第一种:自定义View
首先,自定义一个类MySurfaceView(继承SurfaceView 实现 SurfaceHolder和Runnable):
package com.example.day07ziidngyiview;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback,Runnable{
private SurfaceHolder holder;
private Canvas canvas;
private boolean isDrawing;
private Path path=new Path();
private Paint paint=new Paint();
public MySurfaceView(Context context) {
super(context);
initView();
}
public MySurfaceView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
private void initView(){
holder=getHolder();
holder.addCallback(this);
setFocusable(true);
setFocusableInTouchMode(true);
setKeepScreenOn(true);
paint.setColor(Color.BLUE);
paint.setStrokeWidth(5);
paint.setStyle(Paint.Style.STROKE);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
isDrawing=true;
new Thread(this).start();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
@Override
public void run() {
long start = System.currentTimeMillis();//开始的毫秒值
while (isDrawing){
canvas=holder.lockCanvas();
canvas.drawPath(path,paint);
holder.unlockCanvasAndPost(canvas);
}
long end = System.currentTimeMillis();//结束的毫秒值
if((end-start)<100){
try {
Thread.sleep(100-(end-start));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
int action = event.getAction();
switch (action){
case MotionEvent.ACTION_DOWN:
path.moveTo(x,y);
break;
case MotionEvent.ACTION_MOVE:
path.lineTo(x,y);
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
}
然后这是主布局xml为刚才自定义的MySurfaceView类:
<?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">
<com.example.day07ziidngyiview.MySurfaceView
android:layout_width="match_parent"
android:layout_height="match_parent" />
</android.support.constraint.ConstraintLayout>主类中没有任何东西...
第二种,特别简单的一种:
package com.example.day07pathhuihua;
import android.annotation.SuppressLint;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
public class MainActivity extends AppCompatActivity {
private SurfaceView surfaceView;
private SurfaceHolder holder;
private Path path = new Path();
private Paint paint = new Paint();
@SuppressLint("ClickableViewAccessibility")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
holder = surfaceView.getHolder();
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(5);
paint.setColor(Color.YELLOW);
//可写可不写
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:
path.moveTo(x, y);//没有这个的话,所有的线都会连在一块
break;
case MotionEvent.ACTION_MOVE:
Canvas canvas = holder.lockCanvas();
path.lineTo(x, y);//先连线
canvas.drawPath(path, paint);//再用canvas画线
holder.unlockCanvasAndPost(canvas);
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.item,menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int itemId = item.getItemId();
switch (itemId){
case R.id.ten:
paint.setStrokeWidth(10);
paint.setColor(Color.GREEN);
break;
case R.id.shiwu:
paint.setStrokeWidth(15);
paint.setColor(Color.BLUE);
break;
}
return super.onOptionsItemSelected(item);
}
private void initView() {
surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
}
}
主布局:
<?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>
