Xamarin Android：在覆盖on Draw方法中调用Invalidate（）

发布于 2025-01-27 23:00:30 字数 778 浏览 2 评论 0原文

我正在创建一个自定义渲染器，需要显示我在Vulkan引擎中渲染的内容。为此，我有一个vulkansurfaceview，它从iOS上的metalkit.mtkview继承，以及android.views.surfaceview和isurfaceview和isurfaceholdercallback上的android上。

对于iOS，我可以简单地执行此操作，只要视图的焦点是：

public class VulkanSurfaceView : MTKView, IVulkanAppHost
{
    ...

    public override void Draw()
    {
        Renderer.Tick();
        base.Draw();
    }
}

但是，在Android上，我必须这样做，在Android上，我从OnDraw方法中调用Invalidate（），否则是只打电话一次。我认为此代码闻起来有点闻，我不确定这是这样做的“好”方式。我的解决方案还可以吗？如果没有，有人有更好的主意吗？

public class VulkanSurfaceView : SurfaceView, ISurfaceHolderCallback, IVulkanAppHost
{
    ...

    protected override void OnDraw(Canvas? canvas)
    {
        Renderer.Tick();
        base.OnDraw(canvas);
        Invalidate();
    }
}

原文

I am creating a custom renderer, that needs to display whatever I have rendered in my Vulkan engine. For this I have a VulkanSurfaceView, which inherits from MetalKit.MTKView on iOS, and from Android.Views.SurfaceView and ISurfaceHolderCallback on Android.

For iOS I can simply do this, which will draw a new frame continually, as long as the view is in focus:

public class VulkanSurfaceView : MTKView, IVulkanAppHost
{
    ...

    public override void Draw()
    {
        Renderer.Tick();
        base.Draw();
    }
}

However, on Android I have to do this, where I call Invalidate() from within the OnDraw method, else it is only called once. I think this code smells a bit, and I am not sure, if this is the "good" way of doing it. Is my solution okay? If not, does anyone have a better idea?

public class VulkanSurfaceView : SurfaceView, ISurfaceHolderCallback, IVulkanAppHost
{
    ...

    protected override void OnDraw(Canvas? canvas)
    {
        Renderer.Tick();
        base.OnDraw(canvas);
        Invalidate();
    }
}

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迷你仙 2025-02-03 23:00:30

您是否尝试在您的表面处理方法中调用setWillnotDraw（false）？
请参阅 link

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嘿哥们儿 2025-02-03 23:00:30

谢谢@toolmakersteve。

如果已经请求新框架（由简单的bool请求新框架），我创建了一个计时器，在该计时器中我调用Invalidate（）。对于任何有兴趣的人，我都这样做：

protected override void OnDraw(Canvas? canvas) // Just to show the updated OnDraw-method
{
    Renderer.Tick();
    base.OnDraw(canvas);
}

public void SurfaceCreated(ISurfaceHolder holder)
{
    TickTimer = new System.Threading.Timer(state =>
    {
        AndroidApplication.SynchronizationContext.Send(_ => { if (NewFrameRequested) Invalidate(); }, state);

        try { TickTimer.Change(0, Timeout.Infinite); } catch (ObjectDisposedException) { }

    }, null, 0, Timeout.Infinite);
}

现在它很简单，但是它可以起作用，并且可能会成长。使用这种方法，我最初的不良帧率的原因是对计时器的“ dueTime”的误解（请参阅 noreflow noreferrer“> timer class ），虽然我是框架。 这实际上是帧之间的时间，现在似乎很明显 。

正如@bhargavi还提到的那样，您需要设置“ setWillNotDraw（false）”，如果在视图无效时未调用ondraw。

Thank you to @ToolmakerSteve.

I created a Timer where I call Invalidate() if a new frame has been requested (by me via a simple bool). For anyone interested I do it like so:

protected override void OnDraw(Canvas? canvas) // Just to show the updated OnDraw-method
{
    Renderer.Tick();
    base.OnDraw(canvas);
}

public void SurfaceCreated(ISurfaceHolder holder)
{
    TickTimer = new System.Threading.Timer(state =>
    {
        AndroidApplication.SynchronizationContext.Send(_ => { if (NewFrameRequested) Invalidate(); }, state);

        try { TickTimer.Change(0, Timeout.Infinite); } catch (ObjectDisposedException) { }

    }, null, 0, Timeout.Infinite);
}

For now it is very simple, but it works and will probably grow. The reason for my initial bad framerate with this method was a misunderstanding of the "dueTime" of the Timer (see Timer Class), which I though was the framerate sought. This is actually the time between frames, which seems obvious now.

As @Bhargavi also kindly mentioned you need to set "setWillNotDraw(false)" if OnDraw is not being called when invalidating the view.

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