACTION_MOVE) {
x = event.getX();
y = event.getY();
object.rotate(x, y);
object1.rotate(x, y);
}
if (event.getAction() == MotionEvent.ACTION_UP) {
}
return true;
}
@Override
public void onDraw(Canvas canvas){
super.onDraw(canvas);
canvas.drawColor(Color.LTGRAY);
if(object != null)
object.draw(canvas);
if(object1 != null)
object1.draw(canvas);
if(line != null){
line._drawLine(canvas);
}
}
}
应该连接两个矩形的线类（我为它创建了类，但不需要）
public class Line {
private Point point1,point2;
private Paint p;
Matrix m;
public Line(Point p1,Point p2){
this.point1 = p1;
this.point2 = p2;
p = new Paint();
p.setStyle(Style.FILL);
p.setColor(Color.RED);
m = new Matrix();
}
public void _drawLine(Canvas c){
c.setMatrix(m);
c.save();
c.drawLine(point1.x, point1.y, point2.x, point2.y, p);
c.restore();
}
public Matrix getMatrix(){
return m;
}
}
如果可能的话，我想使用 Matrix 对象来实现。还有 MainActivity 和 Thread 类，但我不发布它们，因为它们与这个问题无关。
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