#盲盒+码##跟着小白一起学鸿蒙# [番外三]一起学做Tetris(上)

简介
小时候有个游戏叫俄罗斯方块，大人小孩都喜欢玩，我们就一起看看如何能用OpenHarmony学习做个Tetris。

开发
1. HAP应用建立
《#跟着小白一起学鸿蒙#[六]如何编写一个hap应用》里我们介绍了简单的Hap应用的开发以及基础控件的介绍，这里我们就不赘述Hap项目的建立过程，以下就是基础的Hap的page文件：index.ets

build() {
Row() {
Column() {
Canvas(this.context)
.width(‘100%’)
.height(‘100%’)
.onClick((ev: ClickEvent) => {
console.info(“click!!”)
this.doClick()
})
.onReady(() =>{
this.context.imageSmoothingEnabled = false
this.randomType()
this.drawall()
})
}
.width(‘100%’)
}
.height(‘100%’)
.backgroundColor(“#cccccc”)
}

build是基础页面的构造函数，用于界面的元素构造，其他的页面的生命周期函数如下：

declare class CustomComponent {
/**
* Customize the pop-up content constructor.
* @since 7
*/
build(): void;

/**
* aboutToAppear Method
* @since 7
*/
aboutToAppear?(): void;

/**
* aboutToDisappear Method
* @since 7
*/
aboutToDisappear?(): void;

/**
* onPageShow Method
* @since 7
*/
onPageShow?(): void;

/**
* onPageHide Method
* @since 7
*/
onPageHide?(): void;

/**
* onBackPress Method
* @since 7
*/
onBackPress?(): void;
}

2. Canvas介绍
canvas是画布组件用于自定义绘制图形，具体的API页面如下：

https://developer.harmonyos.com/cn/docs/documentation/doc-references/ts-components-canvas-canvas-0000001333641081

页面显示前会调用aboutToAppear()函数，此函数为页面生命周期函数

canvas组件初始化完毕后会调用onReady()函数，函数内部实现小游戏的初始页面的绘制

2.1 初始化页面数据
drawall() {
this.drawBox()
this.drawSideBlock()
this.drawBoxBlock()
this.drawScore()
}
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因为都是画布画的，所以布局有点麻烦，需要画几个部分：

中间的大框：方块下落和堆叠区域
右边提升框：下个方块类型
中间方块：方块运动和堆叠
下方计分：行数得分
2.2 绘制大框
drawBox() {
this.context.lineWidth = 4
this.context.beginPath()
this.context.lineCap = ‘butt’
this.context.moveTo(0, 100)
this.context.lineTo(270, 100)
this.context.moveTo(270, 100)
this.context.lineTo(270, 690)
this.context.moveTo(0, 690)
this.context.lineTo(270, 690)
}

2.3 绘制提示方块
drawSideBlock() {
this.context.fillStyle = ‘rgb(250,0,0)’
let bs = this.blockSize
let coords = this.blockShapBasic[this.blockType]
let x = this.sideStartX + coords[0][0]*this.blockSize
let y = this.sideStartY + coords[0][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.sideStartX + coords[1][0]*this.blockSize
y = this.sideStartY + coords[1][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.sideStartX + coords[2][0]*this.blockSize
y = this.sideStartY + coords[2][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.sideStartX + coords[3][0]*this.blockSize
y = this.sideStartY + coords[3][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
this.context.stroke()
}

2.4 绘制运动方块
drawBoxBlock() {
this.setDirection()
this.context.fillStyle = ‘rgb(250,0,0)’
let bs = this.blockSize
let coords = this.curBlockShap
let starty = this.slotStartY + this.step * this.blockSize
let x = this.slotStartX + coords[0][0]*this.blockSize
let y = starty + coords[0][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.slotStartX + coords[1][0]*this.blockSize
y = starty + coords[1][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.slotStartX + coords[2][0]*this.blockSize
y = starty + coords[2][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.slotStartX + coords[3][0]*this.blockSize
y = starty + coords[3][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
this.context.stroke()
this.slotBottomY = y
}

2.5 绘制得分区域
drawScore() {
this.context.fillStyle = ‘rgb(0,0,0)’
this.context.font = ’80px sans-serif’
this.context.fillText(“Score:”+this.score.toString(), 20, 740)
}
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3. 游戏逻辑
简单的小游戏主体游戏逻辑为：等待开始，开始，结束流程图如下：

doClick() {
this.direction += 1
}

4. 完整逻辑
@Entry
@Component
struct Index {
@State message: string = ‘Hello World’
private settings: RenderingContextSettings = new RenderingContextSettings(true);
private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings);
private blockType: number = 0
private blockSize: number = 30
private blockShapBasic = [
[[0,0],[0,1],[0,2],[0,3]],
[[0,0],[0,1],[0,2],[1,2]],
[[0,0],[0,1],[1,1],[0,2]],
[[0,0],[0,1],[1,1],[1,2]],
[[0,0],[0,1],[1,0],[1,1]],
]
private blockShap = [
[[0,0],[0,1],[0,2],[0,3]],
[[0,0],[0,1],[0,2],[1,2]],
[[0,0],[0,1],[1,1],[0,2]],
[[0,0],[0,1],[1,1],[1,2]],
[[0,0],[0,1],[1,0],[1,1]],
]
private curBlockShap = []
private sideStartX = 300;
private sideStartY = 150;

private slotStartX = 120;
private slotStartY = 150;
private slotBottomY = 150;;

private score = 0;
private step = 0;
private direction = 0;

aboutToDisappear() {
}

aboutToAppear() {
this.sleep(1000)
}

async sleep(ms: number) {
return new Promise((r) => {
setInterval(() => {
console.log(this.message)
this.drawStep()

}, ms)
})
}

doClick() {
this.direction += 1
}

drawBox() {
this.context.lineWidth = 4
this.context.beginPath()
this.context.lineCap = ‘butt’
this.context.moveTo(0, 100)
this.context.lineTo(270, 100)
this.context.moveTo(270, 100)
this.context.lineTo(270, 690)
this.context.moveTo(0, 690)
this.context.lineTo(270, 690)
}

setDirection() {
this.curBlockShap = this.blockShap[this.blockType]
if (this.direction > 0) {
for (let i=0;i<4;i++) {
let x = this.curBlockShap[i][0]
this.curBlockShap[i][0] = this.curBlockShap[i][1]
this.curBlockShap[i][1] = x
}
this.direction = 0
}
}

drawSideBlock() {
this.context.fillStyle = ‘rgb(250,0,0)’
let bs = this.blockSize
let coords = this.blockShapBasic[this.blockType]
let x = this.sideStartX + coords[0][0]*this.blockSize
let y = this.sideStartY + coords[0][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.sideStartX + coords[1][0]*this.blockSize
y = this.sideStartY + coords[1][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.sideStartX + coords[2][0]*this.blockSize
y = this.sideStartY + coords[2][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.sideStartX + coords[3][0]*this.blockSize
y = this.sideStartY + coords[3][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
this.context.stroke()
}

drawBoxBlock() {
this.setDirection()
this.context.fillStyle = ‘rgb(250,0,0)’
let bs = this.blockSize
let coords = this.curBlockShap
let starty = this.slotStartY + this.step * this.blockSize
let x = this.slotStartX + coords[0][0]*this.blockSize
let y = starty + coords[0][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.slotStartX + coords[1][0]*this.blockSize
y = starty + coords[1][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.slotStartX + coords[2][0]*this.blockSize
y = starty + coords[2][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
x = this.slotStartX + coords[3][0]*this.blockSize
y = starty + coords[3][1]*this.blockSize
this.context.fillRect(x, y, bs, bs)
this.context.rect(x, y, bs, bs)
console.info(“x,y”+x.toString()+”:”+y.toString())
this.context.stroke()
this.slotBottomY = y
}

drawScore() {
this.context.fillStyle = ‘rgb(0,0,0)’
this.context.font = ’80px sans-serif’
this.context.fillText(“Score:”+this.score.toString(), 20, 740)
}

randomType() {
this.blockType = Math.floor(Math.random()*5)
console.info(“blocktype:”+this.blockType.toString())
}

drawStep() {
this.context.clearRect(0,0,this.context.width,this.context.height)
this.step += 1
this.drawBox()
this.drawSideBlock()
this.drawBoxBlock()
this.drawScore()
if (this.slotBottomY >= 660) {
this.step = 0
this.randomType()
}
}

drawall() {
this.drawBox()
this.drawSideBlock()
this.drawBoxBlock()
this.drawScore()
}