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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>

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