中原工学院鸿蒙期末大作业——转盘抽奖

一、摘要

1.通过画布组件Canvas，画出抽奖圆形转盘。
2.通过显式动画启动抽奖功能。
3.通过自定义弹窗弹出抽中的奖品。

二、环境搭建

1.软件要求
DevEco Studio版本：DevEco Studio 3.1 Release。
HarmonyOS SDK版本：API version 9。
2.硬件要求
设备类型：华为手机或运行在DevEco Studio上的华为手机设备模拟器。
HarmonyOS系统：3.1.0 Developer Release。

三、程序设计

1.构建主页面

效果图如下!

在绘制抽奖圆形转盘前，首先需要在CanvasPage.ets的aboutToAppear方法中获取屏幕的宽高。

let context = getContext(this);

aboutToAppear() {
  // 获取屏幕的宽高
  window.getLastWindow(context)
    .then((windowClass: window.Window) => {
      let windowProperties = windowClass.getWindowProperties();
      this.screenWidth = px2vp(windowProperties.windowRect.width);
      this.screenHeight = px2vp(windowProperties.windowRect.height);
    })
    .catch((error: Error) => {
      Logger.error('Failed to obtain the window size. Cause: ' + JSON.stringify(error));
    })
}

在CanvasPage.ets布局界面中添加Canvas组件，在onReady方法中进行绘制。

  build() {
    Stack({ alignContent: Alignment.Center }) {
      Canvas(this.canvasContext)
        .width(StyleConstants.FULL_PERCENT)
        .height(StyleConstants.FULL_PERCENT)
        .onReady(() => {
          this.drawModel.draw(this.canvasContext, this.screenWidth, this.screenHeight);
        })
        .rotate({
          x: 0,
          y: 0,
          z: 1,
          angle: this.rotateDegree,
          centerX: this.screenWidth / CommonConstants.TWO,
          centerY: this.screenHeight / CommonConstants.TWO
        })

      Image($r('app.media.ic_center'))
        .width(StyleConstants.CENTER_IMAGE_WIDTH)
        .height(StyleConstants.CENTER_IMAGE_HEIGHT)
        .enabled(this.enableFlag)
        .onClick(() => {
          this.enableFlag = !this.enableFlag;
          this.startAnimator();
        })
    }
    .width(StyleConstants.FULL_PERCENT)
    .height(StyleConstants.FULL_PERCENT)
    .backgroundImage($r('app.media.ic_background'), ImageRepeat.NoRepeat)
    .backgroundImageSize({
      width: StyleConstants.FULL_PERCENT,
      height: StyleConstants.BACKGROUND_IMAGE_SIZE
    })
  }

在DrawModel.ets中，通过draw方法逐步进行自定义圆形抽奖转盘的绘制。

draw(canvasContext: CanvasRenderingContext2D, screenWidth: number, screenHeight: number) {
  if (CheckEmptyUtils.isEmptyObj(canvasContext)) {
    Logger.error('[DrawModel][draw] canvasContext is empty.');
    return;
  }
  this.canvasContext= canvasContext;
  this.screenWidth = screenWidth;
  this.canvasContext.clearRect(0, 0, this.screenWidth, screenHeight);
  // 将画布沿X、Y轴平移指定距离
  this.canvasContext.translate(this.screenWidth / CommonConstants.TWO,
    screenHeight / CommonConstants.TWO);
  // 画外部圆盘的花瓣
  this.drawFlower();
  // 画外部圆盘、小圈圈
  this.drawOutCircle();
  // 画内部圆盘
  this.drawInnerCircle();
  // 画内部扇形抽奖区域
  this.drawInnerArc();
  // 画内部扇形区域文字
  this.drawArcText();
  // 画内部扇形区域奖品对应的图片
  this.drawImage();
  this.canvasContext.translate(-this.screenWidth / CommonConstants.TWO,
    -screenHeight / CommonConstants.TWO);
}

2.外部圆盘

画外部圆盘的花瓣：通过调用rotate()方法，将画布旋转指定角度。再通过调用save()和restore()方法，使画布保存最新的绘制状态。根据想要绘制的花瓣个数，改变旋转角度，循环画出花瓣效果。

// 画外部圆盘的花瓣
drawFlower() {
  let beginAngle = this.startAngle + this.avgAngle;
  const pointY = this.screenWidth * CommonConstants.FLOWER_POINT_Y_RATIOS;
  const radius = this.screenWidth * CommonConstants.FLOWER_RADIUS_RATIOS;
  const innerRadius = this.screenWidth * CommonConstants.FLOWER_INNER_RATIOS;
  for (let i = 0; i < CommonConstants.COUNT; i++) {
    this.canvasContext?.save();
    this.canvasContext?.rotate(beginAngle * Math.PI / CommonConstants.HALF_CIRCLE);
    this.fillArc(new FillArcData(0, -pointY, radius, 0, Math.PI * CommonConstants.TWO),
      ColorConstants.FLOWER_OUT_COLOR);

    this.fillArc(new FillArcData(0, -pointY, innerRadius, 0, Math.PI * CommonConstants.TWO),
      ColorConstants.FLOWER_INNER_COLOR);
    beginAngle += this.avgAngle;
    this.canvasContext?.restore();
  }
}

// 画弧线方法
fillArc(fillArcData: FillArcData, fillColor: string) {
  if (CheckEmptyUtils.isEmptyObj(fillArcData) || CheckEmptyUtils.isEmptyStr(fillColor)) {
    Logger.error('[DrawModel][fillArc] fillArcData or fillColor is empty.');
    return;
  }
  if (this.canvasContext !== undefined) {
    this.canvasContext.beginPath();
    this.canvasContext.fillStyle = fillColor;
    this.canvasContext.arc(fillArcData.x, fillArcData.y, fillArcData.radius,
      fillArcData.startAngle, fillArcData.endAngle);
    this.canvasContext.fill();
  }

drawOutCircle() {
  // 画外部圆盘
  this.fillArc(new FillArcData(0, 0, this.screenWidth * CommonConstants.OUT_CIRCLE_RATIOS, 0,
    Math.PI * CommonConstants.TWO), ColorConstants.OUT_CIRCLE_COLOR);

  let beginAngle = this.startAngle;
  // 画小圆圈
  for (let i = 0; i < CommonConstants.SMALL_CIRCLE_COUNT; i++) {
    this.canvasContext?.save();
    this.canvasContext?.rotate(beginAngle * Math.PI / CommonConstants.HALF_CIRCLE);
    this.fillArc(new FillArcData(this.screenWidth * CommonConstants.SMALL_CIRCLE_RATIOS, 0,
      CommonConstants.SMALL_CIRCLE_RADIUS, 0, Math.PI * CommonConstants.TWO),
      ColorConstants.WHITE_COLOR);
    beginAngle = beginAngle + CommonConstants.CIRCLE / CommonConstants.SMALL_CIRCLE_COUNT;
    this.canvasContext?.restore();
  }
}

3.画内部扇形抽奖区域

// 画内部圆盘
drawInnerCircle() {
  this.fillArc(new FillArcData(0, 0, this.screenWidth * CommonConstants.INNER_CIRCLE_RATIOS, 0,
    Math.PI * CommonConstants.TWO), ColorConstants.INNER_CIRCLE_COLOR);
  this.fillArc(new FillArcData(0, 0, this.screenWidth * CommonConstants.INNER_WHITE_CIRCLE_RATIOS, 0,
    Math.PI * CommonConstants.TWO), ColorConstants.WHITE_COLOR);
}

// 画内部扇形抽奖区域
drawInnerArc() {
  // 颜色集合
  let colors = [
    ColorConstants.ARC_PINK_COLOR, ColorConstants.ARC_YELLOW_COLOR,
    ColorConstants.ARC_GREEN_COLOR, ColorConstants.ARC_PINK_COLOR,
    ColorConstants.ARC_YELLOW_COLOR, ColorConstants.ARC_GREEN_COLOR
  ];
  let radius = this.screenWidth * CommonConstants.INNER_ARC_RATIOS;
  for (let i = 0; i < CommonConstants.COUNT; i++) {
    this.fillArc(new FillArcData(0, 0, radius, this.startAngle * Math.PI / CommonConstants.HALF_CIRCLE,
      (this.startAngle + this.avgAngle) * Math.PI / CommonConstants.HALF_CIRCLE), colors[i]);
    this.canvasContext?.lineTo(0, 0);
    this.canvasContext?.fill();
    this.startAngle += this.avgAngle;
  }
}

// 画内部扇形区域文字
drawArcText() {
  if (this.canvasContext !== undefined) {
    this.canvasContext.textAlign = CommonConstants.TEXT_ALIGN;
    this.canvasContext.textBaseline = CommonConstants.TEXT_BASE_LINE;
    this.canvasContext.fillStyle = ColorConstants.TEXT_COLOR;
    this.canvasContext.font = StyleConstants.ARC_TEXT_SIZE + CommonConstants.CANVAS_FONT;
  }
  // 需要绘制的文本数组集合
  let textArrays = [
    $r('app.string.text_smile'),
    $r('app.string.text_hamburger'),
    $r('app.string.text_cake'),
    $r('app.string.text_smile'),
    $r('app.string.text_beer'),
    $r('app.string.text_watermelon')
  ];
  let arcTextStartAngle = CommonConstants.ARC_START_ANGLE;
  let arcTextEndAngle = CommonConstants.ARC_END_ANGLE;
  for (let i = 0; i < CommonConstants.COUNT; i++) {
    this.drawCircularText(this.getResourceString(textArrays[i]),
      (this.startAngle + arcTextStartAngle) * Math.PI / CommonConstants.HALF_CIRCLE,
      (this.startAngle + arcTextEndAngle) * Math.PI / CommonConstants.HALF_CIRCLE);
    this.startAngle += this.avgAngle;
  }
}

// 绘制圆弧文本
drawCircularText(textString: string, startAngle: number, endAngle: number) {
  if (CheckEmptyUtils.isEmptyStr(textString)) {
    Logger.error('[DrawModel][drawCircularText] textString is empty.');
    return;
  }
  class CircleText {
    x: number = 0;
    y: number = 0;
    radius: number = 0;
  };
  let circleText: CircleText = {
    x: 0,
    y: 0,
    radius: this.screenWidth * CommonConstants.INNER_ARC_RATIOS
  };
  // 圆的半径
  let radius = circleText.radius - circleText.radius / CommonConstants.COUNT;
  // 每个字母占的弧度
  let angleDecrement = (startAngle - endAngle) / (textString.length - 1);
  let angle = startAngle;
  let index = 0;
  let character: string;

  while (index < textString.length) {
    character = textString.charAt(index);
    this.canvasContext?.save();
    this.canvasContext?.beginPath();
    this.canvasContext?.translate(circleText.x + Math.cos(angle) * radius,
      circleText.y - Math.sin(angle) * radius);
    this.canvasContext?.rotate(Math.PI / CommonConstants.TWO - angle);
    this.canvasContext?.fillText(character, 0, 0);
    angle -= angleDecrement;
    index++;
    this.canvasContext?.restore();
  }

// 画内部扇形区域文字对应的图片
drawImage() {
  let beginAngle = this.startAngle;
  let imageSrc = [
    CommonConstants.WATERMELON_IMAGE_URL, CommonConstants.BEER_IMAGE_URL,
    CommonConstants.SMILE_IMAGE_URL, CommonConstants.CAKE_IMAGE_URL,
    CommonConstants.HAMBURG_IMAGE_URL, CommonConstants.SMILE_IMAGE_URL
  ];
  for (let i = 0; i < CommonConstants.COUNT; i++) {
    let image = new ImageBitmap(imageSrc[i]);
    this.canvasContext?.save();
    this.canvasContext?.rotate(beginAngle * Math.PI / CommonConstants.HALF_CIRCLE);
    this.canvasContext?.drawImage(image, this.screenWidth * CommonConstants.IMAGE_DX_RATIOS,
      this.screenWidth * CommonConstants.IMAGE_DY_RATIOS, CommonConstants.IMAGE_SIZE,
      CommonConstants.IMAGE_SIZE);
    beginAngle += this.avgAngle;
    this.canvasContext?.restore();
  }
}

4.实现抽奖功能

圆形转盘开始转动抽奖：给转盘指定一个随机的转动角度randomAngle，保证每次转动的角度是随机的，即每次抽到的奖品也是随机的。动画结束后，转盘停止转动，抽奖结束，弹出抽中的奖品信息。

dialogController: CustomDialogController = new CustomDialogController({
  builder: PrizeDialog({
    prizeData: $prizeData,
    enableFlag: $enableFlag
  }),
  autoCancel: false
});

// 开始抽奖
startAnimator() {
  let randomAngle = Math.round(Math.random() * CommonConstants.CIRCLE);
  // 获取中奖信息
  this.prizeData = this.drawModel.showPrizeData(randomAngle);

  animateTo({
    duration: CommonConstants.DURATION,
    curve: Curve.Ease,
    delay: 0,
    iterations: 1,
    playMode: PlayMode.Normal,
    onFinish: () => {
      this.rotateDegree = CommonConstants.ANGLE - randomAngle;
      // 打开自定义弹窗，弹出抽奖信息
      this.dialogController.open();
    }
  }, () => {
    this.rotateDegree = CommonConstants.CIRCLE * CommonConstants.FIVE +
      CommonConstants.ANGLE - randomAngle;
  })

弹出抽中的奖品信息：抽奖结束后，弹出抽中的文本和图片信息，通过自定义弹窗实现。

@CustomDialog
export default struct PrizeDialog {
  @Link prizeData: PrizeData;
  @Link enableFlag: boolean;
  private controller?: CustomDialogController;

  build() {
    Column() {
      Image(this.prizeData.imageSrc !== undefined ? this.prizeData.imageSrc : '')
        .width($r('app.float.dialog_image_size'))
        .height($r('app.float.dialog_image_size'))
        .margin({
          top: $r('app.float.dialog_image_top'),
          bottom: $r('app.float.dialog_image_bottom')
        })
        .transform(matrix4.identity().rotate({
          x: 0,
          y: 0,
          z: 1,
          angle: CommonConstants.TRANSFORM_ANGLE
        }))

      Text(this.prizeData.message)
        .fontSize($r('app.float.dialog_font_size'))
        .textAlign(TextAlign.Center)
        .margin({ bottom: $r('app.float.dialog_message_bottom') })

      Text($r('app.string.text_confirm'))
        .fontColor($r('app.color.text_font_color'))
        .fontWeight(StyleConstants.FONT_WEIGHT)
        .fontSize($r('app.float.dialog_font_size'))
        .textAlign(TextAlign.Center)
        .onClick(() => {
          this.controller?.close();
          this.enableFlag = !this.enableFlag;
        })
    }
    .backgroundColor($r('app.color.dialog_background'))
    .width(StyleConstants.FULL_PERCENT)
    .height($r('app.float.dialog_height'))
  }
}

四、总结

虽然通过一个学期的学习对鸿蒙有了更多的认识，但是还是远远不够，尽管在借鉴多个demo下完成了期末大作业，想要将鸿蒙学习更进一步，还需要日后进一步的学习。最后，我相信在今后的工作和学习中，鸿蒙操作系统都将成为一个非常重要的工具和平台。我将继续深入学习和开发，探索更多的鸿蒙技术领域，努力成为一名专业的鸿蒙操作系统开发者，并在这个领域中取得更大的成就和贡献。