Javascript html5画布在滑块移动时绘制曲线
嗨，我想在移动滑块时绘制一条曲线。我有两种曲线。贝塞尔曲线和二次曲线。同样，当我绘制曲线时，我想在同一路径上移动一个对象。我希望它是动态的，所以如果我应该能够改变曲线点。 所以我需要一个函数，我可以调用滑块的变化，因为我做的直线。 这是我的密码。此代码仅在chrome中有效Javascript html5画布在滑块移动时绘制曲线,javascript,html5-canvas,Javascript,Html5 Canvas,嗨，我想在移动滑块时绘制一条曲线。我有两种曲线。贝塞尔曲线和二次曲线。同样，当我绘制曲线时，我想在同一路径上移动一个对象。我希望它是动态的，所以如果我应该能够改变曲线点。 所以我需要一个函数，我可以调用滑块的变化，因为我做的直线。 这是我的密码。此代码仅在chrome中有效 <!DOCTYPE HTML> <html> <head> <
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style type="text/css">
.wrapper {
margin: 0 auto;
width: 1000px;
}
.canHdr {
float: left;
width: 450px;
height: 400px;
border: 1px solid red;
}
</style>
</head>
<body>
<form>
<!-- wrapper -->
<div class="wrapper">
<!-- canHdr -->
<div id="canHdr" class="canHdr" >
<p>
This is my 1st div with quadratic curve I want to draw this curve as I move the slider. I want to make it dynamic so when I should be able to change the curve points. Also I want to move an object on that curve as I am doing in my 3rd div.
</p>
<div class="canOuterHdr" >
<canvas id="myCanvas1" width="300" height="195" style="position: relative;">
[No canvas support]
</canvas>
</div>
<div id="slider1" class="newBg">
<input id="slide1" type="range" min="0" max="100" step="1" value="0" onchange="counterSlider('slide1');" />
</div>
</div>
<!--/ canHdr -->
<!-- canHdr2 -->
<div id="canHdr2" class="canHdr" >
<p>
This is my 2nd div. I have bezier curve. I want to make it dynamic so when I should be able to change the curve points. Also I want to move an object on that curve as I am doing in my 3rd div.
</p>
<div class="canOuterHdr" >
<canvas id="myCanvas2" width="300" height="195" style="position: relative;">
[No canvas support]
</canvas>
</div>
<div id="slider2" class="newBg">
<input id="slide2" type="range" min="0" max="100" step="1" value="0" onchange="counterSlider('slide2');" />
</div>
</div>
<!-- canHdr2 -->
<!-- canHdr3 -->
<div id="canHdr3" class="canHdr" >
<p>
This is my 3rd div with slanting line. I want to move a ball on this line when I move the slider. So as the line increases ball will also move on the line.
</p>
<div class="canOuterHdr" >
<canvas id="myCanvas3" width="300" height="195" style="position: relative;">
[No canvas support]
</canvas>
</div>
<div id="slider3" class="newBg">
<input id="slide3" type="range" min="0" max="100" step="1" value="0" onchange=" drawSlopeCurve2('slide3','100'); " />
</div>
</div>
<!--/ canHdr3 -->
<!-- canHdr4 -->
<div id="canHdr4" class="canHdr" >
<p>
This is my 4th div with slanting line. I want to move a ball on this line when I move the slider. So as the line increases ball will also move on the line.
</p>
<div class="canOuterHdr" >
<canvas id="myCanvas4" width="300" height="195" style="position: relative;">
[No canvas support]
</canvas>
</div>
<div id="slider4" class="newBg">
<input id="slide4" type="range" min="0" max="100" step="1" value="0" onchange=" drawSlopeCurve1('slide4','100'); " />
</div>
</div>
<!--/ canHdr4 -->
</div>
<!-- /wrapper -->
<script type="text/javascript">
newSprite('myCanvas3', 16, 170);
quadraticCurve('myCanvas1', 18.8, 45, 28, 160, 228, 165);
bezierCurve('myCanvas2', 20, 75, 55.2, 150.0, 200,100, 228, 165)
function counterSlider(sID) {
var slideVal = document.getElementById(sID).value;
/*if (maxValue ==100){
slideVal=slideVal/100;
}*/
slideVal = slideVal / 100;
if (slideVal == 0) {
/* erase('myCanvas2');
erase('myCanvas3');
erase('myCanvas4');*/
//newSprite('myCanvas1b', 18.8, 45);
newSprite('myCanvas3', 16, 170);
} else if (slideVal > 0 && slideVal <= 34) {
/*erase('myCanvas1');
//erase('myCanvas1b');
erase('myCanvas2');
erase('myCanvas3');
erase('myCanvas4');*/
} else if (slideVal > 34 && slideVal <= 67) {
/*erase('myCanvas1');
erase('myCanvas2');
erase('myCanvas3');
erase('myCanvas4');*/
} else if (slideVal > 67 && slideVal <= 100) {
/*erase('myCanvas1');
erase('myCanvas2');
erase('myCanvas3');
erase('myCanvas4');*/
}
}
function erase(canvasId) {
var canvas = document.getElementById(canvasId);
var context = canvas.getContext("2d");
context.beginPath();
context.clearRect(0, 0, canvas.width, canvas.height);
canvas.width = canvas.width;
}
/**********for backgroundImage********************/
function quadraticCurve(canId, spx, spy, cpx, cpy, endx, endy) {
var canvas = document.getElementById(canId);
var ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.moveTo(spx, spy);
ctx.quadraticCurveTo(cpx, cpy, endx, endy);
ctx.strokeStyle = "#eaca2d";
ctx.stroke();
}
function bezierCurve(canId, spx, spy, cpx1, cpy1, cpx2, cpy2, endx, endy) {
var canvas = document.getElementById(canId);
var ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.moveTo(spx, spy);
ctx.quadraticCurveTo(cpx1, cpy1, cpx2, cpy2, endx, endy);
ctx.strokeStyle = "#eaca2d";
ctx.stroke();
}
function newSprite(canId, mvx, mvy) {
var canvas = document.getElementById(canId);
var ctx = canvas.getContext('2d');
ctx.globalCompositeOperation = 'source-over';
//ctx.globalCompositeOperation = "destination-over";
ctx.beginPath();
ctx.fillStyle = "#0077c1";
ctx.arc(mvx, mvy, 6, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fill();
}
function drawSlopeCurve1(sID, maxValue) {
// erase('canvasTwo');
var canId = 'myCanvas4';
var slideVal = parseInt(document.getElementById(sID).value);
var canvas = document.getElementById(canId);
var context = canvas.getContext('2d');
canvas.width = canvas.width;
//line end points
x1 = 16;
y1 = 170;
x2 = 200;
y2 = 80;
//get slope (rise over run)
var m = (y2 - y1) / (x2 - x1);
//get y-intercept
var b = y1 - (m * x1);
//get distance between the two points
var distance = Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
//get new x and y values
var x = x1 + parseInt(distance / maxValue * slideVal);
var y = parseInt(m * x + b);
context.beginPath();
context.moveTo(x1, y1);
context.lineTo(x, y);
context.lineWidth = 0.6;
context.stroke();
newSprite(canId, x, y);
}
function drawSlopeCurve2(sID, maxValue) {
// erase('canvasTwo');
var canId = 'myCanvas3';
var slideVal = parseInt(document.getElementById(sID).value);
var canvas = document.getElementById(canId);
var context = canvas.getContext('2d');
canvas.width = canvas.width;
//line end points
x1 = 16;
y1 = 170;
x2 = 160;
y2 = 72;
//get slope (rise over run)
var m = (y2 - y1) / (x2 - x1);
//get y-intercept
var b = y1 - (m * x1);
//get distance between the two points
var distance = Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
//get new x and y values
var x = x1 + parseInt(distance / maxValue * slideVal);
var y = parseInt(m * x + b);
context.beginPath();
context.moveTo(x1, y1);
context.lineTo(x, y);
context.lineWidth = 0.6;
context.stroke();
newSprite(canId, x, y);
}
</script>
</form>
</body>
</html>
.包装纸{
保证金：0自动；
宽度：1000px；
}
canHdr先生{
浮动：左；
宽度：450px；
高度：400px；
边框：1px纯红；
}
这是我的第一个二次曲线div，我想在移动滑块时绘制这条曲线。我想让它动态，所以当我应该能够改变曲线点。我还想在曲线上移动一个对象，就像我在第三个div中所做的那样。
[无画布支持]
这是我的第二部。我有贝塞尔曲线。我想让它动态，所以当我应该能够改变曲线点。我还想在曲线上移动一个对象，就像我在第三个div中所做的那样。
[无画布支持]
这是我的第三个斜线div。当我移动滑块时，我想在这条线上移动一个球。所以随着线的增加，球也会在线上移动。
[无画布支持]
这是我的第四个斜线。当我移动滑块时，我想在这条线上移动一个球。所以随着线的增加，球也会在线上移动。
[无画布支持]
newSprite（'myCanvas3'，16170）；
二次曲线（'myCanvas1'，18.8,45,28,160,228,165）；
贝塞尔曲线（'myCanvas2'，20,75,55.2150.012001228165）
功能计数器（sID）{
var slideVal=document.getElementById（sID）.value；
/*如果（最大值==100）{
slideVal=slideVal/100；
}*/
slideVal=slideVal/100；
如果（slideVal==0）{
/*擦除（“myCanvas2”）；
擦除（“myCanvas3”）；
擦除（“myCanvas4”）*/
//newSprite（'myCanvas1b'，18.8,45）；
newSprite（'myCanvas3'，16170）；
}否则，如果（slideVal>0&&slideVal 34&&slideVal 67&&slideVal您应该从在函数中定义曲线开始，这样您就可以计算每个x位置的图形应该结束的位置。然后您还知道在哪里绘制结束点
我的演示函数具有在画布上绘制正弦的功能：
function calc(x){
var y = 100 + ( 50*Math.sin(x*400));
return y;
}
通过在点之间画一条线（而不是曲线！）可以得到图形
for (var x=0; x<=400 && (x <= slider.value); x+=3){
y= calc(x);
ctx.lineTo(x, y);
}
用于（var x=0；x您尝试过什么？您已经有了绘制曲线的代码，所以只要在滑块更改时更改值，您就已经编写了滑块值更改的处理程序。非常感谢您的帮助。我已经获得了绘制曲线的代码。但是绘制曲线没有您的代码平滑。有人可以帮助使其平滑工作吗ly？我还想在同一条曲线上移动一个对象。最后一个问题是如何在bezier曲线中实现这一点。我正在工作的js fiddle链接：您的代码有多条路径（如果/否则有点集），但这并不会使它变得更简单！用y这样的等式定义您的直线