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Explanation of javascript image cropping techniques

Source: Internet
Author: User
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Learning the php gd library, we can see that there is an image cropping which is exactly the same. Well, it's actually quite simple.
Php version Copy codeThe Code is as follows: <! DOCTYPE html>
<Html xmlns = "http://www.w3.org/1999/xhtml">
<Head>
<Meta http-equiv = "Content-Type" content = "text/html; charset = UTF-8"/>
<Title> Resize </title>
<Style type = "text/css">
* {Padding: 0; margin: 0 ;}
Ul {list-style-type: none; overflow: hidden; zoom: 1; width: 1000px; margin: 30px auto ;}
Li {float: left; width: 500px ;}
# Container {width: 480px; height: 480px; margin: 0 auto; border: 1px solid #999; position: relative; background: url (http://images.cnblogs.com/cnblogs_com/wtcsy/192373/r_xx.jpg );}
# Container. block {height: 100px; width: 100px; border: 1px solid #000000; position: absolute; left: 50px; top: 50px; background: # fff; filter: alpha (opacity = 30); opacity: 0.3; cursor: move ;}
. RRightDown,. rLeftDown,. rLeftUp,. rRightUp,. rRight,. rLeft,. rUp,. rDown {
Position: absolute; background: # f00; width: 6px; height: 6px; z-index: 5; font-size: 0 ;}
. RLeftDown,. rRightUp {cursor: ne-resize ;}
. RRightDown,. rLeftUp {cursor: nw-resize ;}
. RRight,. rLeft {cursor: e-resize ;}
. RUp,. rDown {cursor: n-resize ;}
. RRightDown {bottom:-3px; right:-3px ;}
. RLeftDown {bottom:-3px; left:-3px ;}
. RRightUp {top:-3px; right:-3px ;}
. RLeftUp {top:-3px; left:-3px ;}
. RRight {right:-3px; top: 50%}
. RLeft {left:-3px; top: 50%}
. RUp {top:-3px; left: 50%}
. RDown {bottom:-3px; left: 50%}
# ImgC {border: 1px solid # CCC; width: 0; height: 0; margin: 0 auto; background: url (http://images.cnblogs.com/cnblogs_com/wtcsy/192373/r_xx.jpg );}
</Style>
</Head>
<Body>
<Ul>
<Li>
<Div id = "container"> </div>
</Li>
<Li>
<Div id = "imgC"> </div>
</Li>
</Ul>
<Script type = "text/javascript" src = "http://common.cnblogs.com/script/jquery.js"> </script>
<Script type = "text/javascript">
(Function (){
Var dBody = document. body,
DDoc = document.doc umentElement;
Var clip = function (options ){
This. init. call (this, options );
}
Clip. prototype = {
Options :{
MoveCallBack: function (){},
ClassName: "block"
},
Init: function (options ){
$. Extend (this, this. options, options || {});
If (! This. container |! This. imgC ){
Return;
}
This. container = $ (this. container );
Var self = this;
This. block = $ ('<div class = "' + this. className + '"> \
<Div action = "rightDown" class = "rRightDown"> </div> \
<Div action = "leftDown" class = "rLeftDown"> </div> \
<Div action = "rightUp" class = "rRightUp"> </div> \
<Div action = "leftUp" class = "rLeftUp"> </div> \
<Div action = "right" class = "rRight"> </div> \
<Div action = "left" class = "rLeft"> </div> \
<Div action = "up" class = "rUp"> </div> \
<Div action = "down" class = "rDown"> </div> \
</Div> ')
. Bind ("mousedown. r", function (e) {self. start (e )})
. AppendTo (this. container [0]);
This. setImg ();
},
SetImg: function (){
Var block = this. block;
This.imgC.css ({
Height: block. height (),
Width: block. width (),
"Background-position": "-" +block.css ("left") + "-" +block.css ("top ")
});
},
Start: function (e ){
Var $ elem = values (e.tar get ),
Block = this. block,
Self = this,
Move = false,
Container = this. container,
Action = $ elem. attr ("action ");
// Every time you calculate the change of the basic dom structure, the browser's scaling will change the value.
This. offset = $. extend ({height: container. height (), width: container. width ()}, container. offset ());
This. blockOriginal = {height: block. height (), width: block. width (), left: parseInt(block.css ("left"), top: parseInt(block.css ("top "))};
If (action ){
This. fun = this [action];
} Else {
This. x = e. clientX-this. offset. left-this. blockOriginal. left;
This. y = e. clientY-this. offset. top-this. blockOriginal. top;
Move = true;
}
$ (Document)
. Bind ("mousemove. r", function (e) {self. move (e, move )})
. Bind ("mouseup. r", function () {self. end ()});
},
End: function (){
$ (Document)
. Unbind ("mousemove. r ")
. Unbind ("mouseup. r ");
},
Move: function (e, isMove ){
Window. getSelection
? Window. getSelection (). removeAllRanges ()
: Document. selection. empty ();

Var block = this. block;
If (isMove ){
Var left = Math. max (0, e. clientX-this. offset. left-this. x );
Left = Math. min (left, this. offset. width-this. blockOriginal. width );
Var top = Math. max (0, e. clientY-this. offset. top-this. y );
Top = Math. min (top, this. offset. height-this. blockOriginal. height );
Block.css ({left: left, top: top });
} Else {
Var offset = this. fun (e );
Block.css (offset );
}
This. setImg ();
This. moveCallBack ();
},
Down: function (e ){
Var blockOriginal = this. blockOriginal,
STop = Math. max (dBody. scrollTop, dDoc. scrollTop), // calculate this when a vertical scroll bar appears.
Offset = this. offset;

If (e. clientY-offset.top> = blockOriginal. top-sTop ){
Var height = Math. min (offset. height-blockOriginal. top, e. clientY-offset.top-blockOriginal.top + sTop ),
Top = blockOriginal. top;
} Else {
Var height = Math. min (offset. top + blockOriginal. top-e.clientY-sTop, blockOriginal. top ),
Top = Math. max (e. clientY-offset. top + sTop, 0 );
}
Return {height: height, top: top };
},
Up: function (e ){
Var blockOriginal = this. blockOriginal,
STop = Math. max (dBody. scrollTop, dDoc. scrollTop ),
Offset = this. offset;
If (e. clientY-offset.top-blockOriginal.height <= blockOriginal. top-sTop ){
Var top = Math. max (e. clientY-offset.top + sTop, 0 ),
MaxHeight = blockOriginal. top + blockOriginal. height,
Height = Math. min (maxHeight, blockOriginal. top + blockOriginal. height-(e. clientY-offset.top)-sTop );
} Else {

Var height = Math. min (e. clientY-offset.top-blockOriginal.top-blockOriginal.height + sTop, offset. height-blockOriginal.top-blockOriginal.height ),
Top = blockOriginal. top + blockOriginal. height;
}
Return {height: height, top: top };
},
Left: function (e ){
Var blockOriginal = this. blockOriginal,
Offset = this. offset;

If (e. clientX-offset. left-blockOriginal. width-blockOriginal. left <= 0 ){
Var left = Math. max (e. clientX-offset. left, 0 ),
Width = Math. min (blockOriginal. left + blockOriginal. width, blockOriginal. left + blockOriginal. width-(e. clientX-offset.left ));
} Else {
Var width = Math. Minute (e. clientX-offset.left-blockOriginal.left-blockOriginal.width, offset. width-blockOriginal.left-blockOriginal.width ),
Left = blockOriginal. left + blockOriginal. width;
}
Return {left: left, width: width };
},
Right: function (e ){
Var blockOriginal = this. blockOriginal,
Offset = this. offset;
If (e. clientX-offset.left> = blockOriginal. left ){
Var width = Math. min (offset. width-blockOriginal. left, e. clientX-offset. left-blockOriginal. left ),
Left = blockOriginal. left;
} Else {
Var width = Math. min (offset. left + blockOriginal. left-e. clientX, blockOriginal. left ),
Left = Math. max (e. clientX-offset. left, 0 );
}
Return {left: left, width: width };
},
RightDown: function (e ){
Return $. extend (this. right (e), this. down (e ));
},
LeftDown: function (e ){
Return $. extend (this. left (e), this. down (e ));
},
RightUp: function (e ){
Return $. extend (this. right (e), this. up (e ));
},
LeftUp: function (e ){
Return $. extend (this. left (e), this. up (e ));
},
GetValue: function (){
Var block = this. block;
Return {
Left: parseInt(block.css ("left ")),
Top: parseInt(block.css ("top ")),
Width: block. width (),
Height: block. height ()
}
}
}
$. Fn. clip = function (options ){
Options. container = this;
Return new clip (options );
}
})();
$ ("# Container"). clip ({
ImgC: $ ("# imgC ")
})
</Script>
</Body>
</Html>

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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