我有这个滑动益智游戏的代码。 当我使用恰好 500x500 像素的图像时，一切正常，但是当我插入大图像时，只有图像的左上角可见，并且只有这部分被分成 16 个拼图部分。如何使整个图像适合 Canvas ？
<!DOCTYPE html>
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta charset="utf-8">
<style>
.picture {
border: 1px solid black;
}
</style>
</head>
<body>
<div id="title">
<h2>Sliding Puzzle</h2>
</div>
<div id="slider">
<form>
<label>Easy</label>
<input type="range" id="scale" value="4" min="3" max="5" step="1">
<label>Hard</label>
</form>
<br>
</div>
<div id="main" class="main">
<canvas id="puzzle" width="500px" height="500px"></canvas>
</div>
<script>
var context = document.getElementById('puzzle').getContext('2d');
var img = new Image();
img.src = 'http://www.antilimit.com/nature/i/37.jpg';
img.addEventListener('load', drawTiles, false);
var boardSize = document.getElementById('puzzle').width;
var tileCount = 4
var tileSize = boardSize / tileCount;
var clickLoc = new Object;
clickLoc.x = 0;
clickLoc.y = 0;
var emptyLoc = new Object;
emptyLoc.x = 0;
emptyLoc.y = 0;
var solved = false;
var boardParts;
setBoard();
document.getElementById('scale').onchange = function() {
tileCount = this.value;
tileSize = boardSize / tileCount;
setBoard();
drawTiles();
};
document.getElementById('puzzle').onclick = function(e) {
clickLoc.x = Math.floor((e.pageX - this.offsetLeft) / tileSize);
clickLoc.y = Math.floor((e.pageY - this.offsetTop) / tileSize);
if (distance(clickLoc.x, clickLoc.y, emptyLoc.x, emptyLoc.y) == 1) {
slideTile(emptyLoc, clickLoc);
drawTiles();
}
if (solved) {
setTimeout(function() {alert("You solved it!");}, 500);
}
};
function setBoard() {
boardParts = new Array(tileCount);
for (var i = 0; i < tileCount; ++i) {
boardParts[i] = new Array(tileCount);
for (var j = 0; j < tileCount; ++j) {
boardParts[i][j] = new Object;
boardParts[i][j].x = (tileCount - 1) - i;
boardParts[i][j].y = (tileCount - 1) - j;
}
}
emptyLoc.x = boardParts[tileCount - 1][tileCount - 1].x;
emptyLoc.y = boardParts[tileCount - 1][tileCount - 1].y;
solved = false;
}
function drawTiles() {
context.clearRect ( 0 , 0 , boardSize , boardSize );
for (var i = 0; i < tileCount; ++i) {
for (var j = 0; j < tileCount; ++j) {
var x = boardParts[i][j].x;
var y = boardParts[i][j].y;
if(i != emptyLoc.x || j != emptyLoc.y || solved == true) {
context.drawImage(img, x * tileSize, y * tileSize, tileSize, tileSize,
i * tileSize, j * tileSize, tileSize, tileSize);
}
}
}
}
function distance(x1, y1, x2, y2) {
return Math.abs(x1 - x2) + Math.abs(y1 - y2);
}
function slideTile(toLoc, fromLoc) {
if (!solved) {
boardParts[toLoc.x][toLoc.y].x = boardParts[fromLoc.x][fromLoc.y].x;
boardParts[toLoc.x][toLoc.y].y = boardParts[fromLoc.x][fromLoc.y].y;
boardParts[fromLoc.x][fromLoc.y].x = tileCount - 1;
boardParts[fromLoc.x][fromLoc.y].y = tileCount - 1;
toLoc.x = fromLoc.x;
toLoc.y = fromLoc.y;
checkSolved();
}
}
function checkSolved() {
var flag = true;
for (var i = 0; i < tileCount; ++i) {
for (var j = 0; j < tileCount; ++j) {
if (boardParts[i][j].x != i || boardParts[i][j].y != j) {
flag = false;
}
}
}
solved = flag;
}
</script>
</body></html>
最佳答案
您在示例中使用的图像是 1000 像素 x 1000 像素，因此将其分成 16 个图 block 需要将每个图像分成 16 个部分，每个部分的大小为 250 像素 x 250 像素。目前您正在使用 16 个部分，每个部分为 125px x 125px，因此您只复制图像的左上四分之一。
获取宽度为 W 和高度为 H 的矩形图像，然后从左上角开始，您可以获取 imgSize = W if W<=H 或 imgSize = H if H 的正方形图像
你求比例因子imgScale = imgSize/500
在您的示例中 imgSize = 1000 等 imgScale = 2 因此您要复制的部分是图 block 宽度和高度的两倍
将drawTiles函数改为
function drawTiles() {
var imgSize=Math.min(img.width,img.height);
var imgScale=imgSize/500;
context.clearRect ( 0 , 0 , boardSize , boardSize );
for (var i = 0; i < tileCount; ++i) {
for (var j = 0; j < tileCount; ++j) {
var x = boardParts[i][j].x;
var y = boardParts[i][j].y;
if(i != emptyLoc.x || j != emptyLoc.y || solved == true) {
context.drawImage(img, x * tileSize*imgScale, y * tileSize*imgScale, tileSize*imgScale, tileSize*imgScale,
i * tileSize, j * tileSize, tileSize, tileSize);
}
}
}
}
这是一个jsfiddle
关于javascript - 如何使图像完全适合 HTML5 Canvas ？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28543775/