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481
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1 // fixed.js: fix fixed positioning and fixed backgrounds in IE/Win
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2 // version 1.8, 08-Aug-2003
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3 // written by Andrew Clover <and@doxdesk.com>, use freely
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4
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5 /*@cc_on
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6 @if (@_win32 && @_jscript_version>4)
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7
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8 var fixed_positions= new Array();
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9 var fixed_backgrounds= new Array();
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10 var fixed_viewport;
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11
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12 // Initialisation. Called when the <body> tag arrives. Set up viewport so the
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13 // rest of the script knows we're going, and add a measurer div, used to detect
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14 // font size changes and measure image sizes for backgrounds later
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15
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16 function fixed_init() {
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17 fixed_viewport= (document.compatMode=='CSS1Compat') ?
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18 document.documentElement : document.body;
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19 var el= document.createElement('div');
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20 el.setAttribute('id', 'fixed-measure');
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21 el.style.position= 'absolute';
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22 el.style.top= '0'; el.style.left= '0';
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23 el.style.overflow= 'hidden'; el.style.visibility= 'hidden';
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24 el.style.fontSize= 'xx-large'; el.style.height= '5em';
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25 el.style.setExpression('width', 'fixed_measureFont()');
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26 document.body.insertBefore(el, document.body.firstChild);
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27 }
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28
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29 // Binding. Called every time an element is added to the document, check it
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30 // for fixed features, if found add to our lists and set initial props
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31
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32 function fixed_bind(el) {
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33 var needLayout= false;
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34 var tag= el.tagName.toLowerCase();
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35 var st= el.style;
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36 var cst= el.currentStyle;
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37 var anc;
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38
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39 // find fixed-position elements
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40 if (cst.position=='fixed') {
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41 needLayout= true;
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42 fixed_positions[fixed_positions.length]= el;
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43 // store original positioning as we'll overwrite it
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44 st.position= 'absolute';
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45 st.fixedPLeft= cst.left;
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46 st.fixedPTop= cst.top;
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47 st.fixedPRight= cst.right;
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48 st.fixedPBottom= cst.bottom;
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49 st.fixedPWidth= fixed_parseLength(cst.width);
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50 st.fixedPHeight= fixed_parseLength(cst.height);
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51 // find element that will act as containing box, for convenience later
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52 st.fixedCB= null;
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53 for (anc= el; (anc= anc.parentElement).parentElement;) {
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54 if (anc.currentStyle.position!='static') {
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55 st.fixedCB= anc;
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56 break;
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57 } }
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58 // detect nested fixed positioning (only ancestor need move)
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59 st.fixedNest= false;
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60 for (anc= el; anc= anc.parentElement;) {
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61 if (anc.style.fixedNest!=null)
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62 st.fixedNest= true;
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63 break;
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64 }
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65 }
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66
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67 // find fixed-background elements (not body/html which IE already gets right)
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68 if (cst.backgroundAttachment=='fixed' && tag!='body' && tag!='html') {
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69 needLayout= true;
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70 fixed_backgrounds[fixed_backgrounds.length]= el;
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71 // get background offset, converting from keyword if necessary
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72 st.fixedBLeft= fixed_parseLength(cst.backgroundPositionX);
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73 st.fixedBTop= fixed_parseLength(cst.backgroundPositionY);
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74 // if it's a non-zero %age, need to know size of image for layout
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75 if (st.fixedBLeft[1]=='%' || st.fixedBTop[1]=='%') {
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76 st.fixedBWidth= 0; st.fixedBHeight= 0;
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77 fixed_measureBack(el);
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78 }
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79 }
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80 if (needLayout) fixed_layout();
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81 }
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82
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83 // Layout. On every window or font size change, recalculate positioning
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84
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85 // Request re-layout at next free moment
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86 var fixed_delaying= false;
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87 function fixed_delayout() {
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88 if (fixed_delaying) return;
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89 fixed_delaying= true;
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90 window.setTimeout(fixed_layout, 0);
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91 }
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92
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93 var fixed_ARBITRARY= 200;
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94
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95 function fixed_layout() {
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96 fixed_delaying= false;
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97 if (!fixed_viewport) return;
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98 var i, el, st, j, pr, tmp, A= 'auto';
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99 var cb, cbLeft, cbTop, cbRight, cbBottom, oLeft, oTop, oRight, oBottom;
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100 var vpWidth=fixed_viewport.clientWidth, vpHeight=fixed_viewport.clientHeight;
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101
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102 // calculate initial position for fixed-position elements [black magic]
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103 for (i= fixed_positions.length; i-->0;) {
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104 el= fixed_positions[i]; st= el.style;
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105 // find positioning of containing block
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106 cb= st.fixedCB; if (!cb) cb= fixed_viewport;
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107 cbLeft= fixed_pageLeft(cb); cbTop= fixed_pageTop(cb);
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108 if (cb!=fixed_viewport) { cbLeft+= cb.clientLeft; cbTop+= cb.clientTop; }
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109 cbRight= fixed_viewport.clientWidth-cbLeft-cb.clientWidth;
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110 cbBottom= fixed_viewport.clientHeight-cbTop-cb.clientHeight;
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111 // if size is in %, must recalculate relative to viewport
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112 if (st.fixedPWidth[1]=='%')
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113 st.width= Math.round(vpWidth*st.fixedPWidth[0]/100)+'px';
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114 if (st.fixedPHeight[1]=='%')
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115 st.height= Math.round(vpHeight*st.fixedPHeight[0]/100)+'px';
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116 // find out offset values at max size, to account for margins
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117 st.left= A; st.right= '0'; st.top= A; st.bottom= '0';
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118 oRight= el.offsetLeft+el.offsetWidth; oBottom= el.offsetTop+el.offsetHeight;
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119 st.left= '0'; st.right= A; st.top= '0'; st.bottom= A;
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120 oLeft= el.offsetLeft; oTop= el.offsetTop;
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121 // use this to convert all edges to pixels
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122 st.left= A; st.right= st.fixedPRight;
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123 st.top= A; st.bottom= st.fixedPBottom;
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124 oRight-= el.offsetLeft+el.offsetWidth;
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125 oBottom-= el.offsetTop+el.offsetHeight;
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126 st.left= st.fixedPLeft; st.top= st.fixedPTop;
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127 oLeft= el.offsetLeft-oLeft; oTop= el.offsetTop-oTop;
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128 // edge positioning fix
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129 if (st.fixedPWidth[1]==A && st.fixedPLeft!=A && st.fixedPRight!=A) {
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130 tmp= el.offsetLeft; st.left= A; st.width= fixed_ARBITRARY+'px';
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131 tmp= fixed_ARBITRARY+el.offsetLeft-tmp+cbLeft+cbRight;
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132 st.left= st.fixedPLeft; st.width= ((tmp<1)?1:tmp)+'px';
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133 }
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134 if (st.fixedPHeight[1]==A && st.fixedPTop!=A && st.fixedPBottom!=A) {
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135 tmp= el.offsetTop; st.top= A; st.height= fixed_ARBITRARY+'px';
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136 tmp= fixed_ARBITRARY+el.offsetTop-tmp+cbTop+cbBottom;
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137 st.top= st.fixedPTop; st.height= ((tmp<1)?1:tmp)+'px';
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138 }
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139 // move all non-auto edges relative to the viewport
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140 st.fixedCLeft= (st.fixedPLeft=='auto') ? oLeft : oLeft-cbLeft;
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141 st.fixedCTop= (st.fixedPTop=='auto') ? oTop : oTop-cbTop;
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142 st.fixedCRight= (st.fixedPRight=='auto') ? oRight : oRight-cbRight;
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143 st.fixedCBottom= (st.fixedPBottom=='auto') ? oBottom : oBottom-cbBottom;
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144 // remove left-positioning of right-positioned elements
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145 if (st.fixedPLeft=='auto' && st.fixedPRight!='auto') st.fixedCLeft= 'auto';
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146 if (st.fixedPTop=='auto' && st.fixedPBottom!='auto') st.fixedCTop= 'auto';
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147 }
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148
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149
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150 // calculate initial positioning of fixed backgrounds
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151 for (i= fixed_backgrounds.length; i-->0;) {
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152 el= fixed_backgrounds[i]; st= el.style;
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153 tmp= st.fixedBImage;
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154 if (tmp) {
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155 if (tmp.readyState!='uninitialized') {
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156 st.fixedBWidth= tmp.offsetWidth;
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157 st.fixedBHeight= tmp.offsetHeight;
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158 st.fixedBImage= window.undefined;
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159 }
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160 }
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161 st.fixedBX= fixed_length(el, st.fixedBLeft, vpWidth-st.fixedBWidth);
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162 st.fixedBY= fixed_length(el, st.fixedBTop, vpHeight-st.fixedBHeight);
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163 }
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164
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165 // now call scroll() to set the positions from the values just calculated
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166 fixed_scroll();
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167 }
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168
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169 // Scrolling. Offset fixed elements relative to viewport scrollness
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170
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171 var fixed_lastX, fixed_lastY;
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172 var fixed_PATCHDELAY= 300;
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173 var fixed_patching= false;
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174
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175 // callback function after a scroll, because incorrect scroll position is
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176 // often reported first go!
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177 function fixed_patch() {
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178 fixed_patching= false;
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179 var scrollX= fixed_viewport.scrollLeft, scrollY= fixed_viewport.scrollTop;
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180 if (scrollX!=fixed_lastX && scrollY!=fixed_lastY) fixed_scroll();
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181 }
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182
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183 function fixed_scroll() {
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184 if (!fixed_viewport) return;
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185 var i, el, st, viewportX, viewportY;
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186 var scrollX= fixed_viewport.scrollLeft, scrollY= fixed_viewport.scrollTop;
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187 fixed_lastX= scrollX; fixed_lastY= scrollY;
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188
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189 // move non-nested fixed-position elements
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190 for (i= fixed_positions.length; i-->0;) {
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191 st= fixed_positions[i].style;
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192 viewportX= (st.fixedNest) ? 0 : scrollX;
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193 viewportY= (st.fixedNest) ? 0 : scrollY;
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194 if (st.fixedCLeft!='auto') st.left= (st.fixedCLeft+viewportX)+'px';
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195 if (st.fixedCTop!='auto') st.top= (st.fixedCTop+viewportY)+'px';
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196 viewportX= (st.fixedCB==null || st.fixedCB==fixed_viewport) ? 0 : viewportX;
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197 viewportY= (st.fixedCB==null || st.fixedCB==fixed_viewport) ? 0 : viewportY;
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198 st.right= (st.fixedCRight-viewportX+1)+'px'; st.right= (st.fixedCRight-viewportX)+'px';
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199 st.bottom= (st.fixedCBottom-viewportY+1)+'px'; st.bottom= (st.fixedCBottom-viewportY)+'px';
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200 }
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201
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202 // align fixed backgrounds to viewport
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203 for (i= fixed_backgrounds.length; i-->0;) {
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204 el= fixed_backgrounds[i]; st= el.style;
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205 viewportX= scrollX;
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206 viewportY= scrollY;
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207 while (el.offsetParent) {
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208 viewportX-= el.offsetLeft+el.clientLeft;
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209 viewportY-= el.offsetTop +el.clientTop;
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210 el= el.offsetParent;
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211 }
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212 st.backgroundPositionX= (st.fixedBX+viewportX)+'px';
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213 st.backgroundPositionY= (st.fixedBY+viewportY)+'px';
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214 }
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215
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216 // call back again in a tic
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217 if (!fixed_patching) {
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218 fixed_patching= true;
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219 window.setTimeout(fixed_patch, fixed_PATCHDELAY);
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220 }
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221 }
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222
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223 // Measurement. Load bg-image into an invisible element on the page, when
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224 // loaded write the width/height to an element's style for layout use; detect
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225 // when font size changes
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226
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227 function fixed_measureBack(el) {
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228 var measure= document.getElementById('fixed-measure');
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229 var img= document.createElement('img');
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230 img.setAttribute('src', fixed_parseURL(el.currentStyle.backgroundImage));
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231 measure.appendChild(img);
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232 el.style.fixedBImage= img;
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233 if (img.readyState=='uninitialized')
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234 img.attachEvent('onreadystatechange', fixed_measureBackImage_ready);
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235 }
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236
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237 function fixed_measureBackImage_ready() {
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238 var img= event.srcElement;
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239 if (img && img.readyState!='uninitialized') {
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240 img.detachEvent('onreadystatechange', fixed_measureBackImage_ready);
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241 fixed_layout();
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242 }
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243 }
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244
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245 var fixed_fontsize= 0;
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246 function fixed_measureFont() {
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247 var fs= document.getElementById('fixed-measure').offsetHeight;
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248 if (fixed_fontsize!=fs && fixed_fontsize!=0)
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249 fixed_delayout();
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250 fixed_fontsize= fs;
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251 return '5em';
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252 }
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253
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254 // Utility. General-purpose functions
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255
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256 // parse url() to get value inside
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257
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258 function fixed_parseURL(v) {
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259 v= v.substring(4, v.length-1);
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260 if (v.charAt(0)=='"' && v.charAt(v.length-1)=='"' ||
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261 v.charAt(0)=="'" && v.charAt(v.length-1)=="'")
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262 return v.substring(1, v.length-1);
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263 else return v;
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264 }
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265
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266 // parse length or auto or background-position keyword into number and unit
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267
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268 var fixed_numberChars= '+-0123456789.';
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269 var fixed_ZERO= new Array(0, 'px');
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270 var fixed_50PC= new Array(50, '%');
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271 var fixed_100PC= new Array(100, '%');
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272 var fixed_AUTO= new Array(0, 'auto');
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273
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274 function fixed_parseLength(v) {
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275 var num, i;
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276 if (v=='left' || v=='top') return fixed_ZERO;
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277 if (v=='right' || v=='bottom') return fixed_100PC;
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278 if (v=='center') return fixed_50PC;
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279 if (v=='auto') return fixed_AUTO;
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280 i= 0;
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281 while (i<v.length && fixed_numberChars.indexOf(v.charAt(i))!=-1)
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282 i++;
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283 num= parseFloat(v.substring(0, i));
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284 if (num==0) return fixed_ZERO;
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285 else return new Array(num, v.substring(i));
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286 }
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287
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288 // convert parsed (number, unit) into a number of pixels
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289
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290 function fixed_length(el, l, full) {
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291 var tmp, x;
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292 if (l[1]=='px') return l[0];
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293 if (l[1]=='%') return Math.round(full*l[0]/100);
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294 // other units - measure by setting position; this is rather inefficient
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295 // but then these units are used for background-position so seldom...
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296 tmp= el.currentStyle.left;
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297 el.style.left= '0';
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298 x= el.offsetLeft;
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299 el.style.left= l[0]+l[1];
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300 x= el.offsetLeft-x;
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301 el.style.left= tmp;
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302 return x;
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303 }
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304
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305 // convert stupid IE offsetLeft/Top to page-relative values
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306
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307 function fixed_pageLeft(el) {
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308 var v= 0;
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309 while (el.offsetParent) {
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310 v+= el.offsetLeft;
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311 el= el.offsetParent;
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312 }
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313 return v;
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314 }
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315 function fixed_pageTop(el) {
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316 var v= 0;
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317 while (el.offsetParent) {
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318 v+= el.offsetTop;
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319 el= el.offsetParent;
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320 }
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321 return v;
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322 }
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323
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324 // Scanning. Check document every so often until it has finished loading. Do
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325 // nothing until <body> arrives, then call main init. Pass any new elements
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326 // found on each scan to be bound
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327
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328 var fixed_SCANDELAY= 500;
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329
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330 function fixed_scan() {
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331 if (!document.body) return;
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332 if (!fixed_viewport) fixed_init();
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333 var el;
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334 for (var i= 0; i<document.all.length; i++) {
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335 el= document.all[i];
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336 if (!el.fixed_bound) {
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337 el.fixed_bound= true;
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338 fixed_bind(el);
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339 } }
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340 }
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341
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342 var fixed_scanner;
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343 function fixed_stop() {
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344 window.clearInterval(fixed_scanner);
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345 fixed_scan();
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346 }
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347
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348 fixed_scan();
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349 fixed_scanner= window.setInterval(fixed_scan, fixed_SCANDELAY);
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350 window.attachEvent('onload', fixed_stop);
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351 window.attachEvent('onresize', fixed_delayout);
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352 window.attachEvent('onscroll', fixed_scroll);
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353
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354 @end @*/
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