(转)android图片根据手势路线进行移动

做游戏的时候遇到的问题，在CSDN问的，有人提供了好的方法，记录一下。

用手指画一条路线，然后图跟着路线移动。

import java.util.ArrayList;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PointF;
import android.view.MotionEvent;
import android.view.View;

class CustomView1 extends View {

private Paint paint;
private ArrayList<PointF> graphics = new ArrayList<PointF>();
private Paint lPaint;
private Path mPath;
private int of = 0;
private Boolean over =false;
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;

public CustomView1(Context context) {
super(context);
paint = new Paint(Paint.ANTI_ALIAS_FLAG); // 抗锯齿
paint.setColor(Color.RED);
paint.setStrokeJoin(Paint.Join.ROUND); // 让画的线圆滑
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeWidth(65); // 画笔划线的宽度，设为65可以将一个点画成一个圆，便于观察

lPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
lPaint.setColor(Color.BLACK);
lPaint.setStyle(Paint.Style.STROKE);//空心
lPaint.setStrokeJoin(Paint.Join.ROUND);
lPaint.setStrokeCap(Paint.Cap.ROUND);
lPaint.setStrokeWidth(5);

mPath = new Path();

}

@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
over = false;
graphics.clear();
of=0;
graphics.add(new PointF(x, y));
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
graphics.add(new PointF(x, y));
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
over = true;
touch_up();
invalidate();
break;
}

return true;
}

private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
}
}
private void touch_up() {
//mPath.lineTo(mX, mY);
}

@Override
protected void onDraw(Canvas canvas) {
// canvas.drawColor(Color.TRANSPARENT,Mode.CLEAR);
canvas.drawColor(Color.WHITE);//清理
canvas.drawPath(mPath, lPaint);
if(over&&graphics.size()>0){
canvas.drawPoint(graphics.get(of).x, graphics.get(of).y, paint);
of+=1;
if(of<graphics.size()){
if(of==graphics.size()-1){
mPath.reset();//移动完成后移除线条
}
invalidate();
}
}
}
}

原文地址：http://topic.csdn.net/u/20110821/11/2bcab963-401a-44ae-9dab-cb9a543d2c22.html