터치 스크린 사용자가 원시 JavaScript를 통해 캔버스 태그에 그림을 그릴 수 있는지 알아보기 위해 조금만 조사했습니다. 지금까지 나는 행운이별로 없으며 상호 작용할 수없는 캔버스를 가지고 다시 광장으로 돌아 가게됩니다. div 안에 캔버스가 있습니다. 이걸 어떻게 성취 할 수 있겠 어? 일부 자습서를 사용해 보았는데 사용자가 캔버스에서 손가락을 움직일 때가 아니라 데스크톱 장치 및 클릭 이벤트에서만 작동하는 것 같습니다.터치 스크린 장치를 사용하여 캔버스에 그리기
<html>
<head>
<title>Sketchpad</title>
<script type="text/javascript">
// Variables for referencing the canvas and 2dcanvas context
var canvas,ctx;
// Variables to keep track of the mouse position and left-button status
var mouseX,mouseY,mouseDown=0;
// Draws a dot at a specific position on the supplied canvas name
// Parameters are: A canvas context, the x position, the y position, the size of the dot
function drawDot(ctx,x,y,size) {
// Let's use black by setting RGB values to 0, and 255 alpha (completely opaque)
r=0; g=0; b=0; a=255;
// Select a fill style
ctx.fillStyle = "rgba("+r+","+g+","+b+","+(a/255)+")";
// Draw a filled circle
ctx.beginPath();
ctx.arc(x, y, size, 0, Math.PI*2, true);
ctx.closePath();
ctx.fill();
}
// Clear the canvas context using the canvas width and height
function clearCanvas(canvas,ctx) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
// Keep track of the mouse button being pressed and draw a dot at current location
function sketchpad_mouseDown() {
mouseDown=1;
drawDot(ctx,mouseX,mouseY,12);
}
// Keep track of the mouse button being released
function sketchpad_mouseUp() {
mouseDown=0;
}
// Keep track of the mouse position and draw a dot if mouse button is currently pressed
function sketchpad_mouseMove(e) {
// Update the mouse co-ordinates when moved
getMousePos(e);
// Draw a dot if the mouse button is currently being pressed
if (mouseDown==1) {
drawDot(ctx,mouseX,mouseY,12);
}
}
// Get the current mouse position relative to the top-left of the canvas
function getMousePos(e) {
if (!e)
var e = event;
if (e.offsetX) {
mouseX = e.offsetX;
mouseY = e.offsetY;
}
else if (e.layerX) {
mouseX = e.layerX;
mouseY = e.layerY;
}
}
// Set-up the canvas and add our event handlers after the page has loaded
function init() {
// Get the specific canvas element from the HTML document
canvas = document.getElementById('sketchpad');
// If the browser supports the canvas tag, get the 2d drawing context for this canvas
if (canvas.getContext)
ctx = canvas.getContext('2d');
// Check that we have a valid context to draw on/with before adding event handlers
if (ctx) {
canvas.addEventListener('mousedown', sketchpad_mouseDown, false);
canvas.addEventListener('mousemove', sketchpad_mouseMove, false);
window.addEventListener('mouseup', sketchpad_mouseUp, false);
}
}
</script>
<style>
/* Some CSS styling */
#sketchpadapp {
/* Prevent nearby text being highlighted when accidentally dragging mouse outside confines of the canvas */
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
#sketchpad {
float:left;
border:2px solid #888;
border-radius:4px;
position:relative; /* Necessary for correct mouse co-ords in Firefox */
}
</style>
</head>
<body onload="init()">
<div id="sketchpadapp">
<div class="leftside1">
<input type="submit" value="Clear Sketchpad" onclick="clearCanvas(canvas,ctx);">
</div>
<div class="rightside">
<canvas id="sketchpad" height="300" width="400">
</canvas>
</div>
</div>
</body>
</html>
중대 그! 처음에는 터치 스크린에서도 제대로 작동하지 않았지만 EventListeners를 touchmove로 교체했습니다. 트릭을 완료 한 것으로 보입니다. 나는 어쨌든 그걸 가지고 놀기를 계속 할 것입니다. 고맙습니다. – userrandomuser