zoom by js

share/pdf2htmlEX.js

@@ -16,10 +16,20 @@ var pdf2htmlEX = (function(){
     page_boxes : [],
     container : null,
     selective_render_timer : null,
+    default_scale_ratio : 1.0,
+    cur_scale_ratio : 1.0,
+
+
+
+    /* Constants */
+    render_timeout : 200,
+    scale_step : 0.9,
+
+
 
     init_before_loading_content : function() {
       /*hide all pages before loading, will reveal only visible ones later */
-      this.hide_pages();
+      this.pre_hide_pages();
     },
 
     init_after_loading_content : function() {
@@ -27,16 +37,17 @@ var pdf2htmlEX = (function(){
       this.page_boxes = $(".b");
       this.container = $("#pdf-main");
 
+      if(this.pages.length > 0)
+      {
+        this.default_scale_ratio = this.cur_scale_ratio 
+          = $(this.pages[0]).height() / $(this.page_boxes[0]).height();
+      }
+
       this.selective_render();
 
       var _ = this;
-      this.container.scroll(function(){
-        if(_.selective_render_timer)
-          clearTimeout(_.selective_render_timer);
-        _.selective_render_timer = setTimeout(function () {
-          _.selective_render();
-        }, 200);
-      });
+      this.container.scroll(function(){ _.schedule_render(); });
+      this.zoom_fixer();
     },
 
     init : function() {
@@ -48,7 +59,7 @@ var pdf2htmlEX = (function(){
       return this;
     },
 
-    hide_pages : function() {
+    pre_hide_pages : function() {
       /* pages might have not been loaded yet, so add a CSS rule */
       var s = '.b{display:none;}';
       var n = document.createElement("style");
@@ -61,6 +72,13 @@ var pdf2htmlEX = (function(){
       document.getElementsByTagName("head")[0].appendChild(n);
     },
 
+    hide_pages : function() {
+      for(var i = 0, l = this.page_boxes.length; i < l; ++i)
+      {
+        $(this.page_boxes[i]).hide();
+      }
+    },
+
     selective_render : function () {
       /* hide (positional) invisible pages */
       var l = this.pages.length;
@@ -87,6 +105,77 @@ var pdf2htmlEX = (function(){
       }
     },
 
+    schedule_render : function() {
+      if(this.selective_render_timer)
+        clearTimeout(this.selective_render_timer);
+
+      var _ = this;
+      this.selective_render_timer = setTimeout(function () {
+        _.selective_render();
+      }, this.render_timeout);
+    },
+
+    zoom_fixer : function () {
+      /* 
+       * When user try to zoom in/out using ctrl + +/- or mouse wheel
+       * handle this and prevent the default behaviours
+       *
+       * Code credit to PDF.js
+       */
+      var _ = this;
+      // Firefox specific event, so that we can prevent browser from zooming
+      $(window).on('DOMMouseScroll', function(e) {
+        if (e.ctrlKey) {
+          e.preventDefault();
+          _.rescale(Math.pow(_.scale_step, e.detail), true);
+        }
+      });
+
+      $(window).on('keydown', function keydown(e) {
+        if (e.ctrlKey || e.metaKey) {
+          switch (e.keyCode) {
+            case 61: // FF/Mac '='
+            case 107: // FF '+' and '='
+            case 187: // Chrome '+'
+              _.rescale(1.0 / _.scale_step, true);
+              break;
+            case 173: // FF/Mac '-'
+            case 109: // FF '-'
+            case 189: // Chrome '-'
+              _.rescale(_.scale_step, true);
+              break;
+            case 48: // '0'
+              _.rescale(_.default_scale_ratio, false);
+              break;
+            default:
+              return;
+          }
+        }
+        e.preventDefault();
+      });
+    },
+
+    rescale : function (ratio, is_relative) {
+      console.log('RESCALE');
+
+      if(is_relative)
+        ratio *= this.cur_scale_ratio;
+
+      this.cur_scale_ratio = ratio;
+      this.hide_pages();
+
+      for(var i = 0, l = this.page_boxes.length; i < l; ++i)
+      {
+        var p = $(this.pages[i]);
+        var pb = $(this.page_boxes[i]);
+        p.height(pb.height() * ratio);
+        p.width(pb.width() * ratio);
+        pb.css('transform', 'scale('+ratio+')');
+      }
+
+      this.schedule_render();
+    },
+
     __last_member__ : 'no comma' /*,*/
   }.init();
 })();