Android 使用Path实现涂鸦功能

Z时代
2024-01-10
分类：综合

今天实现一个涂鸦效果,会分几步实现,这里有一个重要的知识点就是图层,要理解这个,不然你看这篇博客,很迷茫,迷茫的苍茫的天涯是我的爱,先从简单的需求做起,绘制一条线,代码如下：


package com.tuya;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
/**
 * Created by admin on 2016/12/16.
 */
public class GraffitiView extends View{
  private Paint paint;
  private Path path;
  private float downX,downY;
  private float tempX,tempY;
  public GraffitiView(Context context) {
    this(context,null);
  }
  public GraffitiView(Context context, AttributeSet attrs) {
    this(context, attrs,0);
  }
  public GraffitiView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
  }
  private void init() {
    paint = new Paint();
    paint.setAntiAlias(true);
    paint.setStrokeWidth(10);
    paint.setStyle(Paint.Style.STROKE);
    path = new Path();
  }
  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if(path!=null){
      canvas.drawPath(path,paint);
    }
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()){
      case MotionEvent.ACTION_DOWN:
        downX = event.getX();
        downY = event.getY();
        path.moveTo(downX,downY);
        invalidate();
        tempX = downX;
        tempY = downY;
        break;
      case MotionEvent.ACTION_MOVE:
        float moveX = event.getX();
        float moveY = event.getY();
        path.quadTo(tempX,tempY,moveX,moveY);
        invalidate();
        tempX = moveX;
        tempY = moveY;
        break;
    }
    return true;
  }
}