Capturing Full Div Content as Image with HTML2Canvas: How ReSetting HTML Height to 100% Solved the Issue

If you’ve ever tried to capture the full content of a scrollable div element as an image using HTML2Canvas, you may have run into the issue where only the visible portion of the div is captured. This can be particularly problematic if you’re building a chat application, where you need to capture the entire conversation history, including messages that have scrolled out of view.

In this blog post, we’ll explore how to overcome this issue and capture the full content of a div element using HTML2Canvas. We’ll also dive into a specific case where HTML2Canvas wasn’t working as expected in a chat application, and how we solved the problem by setting the HTML height to 100% and adding scrollY = -window.scrollY to the code.

How it works

// Set the height of the HTML element to auto when the user clicks on the capture button
document.getElementById("capture-btn").addEventListener("click", function() {
  document.documentElement.style.height = "auto";
  
  html2canvas(document.getElementById("chat-history")).then(function(canvas) {
    // Do something with the captured canvas
  });
  
  // Reset the height of the HTML element to 100% after capturing the chat history
  document.documentElement.style.height = "100%";
});

In the code above, we first set the height of the HTML element to “auto” when the user clicks on the capture button. This allows the html2canvas library to capture the entire chat history, including any overflow content. Once the capture is complete, we reset the height of the HTML element to “100%” to restore the layout of the page.

Note that the chat-history element is the one containing the chat history that we want to capture. You can replace this with the ID or class name of the element you want to capture.