android 利用path 实现手写板的手写效果

代码其实比较简单，这种需求一般出现在图库软件里面，可以让用户，触摸来在图片上面写字，画圈圈之类的。反正就是记录触摸轨迹吧。

public class TouchView extends View {    private float currentX;    private float currentY;    private Paint paint;    private Path path;    public TouchView(Context context) {        super(context);    }    public TouchView(Context context, @Nullable AttributeSet attrs) {        super(context, attrs);    }    public TouchView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    public TouchView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {        super(context, attrs, defStyleAttr, defStyleRes);    }    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {        super.onSizeChanged(w, h, oldw, oldh);        paint = new Paint();        paint.setAntiAlias(true);        paint.setStyle(Paint.Style.STROKE);        paint.setStrokeWidth(getResources().getDimension(R.dimen.paint_width));        paint.setStrokeCap(Paint.Cap.ROUND);        path = new Path();    }    @Override    public boolean onTouchEvent(MotionEvent event) {        currentX = event.getX();        currentY = event.getY();        switch (event.getAction()) {            case MotionEvent.ACTION_DOWN:                path.moveTo(currentX, currentY);                break;            case MotionEvent.ACTION_MOVE:            case MotionEvent.ACTION_UP:            case MotionEvent.ACTION_CANCEL:                path.lineTo(currentX, currentY);                break;        }        postInvalidate();        return true;    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        canvas.drawPath(path, paint);    }}

代码这就行了，比较简单。效果类似下面这种：

不要在意图片和大红背景色

需要注意的地方：

switch (event.getAction()) {    case MotionEvent.ACTION_DOWN:        path.moveTo(currentX, currentY); // 这里是 moveTo        break;    case MotionEvent.ACTION_MOVE:    case MotionEvent.ACTION_UP:    case MotionEvent.ACTION_CANCEL:        path.lineTo(currentX, currentY); // 这里是 lineTo        break;}

没有了。

更多相关文章

随机推荐