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How to put a gif with Canvas

I'm creating a game, and in my game, when the HERO stay near the MONSTER, a gif will be showed, to scare the player. But I have no idea how to do this. I tried to put PHP or HTML code, but it doesn't works... The function is AtualizaTela2(). This is my main code:

<!DOCTYPE HTML>
<html>
<head>
<title>Hero's Escape Game</title>
<script language="JavaScript" type="text/javascript">

var objCanvas=null; // object that represents the canvas
var objContexto=null; 

// Hero positioning control
var xHero=300;
var yHero=100;

// Monster positioning control
var xMonster=620;
var yMonster=0;

var imgFundo2 = new Image();
imgFundo2.src = "Images/Pista2.png";

var imgMonster = new Image();
imgMonster.src = "Images/Monster.png";

var imgHero = new Image();
imgHero.src = "Images/Hero.png";

function AtualizaTela2(){

if((xHero >= xMonster-10)&&(xHero <= xMonster + 10))
{

/*gif here*/

}

objContexto.drawImage(imgFundo2,0,0);
objContexto.drawImage(imgHero, xHero, yHero);
objContexto.drawImage(imgMonster, xMonster, yMonster);

function Iniciar(){

objCanvas = document.getElementById("meuCanvas");
objContexto = objCanvas.getContext("2d");
AtualizaTela2();

}

/* the function HeroMovement() and MonsterMovement() are not here */

}

</script>
</head>
<body onLoad="Iniciar();" onkeydown="HeroMovement(event);">

<canvas id="meuCanvas" width="1233"
height="507"
style="border:1px solid #000000;">
Seu browser não suporta o elemento CANVAS, atualize-se!!!
</canvas><BR>
</body>
</html>

This is the simplified code, because the real code is very big!

Thanks for the help! :)

like image 234
Grandtour Avatar asked Jan 12 '18 22:01

Grandtour


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How do I add a GIF to canvas?

Add a GIF from Giphy to your canvasFrom the menu, choose Image/GIF from Web. Choose GIPHY. Search for the GIF you'd like to add to your canvas — you can choose one of the featured GIFs or use the search bar to find what you're looking for. Once found, select the GIF's thumbnail — it'll be added to your canvas.

Does canvas accept GIFs?

Displaying images is a good first step as you learn to embed media in Canvas. The image insertion tools allow you to add still images and animated gifs.

How do I view a GIF in canvas?

The only way to get a GIF animated in canvas is to decode the GIF image in javascript. Luckily the format is not too complicated with data arranged in blocks that contain image size, color pallets, timing information, a comment field, and how frames are drawn.


2 Answers

Loading and playing GIF image to canvas.

Sorry answer exceeded size limit, had to remove much of the detailed code comments.

I am not going to go into details as the whole process is rather complicated.

The only way to get a GIF animated in canvas is to decode the GIF image in javascript. Luckily the format is not too complicated with data arranged in blocks that contain image size, color pallets, timing information, a comment field, and how frames are drawn.

Custom GIF load and player.

The example below contains an object called GIF that will create custom format GIF images from URLs that can play a GIF similar to how a video is played. You can also randomly access all GIF frames in any order.

There are many callbacks and options. There is basic usage information in comments and the code shows how to load the gif. There are functions to pause and play, seek(timeInSeconds) and seekFrame(frameNumber), properties to control playSpeed and much more. There are no shuttling events as access is immediate.

 var myGif = GIF();
 myGif.load("GIFurl.gif");

Once loaded

 ctx.drawImage(myGif.image,0,0); // will draw the playing gif image

Or access the frames via the frames buffer

 ctx.drawImage(myGif.frames[0].image,0,0); // draw frame 0 only.

Go to the bottom of the GIF object to see all the options with comments.

The GIF must be same domain or have CORS header

The gif in he demo is from wiki commons and contains 250+ frames, some low end devices will have trouble with this as each frame is converted to a full RGBA image making the loaded GIF significantly larger than the gif file size.

The demo

Loads the gif displaying the frames and frame count as loaded. When loaded 100 particles each with random access frames playing at independent speeds and independent directions are displayed in the background.

The foreground image is the gif playing at the frame rate embedded in the file.

Code is as is, as an example only and NOT for commercial use.

const ctx = canvas.getContext("2d");

var myGif;
// Can not load gif cross domain unless it has CORS header
const gifURL = "https://upload.wikimedia.org/wikipedia/commons/a/a2/Wax_fire.gif";
// timeout just waits till script has been parsed and executed
// then starts loading a gif
setTimeout(()=>{
    myGif = GIF();                  // creates a new gif  
    myGif.onerror = function(e){
       console.log("Gif loading error " + e.type);
    }
    myGif.load(gifURL);  

},0); 
// Function draws an image
function drawImage(image,x,y,scale,rot){
    ctx.setTransform(scale,0,0,scale,x,y);
    ctx.rotate(rot);
    ctx.drawImage(image,-image.width / 2, -image.height / 2);
}
// helper functions
const rand  = (min = 1, max = min + (min = 0)) => Math.random() * (max - min) + min;
const setOf     =(c,C)=>{var a=[],i=0;while(i<c){a.push(C(i++))}return a};
const eachOf    =(a,C)=>{var i=0;const l=a.length;while(i<l && C(a[i],i++,l)!==true);return i};
const mod = (v,m) => ((v % m) + m) % m;

// create 100 particles
const particles = setOf(100,() => {
    return {
      x : rand(innerWidth),
      y : rand(innerHeight),
      scale : rand(0.15, 0.5),
      rot : rand(Math.PI * 2),
      frame : 0,
      frameRate : rand(-2,2),
      dr : rand(-0.1,0.1),
      dx : rand(-4,4),
      dy : rand(-4,4),
   };
});
// Animate and draw 100 particles
function drawParticles(){
  eachOf(particles, part => {
     part.x += part.dx;
     part.y += part.dy;
     part.rot += part.dr;
     part.frame += part.frameRate;
     part.x = mod(part.x,innerWidth);
     part.y = mod(part.y,innerHeight);
     var frame = mod(part.frame ,myGif.frames.length) | 0;
 
     drawImage(myGif.frames[frame].image,part.x,part.y,part.scale,part.rot);
  });
}      


var w = canvas.width;
var h = canvas.height;
var cw = w / 2; // center 
var ch = h / 2;

// main update function
function update(timer) {
  ctx.setTransform(1, 0, 0, 1, 0, 0); // reset transform
  if (w !== innerWidth || h !== innerHeight) {
    cw = (w = canvas.width = innerWidth) / 2;
    ch = (h = canvas.height = innerHeight) / 2;
  } else {
    ctx.clearRect(0, 0, w, h);
  }
  if(myGif) { // If gif object defined
    if(!myGif.loading){  // if loaded
        // draw random access to gif frames
        drawParticles();
        drawImage(myGif.image,cw,ch,1,0); // displays the current frame.
    }else if(myGif.lastFrame !== null){  // Shows frames as they load
        ctx.drawImage(myGif.lastFrame.image,0,0); 
        ctx.fillStyle = "white";
        ctx.fillText("GIF loading frame " + myGif.frames.length ,10,21);
        ctx.fillText("GIF loading frame " + myGif.frames.length,10,19);
        ctx.fillText("GIF loading frame " + myGif.frames.length,9,20);
        ctx.fillText("GIF loading frame " + myGif.frames.length,11,20);
        ctx.fillStyle = "black";
        ctx.fillText("GIF loading frame " + myGif.frames.length,10,20);
        
    }
  
  }else{
        ctx.fillText("Waiting for GIF image ",10,20);
  
  }
  requestAnimationFrame(update);
}
requestAnimationFrame(update);

/*============================================================================
  Gif Decoder and player for use with Canvas API's

**NOT** for commercial use.

To use

    var myGif = GIF();                  // creates a new gif  
    var myGif = new GIF();              // will work as well but not needed as GIF() returns the correct reference already.    
    myGif.load("myGif.gif");            // set URL and load
    myGif.onload = function(event){     // fires when loading is complete
                                        //event.type   = "load"
                                        //event.path   array containing a reference to the gif
    }
    myGif.onprogress = function(event){ // Note this function is not bound to myGif
                                        //event.bytesRead    bytes decoded
                                        //event.totalBytes   total bytes
                                        //event.frame        index of last frame decoded
    }
    myGif.onerror = function(event){    // fires if there is a problem loading. this = myGif
                                        //event.type   a description of the error
                                        //event.path   array containing a reference to the gif
    }

Once loaded the gif can be displayed
    if(!myGif.loading){
        ctx.drawImage(myGif.image,0,0); 
    }
You can display the last frame loaded during loading

    if(myGif.lastFrame !== null){
        ctx.drawImage(myGif.lastFrame.image,0,0); 
    }


To access all the frames
    var gifFrames = myGif.frames; // an array of frames.

A frame holds various frame associated items.
    myGif.frame[0].image; // the first frames image
    myGif.frame[0].delay; // time in milliseconds frame is displayed for




Gifs use various methods to reduce the file size. The loaded frames do not maintain the optimisations and hold the full resolution frames as DOM images. This mean the memory footprint of a decode gif will be many time larger than the Gif file.
 */
const GIF = function () {
    // **NOT** for commercial use.
    var timerID;                          // timer handle for set time out usage
    var st;                               // holds the stream object when loading.
    var interlaceOffsets  = [0, 4, 2, 1]; // used in de-interlacing.
    var interlaceSteps    = [8, 8, 4, 2];
    var interlacedBufSize;  // this holds a buffer to de interlace. Created on the first frame and when size changed
    var deinterlaceBuf;
    var pixelBufSize;    // this holds a buffer for pixels. Created on the first frame and when size changed
    var pixelBuf;
    const GIF_FILE = { // gif file data headers
        GCExt   : 0xF9,
        COMMENT : 0xFE,
        APPExt  : 0xFF,
        UNKNOWN : 0x01, // not sure what this is but need to skip it in parser
        IMAGE   : 0x2C,
        EOF     : 59,   // This is entered as decimal
        EXT     : 0x21,
    };      
    // simple buffered stream used to read from the file 
    var Stream = function (data) { 
        this.data = new Uint8ClampedArray(data);
        this.pos  = 0;
        var len   = this.data.length;
        this.getString = function (count) { // returns a string from current pos of len count
            var s = "";
            while (count--) { s += String.fromCharCode(this.data[this.pos++]) }
            return s;
        };
        this.readSubBlocks = function () { // reads a set of blocks as a string
            var size, count, data  = "";
            do {
                count = size = this.data[this.pos++];
                while (count--) { data += String.fromCharCode(this.data[this.pos++]) }
            } while (size !== 0 && this.pos < len);
            return data;
        }
        this.readSubBlocksB = function () { // reads a set of blocks as binary
            var size, count, data = [];
            do {
                count = size = this.data[this.pos++];
                while (count--) { data.push(this.data[this.pos++]);}
            } while (size !== 0 && this.pos < len);
            return data;
        }
    };
    // LZW decoder uncompressed each frames pixels
    // this needs to be optimised.
    // minSize is the min dictionary as powers of two
    // size and data is the compressed pixels
    function lzwDecode(minSize, data) {
        var i, pixelPos, pos, clear, eod, size, done, dic, code, last, d, len;
        pos = pixelPos = 0;
        dic      = [];
        clear    = 1 << minSize;
        eod      = clear + 1;
        size     = minSize + 1;
        done     = false;
        while (!done) { // JavaScript optimisers like a clear exit though I never use 'done' apart from fooling the optimiser
            last = code;
            code = 0;
            for (i = 0; i < size; i++) {
                if (data[pos >> 3] & (1 << (pos & 7))) { code |= 1 << i }
                pos++;
            }
            if (code === clear) { // clear and reset the dictionary
                dic = [];
                size = minSize + 1;
                for (i = 0; i < clear; i++) { dic[i] = [i] }
                dic[clear] = [];
                dic[eod] = null;
            } else {
                if (code === eod) {  done = true; return }
                if (code >= dic.length) { dic.push(dic[last].concat(dic[last][0])) }
                else if (last !== clear) { dic.push(dic[last].concat(dic[code][0])) }
                d = dic[code];
                len = d.length;
                for (i = 0; i < len; i++) { pixelBuf[pixelPos++] = d[i] }
                if (dic.length === (1 << size) && size < 12) { size++ }
            }
        }
    };
    function parseColourTable(count) { // get a colour table of length count  Each entry is 3 bytes, for RGB.
        var colours = [];
        for (var i = 0; i < count; i++) { colours.push([st.data[st.pos++], st.data[st.pos++], st.data[st.pos++]]) }
        return colours;
    }
    function parse (){        // read the header. This is the starting point of the decode and async calls parseBlock
        var bitField;
        st.pos                += 6;  
        gif.width             = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        gif.height            = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        bitField              = st.data[st.pos++];
        gif.colorRes          = (bitField & 0b1110000) >> 4;
        gif.globalColourCount = 1 << ((bitField & 0b111) + 1);
        gif.bgColourIndex     = st.data[st.pos++];
        st.pos++;                    // ignoring pixel aspect ratio. if not 0, aspectRatio = (pixelAspectRatio + 15) / 64
        if (bitField & 0b10000000) { gif.globalColourTable = parseColourTable(gif.globalColourCount) } // global colour flag
        setTimeout(parseBlock, 0);
    }
    function parseAppExt() { // get application specific data. Netscape added iterations and terminator. Ignoring that
        st.pos += 1;
        if ('NETSCAPE' === st.getString(8)) { st.pos += 8 }  // ignoring this data. iterations (word) and terminator (byte)
        else {
            st.pos += 3;            // 3 bytes of string usually "2.0" when identifier is NETSCAPE
            st.readSubBlocks();     // unknown app extension
        }
    };
    function parseGCExt() { // get GC data
        var bitField;
        st.pos++;
        bitField              = st.data[st.pos++];
        gif.disposalMethod    = (bitField & 0b11100) >> 2;
        gif.transparencyGiven = bitField & 0b1 ? true : false; // ignoring bit two that is marked as  userInput???
        gif.delayTime         = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        gif.transparencyIndex = st.data[st.pos++];
        st.pos++;
    };
    function parseImg() {                           // decodes image data to create the indexed pixel image
        var deinterlace, frame, bitField;
        deinterlace = function (width) {                   // de interlace pixel data if needed
            var lines, fromLine, pass, toline;
            lines = pixelBufSize / width;
            fromLine = 0;
            if (interlacedBufSize !== pixelBufSize) {      // create the buffer if size changed or undefined.
                deinterlaceBuf = new Uint8Array(pixelBufSize);
                interlacedBufSize = pixelBufSize;
            }
            for (pass = 0; pass < 4; pass++) {
                for (toLine = interlaceOffsets[pass]; toLine < lines; toLine += interlaceSteps[pass]) {
                    deinterlaceBuf.set(pixelBuf.subarray(fromLine, fromLine + width), toLine * width);
                    fromLine += width;
                }
            }
        };
        frame                = {}
        gif.frames.push(frame);
        frame.disposalMethod = gif.disposalMethod;
        frame.time           = gif.length;
        frame.delay          = gif.delayTime * 10;
        gif.length          += frame.delay;
        if (gif.transparencyGiven) { frame.transparencyIndex = gif.transparencyIndex }
        else { frame.transparencyIndex = undefined }
        frame.leftPos = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        frame.topPos  = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        frame.width   = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        frame.height  = (st.data[st.pos++]) + ((st.data[st.pos++]) << 8);
        bitField      = st.data[st.pos++];
        frame.localColourTableFlag = bitField & 0b10000000 ? true : false; 
        if (frame.localColourTableFlag) { frame.localColourTable = parseColourTable(1 << ((bitField & 0b111) + 1)) }
        if (pixelBufSize !== frame.width * frame.height) { // create a pixel buffer if not yet created or if current frame size is different from previous
            pixelBuf     = new Uint8Array(frame.width * frame.height);
            pixelBufSize = frame.width * frame.height;
        }
        lzwDecode(st.data[st.pos++], st.readSubBlocksB()); // decode the pixels
        if (bitField & 0b1000000) {                        // de interlace if needed
            frame.interlaced = true;
            deinterlace(frame.width);
        } else { frame.interlaced = false }
        processFrame(frame);                               // convert to canvas image
    };
    function processFrame(frame) { // creates a RGBA canvas image from the indexed pixel data.
        var ct, cData, dat, pixCount, ind, useT, i, pixel, pDat, col, frame, ti;
        frame.image        = document.createElement('canvas');
        frame.image.width  = gif.width;
        frame.image.height = gif.height;
        frame.image.ctx    = frame.image.getContext("2d");
        ct = frame.localColourTableFlag ? frame.localColourTable : gif.globalColourTable;
        if (gif.lastFrame === null) { gif.lastFrame = frame }
        useT = (gif.lastFrame.disposalMethod === 2 || gif.lastFrame.disposalMethod === 3) ? true : false;
        if (!useT) { frame.image.ctx.drawImage(gif.lastFrame.image, 0, 0, gif.width, gif.height) }
        cData = frame.image.ctx.getImageData(frame.leftPos, frame.topPos, frame.width, frame.height);
        ti  = frame.transparencyIndex;
        dat = cData.data;
        if (frame.interlaced) { pDat = deinterlaceBuf }
        else { pDat = pixelBuf }
        pixCount = pDat.length;
        ind = 0;
        for (i = 0; i < pixCount; i++) {
            pixel = pDat[i];
            col   = ct[pixel];
            if (ti !== pixel) {
                dat[ind++] = col[0];
                dat[ind++] = col[1];
                dat[ind++] = col[2];
                dat[ind++] = 255;      // Opaque.
            } else
                if (useT) {
                    dat[ind + 3] = 0; // Transparent.
                    ind += 4;
                } else { ind += 4 }
        }
        frame.image.ctx.putImageData(cData, frame.leftPos, frame.topPos);
        gif.lastFrame = frame;
        if (!gif.waitTillDone && typeof gif.onload === "function") { doOnloadEvent() }// if !waitTillDone the call onload now after first frame is loaded
    };
    // **NOT** for commercial use.
    function finnished() { // called when the load has completed
        gif.loading           = false;
        gif.frameCount        = gif.frames.length;
        gif.lastFrame         = null;
        st                    = undefined;
        gif.complete          = true;
        gif.disposalMethod    = undefined;
        gif.transparencyGiven = undefined;
        gif.delayTime         = undefined;
        gif.transparencyIndex = undefined;
        gif.waitTillDone      = undefined;
        pixelBuf              = undefined; // dereference pixel buffer
        deinterlaceBuf        = undefined; // dereference interlace buff (may or may not be used);
        pixelBufSize          = undefined;
        deinterlaceBuf        = undefined;
        gif.currentFrame      = 0;
        if (gif.frames.length > 0) { gif.image = gif.frames[0].image }
        doOnloadEvent();
        if (typeof gif.onloadall === "function") {
            (gif.onloadall.bind(gif))({   type : 'loadall', path : [gif] });
        }
        if (gif.playOnLoad) { gif.play() }
    }
    function canceled () { // called if the load has been cancelled
        finnished();
        if (typeof gif.cancelCallback === "function") { (gif.cancelCallback.bind(gif))({ type : 'canceled', path : [gif] }) }
    }
    function parseExt() {              // parse extended blocks
        const blockID = st.data[st.pos++];
        if(blockID === GIF_FILE.GCExt) { parseGCExt() }
        else if(blockID === GIF_FILE.COMMENT) { gif.comment += st.readSubBlocks() }
        else if(blockID === GIF_FILE.APPExt) { parseAppExt() }
        else {
            if(blockID === GIF_FILE.UNKNOWN) { st.pos += 13; } // skip unknow block
            st.readSubBlocks();
        }

    }
    function parseBlock() { // parsing the blocks
        if (gif.cancel !== undefined && gif.cancel === true) { canceled(); return }

        const blockId = st.data[st.pos++];
        if(blockId === GIF_FILE.IMAGE ){ // image block
            parseImg();
            if (gif.firstFrameOnly) { finnished(); return }
        }else if(blockId === GIF_FILE.EOF) { finnished(); return }
        else { parseExt() }
        if (typeof gif.onprogress === "function") {
            gif.onprogress({ bytesRead  : st.pos, totalBytes : st.data.length, frame : gif.frames.length });
        }
        setTimeout(parseBlock, 0); // parsing frame async so processes can get some time in.
    };
    function cancelLoad(callback) { // cancels the loading. This will cancel the load before the next frame is decoded
        if (gif.complete) { return false }
        gif.cancelCallback = callback;
        gif.cancel         = true;
        return true;
    }
    function error(type) {
        if (typeof gif.onerror === "function") { (gif.onerror.bind(this))({ type : type, path : [this] }) }
        gif.onload  = gif.onerror = undefined;
        gif.loading = false;
    }
    function doOnloadEvent() { // fire onload event if set
        gif.currentFrame = 0;
        gif.nextFrameAt  = gif.lastFrameAt  = new Date().valueOf(); // just sets the time now
        if (typeof gif.onload === "function") { (gif.onload.bind(gif))({ type : 'load', path : [gif] }) }
        gif.onerror = gif.onload  = undefined;
    }
    function dataLoaded(data) { // Data loaded create stream and parse
        st = new Stream(data);
        parse();
    }
    function loadGif(filename) { // starts the load
        var ajax = new XMLHttpRequest();
        ajax.responseType = "arraybuffer";
        ajax.onload = function (e) {
            if (e.target.status === 404) { error("File not found") }
            else if(e.target.status >= 200 && e.target.status < 300 ) { dataLoaded(ajax.response) }
            else { error("Loading error : " + e.target.status) }
        };
        ajax.open('GET', filename, true);
        ajax.send();
        ajax.onerror = function (e) { error("File error") };
        this.src = filename;
        this.loading = true;
    }
    function play() { // starts play if paused
        if (!gif.playing) {
            gif.paused  = false;
            gif.playing = true;
            playing();
        }
    }
    function pause() { // stops play
        gif.paused  = true;
        gif.playing = false;
        clearTimeout(timerID);
    }
    function togglePlay(){
        if(gif.paused || !gif.playing){ gif.play() }
        else{ gif.pause() }
    }
    function seekFrame(frame) { // seeks to frame number.
        clearTimeout(timerID);
        gif.currentFrame = frame % gif.frames.length;
        if (gif.playing) { playing() }
        else { gif.image = gif.frames[gif.currentFrame].image }
    }
    function seek(time) { // time in Seconds  // seek to frame that would be displayed at time
        clearTimeout(timerID);
        if (time < 0) { time = 0 }
        time *= 1000; // in ms
        time %= gif.length;
        var frame = 0;
        while (time > gif.frames[frame].time + gif.frames[frame].delay && frame < gif.frames.length) {  frame += 1 }
        gif.currentFrame = frame;
        if (gif.playing) { playing() }
        else { gif.image = gif.frames[gif.currentFrame].image}
    }
    function playing() {
        var delay;
        var frame;
        if (gif.playSpeed === 0) {
            gif.pause();
            return;
        } else {
            if (gif.playSpeed < 0) {
                gif.currentFrame -= 1;
                if (gif.currentFrame < 0) {gif.currentFrame = gif.frames.length - 1 }
                frame = gif.currentFrame;
                frame -= 1;
                if (frame < 0) {  frame = gif.frames.length - 1 }
                delay = -gif.frames[frame].delay * 1 / gif.playSpeed;
            } else {
                gif.currentFrame += 1;
                gif.currentFrame %= gif.frames.length;
                delay = gif.frames[gif.currentFrame].delay * 1 / gif.playSpeed;
            }
            gif.image = gif.frames[gif.currentFrame].image;
            timerID = setTimeout(playing, delay);
        }
    }
    var gif = {                      // the gif image object
        onload         : null,       // fire on load. Use waitTillDone = true to have load fire at end or false to fire on first frame
        onerror        : null,       // fires on error
        onprogress     : null,       // fires a load progress event
        onloadall      : null,       // event fires when all frames have loaded and gif is ready
        paused         : false,      // true if paused
        playing        : false,      // true if playing
        waitTillDone   : true,       // If true onload will fire when all frames loaded, if false, onload will fire when first frame has loaded
        loading        : false,      // true if still loading
        firstFrameOnly : false,      // if true only load the first frame
        width          : null,       // width in pixels
        height         : null,       // height in pixels
        frames         : [],         // array of frames
        comment        : "",         // comments if found in file. Note I remember that some gifs have comments per frame if so this will be all comment concatenated
        length         : 0,          // gif length in ms (1/1000 second)
        currentFrame   : 0,          // current frame. 
        frameCount     : 0,          // number of frames
        playSpeed      : 1,          // play speed 1 normal, 2 twice 0.5 half, -1 reverse etc...
        lastFrame      : null,       // temp hold last frame loaded so you can display the gif as it loads
        image          : null,       // the current image at the currentFrame
        playOnLoad     : true,       // if true starts playback when loaded
        // functions
        load           : loadGif,    // call this to load a file
        cancel         : cancelLoad, // call to stop loading
        play           : play,       // call to start play
        pause          : pause,      // call to pause
        seek           : seek,       // call to seek to time
        seekFrame      : seekFrame,  // call to seek to frame
        togglePlay     : togglePlay, // call to toggle play and pause state
    };
    return gif;
}
















/*=========================================================================
End of gif reader

*/

const mouse = {
  bounds: null,
  x: 0,
  y: 0,
  button: false
};

function mouseEvents(e) {
  const m = mouse;
  m.bounds = canvas.getBoundingClientRect();
  m.x = e.pageX - m.bounds.left - scrollX;
  m.y = e.pageY - m.bounds.top - scrollY;
  mouse.x = e.pageX;

  m.button = e.type === "mousedown" ? true : e.type === "mouseup" ? false : m.button;
}
["down", "up", "move"].forEach(name => document.addEventListener("mouse" + name, mouseEvents));
canvas {
  position: absolute;
  top: 0px;
  left: 0px;
}
<canvas id="canvas"></canvas>

NOTES

  • This works for 99% of gifs. Occasionally you will find a gif that does not play correctly. Reason: (I never bothered to find out). Fix: re-encode gif using modern encoder.

  • There are some minor inconsistencies that need fixing. In time I will provide a codePen example with ES6 and improved interface. Stay tuned.

like image 159
Blindman67 Avatar answered Oct 26 '22 22:10

Blindman67


Here ya go: You will need to exctract each frames and make an array out of them split frames: http://gifgifs.com/split/

easier if you have urls or path like http://lol.com/Img1.png ...... http://lol.com/Img27.png with which you can do a simple loop like this:

var Img = [];
for (var i = 0; i < 28; i++) {
  Img[i] = new Image();
  Img[i].src = "http://lol.com/Img"+i+".png";
}

function drawAnimatedImage(arr,x,y,angle,factor,changespeed) {
    if (!factor) {
        factor = 1;
    }
    if (!changespeed) {
        changespeed = 1;
    }
    ctx.save();
    ctx.translate(x, y);
    ctx.rotate(angle * Math.PI / 180);
    if (!!arr[Math.round(Date.now()/changespeed) % arr.length]) {
    ctx.drawImage(arr[Math.round(Date.now()/changespeed) % arr.length], -(arr[Math.round(Date.now()/changespeed) % arr.length].width * factor / 2), -(arr[Math.round(Date.now()/changespeed) % arr.length].height * factor / 2), arr[Math.round(Date.now()/changespeed) % arr.length].width * factor, arr[Math.round(Date.now()/changespeed) % arr.length].height * factor);
    }
    ctx.restore();
}

    var canvas = document.getElementById("myCanvas");
    var ctx = canvas.getContext('2d');
    var waitingWolf = [];
    var url = ["https://i.imgur.com/k3T7psX.gif","https://i.imgur.com/CTSC8FC.gif","https://i.imgur.com/6NHLWKK.gif","https://i.imgur.com/U1u04sY.gif","https://i.imgur.com/4695vnQ.gif","https://i.imgur.com/oDO0YWT.gif","https://i.imgur.com/LqptRh1.gif","https://i.imgur.com/6gTxvul.gif","https://i.imgur.com/ULN5mqK.gif","https://i.imgur.com/RACB9WM.gif","https://i.imgur.com/4TZ6kNi.gif","https://i.imgur.com/9VvlzhK.gif","https://i.imgur.com/nGUnsfW.gif","https://i.imgur.com/2h8vLjK.gif","https://i.imgur.com/ZCdKkF1.gif","https://i.imgur.com/wZmWrYP.gif","https://i.imgur.com/4lhjVSz.gif","https://i.imgur.com/wVO0PbE.gif","https://i.imgur.com/cgGn5tV.gif","https://i.imgur.com/627gH5Y.gif","https://i.imgur.com/sLDSeS7.gif","https://i.imgur.com/1i1QNAs.gif","https://i.imgur.com/V3vDA1A.gif","https://i.imgur.com/Od2psNo.gif","https://i.imgur.com/WKDXFdh.gif","https://i.imgur.com/RlhIjaM.gif","https://i.imgur.com/293hMnm.gif","https://i.imgur.com/ITm0ukT.gif"]
    function setup () {
                for (var i = 0; i < 28; i++) {
                    waitingWolf[i] = new Image();
                    waitingWolf[i].src = url[i];
                }
    }
    setup();
function yop() {
  ctx.clearRect(0,0,1000,1000)
            if (waitingWolf.length == 28) {
                drawAnimatedImage(waitingWolf,300,100,0,1,60)
            }
requestAnimationFrame(yop);
}
requestAnimationFrame(yop);
<canvas id="myCanvas" width="1000" height="1000">
</canvas>
like image 28
Woold Avatar answered Oct 26 '22 23:10

Woold