画板
package com.example.day1113;
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.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {
private Button button_clear;
private SurfaceView sv;
private SurfaceHolder surfaceHolder;
private Path path = new Path();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
@SuppressLint("ClickableViewAccessibility")
private void initView() {
button_clear = (Button) findViewById(R.id.button_clear);
sv = (SurfaceView) findViewById(R.id.sv);
surfaceHolder = sv.getHolder();
surfaceHolder.addCallback(this);
button_clear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
path.reset();
}
});
sv.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
float x = event.getX();
float y = event.getY();
if (action == MotionEvent.ACTION_DOWN){
path.moveTo(x,y);
}else if (action == MotionEvent.ACTION_MOVE){
path.lineTo(x,y);
}
return true;
}
});
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
new MyThread().start();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
class MyThread extends Thread{
@Override
public void run() {
super.run();
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(20);
while (true) {
Canvas canvas = surfaceHolder.lockCanvas();
if (canvas == null){
break;
}
canvas.drawColor(Color.WHITE);
canvas.drawPath(path,paint);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}