How can I convert an HTML element to a canvas element

Question

It would be incredibly useful to be able to temporarily convert a regular element into a canvas  For example  say I have a styled div that I want to flip  I want to dynamically create a canvas   render  the HTMLElement into the canvas  hide the original element and animate the canvas   Can it be done

User · Answer

The easiest solution to animate the DOM elements is using CSS transitions/animations but I think you already know that and you try to use canvas to do stuff CSS doesn't let you to do. What about CSS custom filters? you can transform your elements in any imaginable way if you know how to write shaders. Some other link and don't forget to check the CSS filter lab.
Note: As you can probably imagine browser support is bad.

User · Answer

Take a look at this tutorial on MDN  https   developer mozilla org en HTML Canvas Drawing DOM objects into a canvas  archived   Alternate Link  2019    https   reference codeproject com book dom canvas api drawing dom objects into a canvas  It uses a temporary SVG image to include the HTML content as a  foreign element   then renders said SVG image into a canvas element  There are significant restrictions on what you can include in an SVG image in this way  however   See the  Security  section for details

User · Answer

Building on top of the Mozdev post that natevw references I ve started a small project to render HTML to canvas in Firefox  Chrome  amp  Safari  So for example you can simply do   rasterizeHTML drawHTML   lt span class  color  green  gt This is HTML lt  span gt                             lt img src  local img png   gt    canvas     Source code and a more extensive example is here

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No such thing  sorry   Though the spec states      A future version of the 2D context API may provide a way to render fragments of documents  rendered using CSS  straight to the canvas    Which may be as close as you ll get   A lot of people want a ctx drawArbitraryHTML Element kind of deal but there s nothing built in like that   The only exception is Mozilla s exclusive drawWindow  which draws a snapshot of the contents of a DOM window into the canvas  This feature is only available for code running with Chrome   local only   privileges  It is not allowed in normal HTML pages  So you can use it for writing FireFox extensions like this one does but that s it

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function convert                         dom   document getElementById  divname                        var script                       this   this                      options   this options                      runH2c   function                            try                               var canvas       window html2canvas   document getElementById  divname                                        onrendered  function  canvas                                      window open canvas toDataURL                                                                                                  catch  e                                  this h2cDone   true                              log  Error in html2canvas      e message                                                                         if   window html2canvas     undefined  amp  amp  script     undefined                           else                               html2canvas already loaded  just run it then                         runH2c

User · Answer

the next code can be used in 2 modes  mode 1 save the html code to a image  mode 2 save the html code to a canvas   this code work with the library  https   github com tsayen dom-to-image   the  id div  is the id of the element html that you want to transform     the  canvas out  is the id of the div that will contain the canvas  so try this code        function Guardardiv id div          var mode   2    default 1  save to image   mode 2   save to canvas       console log  Process start          var node   document getElementById id div            get the div that will contain the canvas       var canvas out   document getElementById  canvas out          var canvas   document createElement  canvas          canvas width   node scrollWidth        canvas height   node scrollHeight         domtoimage toPng node  then function  pngDataUrl              var img   new Image              img onload   function                var context   canvas getContext  2d              context drawImage img  0  0                       if  mode    1      save to image              downloadURI pngDataUrl   salida png             else if  mode    2      save to canvas           img src   pngDataUrl            canvas out appendChild img                    console log  Process finish                     so  if you want to save to image just add this function       function downloadURI uri  name            var link   document createElement  a             link download   name          link href   uri          document body appendChild link           link click               Example of use     lt html gt    lt head gt    lt  script src   dom-to-image js  gt  lt  script gt    lt  head gt     lt body gt    lt div id  container  gt     All content that want to transform    lt  div gt     lt button onclick  Guardardiv  container     gt Convert lt button gt      lt  -- if use mode 2 -- gt    lt div id  canvas out  gt  lt  div gt    lt  html gt    Comment if that work  Comenten si les sirvio

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There is a library that try to do what you say   See this examples and get the code  http   hertzen com experiments jsfeedback   http   html2canvas hertzen com   Reads the DOM  from the html and render it to a canvas  fail on some  but in general works

User · Answer

You could spare yourself the transformations  you could use CSS3 Transitions to flip  lt div gt  s and  lt ol gt  s and any HTML tag you want  Here are some demos with source code explain to see and learn  http   www webdesignerwall com trends 47-amazing-css3-animation-demos

User · Answer

Sorry  the browser won t render HTML into a canvas   It would be a potential security risk if you could  as HTML can include content  in particular images and iframes  from third-party sites  If canvas could turn HTML content into an image and then you read the image data  you could potentially extract privileged content from other sites   To get a canvas from HTML  you d have to basically write your own HTML renderer from scratch using drawImage and fillText  which is a potentially huge task  There s one such attempt here but it s a bit dodgy and a long way from complete   It even attempts to parse the HTML CSS from scratch  which I think is crazy  It d be easier to start from a real DOM node with styles applied  and read the styling using getComputedStyle and relative positions of parts of it using offsetTop et al

User · Answer

You can use dom-to-image library  I m the maintainer   Here s how you could approach your problem   var parent   document getElementById  my-node-parent    var node   document getElementById  my-node     var canvas   document createElement  canvas    canvas width   node scrollWidth  canvas height   node scrollHeight   domtoimage toPng node  then function  pngDataUrl        var img   new Image        img onload   function              var context   canvas getContext  2d             context translate canvas width  0           context scale -1  1           context drawImage img  0  0            parent removeChild node           parent appendChild canvas               img src   pngDataUrl        And here is jsfiddle

[html] How can I convert an HTML element to a canvas element?

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