HTML5 Canvas
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HTML5 Canvas
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Your browser does not support the <canvas> element.
The HTML <canvas> element is used to draw graphics on a web page.
The graphic to the left is created with <canvas>. It shows four
elements: a red rectangle, a gradient rectangle,
a multicolor rectangle, and a multicolor text.
var c=document.getElementById("myCanvas");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
ctx.fillStyle="#FF0000";
ctx.fillRect(20,20,100,50);
var grd=ctx.createLinearGradient(140,20,240,70);
grd.addColorStop(0,"black");
grd.addColorStop(1,"white");
ctx.fillStyle=grd;
ctx.fillRect(140,20,100,50);
var grd2=ctx.createLinearGradient(20,90,120,90);
grd2.addColorStop(0,"black");
grd2.addColorStop("0.3","magenta");
grd2.addColorStop("0.5","blue");
grd2.addColorStop("0.6","green");
grd2.addColorStop("0.8","yellow");
grd2.addColorStop(1,"red");
ctx.fillStyle=grd2;
ctx.fillRect(20,90,100,50);
ctx.font="30px Verdana";
var grd3=ctx.createLinearGradient(140,20,240,90);
grd3.addColorStop(0,"black");
grd3.addColorStop("0.3","magenta");
grd3.addColorStop("0.6","blue");
grd3.addColorStop("0.8","green");
grd3.addColorStop(1,"red");
ctx.strokeStyle=grd3;
ctx.strokeText("Smile!",140,120); }
What is HTML Canvas?
The HTML <canvas> element is used to draw graphics, on the fly, via JavaScript.
The <canvas> element is only a container for graphics. You must use
JavaScript to actually draw the graphics.
Canvas has several methods for drawing paths, boxes, circles, text, and adding images.
Browser Support
The numbers in the table specify the first browser version that fully supports the <canvas> element.
| Element | |||||
|---|---|---|---|---|---|
| <canvas> | 4.0 | 9.0 | 2.0 | 3.1 | 9.0 |
Canvas Examples
A canvas is a rectangular area on an HTML page. By default, a canvas has no border and no content.
The markup looks like this:
<canvas id="myCanvas" width="200" height="100"></canvas>
Note: Always specify an id attribute (to be referred to in a script),
and a width and height attribute to define the size of the canvas. To add a border, use the style attribute.
Here is an example of a basic, empty canvas:
Your browser does not support the canvas element.
Example
<canvas id="myCanvas" width="200" height="100"
style="border:1px solid
#000000;">
</canvas>
Try it Yourself »
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Draw a Line
Your browser does not support the canvas element
var c=document.getElementById("myCanvas2");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
ctx.moveTo(0,0);
ctx.lineTo(200,100);
ctx.stroke();
}
Example
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(0, 0);
ctx.lineTo(200, 100);
ctx.stroke();Try it Yourself »
Draw a Circle
Your browser does not support the canvas element
var c=document.getElementById("myCanvas3");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
ctx.beginPath();
ctx.arc(95,50,40,0,2*Math.PI);
ctx.stroke();
}
Example
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95, 50, 40, 0, 2 * Math.PI);
ctx.stroke();Try it Yourself »
Draw a Text
Your browser does not support the canvas element
var c=document.getElementById("myCanvas4");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
ctx.font="30px Arial";
ctx.fillText("Hello World",10,50);
}
Example
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("Hello World", 10, 50);Try it Yourself »
Stroke Text
Your browser does not support the canvas element
var c=document.getElementById("myCanvas5");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
ctx.font="30px Arial";
ctx.strokeText("Hello World",10,50);
}
Example
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.strokeText("Hello World", 10, 50);Try it Yourself »
Draw Linear Gradient
Your browser does not support the canvas element
var c=document.getElementById("myCanvas6");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
// Create gradient
var grd = ctx.createLinearGradient(0,0,200,0);
grd.addColorStop(0,"red");
grd.addColorStop(1,"white");
// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10,10,150,80);
}
Example
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
// Create gradient
var grd = ctx.createLinearGradient(0, 0, 200, 0);
grd.addColorStop(0, "red");
grd.addColorStop(1, "white");
// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);Try it Yourself »
Draw Circular Gradient
Your browser does not support the canvas element
var c=document.getElementById("myCanvas7");
var canvOK=1;
try {c.getContext("2d");}
catch (er) {canvOK=0;}
if (canvOK==1)
{
var ctx=c.getContext("2d");
// Create gradient
var grd = ctx.createRadialGradient(75,50,5,90,60,100);
grd.addColorStop(0,"red");
grd.addColorStop(1,"white");
// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10,10,150,80);
}
Example
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
// Create gradient
var grd = ctx.createRadialGradient(75, 50, 5, 90, 60, 100);
grd.addColorStop(0, "red");
grd.addColorStop(1, "white");
// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);Try it Yourself »
Draw Image
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("scream");
ctx.drawImage(img, 10, 10);Try it Yourself »
HTML Canvas Tutorial
To learn all about HTML <canvas>, Visit our complete HTML Canvas Tutorial.
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