【发布时间】：2013-08-04 18:30:57
【问题描述】：
我刚开始学习html5，我正在尝试用可拖动的船只创建一个战舰界面。我需要帮助使我的拖动方法起作用。我故意不使用库，因为我需要使船只可拖动到另一个画布界面（战舰板）上，我不知道如何使用 Kinetic 库。我觉得我很接近，但我无法弄清楚最后一点。船只应该可以顺利拖动，但在单击时它们似乎会捕捉到鼠标的位置......
这是我的代码：
<!doctype html>
<html>
<head>
<meta charset="UTF-8" />
<title>Canvas Drag and Drop Test</title>
</head>
<body>
<section>
<div align=center>
<canvas id="canvas" width="550" height="550">
This text is displayed if your browser does not support HTML5 Canvas.
</canvas>
</div>
<script type="text/javascript">
var canvas;
var ctx;
var x = 75;
var y = 50;
var WIDTH = 550;
var HEIGHT = 550;
var dragok = false;
var ships = [];
var ship;
var shipFill = "#FF0000";
//Definitions
//Draggable Carrier
var caRectX = 100;
var caRectY = 50;
var caRectHeight = 50;
var caRectWidth = 5 * 50;
var carrier = {
x : caRectX,
y : caRectY,
width : caRectWidth,
height : caRectHeight,
fill : shipFill,
dragging : false,
offsetX : 0,
offsetY : 0,
};
ships.push(carrier);
//Draggable Battleship
var bsRectX = 100;
var bsRectY = 150;
var bsRectHeight = 50;
var bsRectWidth = 4 * 50;
var battleship = {
x : bsRectX,
y : bsRectY,
width : bsRectWidth,
height : bsRectHeight,
fill : shipFill,
dragging : false,
offsetX : 0,
offsetY : 0,
};
ships.push(battleship);
//Draggable Patrolboat
var pbRectX = 100;
var pbRectY = 250;
var pbRectHeight = 50;
var pbRectWidth = 2 * 50;
var patrolboat = {
x : pbRectX,
y : pbRectY,
width : pbRectWidth,
height : pbRectHeight,
fill : shipFill,
dragging : false,
offsetX : 0,
offsetY : 0,
};
ships.push(patrolboat);
//Draggable Submarine
var suRectX = 100;
var suRectY = 350;
var suRectHeight = 50;
var suRectWidth = 3 * 50;
var submarine = {
x : suRectX,
y : suRectY,
width : suRectWidth,
height : suRectHeight,
fill : shipFill,
dragging : false,
offsetX : 0,
offsetY : 0,
};
ships.push(submarine);
//Draggable destroyer
var deRectX = 100;
var deRectY = 450;
var deRectHeight = 50;
var deRectWidth = 3 * 50;
var destroyer = {
x : deRectX,
y : deRectY,
width : deRectWidth,
height : deRectHeight,
dragging : false,
fill : shipFill
};
ships.push(destroyer)
function rect(x, y, w, h) {
ctx.beginPath();
ctx.rect(x, y, w, h);
ctx.closePath();
ctx.fill();
}
function clear() {
ctx.clearRect(0, 0, WIDTH, HEIGHT);
}
function init() {
canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d");
return setInterval(draw, 10);
}
function draw() {
clear();
ctx.fillStyle = "#FAF7F8";
rect(0, 0, WIDTH, HEIGHT);
ctx.fillStyle = "#444444";
for (var i = 0; i < ships.length; i++) {
rect(ships[i].x, ships[i].y, ships[i].width, ships[i].height);
}
}
function myMove(e) {
if (ship.dragging) {
ship.x = e.pageX - canvas.offsetLeft;
ship.y = e.pageY - canvas.offsetTop;
draw()
}
}
function myDown(e) {
ship = getClickedShip(e.pageX,e.pageY);
if (ship!=null) {
ship.x = e.pageX - canvas.offsetLeft;
ship.y = e.pageY - canvas.offsetTop;
ship.dragging = true;
canvas.onmousemove = myMove();
}
}
function myUp() {
ship.dragging = false;
canvas.onmousemove = null;
}
function getClickedShip(sx,sy){
for (var i = 0; i < ships.length; i++){
if(sx > (ships[i].x )+ canvas.offsetLeft && sx < (ships[i].x+ships[i].width+ canvas.offsetLeft) && sy > (ships[i].y + canvas.offsetTop) && sy < (ships[i].y+ships[i].height))
return ships[i];
}
}
init();
canvas.onmousedown = myDown;
canvas.onmouseup = myUp;
</script>
</section>
</body>
</html>
【问题讨论】：
标签： javascript html canvas draggable