Resizing background sprite image to fit div

问题:

I am creating a card game . I have a sprite image of cards . Say in the sprite , each of the cards is 50px wide and 80px high . Now I have some divs where I want to place these cards .

Say the Divs are 100px wide and 160px high .

I have using the first image as a Sprite for the Divs like in the below.

background: url(../images/poker_sprite.gif) no-repeat scroll 0 0 transparent ;

I vary the x and y positions so that different divs get diff cards .

What CSS property do I use to make the background image fit to the Div ? I am not allowed to change the size of the Sprites or the Div .

Now I am going to Drag these cards and place them into some slots as marked 1-13 below .

So the card div will have variable width . The background image will need to resize to fit in the variable width div . How do I go about doing this ? Should I used multiple sprites of various sizes?

Thanks !

回答1:

You can achieve this using the background-size property, although the results might not be too pretty, since it stretches the background image.

So, if you know that your sprite is 13x5 cards exactly in size, you can give the cards background-size: 1300% 500% and then size them any way you want, since the background itself will scale accordingly.

Example

JSFiddle: http://jsfiddle.net/uLnzc/.

HTML

<!-- Hearts --->
<div class="card card-hearts-2"></div>
<div class="card card-hearts-3 card-wide"></div>
<div class="card card-hearts-4 card-high"></div>

<!-- Clubs -->
<div class="card card-clubs-q"></div>
<div class="card card-clubs-k card-wide"></div>
<div class="card card-clubs-a card-high"></div>

CSS

.card {
    width: 81px;
    height: 117px;
    background: url('http://i.stack.imgur.com/WZ9Od.gif') no-repeat;
    background-size: 1300% 500%;
}
.card-wide {
    width: 100px;
}
.card-high {
    height: 130px;
}

/**
 * Backgrouns position of all the cards
 *
 * x offset in %: i * (100/x); i = 0, 1, ..., (x - 1); x = the number of cols in the sprite
 * y offset in %: j * (100/y); j = 0, 1, ..., (y - 1); y = the number of rows in the sprite
 */

.card-hearts-2 { background-position: 0 0; }
.card-hearts-3 { background-position: 8.33% 0; }
.card-hearts-4 { background-position: 16.667% 0; }
/* ... */

/* ... */
.card-clubs-q { background-position: 83.333% 50%; }
.card-clubs-k { background-position: 91.667% 50%; }
.card-clubs-a { background-position: 100% 50%; }

You can read about offsetting backgrounds in percentages at MDN.

JSFiddle: http://jsfiddle.net/uLnzc/.

回答2:

Hi this is the easiest way of doing what you are after!

CSS -

.smking,.king{
position: relative;
background-image: url(http://i.stack.imgur.com/WZ9Od.gif);
background-size: 1300% 500%;
}

.king{
width: 50px;
height: 80px;
background-position: 100px 0px;
}

.smking{
width: 30px;
height: 50px;
background-position:  60px 0px;
}

HTML -

<div class="king"></div>
<div class="smking"></div>

This will load your image once and set it up ready to be resized!

http://jsfiddle.net/j3xXe/10/

Regards

Alphanu

回答3:

Another solution is to create an SVG and assign class attributes to the different path groups (each representing/rendering a card). If all path groups have position: absolute and display: none, you could show only the path group matching the container card element and stretch it to full width and height with pure vector resizing.

This will generate huge amounts of markup, so the best thing here would probably be on SVG per card.

Chris Coyier has an excellent article about using SVGs.

Example

HTML+SVG

<div class="card card-hearts-ace">
    <svg id="cards-svg" ...>
        <g class="svg-card svg-card-hearts-ace">
            <path fill="#FF0000" d="..." />
            <path fill="#FF0000" d="..." />
        </g>
        <g class="svg-card svg-card-hearts-2">
            <path fill="#FF0000" d="..." />
            <path fill="#FF0000" d="..." />
        </g>
        ...
    </svg>
</div>

CSS

.card .svg-card {
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
.card-hearts-ace .svg-card-hearts-ace {
    display: block;
}
.card-hearts-2 .svg-card-hearts-2 {
    display: block;
}
/* And so on... */

回答4:

I would suggest having 2 sprites, mainly because you have a smaller resolution in your example sprite then would look good in the example div.

回答5:

For a regular image max-width: 100% and Max-height: 100% should force the image to resize to the div.

For a background-image background-size: 100% should work.

回答6:

This will do what I believe you are looking for and should be supported for all browsers.

Say you want a king in a specific slot what you would do is place these two classes in your css.

.king{
    width: 50px;
    height: 80px;
    position: relative;
    background-position: 50px 0px;
    background-image: url(http://i.stack.imgur.com/WZ9Od.gif);
}
.play-area{
    width: 50px;
    height: 80px;
    position: absolute;
}

Now for the html you just need

<div class="play-area">
    <div class="king"></div>
</div>

All you need to do is play around with the numbers so the borders of the cards displayed come out correct.

Here's the fiddle: http://jsfiddle.net/j3xXe/4/

回答7:

Alexander Wallin's answer is great! But I believe there is a small error in the formula for computing the percentage offset; where 100 is divided by x, it should be divided by (x-1):

/**
 * Background position of all the cards
 *
 * x offset in %: i * (100/(x-1); i = 0, 1, ..., (x - 1); x = the number of cols in the sprite
 * y offset in %: j * (100/(y-1); j = 0, 1, ..., (y - 1); y = the number of rows in the sprite
 */

PS: Sorry for making this comment as an answer. I do not have the necessary credits for making comments.