关于java:小马哥的-Java-项目实战营完结

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<!DOCTYPE html>
<html>
<head>

<meta charset="utf-8">
<title>DEMO6：自定义画板 </title>

</head>
<body>
<canvas id=”canvas” width=”600″ height=”300″>

 浏览器不反对 canvas   <!-- 如果不反对会显示这段文字 -->

</canvas>
<br/>
<button style=”width:80px;background-color:yellow;” onclick=’linecolor=”yellow”;’>YELLOW</button>
<button style=”width:80px ;background-color:red;” onclick=’linecolor=”red”;’>RED</button>
<button style=”width:80px ;background-color:blue;” onclick=’linecolor=”blue”;’>BLUE</button>
<button style=”width:80px ;background-color:green;” onclick=’linecolor=”green”;’>GREEN</button>
<button style=”width:80px ;background-color:white;” onclick=’linecolor=”white”;’>WHITE</button>
<button style=”width:80px ;background-color:black;” onclick=’linecolor=”black”;’>BLACK</button>
<br/>

<button style=”width: 80px;background-color: white;” onclick=”copyimage();”>EXPORT</button>

var canvas = document.getElementById('canvas');  // 获取标签
var ctx = canvas.getContext("2d");  

var fillStyle = "black";
ctx.fillRect(0,0,600,300);
var onoff = false;  // 按下标记
var oldx = -10;
var oldy = -10;
// 设置色彩
var linecolor = "white";
var linw = 4;
canvas.addEventListener("mousemove",draw,true);  // 鼠标挪动事件
canvas.addEventListener("mousedown",down,false);  // 鼠标按下事件
canvas.addEventListener("mouseup",up,false);  // 鼠标弹起事件
function down(event){
    onoff = true;
    oldx = event.pageX - 10;
    oldy = event.pageY - 10;
}
function up(){onoff = false;}
function draw(event){if (onoff==true) {
        var newx = event.pageX - 10;
        var newy = event.pageY - 10
        ctx.beginPath();
        ctx.moveTo(oldx,oldy);
        ctx.lineTo(newx,newy);
        ctx.strokeStyle = linecolor;
        ctx.lineWidth = linw;
        ctx.lineCap = "round";
        ctx.stroke();

        oldx = newx;
        oldy = newy;
    }
}
function copyimage(event)
{var img_png_src = canvas.toDataURL("image/png");  // 将画板保留为图片格式的函数
    document.getElementById("image_png").src = img_png_src;
}
 
</script>

</body>
</html>

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