布局:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<SurfaceView
android:id="@+id/surfaceview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</android.support.constraint.ConstraintLayout>
主类:
package com.example.day06huihua;
import android.annotation.SuppressLint;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
public class MainActivity extends AppCompatActivity {
private SurfaceView surfaceview;
@SuppressLint("ClickableViewAccessibility")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
final SurfaceHolder holder = surfaceview.getHolder();
holder.addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
});
surfaceview.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
float x = event.getX();
float y = event.getY();
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN://落笔
break;
case MotionEvent.ACTION_MOVE://滚动
Canvas canvas = holder.lockCanvas();//锁定画布
Paint paint = new Paint();//画笔
paint.setColor(Color.BLUE);//设置画笔颜色
paint.setStrokeWidth(20);//画笔的字体大小
canvas.save();//保存上次的画图
canvas.drawPoint(x, y, paint);//画点
canvas.restore();//与上次合并在一块
holder.unlockCanvasAndPost(canvas);//提交画
break;
case MotionEvent.ACTION_UP://提笔
break;
}
return true;
}
});
}
private void initView() {
surfaceview = (SurfaceView) findViewById(R.id.surfaceview);
}
}
效果: