Preserve scrolling positions of nodes on clone (#511)

dist/html2canvas.js

@@ -1542,34 +1542,14 @@ process.umask = function() { return 0; };
 var log = require('./log');
 var Promise = require('./promise');
 
-var html2canvasCanvasCloneAttribute = "data-html2canvas-canvas-clone";
-var html2canvasCanvasCloneIndex = 0;
-
-function cloneNodeValues(document, clone, nodeName) {
-    var originalNodes = document.getElementsByTagName(nodeName);
-    var clonedNodes = clone.getElementsByTagName(nodeName);
-    var count = originalNodes.length;
-    for (var i = 0; i < count; i++) {
-        clonedNodes[i].value = originalNodes[i].value;
-    }
-}
-
 function restoreOwnerScroll(ownerDocument, x, y) {
     if (ownerDocument.defaultView && (x !== ownerDocument.defaultView.pageXOffset || y !== ownerDocument.defaultView.pageYOffset)) {
         ownerDocument.defaultView.scrollTo(x, y);
     }
 }
 
-function labelCanvasElements(ownerDocument) {
+function cloneCanvasContents(canvas, clonedCanvas) {
-    [].slice.call(ownerDocument.querySelectorAll("canvas"), 0).forEach(function(canvas) {
-        canvas.setAttribute(html2canvasCanvasCloneAttribute, "canvas-" + html2canvasCanvasCloneIndex++);
-    });
-}
-
-function cloneCanvasContents(ownerDocument, documentClone) {
-    [].slice.call(ownerDocument.querySelectorAll("[" + html2canvasCanvasCloneAttribute + "]"), 0).forEach(function(canvas) {
     try {
-            var clonedCanvas = documentClone.querySelector('[' + html2canvasCanvasCloneAttribute + '="' + canvas.getAttribute(html2canvasCanvasCloneAttribute) + '"]');
         if (clonedCanvas) {
             clonedCanvas.width = canvas.width;
             clonedCanvas.height = canvas.height;
@@ -1578,49 +1558,47 @@ function cloneCanvasContents(ownerDocument, documentClone) {
     } catch(e) {
         log("Unable to copy canvas content from", canvas, e);
     }
-        canvas.removeAttribute(html2canvasCanvasCloneAttribute);
-    });
 }
 
-function removeScriptNodes(parent) {
+function cloneNode(node, javascriptEnabled) {
-    [].slice.call(parent.childNodes, 0).filter(isElementNode).forEach(function(node) {
-        if (node.tagName === "SCRIPT") {
-            parent.removeChild(node);
-        } else {
-            removeScriptNodes(node);
-        }
-    });
-    return parent;
-}
-
-function isIE9() {
-    return document.documentMode && document.documentMode <= 9;
-}
-
-// https://github.com/niklasvh/html2canvas/issues/503
-function cloneNodeIE9(node, javascriptEnabled) {
     var clone = node.nodeType === 3 ? document.createTextNode(node.nodeValue) : node.cloneNode(false);
 
     var child = node.firstChild;
     while(child) {
         if (javascriptEnabled === true || child.nodeType !== 1 || child.nodeName !== 'SCRIPT') {
-            clone.appendChild(cloneNodeIE9(child, javascriptEnabled));
+            clone.appendChild(cloneNode(child, javascriptEnabled));
         }
         child = child.nextSibling;
     }
 
+    if (node.nodeType === 1) {
+        clone._scrollTop = node.scrollTop;
+        clone._scrollLeft = node.scrollLeft;
+        if (node.nodeName === "CANVAS") {
+            cloneCanvasContents(node, clone);
+        } else if (node.nodeName === "TEXTAREA" || node.nodeName === "SELECT") {
+            clone.value = node.value;
+        }
+    }
+
     return clone;
 }
 
+function initNode(node) {
+    if (node.nodeType === 1) {
+        node.scrollTop = node._scrollTop;
+        node.scrollLeft = node._scrollLeft;
 
-
+        var child = node.firstChild;
-function isElementNode(node) {
+        while(child) {
-    return node.nodeType === Node.ELEMENT_NODE;
+            initNode(child);
+            child = child.nextSibling;
+        }
+    }
 }
 
 module.exports = function(ownerDocument, containerDocument, width, height, options, x ,y) {
-    labelCanvasElements(ownerDocument);
+    var documentElement = cloneNode(ownerDocument.documentElement, options.javascriptEnabled);
-    var documentElement = isIE9() ? cloneNodeIE9(ownerDocument.documentElement, options.javascriptEnabled) : ownerDocument.documentElement.cloneNode(true);
     var container = containerDocument.createElement("iframe");
 
     container.className = "html2canvas-container";
@@ -1637,16 +1615,13 @@ module.exports = function(ownerDocument, containerDocument, width, height, optio
     return new Promise(function(resolve) {
         var documentClone = container.contentWindow.document;
 
-        cloneNodeValues(ownerDocument.documentElement, documentElement, "textarea");
-        cloneNodeValues(ownerDocument.documentElement, documentElement, "select");
-
         /* Chrome doesn't detect relative background-images assigned in inline <style> sheets when fetched through getComputedStyle
          if window url is about:blank, we can assign the url to current by writing onto the document
          */
         container.contentWindow.onload = container.onload = function() {
             var interval = setInterval(function() {
                 if (documentClone.body.childNodes.length > 0) {
-                    cloneCanvasContents(ownerDocument, documentClone);
+                    initNode(documentClone.documentElement);
                     clearInterval(interval);
                     if (options.type === "view") {
                         container.contentWindow.scrollTo(x, y);
@@ -1660,7 +1635,7 @@ module.exports = function(ownerDocument, containerDocument, width, height, optio
         documentClone.write("<!DOCTYPE html><html></html>");
         // Chrome scrolls the parent document for some reason after the write to the cloned window???
         restoreOwnerScroll(ownerDocument, x, y);
-        documentClone.replaceChild(options.javascriptEnabled === true ? documentClone.adoptNode(documentElement) : removeScriptNodes(documentClone.adoptNode(documentElement)), documentClone.documentElement);
+        documentClone.replaceChild(documentClone.adoptNode(documentElement), documentClone.documentElement);
         documentClone.close();
     });
 };

src/clone.js

@@ -1,34 +1,14 @@
 var log = require('./log');
 var Promise = require('./promise');
 
-var html2canvasCanvasCloneAttribute = "data-html2canvas-canvas-clone";
-var html2canvasCanvasCloneIndex = 0;
-
-function cloneNodeValues(document, clone, nodeName) {
-    var originalNodes = document.getElementsByTagName(nodeName);
-    var clonedNodes = clone.getElementsByTagName(nodeName);
-    var count = originalNodes.length;
-    for (var i = 0; i < count; i++) {
-        clonedNodes[i].value = originalNodes[i].value;
-    }
-}
-
 function restoreOwnerScroll(ownerDocument, x, y) {
     if (ownerDocument.defaultView && (x !== ownerDocument.defaultView.pageXOffset || y !== ownerDocument.defaultView.pageYOffset)) {
         ownerDocument.defaultView.scrollTo(x, y);
     }
 }
 
-function labelCanvasElements(ownerDocument) {
+function cloneCanvasContents(canvas, clonedCanvas) {
-    [].slice.call(ownerDocument.querySelectorAll("canvas"), 0).forEach(function(canvas) {
-        canvas.setAttribute(html2canvasCanvasCloneAttribute, "canvas-" + html2canvasCanvasCloneIndex++);
-    });
-}
-
-function cloneCanvasContents(ownerDocument, documentClone) {
-    [].slice.call(ownerDocument.querySelectorAll("[" + html2canvasCanvasCloneAttribute + "]"), 0).forEach(function(canvas) {
     try {
-            var clonedCanvas = documentClone.querySelector('[' + html2canvasCanvasCloneAttribute + '="' + canvas.getAttribute(html2canvasCanvasCloneAttribute) + '"]');
         if (clonedCanvas) {
             clonedCanvas.width = canvas.width;
             clonedCanvas.height = canvas.height;
@@ -37,49 +17,47 @@ function cloneCanvasContents(ownerDocument, documentClone) {
     } catch(e) {
         log("Unable to copy canvas content from", canvas, e);
     }
-        canvas.removeAttribute(html2canvasCanvasCloneAttribute);
-    });
 }
 
-function removeScriptNodes(parent) {
+function cloneNode(node, javascriptEnabled) {
-    [].slice.call(parent.childNodes, 0).filter(isElementNode).forEach(function(node) {
-        if (node.tagName === "SCRIPT") {
-            parent.removeChild(node);
-        } else {
-            removeScriptNodes(node);
-        }
-    });
-    return parent;
-}
-
-function isIE9() {
-    return document.documentMode && document.documentMode <= 9;
-}
-
-// https://github.com/niklasvh/html2canvas/issues/503
-function cloneNodeIE9(node, javascriptEnabled) {
     var clone = node.nodeType === 3 ? document.createTextNode(node.nodeValue) : node.cloneNode(false);
 
     var child = node.firstChild;
     while(child) {
         if (javascriptEnabled === true || child.nodeType !== 1 || child.nodeName !== 'SCRIPT') {
-            clone.appendChild(cloneNodeIE9(child, javascriptEnabled));
+            clone.appendChild(cloneNode(child, javascriptEnabled));
         }
         child = child.nextSibling;
     }
 
+    if (node.nodeType === 1) {
+        clone._scrollTop = node.scrollTop;
+        clone._scrollLeft = node.scrollLeft;
+        if (node.nodeName === "CANVAS") {
+            cloneCanvasContents(node, clone);
+        } else if (node.nodeName === "TEXTAREA" || node.nodeName === "SELECT") {
+            clone.value = node.value;
+        }
+    }
+
     return clone;
 }
 
+function initNode(node) {
+    if (node.nodeType === 1) {
+        node.scrollTop = node._scrollTop;
+        node.scrollLeft = node._scrollLeft;
 
-
+        var child = node.firstChild;
-function isElementNode(node) {
+        while(child) {
-    return node.nodeType === Node.ELEMENT_NODE;
+            initNode(child);
+            child = child.nextSibling;
+        }
+    }
 }
 
 module.exports = function(ownerDocument, containerDocument, width, height, options, x ,y) {
-    labelCanvasElements(ownerDocument);
+    var documentElement = cloneNode(ownerDocument.documentElement, options.javascriptEnabled);
-    var documentElement = isIE9() ? cloneNodeIE9(ownerDocument.documentElement, options.javascriptEnabled) : ownerDocument.documentElement.cloneNode(true);
     var container = containerDocument.createElement("iframe");
 
     container.className = "html2canvas-container";
@@ -96,16 +74,13 @@ module.exports = function(ownerDocument, containerDocument, width, height, optio
     return new Promise(function(resolve) {
         var documentClone = container.contentWindow.document;
 
-        cloneNodeValues(ownerDocument.documentElement, documentElement, "textarea");
-        cloneNodeValues(ownerDocument.documentElement, documentElement, "select");
-
         /* Chrome doesn't detect relative background-images assigned in inline <style> sheets when fetched through getComputedStyle
          if window url is about:blank, we can assign the url to current by writing onto the document
          */
         container.contentWindow.onload = container.onload = function() {
             var interval = setInterval(function() {
                 if (documentClone.body.childNodes.length > 0) {
-                    cloneCanvasContents(ownerDocument, documentClone);
+                    initNode(documentClone.documentElement);
                     clearInterval(interval);
                     if (options.type === "view") {
                         container.contentWindow.scrollTo(x, y);
@@ -119,7 +94,7 @@ module.exports = function(ownerDocument, containerDocument, width, height, optio
         documentClone.write("<!DOCTYPE html><html></html>");
         // Chrome scrolls the parent document for some reason after the write to the cloned window???
         restoreOwnerScroll(ownerDocument, x, y);
-        documentClone.replaceChild(options.javascriptEnabled === true ? documentClone.adoptNode(documentElement) : removeScriptNodes(documentClone.adoptNode(documentElement)), documentClone.documentElement);
+        documentClone.replaceChild(documentClone.adoptNode(documentElement), documentClone.documentElement);
         documentClone.close();
     });
 };

tests/mocha/form-rendering.html

@@ -108,7 +108,7 @@
                 CanvasRenderer.prototype.text = function(text) {
                     expect(text).to.equal('updated');
                 };
-                html2canvas(document.querySelector("#block4"), {renderer: CanvasRenderer, strict: true, logging: true, removeContainer: false}).then(function(canvas) {
+                html2canvas(document.querySelector("#block4"), {renderer: CanvasRenderer, strict: true}).then(function(canvas) {
                     expect(canvas.width).to.equal(200);
                     expect(canvas.height).to.equal(200);
                     done();
@@ -138,7 +138,7 @@
                 CanvasRenderer.prototype.text = function(text) {
                     expect(text).to.equal('3');
                 };
-                html2canvas(document.querySelector("#block5"), {renderer: CanvasRenderer, strict: true, logging: true, removeContainer: false}).then(function(canvas) {
+                html2canvas(document.querySelector("#block5"), {renderer: CanvasRenderer, strict: true}).then(function(canvas) {
                     expect(canvas.width).to.equal(200);
                     expect(canvas.height).to.equal(200);
                     done();

tests/mocha/scrolling.html

@@ -12,6 +12,12 @@
 <body>
 <div id="mocha"></div>
 <script>mocha.setup('bdd')</script>
+<div id="scroll-render" style="height: 200px; width: 200px;">
+    <div style="height: 500px; width: 400px;overflow: scroll;" id="scrollable">
+        <div style="height: 500px;background: red;"></div>
+        <div style="height: 650px; background: green"></div>
+    </div>
+</div>
 <div style="height: 2200px;"></div>
 <div style="height: 500px;background: green;"><a name="content">content</a></div>
 <script>
@@ -32,7 +38,7 @@
             window.location.hash = "#content";
             setTimeout(function() {
                 var top = $(window).scrollTop();
-                html2canvas(document.body, {type: 'view', removeContainer: false}).then(function () {
+                html2canvas(document.body, {type: 'view'}).then(function () {
                     var currentTop = $(window).scrollTop();
                     window.location.hash = "";
                     expect(currentTop).to.be.greaterThan(1500);
@@ -45,7 +51,34 @@
                 });
             }, 0);
         });
+
+        it("with content scroll", function (done) {
+            $("#scrollable").scrollTop(500);
+            setTimeout(function() {
+                html2canvas(document.querySelector("#scroll-render")).then(function (canvas) {
+                    expect($("#scrollable").scrollTop()).to.equal(500);
+                    document.body.appendChild(canvas);
+                    expect(canvas.width).to.equal(200);
+                    expect(canvas.height).to.equal(200);
+                    validCanvasPixels(canvas);
+                    done();
+                }).catch(function (error) {
+                    done(error);
                 });
+            }, 0);
+        });
+    });
+
+    function validCanvasPixels(canvas) {
+        var ctx = canvas.getContext("2d");
+        var data = ctx.getImageData(0, 0, canvas.width, canvas.height).data;
+        for (var i = 0, len = 200*199*4; i < len; i+=4) {
+            if (data[i] !== 0 || data[i+1] !== 128 || data[i+2] !== 0 || data[i+3] !== 255) {
+                console.log(i, data[i], data[i+1], data[i+2], data[i+3]);
+                expect().fail("Invalid canvas data");
+            }
+        }
+    }
 
     after(function() {
         if (history) {