canvas.drawBitmap()使图片全屏显示

本文介绍了一种在Android中使用canvas.drawBitmap()方法使图片全屏显示的方法。具体实现是通过创建一个RectF对象并设置其宽度和高度为屏幕尺寸,然后将其作为参数传递给drawBitmap()方法。

有时候我们这使用canvas.drawBitmap()时,需要使图片全屏显示,这个时候我们可以这样:

Rectf rectF = new RectF(0, 0, w, h);   //w和h分别是屏幕的宽和高,也就是你想让图片显示的宽和高
canvas.drawBitmap(bitmap, null, rectF, null);

package com.example.myapplication; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; import androidx.appcompat.app.AppCompatActivity; import java.net.DatagramPacket; import java.net.DatagramSocket; public class VideoActivity extends AppCompatActivity { private static final int PORT = 8888; private static final int BUFFER_SIZE = 65535; private volatile boolean receiving = true; private SurfaceHolder surfaceHolder; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); SurfaceView surfaceView = findViewById(R.id.surface_view); surfaceHolder = surfaceView.getHolder(); surfaceHolder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceCreated(SurfaceHolder holder) { new Thread(new VideoReceiver()).start(); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {} @Override public void surfaceDestroyed(SurfaceHolder holder) { receiving = false; } }); } private class VideoReceiver implements Runnable { @Override public void run() { try (DatagramSocket socket = new DatagramSocket(PORT)) { byte[] buffer = new byte[BUFFER_SIZE]; while (receiving) { DatagramPacket packet = new DatagramPacket(buffer, buffer.length); socket.receive(packet); // 将接收到的字节数据转换为位图 Bitmap bitmap = BitmapFactory.decodeByteArray( packet.getData(), 0, packet.getLength() ); // 在SurfaceView上绘制图像 if (bitmap != null) { Canvas canvas = surfaceHolder.lockCanvas(); if (canvas != null) { // 缩放到位图以适应SurfaceView尺寸 Bitmap scaledBitmap = Bitmap.createScaledBitmap( bitmap, canvas.getWidth(), canvas.getHeight(), true ); canvas.drawBitmap(scaledBitmap, 0, 0, null); surfaceHolder.unlockCanvasAndPost(canvas); scaledBitmap.recycle(); } bitmap.recycle(); } } } catch (Exception e) { e.printStackTrace(); } } } @Override protected void onDestroy() { super.onDestroy(); receiving = false; } } 根据上述相应的java文件写一个相应的activity_video.xml文件,并且上述程序要放在该xml界面内
最新发布
09-23
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