C#异步LCD写入 [英] C# asynchronous LCD write

问题描述

因此，我正在从事一个涉及LCD屏幕的项目，该屏幕每秒可以更新60次.它使用 BitmapFrame ，我需要将这些像素复制到更新屏幕的库中.目前，我的FPS约为30-35，这太低了.因此，我尝试使用多线程，但这会带来很多问题.

So I'm working on a project that involves a LCD screen that can update 60 times per second. It uses a BitmapFrame and I need to copy those pixels to a library that updates the screen. Currently I'm getting about 30-35 FPS which is too low. So I'm trying to use multi-threading but this creates a lot of problems.

DisplayController已经创建了一个thead来完成所有工作，如下所示:

The DisplayController already creates a thead to do all the work on like so:

public void Start()
{
    _looper = new Thread(Loop);
    _looper.IsBackground = true;
    _looper.Start();
}

private void Loop()
{
    while (_IsRunning)
    {
        renderScreen();
    }
}

将调用 renderScreen 方法，该方法绘制所有元素并将像素复制到 BitmapFrame .但是此过程花费的时间太长，因此我的FPS下降了.我试图解决此问题的方法是创建一个 Task 来绘制，复制和写入像素.但是此解决方案使用大量CPU，并导致屏幕出现故障.

Which calls the renderScreen method that draws all the elements and copies the pixels to the BitmapFrame. But this proces takes too long so my FPS drops. My attempt to solve this problem was by creating a Task that draws, copies and writes the pixels. But this solution uses a lot of CPU and causes glitchtes on the screen.

public void renderScreen()
{
    Task.Run(() =>
    {
        Monitor.Enter(_object);

        // Push screen to LCD
        BitmapFrame bf = BitmapFrame.Create(screen);
        RenderOptions.SetBitmapScalingMode(bf, BitmapScalingMode.LowQuality);
        bf.CopyPixels(new Int32Rect(0, 0, width, height), pixels, width * 4, 0);

        DisplayWrapper.USBD480_DrawFullScreenBGRA32(ref disp, pixels);

        Monitor.Exit(_object);
    });
}

我已经阅读了很多有关C#并发队列的信息，但这不是我所需要的.使用两个线程会导致编译器说该变量归另一个线程所有的问题.

I've been reading a lot about concurrent queues for C# but that's not what I need. And using two threads causes the issue that the compiler says that the variable is owned by another thread.

如何同时渲染新的位图并将该位图每秒写入LCD 60次?

How can I concurrently render a new bitmap and write that bitmap 60 times per second to the LCD?

推荐答案

我认为您应该有两个线程(并且只有两个):

I think you should have two threads (and two only):

1. 一个连续创建位图的对象；和
2. 一个连续获取最新位图并将其推到LCD的人.

---

这是我幼稚的实现方式.

---

Here's my naive implementation.

我使用了一个共享阵列，其中包含最新生成的图像，因为它使分配数保持较低.一个共享数组我们可以摆脱3个数组对象(共享+ 2个线程局部变量).

I used a shared array that contains the latest produced image because it keeps number of allocations low. A shared array we can get away with 3 array objects (shared + 2 thread locals).

public class Program
{
    public class A
    {
        private readonly object pixelsLock = new object();

        Array shared = ...;

        public void Method2()
        {
            Array myPixels = (...);
            while (true)
            {
                // Prepare image
                BitmapFrame bf = BitmapFrame.Create(screen);
                RenderOptions.SetBitmapScalingMode(bf, BitmapScalingMode.LowQuality);
                bf.CopyPixels(new Int32Rect(0, 0, width, height), myPixels, width * 4, 0);

                lock (pixelsLock)
                {
                    // Copy the hard work to shared storage
                    Array.Copy(sourceArray: myPixels, destinationArray: shared, length: myPixels.GetUpperBound(0) - 1);
                }
            }
        }

        public void Method1()
        {
            Array myPixels = (...);
            while (true)
            {
                lock (pixelsLock)
                {
                    //Max a local copy
                    Array.Copy(sourceArray: shared, destinationArray: myPixels, length: myPixels.GetUpperBound(0) - 1);
                }
                DisplayWrapper.USBD480_DrawFullScreenBGRA32(ref disp, myPixels);
            }
        }
    }


    public static async Task Main(string[] args)
    {
        var a = new A();
        new Thread(new ThreadStart(a.Method1)).Start();
        new Thread(new ThreadStart(a.Method2)).Start();
        Console.ReadLine();
    }
}

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