畫布圖像無法顯示全部並被剪切只能顯示圖像的一部分

Question

我得到了顯示的圖像，但只能顯示圖像的一部分。我想知道是否有任何方法來顯示整個圖像！

var canvas=document.getElementById("Mat_canvas"); 
canvas.addEventListener('keydown',doKeyDown,true); 
var canvt=canvas.getContext("2d"); 
var img_obj=new Image(); 
img_obj.onload=function(){ 
    //canvt.align='center'; 
    canvt.drawImage(img_obj,0,0); 
}; 

Answer 1

你可以調整你的畫布圖像的onload回調：

var canvas=document.getElementById("Mat_canvas"); 
canvas.addEventListener('keydown',doKeyDown,true); 
var canvt=canvas.getContext("2d"); 
var img_obj=new Image(); 
img_obj.onload=function(){ 
    //canvt.align='center'; 

    // resize the canvas to the same size as the source image 
    canvas.width=img_obj.width; 
    canvas.height=img_obj.height; 

    canvt.drawImage(img_obj,0,0); 
};