HTML5 Canvas Navigation menu with Fire
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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
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.
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