Canvas framework

應用

hoyo 自己的應用

需求為從主機載入一張圖之後，可以增加箭頭、文字、方框等基本的繪圖需求，編輯完成按儲存後要直接回存。

技術：HTML5 Canvas

使用工具：Fabric.js

參考

Add Delete button on element in Canvas Fabric JS

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title></title>
    <script src="../js/jquery-2.2.4.min.js"></script>
    <script src="../js/fabric.min.js"></script>
</head>
<body>

<canvas id="c" style="border: 1px solid #999;"></canvas>

<button onclick="addText()">增加文字</button>
<button onclick="addBlock()">增加方框</button>
<button onclick="addLine2()">增加箭頭</button>
<button onclick="saveImage()">儲存</button>

<script>
    var canvas = new fabric.Canvas('c');

    var HideControls = {
        'tl':true,
        'tr':false,
        'bl':true,
        'br':true,
        'ml':true,
        'mt':true,
        'mr':true,
        'mb':true,
        'mtr':true
    };

    var image = new Image();
    image.src = 'normal_3206.png';
    image.onload = function() {

        // create a wrapper around native canvas element (with id="c")
        canvas.setHeight(image.width).setWidth(image.height);

        canvas.setBackgroundImage('normal_3206.png', canvas.renderAll.bind(canvas), {
            width: canvas.width,
            height: canvas.height,
            // Needed to position backgroundImage at 0/0
            originX: 'left',
            originY: 'top'
        });
    };

    canvas.renderAll();

    function addDeleteBtn(x, y){
        $(".deleteBtn").remove();
        var btnLeft = x-10;
        var btnTop = y-10;
        var deleteBtn = '<img src="../images/delete-icon.png" class="deleteBtn" style="position:absolute;top:'+btnTop+'px;left:'+btnLeft+'px;cursor:pointer;width:20px;height:20px;"/>';
        $(".canvas-container").append(deleteBtn);
    }

    canvas.on('object:selected',function(e){
        addDeleteBtn(e.target.oCoords.tr.x, e.target.oCoords.tr.y);
    });

    canvas.on('mouse:down',function(e){
        if(!canvas.getActiveObject())
        {
            $(".deleteBtn").remove();
        }
    });

    canvas.on('object:modified',function(e){
        addDeleteBtn(e.target.oCoords.tr.x, e.target.oCoords.tr.y);
    });

    canvas.on('object:scaling',function(e){
        $(".deleteBtn").remove();
    });
    canvas.on('object:moving',function(e){
        $(".deleteBtn").remove();
    });
    canvas.on('object:rotating',function(e){
        $(".deleteBtn").remove();
    });
    $(document).on('click',".deleteBtn",function(){
        if(canvas.getActiveObject())
        {
            canvas.remove(canvas.getActiveObject());
            $(".deleteBtn").remove();
        }
    });

    // ----------------------------------------

    function addBlock(){
        var rect = new fabric.Rect({
            stroke: 'rgb(255,0,0)',
            strokeWidth: 3,
            width: 100, height: 40,
            fill: false, left: 50, top: 50
        }).setControlsVisibility(HideControls);

        canvas.add(rect);
    }

    function addText() {
        var t = new fabric.IText('Tap and Type', {
            fontFamily: 'arial black',
            left: 100,
            top: 100
        });

        var textWithBackground = new fabric.IText('輸入文字', {
            left: 50,
            top: 50,
            textBackgroundColor: 'rgb(255,255,255)'
        }).setControlsVisibility(HideControls);
        canvas.add(textWithBackground);
    }

    function addLine2(){
        var path = new fabric.Path('M512 246.16H36.504l86.98-87.43v-27.895L0 254.943v2.115l123.474 124.107h.01V353.26l-86.98-87.42H512z', {
                    stroke: 'rgb(255,255,255)',
                    strokeWidth: 8,
                    fill: 'rgb(255,0,0)'
                }
        ).scaleToWidth(100).setControlsVisibility(HideControls);

        canvas.add(path);
    }

    // 送出處理後圖像給 PHP
    function saveImage() {
        request = new XMLHttpRequest();
        request.open('POST', 'c1.php', true);

        var $Json = {};
        $Json['image'] = canvas.toDataURL();
        $Json['id'] = 'aa111';
        request.send( JSON.stringify($Json) );
    }

</script>
</body>
</html>

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<!DOCTYPE html>

<html>

<head>

</head>

<body>

var canvas = new fabric.Canvas('c');

var HideControls = {

'tl':true,

'tr':false,

'bl':true,

'br':true,

'ml':true,

'mt':true,

'mr':true,

'mb':true,

'mtr':true

};

var image = new Image();

image.src = 'normal_3206.png';

image.onload = function() {

// create a wrapper around native canvas element (with id="c")

canvas.setHeight(image.width).setWidth(image.height);

canvas.setBackgroundImage('normal_3206.png', canvas.renderAll.bind(canvas), {

width: canvas.width,

height: canvas.height,

// Needed to position backgroundImage at 0/0

originX: 'left',

originY: 'top'

});

};

canvas.renderAll();

function addDeleteBtn(x, y){

$(".deleteBtn").remove();

var btnLeft = x-10;

var btnTop = y-10;

var deleteBtn = '<img src="../images/delete-icon.png" class="deleteBtn" style="position:absolute;top:'+btnTop+'px;left:'+btnLeft+'px;cursor:pointer;width:20px;height:20px;"/>';

$(".canvas-container").append(deleteBtn);

}

canvas.on('object:selected',function(e){

addDeleteBtn(e.target.oCoords.tr.x, e.target.oCoords.tr.y);

});

canvas.on('mouse:down',function(e){

if(!canvas.getActiveObject())

{

$(".deleteBtn").remove();

}

});

canvas.on('object:modified',function(e){

addDeleteBtn(e.target.oCoords.tr.x, e.target.oCoords.tr.y);

});

canvas.on('object:scaling',function(e){

$(".deleteBtn").remove();

});

canvas.on('object:moving',function(e){

$(".deleteBtn").remove();

});

canvas.on('object:rotating',function(e){

$(".deleteBtn").remove();

});

$(document).on('click',".deleteBtn",function(){

if(canvas.getActiveObject())

{

canvas.remove(canvas.getActiveObject());

$(".deleteBtn").remove();

}

});

// ----------------------------------------

function addBlock(){

var rect = new fabric.Rect({

stroke: 'rgb(255,0,0)',

strokeWidth: 3,

width: 100, height: 40,

fill: false, left: 50, top: 50

}).setControlsVisibility(HideControls);

canvas.add(rect);

}

function addText() {

var t = new fabric.IText('Tap and Type', {

fontFamily: 'arial black',

left: 100,

top: 100

});

var textWithBackground = new fabric.IText('輸入文字', {

left: 50,

top: 50,

textBackgroundColor: 'rgb(255,255,255)'

}).setControlsVisibility(HideControls);

canvas.add(textWithBackground);

}

function addLine2(){

var path = new fabric.Path('M512 246.16H36.504l86.98-87.43v-27.895L0 254.943v2.115l123.474 124.107h.01V353.26l-86.98-87.42H512z', {

stroke: 'rgb(255,255,255)',

strokeWidth: 8,

fill: 'rgb(255,0,0)'

}

).scaleToWidth(100).setControlsVisibility(HideControls);

canvas.add(path);

}

// 送出處理後圖像給 PHP

function saveImage() {

request = new XMLHttpRequest();

request.open('POST', 'c1.php', true);

var $Json = {};

$Json['image'] = canvas.toDataURL();

$Json['id'] = 'aa111';

request.send( JSON.stringify($Json) );

}

</script>

</body>

</html>

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hoyo 自己的應用

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