Egret5.2.2 微信小游戏行的示例排行榜

/**
 * 微信开放数据域
 * 使用 Canvas2DAPI 在 SharedCanvas 渲染一个排行榜，
 * 并在主域中渲染此 SharedCanvas
 */







/**
 * 资源加载组，将所需资源地址以及引用名进行注册
 * 之后可通过assets.引用名方式进行获取
 */
var assets = {
  icon: "openDataContext/assets/icon.png",
  box: "openDataContext/assets/box.png",
  panel: "openDataContext/assets/panel.png",
  button: "openDataContext/assets/button.png",
  title: "openDataContext/assets/rankingtitle.png"
};
/**
 * canvas 大小
 * 这里暂时写死
 * 需要从主域传入
 */
let canvasWidth;
let canvasHeight;

/**
 * 加载资源函数
 * 理论上只需要加载一次，且在点击时才开始加载
 * 最好与canvasWidht和canvasHeight数据的传入之后进行
 */
preloadAssets();

//获取canvas渲染上下文
var context = sharedCanvas.getContext("2d");
context.globalCompositeOperation = "source-over";


/**
 * 所有头像数据
 * 包括姓名，头像图片，得分
 * 排位序号i会根据parge*perPageNum+i+1进行计算
 */
let totalGroup = [
  { key: 1, name: "1111111111", url: assets.icon, scroes: 10000 },
  { key: 2, name: "2222222222", url: assets.icon, scroes: 9000 },
  { key: 3, name: "3333333", url: assets.icon, scroes: 8000 },
  { key: 4, name: "4444444", url: assets.icon, scroes: 7000 },
  { key: 5, name: "55555555", url: assets.icon, scroes: 6000 },
  { key: 6, name: "6666666", url: assets.icon, scroes: 5000 },
  { key: 7, name: "7777777", url: assets.icon, scroes: 4000 },
  { key: 8, name: "8888888", url: assets.icon, scroes: 3000 },
  { key: 9, name: "9999999", url: assets.icon, scroes: 2000 },
  { key: 10, name: "1010101010", url: assets.icon, scroes: 2000 },
  { key: 11, name: "111111111111", url: assets.icon, scroes: 2000 },
  { key: 12, name: "121212121212", url: assets.icon, scroes: 2000 },
  { key: 13, name: "13131313", url: assets.icon, scroes: 2000 },
  { key: 14, name: "1414141414", url: assets.icon, scroes: 2000 },
  { key: 15, name: "1515151515", url: assets.icon, scroes: 2000 },
  { key: 16, name: "1616161616", url: assets.icon, scroes: 2000 },
];

/**
 * 创建排行榜
 */
function drawRankPanel() {
  //绘制背景
  context.drawImage(assets.panel, offsetX_rankToBorder, offsetY_rankToBorder, RankWidth, RankHeight);
  //绘制标题
  let title = assets.title;
  //根据title的宽高计算一下位置;
  let titleX = offsetX_rankToBorder + (RankWidth - title.width) / 2;
  let titleY = offsetY_rankToBorder + title.height + 50;
  context.drawImage(title, titleX, titleY);
  //获取当前要渲染的数据组
  let start = perPageMaxNum * page;
  currentGroup = totalGroup.slice(start, start + perPageMaxNum);
  //创建头像Bar
  drawRankByGroup(currentGroup);
  //创建按钮
  drawButton()
}
/**
 * 根据屏幕大小初始化所有绘制数据
 */
function init() {
  //排行榜绘制数据初始化
  RankWidth = stageWidth * 4 / 5;
  RankHeight = stageHeight * 4 / 5;
  barWidth = RankWidth * 4 / 5;
  barHeight = RankWidth / perPageMaxNum;
  offsetX_rankToBorder = (stageWidth - RankWidth) / 2;
  offsetY_rankToBorder = (stageHeight - RankHeight) / 2;
  preOffsetY = (RankHeight - barHeight) / (perPageMaxNum + 1);

  startX = offsetX_rankToBorder + offsetX_rankToBorder;
  startY = offsetY_rankToBorder + preOffsetY;
  avatarSize = barHeight - 10;
  intervalX = barWidth / 20;
  textOffsetY = (barHeight + fontSize) / 2;
  textMaxSize = 250;
  indexWidth = context.measureText("99").width;

  //按钮绘制数据初始化
  buttonWidth = barWidth / 3;
  buttonHeight = barHeight / 2;
  buttonOffset = RankWidth / 3;
  lastButtonX = offsetX_rankToBorder + buttonOffset - buttonWidth;
  nextButtonX = offsetX_rankToBorder + 2 * buttonOffset;
  nextButtonY = lastButtonY = offsetY_rankToBorder + RankHeight - 50 - buttonHeight;
  let data = wx.getSystemInfoSync();
  canvasWidth = data.windowWidth;
  canvasHeight = data.windowHeight;
}

/**
 * 创建两个点击按钮
 */
function drawButton() {
  context.drawImage(assets.button, nextButtonX, nextButtonY, buttonWidth, buttonHeight);
  context.drawImage(assets.button, lastButtonX, lastButtonY, buttonWidth, buttonHeight);
}


/**
 * 根据当前绘制组绘制排行榜
 */
function drawRankByGroup(currentGroup) {
  for (let i = 0; i < currentGroup.length; i++) {
    let data = currentGroup[i];
    drawByData(data, i);
  }
}

/**
 * 根据绘制信息以及当前i绘制元素
 */
function drawByData(data, i) {
  let x = startX;
  //绘制底框
  context.drawImage(assets.box, startX, startY + i * preOffsetY, barWidth, barHeight);
  x += 10;
  //设置字体
  context.font = fontSize + "px Arial";
  //绘制序号
  context.fillText(data.key + "", x, startY + i * preOffsetY + textOffsetY, textMaxSize);
  x += indexWidth + intervalX;
  //绘制头像
  context.drawImage(data.url, x, startY + i * preOffsetY + (barHeight - avatarSize) / 2, avatarSize, avatarSize);
  x += avatarSize + intervalX;
  //绘制名称
  context.fillText(data.name + "", x, startY + i * preOffsetY + textOffsetY, textMaxSize);
  x += textMaxSize + intervalX;
  //绘制分数
  context.fillText(data.scroes + "", x, startY + i * preOffsetY + textOffsetY, textMaxSize);
}

/**
 * 点击处理
 */
function onTouchEnd(event) {
  let x = event.clientX * sharedCanvas.width / canvasWidth;
  let y = event.clientY * sharedCanvas.height / canvasHeight;
  if (x > lastButtonX && x < lastButtonX + buttonWidth
    && y > lastButtonY && y < lastButtonY + buttonHeight) {
    //在last按钮的范围内
    if (page > 0) {
      buttonClick(0);

    }
  }
  if (x > nextButtonX && x < nextButtonX + buttonWidth
    && y > nextButtonY && y < nextButtonY + buttonHeight) {
    //在next按钮的范围内
    if ((page + 1) * perPageMaxNum < totalGroup.length) {
      buttonClick(1);
    }
  }

}
/**
 * 根据传入的buttonKey 执行点击处理
 * 0 为上一页按钮
 * 1 为下一页按钮
 */
function buttonClick(buttonKey) {
  let old_buttonY;
  if (buttonKey == 0) {
    //上一页按钮
    old_buttonY = lastButtonY;
    lastButtonY += 10;
    page--;
    renderDirty = true;
    console.log(‘上一页‘);
    setTimeout(() => {
      lastButtonY = old_buttonY;
      //重新渲染必须标脏
      renderDirty = true;
    }, 100);
  } else if (buttonKey == 1) {
    //下一页按钮
    old_buttonY = nextButtonY;
    nextButtonY += 10;
    page++;
    renderDirty = true;
    console.log(‘下一页‘);
    setTimeout(() => {
      nextButtonY = old_buttonY;
      //重新渲染必须标脏
      renderDirty = true;
    }, 100);
  }

}

/////////////////////////////////////////////////////////////////// 相关缓存数据

/**********************数据相关***************************/

/**
 * 渲染标脏量
 * 会在被标脏（true）后重新渲染
 */
let renderDirty = true;

/**
 * 当前绘制组
 */
let currentGroup = [];
/**
 * 每页最多显示个数
 * 建议大于等于4个
 */
let perPageMaxNum = 5;
/**
 * 当前页数,默认0为第一页
 */
let page = 0;
/***********************绘制相关*************************/
/**
 * 舞台大小
 */
let stageWidth;
let stageHeight;
/**
 * 排行榜大小
 */
let RankWidth;
let RankHeight;

/**
 * 每个头像条目的大小
 */
let barWidth;
let barHeight;
/**
 * 条目与排行榜边界的水平距离
 */
let offsetX_barToRank
/**
 * 绘制排行榜起始点X
 */
let startX;
/**
 * 绘制排行榜起始点Y
 */
let startY;
/**
 * 每行Y轴间隔offsetY
 */
let preOffsetY;
/**
 * 按钮大小
 */
let buttonWidth;
let buttonHeight;
/**
 * 上一页按钮X坐标
 */
let lastButtonX;
/**
 * 下一页按钮x坐标
 */
let nextButtonX;
/**
 * 上一页按钮y坐标
 */
let lastButtonY;
/**
 * 下一页按钮y坐标
 */
let nextButtonY;
/**
 * 两个按钮的间距
 */
let buttonOffset;

/**
 * 字体大小
 */
let fontSize = 45;
/**
 * 文本文字Y轴偏移量
 * 可以使文本相对于图片大小居中
 */
let textOffsetY;
/**
 * 头像大小
 */
let avatarSize;
/**
 * 名字文本最大宽度，名称会根据
 */
let textMaxSize;
/**
 * 绘制元素之间的间隔量
 */
let intervalX;
/**
 * 排行榜与舞台边界的水平距离
 */
let offsetX_rankToBorder;
/**
 * 排行榜与舞台边界的竖直距离
 */
let offsetY_rankToBorder;
/**
 * 绘制排名的最大宽度
 */
let indexWidth;

//////////////////////////////////////////////////////////
/**
 * 监听点击
 */
wx.onTouchEnd((event) => {
  var l = event.changedTouches.length;
  for (var i = 0; i < l; i++) {
    onTouchEnd(event.changedTouches[i]);
  }
});


/**
 * 资源加载
 */
function preloadAssets() {
  var preloaded = 0;
  var count = 0;
  for (var asset in assets) {
    count++;
    var img = wx.createImage();
    img.onload = function () {
      preloaded++;
      if (preloaded == count) {
        setTimeout(function () {
          createScene();
        }, 500);
      }
    }
    img.src = assets[asset];
    assets[asset] = img;
  }
}
/**
 * 绘制屏幕
 * 这个函数会在加载完所有资源之后被调用
 */
function createScene() {
  if (sharedCanvas.width && sharedCanvas.height) {
    console.log(‘初始化完成‘)
    stageWidth = sharedCanvas.width;
    stageHeight = sharedCanvas.height;
  } else {
    console.log(`sharedCanvas.width:${sharedCanvas.width}    sharedCanvas.height：${sharedCanvas.height}`)
  }
  init();
  requestAnimationFrame(loop);
}
/**
 * 循环函数
 * 每帧判断一下是否需要渲染
 * 如果被标脏，则重新渲染
 */
function loop() {
  if (renderDirty) {
    console.log(`stageWidth :${stageWidth}   stageHeight:${stageHeight}`)
    context.setTransform(1, 0, 0, 1, 0, 0);
    context.clearRect(0, 0, sharedCanvas.width, sharedCanvas.height);
    drawRankPanel();
    renderDirty = false;
  }
  requestAnimationFrame(loop);
}