Показать часть изображения холста в теге <img>

Question

Я могу показать полное содержимое canvas в теге <img> с использованием метода canvas.toDataURL().

Я могу получить часть изображения от canvas с помощью метода getImageData() и нарисовать его в другом холсте с помощью метода putImageData().

Проблема в том, что я хочу показать часть изображения, получая getImageData() в теге <img> как canvas.toDataURL(), но я потерпел неудачу.

То, что я пытался до сих пор:

var canvas = $('canvas')[0]; 
 
var ctx = canvas.getContext("2d"); 
 
    
 
$('#baseImg').load(function() { 
 
    ctx.drawImage(this, 0, 0); 
 
}); 
 

 
$('#full').click(function() { 
 
    $('div').html(''); 
 
    var image = new Image(); 
 
    image.onload = function() { 
 
     $('div').html(this); 
 
    }; 
 
    image.src = canvas.toDataURL(); 
 
}); 
 

 
// here i failed  
 
$('#partail').click(function() { 
 
    $('div').html(''); 
 
    var image = new Image(); 
 
    image.onload = function() { 
 
     $('div').html(this); 
 
    }; 
 
    image.src = ctx.getImageData(10, 10, 50, 50); 
 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
 

 
<h3>Canvas</h3> 
 
<canvas id="canvas" width="100" height="100" style="border: 1px solid #000000;"></canvas> 
 

 
<br/><br/> 
 
<img id="baseImg" style="display: none;" src="data:image/png;base64,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" /> 
 
<input id="full" type="button" value="Show Full Image" /> 
 
<input id="partail" type="button" value="Show Partial Image" /> 
 

 
<h3>Image from canvas</h3> 
 
<div style="border: 1px solid #000000; height: 100px; width: 100px;"></div>

Answer 1

Я решил свою проблему с предложениями всех. Я использовал временный canvas, чтобы удерживать часть основного canvas, а затем получить частичное изображение.

И мое решение:

var canvas = $('canvas')[0]; 
 
var ctx = canvas.getContext("2d"); 
 

 
$('#baseImg').load(function() { 
 
    ctx.drawImage(this, 0, 0); 
 
}); 
 

 
$('#full').click(function() { 
 
    $('div').html(''); 
 
    var image = new Image(); 
 
    image.onload = function() { 
 
     $('div').html(this); 
 
    }; 
 
    image.src = canvas.toDataURL(); 
 
}); 
 

 
$('#partail').click(function() { 
 
    $('div').html(''); 
 

 
    var height = 50, width = 50; 
 
    var copyCanvas = $('<canvas id="canvas" width="' + width + '" height="' + height + '"></canvas>')[0]; 
 
    var copyCtx = copyCanvas.getContext("2d"); 
 
    copyCtx.putImageData(ctx.getImageData(10, 10, width, height), 0, 0); 
 

 
    var image = new Image(); 
 
    image.onload = function() { 
 
     $('div').html(this); 
 
    }; 
 
    image.src = copyCanvas.toDataURL(); 
 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
 

 
<h3>Canvas</h3> 
 
<canvas id="canvas" width="100" height="100" style="border: 1px solid #000000;"></canvas> 
 

 
<br /><br /> 
 
<img id="baseImg" style="display: none;" src="data:image/png;base64,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" /> 
 
<input id="full" type="button" value="Show Full Image" /> 
 
<input id="partail" type="button" value="Show Partial Image" /> 
 

 
<h3>Image from canvas</h3> 
 
<div style="border: 1px solid #000000; height: 100px; width: 100px;"></div>

Answer 2

Вы можете использовать context.drawImage нарисовать частичный Обрезанные прямоугольную часть полного изображения.

версия отсечение DrawImage выглядит следующим образом:

context.drawImage(imageObject, 
    XClipFromSource, YClipFromSource, widthToClipFromSource, heightToClipFromSource, 
    canvasX, canvasY, canvasWidth, canvasHeight 
); 

Вот пример кода и демо:

< < === >>

var canvas=document.getElementById("canvas"); 
 
var ctx=canvas.getContext("2d"); 
 

 
var status=1; 
 
var img=document.getElementById('baseImg'); 
 

 
$('#toggle').on('click',function(){ 
 
    status*=-1; 
 
    draw(); 
 
}); 
 

 
draw(); 
 

 
// 
 
function draw(){ 
 
    if(status==1){ 
 
    canvas.width=img.width; 
 
    canvas.height=img.height; 
 
    ctx.drawImage(img,0,0); 
 
    }else{ 
 
    canvas.width=50; 
 
    canvas.height=50; 
 
    ctx.drawImage(img,10,10,50,50,0,0,50,50); 
 
    } 
 
}

body{ background-color: ivory; } 
 
#canvas{border:1px solid red; margin:0 auto; }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script> 
 
<button id=toggle>Toggle img display</button> 
 
     <br> 
 
     <canvas id="canvas" width=300 height=300></canvas> 
 
     <img id="baseImg" style="display: none;" 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