Question

我正在尝试制作它，这样当鼠标位于var play设置的边界内时，它会改变图像。我使用的方法与我在点击时用于更改图像的方法相同，但鼠标悬停和鼠标移除不想在这里工作。

var play = {
    x: 650,
    y: 360,
    width: 200,
    height: 100
}
var playUpButton = new Image();
playUpButton.src = "images/PlayUp.png";
var playDownButton = new Image();
playDownButton.src = "images/PlayDown.png";
var playHovering = false;

thisCanvas.addEventListener('click', checkPlay);
thisCanvas.addEventListener('mouseover', hoverPlay, false);
thisCanvas.addEventListener('mouseout', hoverPlay, false);

function seen_move(e)
{
    var bounding_box = thisCanvas.getBoundingClientRect();
    mouseX = ((e.clientX-bounding_box.left) *(thisCanvas.width/bounding_box.width));
    mouseY = ((e.clientY-bounding_box.top) * (thisCanvas.height/bounding_box.height));
}

function draw_start()
{
    context.drawImage(menubg, menubg.x, menubg.y, menubg.width, menubg.height);
    if(playHovering)
    {
        context.drawImage(playDownButton, play.x, play.y, play.width, play.height);
    }
}


function mouseInArea(top, right, bottom, left)
{
    if(mouseX >= left && mouseX < right && mouseY >= top && mouseY < bottom)
    {
        return true;
    }
    else
    {
        return false;
    }
}   

function hoverPlay()
{
    if(mouseInArea(play.y, play.x + play.width, play.y + play.height, play.x))
    {
        console.log("Hovering");
        if(playHovering)
        {
            playHovering = false;
        }
        else
        {
            playHovering = true;
        }
    }
}

Answer 1

您的代码中似乎缺少以下内容。

var thisCanvas = document.getElementById("thisCanvas");

函数checkPlay似乎也缺失了。

看看这些文章： http://www.html5canvastutorials.com/advanced/html5-canvas-mouse-coordinates/ http://www.informit.com/articles/article.aspx?p=1903884&seqNum=6

Answer 2

您必须致电function seen_move(e)以获得鼠标位置。

顺便说一下，我对seen_move中的额外代码感到困惑。我猜你是在相对于边界框制作鼠标位置。我只是提到它，以防这也是一个问题：

// this usually get the mouse position
var bounding_box = thisCanvas.getBoundingClientRect();
mouseX = e.clientX-bounding_box.left;
mouseY = e.clientY-bounding_box.top;

// and you have this extra bit:
// *(thisCanvas.width/bounding_box.width)); and 
// * (thisCanvas.height/bounding_box.height));
mouseX = ((e.clientX-bounding_box.left) *(thisCanvas.width/bounding_box.width));
mouseY = ((e.clientY-bounding_box.top) * (thisCanvas.height/bounding_box.height));

我试图在mouseover和mouseout

2 个答案: