In this article I’ll explain about concept of canvas you can learn how to draw a image using canvas.

Introduction:

Let’s have some knowledge of the canvas images by understanding its function for drawing the images. To draw a canvas image, the drawImage() method is used that requires an images object and a destination point. The destination point means the top-left corner of the images relative to the top-left corner of the canvas on which the image is to be drawn.

There are the following three variants of this method.
 drawImage(image, dx, dy).
 drawImage(image, dx, dy, dw, dh)

 drawImage(image, sx, sy, sw, sh, dx, dy, dw, dh,).

 

First we should know about all the parameters given in the methods, so we can

understand the use of all the parameters and can easily play with the images.

The parameter "images" is the image that is to be drawn.

The parameters "dx" and "dy" are known as "destinationX" and "destinationY"

respectively and determine where the image is to be drawn on the canvas.

The parameters "dw" and "dh" are known as "destinationWidth" and

"destinationHeight" respectively and determine the scale size of the image.

The parameters "sx" and "sy" are known as "sourceX" and "sourceY" respectively and

determine the where in the source images to start copying the rectangle of the

images onto the canvas.

The parameters "sw" and "sh" are known as "sourceWidth" and "sourceHeight"

respectively and determine the scaling (extent of copying of width and height) of

the source image.

As we all know, the drawImage() method needs an object, so first we should create

an image object and should wait for it to load by

applying the  window.onload() function before the initiation ofthe drawImages()

method.

Example: Drawing and loading:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
</head>
<body>
    <div style="float: left;">
        <p>Image being used:</p>
        <img id="skullash" width="250" height="210" src="Images/images.jpg" alt="The Skull Ash">
    </div>
    <div style="float: left;margin-left:50px;">
        <p>Canvas Image:</p>
        <canvas id="smokeCanvas" width="270" height="180" style="border: 3px solid red;">
            <script>
                window.onload = function ashSkull() {
                    var newCanvas = document.getElementById("smokeCanvas");
                    var context = newCanvas.getContext("2d");
                    var image = document.getElementById("skullash");
                    context.drawImage(image, 0,0);
                }
            </script>
        </canvas>
    </div>
</body>
</html>
Output:


We can observe the image drawn on the canvas (with a Red border).

 

  Modified On Dec-07-2017 04:11:38 AM

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