Bits & Bytes

Posts Tagged ‘display’

How to Fix Problems with Displaying SVG Images within an HTML Image Element

Suppose that you have an image element inside of an HTML file, like this one:

<img width="30px" height="40px" src= "MyImage.svg"  />

and your SVG file, “MyImage.svg”, looks like this:

<svg width="30" height="40" xmlns="">
  <image href="Christ.png" x="10" y="20" width="20" height="20"></image>

In this case, the image inside the svg, “Christ.png”, will not display because the image element will not allow the reference to the external file “Christ.png”.

However, this can be fixed in a few different ways:

  1. Change the image element to an embed element:

    <embed width=”20px” height=”20px” src= “MyImage.svg” />

  2. Eliminate the image element and include the svg element in the HTML directly.
  3. Convert the image into a 64 bit data URI

If you have never seen a 64 bit data URI, they look something like this:


Warning: 64 bit data URI encoded images can be quite long, even for a moderately-sized image. The text above was generate for the small 20 pixel by 20 pixel image shown here:

So, instead of our original svg element, we could use this one with a 64 bit encoded data URI:

<svg width="30" height="40" xmlns="">
  <image x="10" y="20" width="20" height="20" href="data:image/png;base64

Using Arrays in JavaScript

Arrays are containers that hold a sequence of objects that can be accessed via the bracket operator [] and an integer index. Since JavaScript is not a strongly-typed language, JavaScript arrays are very versatile and can hold objects of different types. In this post, I will focus on the basic syntax and usage.

Below, we have the code for an HTML file and a JavaScript file. The HTML file is essentially blank; it is simply used to call the JavaScript file, “Arrays.js,” and execute the code. The rest is boilerplate code that I reuse for all of my JavaScript posts.

The JavaScript code file, “Arrays.js,” contains the entire JavaScript program. In it, I first declare the variable, qaPaintings, and assign it the value [], which makes the variable an Array object with zero elements in it. Then the first entry at index 0 is set to hold a new Image object and its source is set to be the Michelangelo’s painting of the creation of the Sun and the Moon from the Sistene Chapel that was painted in 1511 AD. The call to appendChild() adds the image to the document so that it is displayed.

The same thing is then done for the entries at 1 and 2 in the array. These are assigned the source images of the painting The Descent of the Holy Ghost by Titian circa 1545 AD and the painting of The Last Judgment from the Sistene Chapel by Michelangelo that was completed between 1536 AD and 1541 AD.

All of this shows how to create an array and assign values to its elements. Notice that when we first created the array, it had zero elements. By assigning values to the entries at 0, 1, and 2, we caused the array to be extended each time. Automatic array resizing is a convenient property of JavaScript arrays that differs from other languages like C++. In fact, JavaScript arrays


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="" xml:lang="en" lang="en">
  <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
  <script type="text/javascript" src="Arrays.js"></script>


var qaPaintings = [];

qaPaintings[0] = new Image();
qaPaintings[0].src = "SisteneChapel_Michelangelo_1511_1.jpg"

qaPaintings[1] = new Image();
qaPaintings[1].src = "TheDescentOfTheHolyGhost_Titian_2.jpg"

qaPaintings[2] = new Image();
qaPaintings[2].src = "TheLastJudgment_Michelangelo_3.jpg"

Capturing and Playing Video From a Camera in Actionscript 3.0

This program gives a simple demonstration of how to display video that is captured by a camera. If you have a camera attached to your computer (most laptops do), then you can click the box above to display the video capture from your camera. Note that you will need click the “Allow” button to see the video. To stop the video, refresh the page.

The code for this program is simple and is listed below. The first three lines display the message “Click To Play.” The next line, sets the function CaptureVideo() as a callback to respond to mouse clicks.

After that, we have the CaptureVideo() function, which attempts to get access to a camera and checks whether the attempt was successful. If there is a camera, a Video object is created, attached to the camera, and added to the stage for display.

// Output the initial instructions to user
var qInstructions:TextField = new TextField();
qInstructions.text = "Click To Play";

stage.addEventListener(MouseEvent.CLICK, CaptureVideo);

function CaptureVideo(e:Event):void {
	var qCamera:Camera = Camera.getCamera();
	if (qCamera != null) {
		var qVideo:Video = new Video(320, 240);