我正在创建一个人脸识别应用程序,它会在检测到脸部时绘制矩形。目前,所有的计算都是在主线程上完成的,因为它耗尽了大量的CPU。 我决定在不同的线程上运行计算。现在问题是,是否可以从后台线程本身绘制画布?或者我必须将参数发送到主线程,然后从那里绘制画布?
答案 0 :(得分:6)
是的,从另一个线程而不是从UI线程渲染画布!这将改善和优化绩效。
以下是我编写的一些代码:
package com.webstorms.framework;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.view.SurfaceView;
public class RenderView extends WSObject implements Runnable {
Bitmap gameScreen;
SurfaceView surfaceView;
Thread gameloop;
boolean running;
int sleepTime;
int numberOfFramesSkipped;
int maxFrameSkips;
long beginTime;
long endTime;
long lastTime;
int differenceTime;
int framePeriod;
Canvas frameBuffer;
int frameCount;
int realFPS;
int setFPS;
/**
* This class is the game loop that will update and render the game.
*
*/
public RenderView(Game game, Bitmap gameScreen, int fps, int maxFrameSkips) {
super(game);
this.gameScreen = gameScreen;
surfaceView = new SurfaceView(game);
this.setFPS = fps;
this.framePeriod = 1000/this.setFPS;
this.maxFrameSkips = maxFrameSkips;
lastTime = System.currentTimeMillis();
beginTime = System.currentTimeMillis();
}
public SurfaceView getView() {
return this.surfaceView;
}
@Override
public void run() {
while(running) {
if(this.surfaceView.getHolder().getSurface().isValid()) {
beginTime = System.currentTimeMillis();
this.getGame().getInput().update(); // Synchronize input and call all attached listeneres
this.getGame().getCurrentScreen().update();
this.renderFrameBuffer();
// Frame Per Second Count
frameCount++;
if(lastTime + 1000 < System.currentTimeMillis()) {
WSLog.d(Game.GAME_ENGINE_TAG, this, "REAL FPS: " + frameCount);
this.realFPS = frameCount;
lastTime = System.currentTimeMillis();
frameCount = 0;
}
endTime = System.currentTimeMillis();
differenceTime = (int) (endTime - beginTime);
sleepTime = (int) (framePeriod - differenceTime);
if(sleepTime > 0) {
try {
Thread.sleep(sleepTime);
}
catch (InterruptedException exception) {
exception.printStackTrace();
}
}
else {
while(sleepTime < 0 && numberOfFramesSkipped < this.maxFrameSkips) {
WSLog.d(Game.GAME_ENGINE_TAG, this, "Game thread is only updating the update method and is not rendering anything");
this.getGame().getCurrentScreen().update();
sleepTime += framePeriod;
numberOfFramesSkipped++;
}
}
}
}
}
public int getRealFPS() {
return this.realFPS;
}
public int getSetFPS() {
return this.setFPS;
}
private void renderFrameBuffer() {
// Update the current virtual screen image
this.getGame().getCurrentScreen().render();
// Render the current virtual screen to the real phone screen
frameBuffer = this.surfaceView.getHolder().lockCanvas();
if(frameBuffer != null) { // Fix for mysterious bug ( FATAL EXCEPTION: Thread)
frameBuffer.drawBitmap(this.gameScreen, null, this.getGame().getWSScreen().getGameScreendst(), null);
this.surfaceView.getHolder().unlockCanvasAndPost(frameBuffer);
}
else {
WSLog.e(Game.GAME_ENGINE_TAG, this, "Surface has not been created or otherwise cannot be edited");
}
}
public void resume() {
this.running = true;
gameloop = new Thread(this);
gameloop.start();
}
public void pause() {
this.running = false;
running = false;
while(true) {
try {
gameloop.join();
break;
}
catch (InterruptedException e) {
// retry
}
}
}
}
创建renderview对象时,请为第一个参数传递活动的引用。
在您的活动中也这样做:
this.setContentView(this.renderView.getView());
答案 1 :(得分:0)
这是没有问题的。它可以帮助您优化渲染。