HTML5 Zone is brought to you in partnership with:

I was born in 1981 in one little city. Since I was 10y/o I programmed in different languages. My first languages were basic, then C++/MFC, after .Net (C#, VB.Net, J#, ASP.Net), XSL+XML processing). In the last 5 years I worked with web languages (HTML, CSS, PHP, SQL, XML, XSL, JavaScript). After university I worked in several different companies, eventually becoming a blogger. This is my hobby too. Andrey is a DZone MVB and is not an employee of DZone and has posted 110 posts at DZone. You can read more from them at their website. View Full User Profile

HTML5 Canvas Navigation menu with Fire

06.02.2012
| 5081 views |
  • submit to reddit

HTML5 Canvas Navigation menu with Fire

Have you ever thought about creating some interactive navigation menu in HTML5 directly in the canvas element? Yes, this is a strange idea, but it is possible. I prepared our first pure html5 canvas menu (basically – this is a set of buttons). We will create these buttons with a fire effect at the bottom.  You will be able to set custom click actions for menu elements.

 

Live Demo


Preview

HTML5 Canvas Menu - Preview

Step 1. HTML Markup

Basically our HTML markup is very easy today:

<!DOCTYPE html>
<html lang="en" >
    <head>
        <meta charset="utf-8" />
        <title>HTML5 Canvas Navigation menu with Fire | Script Tutorials</title>
        <link rel="stylesheet" href="css/main.css" type="text/css" />
        <script src="js/vector2d.js"></script>
        <script src="js/fire_menu.js"></script>
    </head>
    <body>
        <canvas id="panel" width="1000px" height="100px">HTML5 compliant browser required</canvas>
        <img id="image" src="images/bg.jpg"  />
    </body>
</html>

There is only single canvas element. Plus – one image directly after this canvas.

Step 2. JS

Now, we should create a new empty file ‘js/fire_menu.js’ and put next code inside:

// Button object
function Button(x, y, w, h, state, image, text) {
    this.x = x;
    this.y = y;
    this.w = w;
    this.h = h;
    this.state = state;
    this.imageShift = 0;
    this.image = image;
    this.text = text;
}

// Draw Button function
function drawButton(ctx, button) {
    // draw button image
    ctx.drawImage(button.image, 0, button.imageShift, button.w, button.h, button.x, button.y, button.w, button.h);

    // and text
    ctx.fillText(button.text, button.x + button.w / 2, 5 + button.y + button.h / 2);
}

// Get mouse position function
function getMousePosition(e){
    if (!e){
        var e = window.event;
    }
    if (e.pageX || e.pageY){
        return new vector2d(e.pageX, e.pageY);
    } else if (e.clientX || e.clientY){
        return new vector2d(e.clientX, e.clientY);
    }
}

// Inner variables
var canvas, ctx;
var data_width;
var data_height;
var colors = [];
var out_data = [];
var buttons = [];

// Fill new array with certain value
function fill_new_array(len, val) {
    var rv = new Array(len);
    while (--len >= 0) {
        rv[len] = val;
    }
    return rv;
}

// Prepare palette function
function prepare_palette() {
    for (var i = 0; i < 64; ++i) {
        colors[i + 0] = {r: 0, g: 0, b: i << 1, a: i};
        colors[i + 64] = {r: i << 3, g: 0, b: 128 - (i << 2), a: i+64};
        colors[i + 128] = {r: 255, g: i << 1, b: 0, a: i+128};
        colors[i + 192] = {r: 255, g: 255, b: i << 2, a: i+192};
    }
}

// Draw Main scene
function drawScene() {
    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // clear canvas

    // Draw fire
    var data_cnt = data_width * (data_height - 1);
    for (var i = 0; i < data_width; i++) {
        out_data[data_cnt + i] = (0.6 > Math.random()) ? 255 : 20;
    }
    for (var y = 0; y < 100; y++){
        for (var x = 10; x < data_width - 10; x++){
            var s = data_cnt + x;

            var temp_data = out_data[s] + out_data[s + 1] + out_data[s - 1] + out_data[s - data_width];
            temp_data >>= 2;
            if (temp_data > 1){
                temp_data -= 1;
            }
            temp_data <<= 0;

            out_data[s - data_width] = temp_data;

            var id = s << 2;
            img_data.data[id + 0] = colors[temp_data].r;
            img_data.data[id + 1] = colors[temp_data].g;
            img_data.data[id + 2] = colors[temp_data].b;
            img_data.data[id + 3] = colors[temp_data].a;
        }
        data_cnt -= data_width;
    }
    ctx.putImageData(img_data, 0, 0);

    // Prepare font
    ctx.font = '26px DS-Digital';
    ctx.fillStyle = '#000000';
    ctx.textAlign = "center";

    // Draw all the buttons
    for (var ib = 0; ib < buttons.length; ib++) { //
        drawButton(ctx, buttons[ib]);
    }
}

// Window Onload event handler
if (window.attachEvent) {
    window.attachEvent('onload', main_init);
} else {
    if(window.onload) {
        var curronload = window.onload;
        var newonload = function() {
            curronload();
            main_init();
        };
        window.onload = newonload;
    } else {
        window.onload = main_init;
    }
}

// Main initialization
function main_init() {

    // Create canvas and context objects
    canvas = document.getElementById('panel');
    ctx = canvas.getContext('2d');

    // Prepare data for our fire object and prepare palette
    img_data = ctx.createImageData(canvas.width, canvas.height);
    data_width = img_data.width,
    data_height = img_data.height,
    prepare_palette();

    // Fill new array with 0
    out_data = fill_new_array(data_width * data_height, 0)

    // Prepare image to buttons
    var buttonImage = new Image();
    buttonImage.src="images/button.png";
    buttonImage.onload = function() {};

    // Prepare 3 different buttons
    buttons.push(new Button(0, 10, 245, 62, 'normal', buttonImage, 'button #1'));
    buttons.push(new Button(250, 10, 245, 62, 'normal', buttonImage, 'button #2'));
    buttons.push(new Button(500, 10, 245, 62, 'normal', buttonImage, 'button #3'));
    buttons.push(new Button(750, 10, 245, 62, 'normal', buttonImage, 'button #4'));

    // Loop main scene
    setInterval(drawScene, 40);

    // Onmousemove event handler
    canvas.onmousemove = function(e) {
        var mouse = getMousePosition(e).sub(new vector2d(canvas.offsetLeft, canvas.offsetTop));

        for (var i = 0; i < buttons.length; i++) { // Apply 'hover' state for buttons
            if (buttons[i].state != 'pressed') {
                buttons[i].state = 'normal';
                buttons[i].imageShift = 0;
                if (mouse.x > buttons[i].x && mouse.x < buttons[i].x+buttons[i].w && mouse.y > buttons[i].y && mouse.y < buttons[i].y+buttons[i].h) {
                    buttons[i].state = 'hover';
                    buttons[i].imageShift = 136;
                }
            }
        }
    }

    // Onmousedown event handler
    canvas.onmousedown = function(e) {
        var mouse = getMousePosition(e).sub(new vector2d(canvas.offsetLeft, canvas.offsetTop));

        for (var i = 0; i < buttons.length; i++) { // Apply 'pressed' state for buttons
            if (mouse.x > buttons[i].x && mouse.x < buttons[i].x+buttons[i].w && mouse.y > buttons[i].y && mouse.y < buttons[i].y+buttons[i].h) {
                buttons[i].state = 'pressed';
                buttons[i].imageShift = 68;
            }
        }
    }

    // Onmouseup event handler
    canvas.onmouseup = function(e) {
        var mouse = getMousePosition(e).sub(new vector2d(canvas.offsetLeft, canvas.offsetTop));

        for (var i = 0; i < buttons.length; i++) { // Reset states for buttons
            if (mouse.x > buttons[i].x && mouse.x < buttons[i].x+buttons[i].w && mouse.y > buttons[i].y && mouse.y < buttons[i].y+buttons[i].h) {
                alert(buttons[i].text + ' is pushed');
            }

            buttons[i].state = 'normal';
            buttons[i].imageShift = 0;
        }
    }
}

The main idea of our menu – put several buttons at canvas element, and then – add event handlers. Also, as extra feature – animated fire at the background. This demonstration can bring you new ideas for your projects.

Step 3. Extra files

It’s possible that you have noticed that I use the addition files in our project: main.css, Ds-digib.ttf, bg.jpg, button.png and vector2d.js. All these files are available in our download package.


Live Demo

Conclusion

I hope that you like our html5 experiments. Welcome back.

 

 

 

Published at DZone with permission of Andrey Prikaznov, author and DZone MVB. (source)

(Note: Opinions expressed in this article and its replies are the opinions of their respective authors and not those of DZone, Inc.)