这里的问题是你只使用一个路径。
您应该在每个 ACTION_DOWN 上创建一个新路径。对于这些路径中的每一个，您还必须存储 Paint。
例如，您可以定义一个将两个元素都作为成员的类：
public class Stroke {
private Path _path;
private Paint _paint;
}// add constructor(Path, Paint) and accessors
以及您的上下文中的 Stroke 列表：
List<Stroke> allStrokes = new ArrayList<Stroke>();
所以在每一个上ACTION_DOWN，你都会创建一个新的 Stroke（所以是一个新的路径，以及一个具有您选择的颜色的新油漆）。
并且在每一个上ACTION_MOVE，您都检索了最后添加的路径，然后您可以lineTo最后一点。
然后在你的 onDraw 上，画出所有创建的 Stroke：
for (Stroke s : allStrokes) {
canvas.drawPath(s.getPath(), s.getPaint());
}
请注意，使用这个简单的解决方案，您不能进行多点触控绘图。为此，您还必须存储和处理 MotionEvent ID。
编辑：这是一个有效的多点触控绘画示例，它创建填充随机颜色的笔触：
绘图区.java：
import android.content.Context;
import android.graphics.*;
import android.util.SparseArray;
import android.view.MotionEvent;
import android.view.View;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class DrawArea extends View {
private List<Stroke> _allStrokes; //all strokes that need to be drawn
private SparseArray<Stroke> _activeStrokes; //use to retrieve the currently drawn strokes
private Random _rdmColor = new Random();
public DrawArea(Context context) {
super(context);
_allStrokes = new ArrayList<Stroke>();
_activeStrokes = new SparseArray<Stroke>();
setFocusable(true);
setFocusableInTouchMode(true);
setBackgroundColor(Color.WHITE);
}
public void onDraw(Canvas canvas) {
if (_allStrokes != null) {
for (Stroke stroke: _allStrokes) {
if (stroke != null) {
Path path = stroke.getPath();
Paint painter = stroke.getPaint();
if ((path != null) && (painter != null)) {
canvas.drawPath(path, painter);
}
}
}
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
final int action = event.getActionMasked();
final int pointerCount = event.getPointerCount();
switch (action) {
case MotionEvent.ACTION_DOWN: {
pointDown((int)event.getX(), (int)event.getY(), event.getPointerId(0));
break;
}
case MotionEvent.ACTION_MOVE: {
for (int pc = 0; pc < pointerCount; pc++) {
pointMove((int) event.getX(pc), (int) event.getY(pc), event.getPointerId(pc));
}
break;
}
case MotionEvent.ACTION_POINTER_DOWN: {
for (int pc = 0; pc < pointerCount; pc++) {
pointDown((int)event.getX(pc), (int)event.getY(pc), event.getPointerId(pc));
}
break;
}
case MotionEvent.ACTION_UP: {
break;
}
case MotionEvent.ACTION_POINTER_UP: {
break;
}
}
invalidate();
return true;
}
private void pointDown(int x, int y, int id) {
//create a paint with random color
Paint paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(10);
paint.setColor(_rdmColor.nextInt());
//create the Stroke
Point pt = new Point(x, y);
Stroke stroke = new Stroke(paint);
stroke.addPoint(pt);
_activeStrokes.put(id, stroke);
_allStrokes.add(stroke);
}
private void pointMove(int x, int y, int id) {
//retrieve the stroke and add new point to its path
Stroke stroke = _activeStrokes.get(id);
if (stroke != null) {
Point pt = new Point(x, y);
stroke.addPoint(pt);
}
}
}
中风.java：
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
public class Stroke {
private Path _path;
private Paint _paint;
public Stroke (Paint paint) {
_paint = paint;
}
public Path getPath() {
return _path;
}
public Paint getPaint() {
return _paint;
}
public void addPoint(Point pt) {
if (_path == null) {
_path = new Path();
_path.moveTo(pt.x, pt.y);
} else {
_path.lineTo(pt.x, pt.y);
}
}
}
我的活动.java：
import android.app.Activity;
import android.os.Bundle;
public class MyActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DrawArea da = new DrawArea(this);
setContentView(da);
}
}