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| <!DOCTYPE html>
<html lang="fr">
<head>
<meta charset="utf-8" />
<title>Faire varier une droite</title>
<script src="https://code.jquery.com/jquery-3.4.1.min.js"></script>
</head>
<body>
<!-- curseur -->
<form action="input-type-range-min-max.php" method="post">
<input type="range" id="champ1" name="range" value="50" min="-100" max="110" step="5" />
<p>Pente</p>
<input type="range" id="champ3" name="range2" value="0" min="-20" max="20" step="1" />
<p>Décalage parallèle</p>
</form>
<style type="text/css">.canvasgroupe {
position: relative; /* pour servir de référent */
}
#canvasfond {
position: absolute;
top: 0;
left: 0;
}
#canvascourbe1 {
position: relative;
}
</style>
<section class="canvasgroupe">
<canvas id="canvasfond" width="1000" height="400"></canvas>
<canvas id="canvascourbe1" width="1000" height="400"></canvas>
</section>
<script type="text/javascript">
'use strict';
// Constantes
const x1 = 300;
const x2 = 798;
function rectangle(context) {
var canvas = document.getElementById("canvasfond");
var context = canvas.getContext("2d");
context.beginPath();
context.strokeStyle="blue";
context.lineWidth="2";
context.rect(299,0,500,300);
context.fillStyle="yellow";
context.fill();
context.stroke();
}
function drawLine1(y1, y2, context) {
var canvascourbe1 = context.canvas;
context.clearRect(0, 0, canvascourbe1.width, canvascourbe1.height);
context.beginPath();
context.moveTo(x1, y1);
context.lineTo(x2, y2);
context.stroke();
}
// Fonction appelée au chargement de la page
$(function () {
var canvasCourbe1 = document.getElementById('canvascourbe1');
var contextCourbe1 = canvasCourbe1.getContext('2d');
var canvasFond = document.getElementById('canvasfond');
var contextFond = canvasFond.getContext('2d');
// initialisation des contextes : strokeStyle, lineWidth, etc.
contextFond.strokeStyle = 'blue';
contextFond.lineWidth = '2';
contextFond.fillStyle = 'yellow';
contextCourbe1.strokeStyle = 'red';
contextCourbe1.lineCap = 'round';
contextCourbe1.lineWidth = '4';
// variables locales
var a1 = 0;
var y1 = 200;
var y2 = 10;
$('#champ1').after('<output class="y2"></output>');
$('#champ1').on('input', function () {
y2 = $(this).val(); // on omet var ici
$('output.y2').text(y2);
drawLine1(y1, y2, contextCourbe1);
});
$('#champ3').after('<output class="a1"></output>');
$('#champ3').on('input', function () {
a1 = $(this).val(); // on omet var ici
$('output.a1').text(a1);
drawLine1(y1-a1, y2-a1, contextCourbe1);
});
// premier appel
rectangle(contextFond);
drawLine1(y1, y2, contextCourbe1);
});
</script>
</body>
</html> |
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