Canvas学习，用Canvas画五子棋并进行简单判断输赢

Love The Way You Lie 2022-10-07 09:00 159阅读 0赞

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<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>五子棋</title>
        <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0, user-scalable=0">
        <style>
            #myCanvas {
                background-color: oldlace;
                box-shadow: 0 0 5px 0px rgba(0, 0, 0, .8);
                border-radius: 5px;
            }
        </style>
    </head>
    <body>
    <canvas id="myCanvas" width="470" height="470"></canvas>
    
    <div></div>
    <button onclick="backChess()">回退</button>
    <button onclick="resetChess(100)">恢复棋局</button>
    </body>
    
    <script>
        var canvas = document.querySelector('#myCanvas')
        var context = canvas.getContext('2d')
    
        let stepArr = [],
            gap = 30,
            edgeGap = 25,
            // 记录棋盘上所有标记数字
            boardArr = [],
            // 一个小方格的斜边一半大小，用来判断棋子放置的位置
            chessRadius = Math.sqrt(Math.pow(gap, 2) + Math.pow(gap, 2)) / 2,
            // 棋子的半径大小
            chessSize = 13
    
        // let stepStorage = window.localStorage.getItem('step')
        // if(stepStorage){
        //     stepArr = JSON.parse(stepStorage)
        // }
    
        /**
         * 窗口坐标转换为Canvas坐标
         * @param canvas
         * @param x 窗口坐标x
         * @param y 容器坐标y
         * @return {
       {x: number, y: number}}
         */
        function windowToCanvas(canvas, x, y) {
            var bbox = canvas.getBoundingClientRect()
            return {
                x: (x - bbox.left) * canvas.width / bbox.width,
                y: (y - bbox.top) * canvas.width / bbox.width
            }
        }
    
        /**
         * 根据数字标记转换成坐标值
         */
        function cor2xy(ij) {
            let arr = ij.split('-')
            return {
                x: arr[0] * gap + edgeGap,
                y: arr[1] * gap + edgeGap
            }
        }
    
        /**
         * 画棋盘上的线
         */
        function drawLine() {
            context.strokeStyle = '#333'
            context.strokeWidth = 1
            for (let i = 0; i < 15; i++) {
                let x1 = edgeGap + i * gap,
                    y1 = edgeGap,
                    x2 = x1,
                    y2 = edgeGap + gap * 14
                context.moveTo(x1 + 0.5, y1)
                context.lineTo(x2 + 0.5, y2)
            }
            for (let i = 0; i < 15; i++) {
                let x1 = edgeGap,
                    y1 = edgeGap + i * gap,
                    x2 = edgeGap + gap * 14,
                    y2 = y1
                context.moveTo(x1 + 0.5, y1)
                context.lineTo(x2 + 0.5, y2)
            }
            for (let i = 0; i < 15; i++) {
                let x = edgeGap + i * gap
                let lineArr = []
                for (let j = 0; j < 15; j++) {
                    let y = edgeGap + j * gap
                    boardArr.push(`${i}-${j}`)
                }
            }
            context.stroke()
        }
    
        /**
         * 画中心点
         */
        function drawCenter() {
            context.beginPath()
    
            let x = edgeGap + 7 * gap,
                y = edgeGap + 7 * gap
    
            context.arc(x, y, 5, 0, 2 * Math.PI)
            context.fillStyle = '#333'
            context.fill()
        }
    
        /**
         * 画棋子
         */
        function drawChess(x, y, color) {
            if (!color) {
                color = 'black'
            }
            context.save()
            context.beginPath()
            context.shadowOffsetX = 0; // 阴影Y轴偏移
            context.shadowOffsetY = 0; // 阴影X轴偏移
            context.shadowBlur = 2; // 模糊尺寸
            context.shadowColor = 'rgba(0, 0, 0, .5)'; // 颜色
    
            context.fillStyle = color
            console.log(color)
            context.arc(x, y, chessSize, 0, 2 * Math.PI)
            context.fill()
            context.restore()
        }
    
        /**
         * 在交点处画棋子
         */
        function getNearestPos(pos) {
            for (let i = 0; i < boardArr.length; i++) {
                let ijStr = boardArr[i]
                let bPos = cor2xy(ijStr)
                let distance = Math.sqrt(Math.pow(pos.x - bPos.x, 2) + Math.pow(pos.y - bPos.y, 2))
                if (distance <= chessRadius) {
                    if (stepArr.indexOf(ijStr) !== -1) {
                        return;
                    }
                    return {
                        bPos,
                        ijStr
                    }
                }
            }
        }
    
        function checkAllLink(ijStr, x, y, x2, y2) {
            let ijArr = ijStr.split('-')
            // 判断当前棋子的颜色，单数还是双数
            let index = stepArr.indexOf(ijStr) % 2
            // 四个角度判断棋子颜色是否连成5个
            let linkSize = 1
            for (let i = 1; i <= 4; i++) {
                let newijStr = (parseInt(ijArr[0]) + i * x) + '-' + (parseInt(ijArr[1]) + i * y)
                console.log(newijStr, stepArr.indexOf(newijStr))
                if (stepArr.indexOf(newijStr) % 2 !== index) {
                    break;
                }
                linkSize++
            }
            for (let i = 1; i <= 4; i++) {
                let newijStr = (parseInt(ijArr[0]) + i * x2) + '-' + (parseInt(ijArr[1]) + i * y2)
                console.log(newijStr, stepArr.indexOf(newijStr))
                if (stepArr.indexOf(newijStr) % 2 !== index) {
                    break;
                }
                linkSize++
            }
            return linkSize
        }
    
        /**
         * 检查输赢
         */
        function checkWin(ijStr) {
    
            let size = checkAllLink(ijStr, 0, 1, 0, -1)
            if (size >= 5) {
                return true
            }
            size = checkAllLink(ijStr, 1, 0, -1, 0)
            if (size >= 5) {
                return true
            }
            size = checkAllLink(ijStr, 1, -1, -1, 1)
            if (size >= 5) {
                return true
            }
            size = checkAllLink(ijStr, 1, 1, -1, -1)
            if (size >= 5) {
                return true
            }
            return false
        }
    
        /**
         *  初始化棋盘
         */
        function drawBoard() {
            context.beginPath()
            context.fillStyle = '#f3c281'
            context.fillRect(0, 0, canvas.width, canvas.height)
            drawLine()
            drawCenter()
        }
    
        function drawChessCover(pos) {
            drawBoard()
            stepArr.forEach((ijStr, index) => {
                let bPos = cor2xy(ijStr)
                if (index % 2 == 0) {
                    drawChess(bPos.x, bPos.y)
                } else {
                    drawChess(bPos.x, bPos.y, 'white')
                }
            })
            let drawChessTemp = function(x, y, color) {
                context.save()
                context.beginPath()
    
                let fillColor = 'rgba(255,255,255,.5)'
                if (color == 'black') {
                    fillColor = 'rgba(0,0,0,.5)'
                }
    
                context.fillStyle = fillColor
                context.arc(x, y, chessSize, 0, 2 * Math.PI)
                context.fill()
                context.strokeStyle = color
                context.stroke()
                context.restore()
            }
            if (stepArr.length % 2 == 0) {
                drawChessTemp(pos.x, pos.y, 'black')
            } else {
                drawChessTemp(pos.x, pos.y, 'white')
            }
        }
    
        /**
         * 下棋事件
         */
        canvas.addEventListener('click', (e) => {
            let pos = windowToCanvas(canvas, e.clientX, e.clientY)
    
            let res = getNearestPos(pos)
            if (!res) {
                return
            }
            let {bPos, ijStr} = res
            if (stepArr.length % 2 == 0) {
                drawChess(bPos.x, bPos.y)
            } else {
                drawChess(bPos.x, bPos.y, 'white')
            }
            stepArr.push(ijStr)
            // window.localStorage.setItem('step',JSON.stringify(stepArr))
            console.log(stepArr)
            if (checkWin(ijStr)) {
                setTimeout(() => {
                    alert('赢了')
                }, 300)
            }
    
            drawChessCover(pos)
        })
    
        canvas.addEventListener('mousemove', (e) => {
            let pos = windowToCanvas(canvas, e.clientX, e.clientY)
    
            let res = getNearestPos(pos)
            if (!res) {
                return
            }
            let {bPos, ijStr} = res
    
            drawChessCover(bPos)
        })
    
        /**
         * 回退一步棋
         */
        function backChess() {
            drawBoard()
            stepArr.pop()
            console.log(stepArr)
            stepArr.forEach((ijStr, index) => {
                let bPos = cor2xy(ijStr)
                if (index % 2 == 0) {
                    drawChess(bPos.x, bPos.y)
                } else {
                    drawChess(bPos.x, bPos.y, 'white')
                }
            })
        }
    
        /**
         * 恢复棋局`
         */
        function resetChess(timestamp) {
            // 画棋盘
            drawBoard()
    
            // 恢复棋盘
            stepArr.forEach((ijStr, index) => {
                let bPos = cor2xy(ijStr)
                setTimeout(() => {
                    if (index % 2 == 0) {
                        drawChess(bPos.x, bPos.y)
                    } else {
                        drawChess(bPos.x, bPos.y, 'white')
                    }
                }, timestamp * index)
            })
        }
    
        resetChess(100)
    </script>
    </html>

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