使用 KeyDown 事件 UWP 在 canvas 上平滑元素运动

Question

我正在尝试创建一种宇宙飞船游戏，您可以在其中使用箭头键控制图像（显然是宇宙飞船）来移动 UP/DOWN/R/L。为此，我使用了 CoreWindow.KeyDown 事件。

其实还可以，就是动作不够流畅。每次我按下其中一个箭头键时，图像就会出现： 1. 向那个方向移动一步 2. 冻结，大约半秒（甚至更短） 3. 然后继续无障碍地移动。（A "step" 是一个 'int' 变量，它包含多个像素，比如 20 个）。

当然，那是没办法运行一场比赛。当我按下其中一个箭头键时，我希望船立即平稳移动，没有 "Half a second" 延迟。这是我的代码：

public sealed partial class MainPage : Page
{
    double playerYAxisPosition;
    double playerXAxisPosition;
    int steps = 20;
    bool upMovement;
    bool downMovement;
    bool rightMovement;
    bool leftMovement;

    public MainPage()
    {
        this.InitializeComponent();
        Window.Current.CoreWindow.KeyDown += CoreWindow_KeyDown;
        Window.Current.CoreWindow.KeyUp += CoreWindow_KeyUp;
    }

    // Recognizes the KeyDown press and sets the relevant booleans to "true"
    private void CoreWindow_KeyDown(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args) {
        playerYPosition = (double) playerShip.GetValue(Canvas.TopProperty);
        playerXPosition = (double) playerShip.GetValue(Canvas.LeftProperty);

        if (args.VirtualKey == Windows.System.VirtualKey.Up) {
            upMovement = true;
        }
        else if (args.VirtualKey == Windows.System.VirtualKey.Down) {
            downMovement = true;
        }
        else if (args.VirtualKey == Windows.System.VirtualKey.Left) {
            leftMovement = true;
        }
        else if (args.VirtualKey == Windows.System.VirtualKey.Right) {
            rightMovement = true;
        }
        movePlayer();
    }

    // recognizes the KeyUp event and sets the relevant booleans to "false"
    private void CoreWindow_KeyUp(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args) {
        if (args.VirtualKey == Windows.System.VirtualKey.Up) {
            upMovement = false;
        }
        else if (args.VirtualKey == Windows.System.VirtualKey.Down) {
            downMovement = false;
        }
        else if (args.VirtualKey == Windows.System.VirtualKey.Left) {
            leftMovement = false;
        }
        else if (args.VirtualKey == Windows.System.VirtualKey.Right) {
            rightMovement = false;
        }
    }

    // Calls the movement Methods of the relevant direction
    private void movePlayer() {
        if (upMovement) {
            moveUp();
        }
        if (downMovement) {
            moveDown();
        }
        if (rightMovement) {
            moveRight();
        }
        if (leftMovement) {
            moveLeft();
        }
    }

    private void moveUp() {
        playerShip.SetValue(Canvas.TopProperty, playerYPosition - stepsToMove);
    }

    private void moveDown() {
        playerShip.SetValue(Canvas.TopProperty, playerYPosition + stepsToMove);
    }

    private void moveRight() {
        playerShip.SetValue(Canvas.LeftProperty, playerXPosition + stepsToMove);
    }

    private void moveLeft() {
        playerShip.SetValue(Canvas.LeftProperty, playerXPosition - stepsToMove);
    }

顺便说一句，我创建了一些专用的布尔值，这些布尔值将在每个 KeyDown 事件上设置为 'true' 或 'false'，而不是直接使用 KeyDown 事件，因为这种分离允许元素（船图像）也沿对角线移动，而直接使用 "args.VirtualKey == Windows.System.VirtualKey.SomeArrowKey" 由于某种原因不允许它。

感谢您的帮助。

Answer 1

如果你想创建一个游戏，你应该在你的游戏循环中移动 playerShip。您可以使用 DispatcherTimer or register CompositionTarget.Rendering 事件来创建游戏循环。

Windows.UI.Xaml.Media.CompositionTarget.Rendering += CompositionTarget_Rendering;

更改 CoreWindow_KeyDown 事件处理程序如下：

private void CoreWindow_KeyDown(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args)
{
    if (args.VirtualKey == Windows.System.VirtualKey.Up)
    {
        upMovement = true;
    }
    else if (args.VirtualKey == Windows.System.VirtualKey.Down)
    {
        downMovement = true;
    }
    else if (args.VirtualKey == Windows.System.VirtualKey.Left)
    {
        leftMovement = true;
    }
    else if (args.VirtualKey == Windows.System.VirtualKey.Right)
    {
        rightMovement = true;
    }
}

接下来，在 CompositionTarget.Rendering 事件处理程序中移动你的飞船。

private void CompositionTarget_Rendering(object sender, object e)
{
    playerYPosition = (double)playerShip.GetValue(Canvas.TopProperty);
    playerXPosition = (double)playerShip.GetValue(Canvas.LeftProperty);
    movePlayer();
}

使用 KeyDown 事件 UWP 在 canvas 上平滑元素运动

Smooth element motion on canvas with KeyDown event UWP

c#

xaml

canvas

uwp

uwp-xaml