检测拖放和检测长按（XNA 或 as3）

Question

我正在尝试为一个对象实现拖放行为，我需要在触摸被按下时进行注册，并且在稍微移动它之后它应该开始拖动。

不幸的是，我使用的是用 C# 实现的自定义框架，它类似于 XNA。

您将如何在 XNA 上做到这一点？

（适用于安卓平板电脑）。

Answer 1

显然这个例子应该被重构以使用输入服务和更好地处理触摸上/下概念，但答案的核心保持不变：

// I don't remember the exact property names, but you probably understand what I mean
public override void Update(GameTime time) 
{
    var currentState = TouchPanel.GetState();
    var gestures = currentState.TouchGestures;
    var oldGests = this.oldState.TouchGestures;

    if (oldGests.Count == 0 && gestures.Count == 1 && gestures[0].State == Pressed)
    {
        // Went from Released to Pressed
        this.touchPressed = true;
    }
    else
    {
        // Not the frame it went to Pressed
        this.touchPressed = false;
    }

    if (oldGests.Count == 1 && gestures.Count == 1 && oldGests[0].State == Pressed && gestures[0].State == Pressed)
    {
        // Touch is down, and has for more than 1 frame (aka. the user is dragging)
        this.touchDown = true;
    }
    else
    {
        this.touchDown = false;
    }


    if (oldGests.Count == 1 && oldGests[0].State == Pressed && gestures.Count == 0)
    {
        // Went from Released to Pressed
        this.touchReleased = true;
    }
    else
    {
        // Not the frame it went to Pressed
        this.touchReleased = false;
    }

    this.oldState = currentState;
}

您可能需要稍微调整一下“ifs”，因为我实际上不记得手势在您松开手指后的第一帧是否下降到 0，或者它是否仍然显示 1 个称为“已释放”的手势。测试一下，你就会得到答案！

现在您可以在代码的其他地方使用“this.touchDown”来确定您的对象是否应该移动。