当鼠标在画布上时，它在鼠标周围显示一个红色圆圈。我想在鼠标悬停图像时获得红圈鼠标效果。
当光标在图像上的任何位置时，我想在右侧放大视图，同时在鼠标光标上也有悬停效果。
提前感谢帮助和提出建议！
iPhone缩放代码由codeplayer编写。
http://thecodeplayer.com/walkthrough/magnifying-glass-for-images-using-jquery-and-css3
鼠标光标圈代码由Kirupa编写。
https://www.kirupa.com/canvas/follow_mouse_cursor.htm
var canvas = document.querySelector("#myCanvas");
var context = canvas.getContext("2d");
var canvasPos = getPosition(canvas);
var mouseX = 0;
var mouseY = 0;
function getPosition(el) {
var xPosition = 0;
var yPosition = 0;
while (el) {
xPosition += (el.offsetLeft - el.scrollLeft + el.clientLeft);
yPosition += (el.offsetTop - el.scrollTop + el.clientTop);
el = el.offsetParent;
}
return {
x: xPosition,
y: yPosition
};
}
function update() {
context.clearRect(0, 0, canvas.width, canvas.height);
context.beginPath();
context.arc(mouseX, mouseY, 20, 0, 2 * Math.PI, true);
context.fillStyle = "#FF6A6A";
context.fill();
requestAnimationFrame(update);
}
function setMousePosition(e) {
mouseX = e.clientX - canvasPos.x;
mouseY = e.clientY - canvasPos.y;
context.clearRect(0, 0, canvas.width, canvas.height);
context.beginPath();
context.arc(mouseX, mouseY, 20, 0, 2 * Math.PI, true);
context.fillStyle = "#FF6A6A";
context.fill();
}
canvas.addEventListener("mousemove", setMousePosition, false);
update();
$(document).ready(function() {
var native_width = 0;
var native_height = 0;
//Now the mousemove function
$(".magnify").mousemove(function(e) {
//When the user hovers on the image, the script will first calculate
//the native dimensions if they don't exist. Only after the native dimensions
//are available, the script will show the zoomed version.
if (!native_width && !native_height) {
//This will create a new image object with the same image as that in .small
//We cannot directly get the dimensions from .small because of the
//width specified to 200px in the html. To get the actual dimensions we have
//created this image object.
var image_object = new Image();
image_object.src = $(".small").attr("src");
//This code is wrapped in the .load function which is important.
//width and height of the object would return 0 if accessed before
//the image gets loaded.
native_width = image_object.width;
native_height = image_object.height;
} else {
//x/y coordinates of the mouse
//This is the position of .magnify with respect to the document.
var magnify_offset = $(this).offset();
//We will deduct the positions of .magnify from the mouse positions with
//respect to the document to get the mouse positions with respect to the
//container(.magnify)
var mx = e.pageX - magnify_offset.left;
var my = e.pageY - magnify_offset.top;
//Finally the code to fade out the glass if the mouse is outside the container
if (mx < $(this).width() && my < $(this).height() && mx > 0 && my > 0) {
$(".large").fadeIn(100);
} else {
$(".large").fadeOut(100);
}
if ($(".large").is(":visible")) {
//The background position of .large will be changed according to the position
//of the mouse over the .small image. So we will get the ratio of the pixel
//under the mouse pointer with respect to the image and use that to position the
//large image inside the magnifying glass
var rx = Math.round(mx / $(".small").width() * native_width - $(".large").width() / 2) * -1;
var ry = Math.round(my / $(".small").height() * native_height - $(".large").height() / 2) * -1;
var bgp = rx + "px " + ry + "px";
//Time to move the magnifying glass with the mouse
var px = mx - $(".large").width() / 2;
var py = my - $(".large").height() / 2;
//Now the glass moves with the mouse
//The logic is to deduct half of the glass's width and height from the
//mouse coordinates to place it with its center at the mouse coordinates
//If you hover on the image now, you should see the magnifying glass in action
$(".large").css({
left: px,
top: py,
backgroundPosition: bgp
});
}
}
})
})canvas {
border: #333 5px solid;
z-index: 1;
}
/*Some CSS*/
.magnify {
width: 100px;
position: relative;
margin-top: -205px;
margin-left: 5px;
z-index: 10;
}
/*Lets create the magnifying glass*/
.large {
width: 120px;
height: 120px;
position: absolute;
/*Multiple box shadows to achieve the glass effect*/
box-shadow: 0 0 0 7px rgba(255, 255, 255, 0.85), 0 0 7px 7px rgba(0, 0, 0, 0.25), inset 0 0 40px 2px rgba(0, 0, 0, 0.25);
/*Lets load up the large image first*/
background: url('http://thecodeplayer.com/uploads/media/iphone.jpg') no-repeat;
/*hide the glass by default*/
display: none;
margin-left: 150px;
}
/*To solve overlap bug at the edges during magnification*/
.small {
display: block;
}<canvas id="myCanvas" width="500px" height="195px"></canvas>
<!-- Lets make a simple image magnifier -->
<div class="magnify">
<!-- This is the magnifying glass which will contain the original/large version -->
<div class="large"></div>
<!-- This is the small image -->
<img class="small" src="http://thecodeplayer.com/uploads/media/iphone.jpg" width="102"/>
</div>
<!-- Lets load up prefixfree to handle CSS3 vendor prefixes -->
<script src="http://thecodeplayer.com/uploads/js/prefixfree.js" type="text/javascript"></script>
<!-- You can download it from http://leaverou.github.com/prefixfree/ -->
<!-- Time for jquery action -->
<script src="http://thecodeplayer.com/uploads/js/jquery-1.7.1.min.js" type="text/javascript"></script>
答案 0 :(得分：1)
因为你想在图像上悬停效果所以我在画布上渲染了图像。 我已经更新了答案。我认为这就是你的想法。
var canvas = document.querySelector("#myCanvas");
var context = canvas.getContext("2d");
var canvasPos = getPosition(canvas);
var mouseX = 0;
var mouseY = 0;
function getPosition(el) {
var xPosition = 0;
var yPosition = 0;
while (el) {
xPosition += (el.offsetLeft - el.scrollLeft + el.clientLeft);
yPosition += (el.offsetTop - el.scrollTop + el.clientTop);
el = el.offsetParent;
}
return {
x: xPosition,
y: yPosition
};
}
function update() {
context.clearRect(0, 0, canvas.width, canvas.height);
/*context.beginPath();
context.arc(mouseX, mouseY, 20, 0, 2 * Math.PI, true);
context.fillStyle = "#FF6A6A";
context.fill();*/
requestAnimationFrame(update);
}
function setMousePosition(e) {
mouseX = e.clientX - canvasPos.x;
mouseY = e.clientY - canvasPos.y;
context.clearRect(0, 0, canvas.width, canvas.height);
context.beginPath();
context.arc(mouseX, mouseY, 20, 0, 2 * Math.PI, true);
context.fillStyle = "#FF6A6A";
context.fill();
}
canvas.addEventListener("mousemove", setMousePosition, false);
update();
$(document).ready(function() {
var native_width = 0;
var native_height = 0;
//Now the mousemove function
$(".magnify").mousemove(function(e) {
//When the user hovers on the image, the script will first calculate
//the native dimensions if they don't exist. Only after the native dimensions
//are available, the script will show the zoomed version.
if (!native_width && !native_height) {
//This will create a new image object with the same image as that in .small
//We cannot directly get the dimensions from .small because of the
//width specified to 200px in the html. To get the actual dimensions we have
//created this image object.
var image_object = new Image();
image_object.src = $(".small").attr("src");
//This code is wrapped in the .load function which is important.
//width and height of the object would return 0 if accessed before
//the image gets loaded.
native_width = image_object.width;
native_height = image_object.height;
} else {
//x/y coordinates of the mouse
//This is the position of .magnify with respect to the document.
var magnify_offset = $(this).offset();
//We will deduct the positions of .magnify from the mouse positions with
//respect to the document to get the mouse positions with respect to the
//container(.magnify)
var mx = e.pageX - magnify_offset.left;
var my = e.pageY - magnify_offset.top;
//Finally the code to fade out the glass if the mouse is outside the container
if (mx < $(this).width() && my < $(this).height() && mx > 0 && my > 0) {
$(".large").fadeIn(100);
} else {
$(".large").fadeOut(100);
}
if ($(".large").is(":visible")) {
//The background position of .large will be changed according to the position
//of the mouse over the .small image. So we will get the ratio of the pixel
//under the mouse pointer with respect to the image and use that to position the
//large image inside the magnifying glass
var rx = Math.round(mx / $(".small").width() * native_width - $(".large").width() / 2) * -1;
var ry = Math.round(my / $(".small").height() * native_height - $(".large").height() / 2) * -1;
var bgp = rx + "px " + ry + "px";
//Time to move the magnifying glass with the mouse
var px = mx - $(".large").width() / 2;
var py = my - $(".large").height() / 2;
//Now the glass moves with the mouse
//The logic is to deduct half of the glass's width and height from the
//mouse coordinates to place it with its center at the mouse coordinates
//If you hover on the image now, you should see the magnifying glass in action
$(".large").css({
backgroundPosition: bgp
});
$(".pointer").css({
left: mx - 25,
top: my - 25
});
}
}
})
})canvas {
border: #333 5px solid;
z-index: 0;
}
/*Some CSS*/
.magnify {
width: 100px;
position: relative;
margin-top: -205px;
margin-left: 5px;
z-index: 10;
}
/*Lets create the magnifying glass*/
.large {
width: 120px;
height: 120px;
position: absolute;
/*Multiple box shadows to achieve the glass effect*/
box-shadow: 0 0 0 7px rgba(255, 255, 255, 0.85), 0 0 7px 7px rgba(0, 0, 0, 0.25), inset 0 0 40px 2px rgba(0, 0, 0, 0.25);
/*Lets load up the large image first*/
background: url('http://thecodeplayer.com/uploads/media/iphone.jpg') no-repeat;
/*hide the glass by default*/
display: none;
margin-left: 150px;
}
/*To solve overlap bug at the edges during magnification*/
.small {
display: block;
z-index: 1;
position: relative;
}
.pointer {
width: 50px;
height: 50px;
border-radius: 50%;
background: #FF6A6A;
position: absolute;
top: 0;
left: 0;
z-index: 9999999;
opacity: 0.5;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<canvas id="myCanvas" width="500px" height="195px"></canvas>
<!-- Lets make a simple image magnifier -->
<div class="magnify">
<!-- This is the magnifying glass which will contain the original/large version -->
<div class="large"></div>
<!-- This is the small image -->
<img class="small" src="http://thecodeplayer.com/uploads/media/iphone.jpg" width="102" />
<div class="pointer"></div>
</div>