兔年了，一起用Compose来画兔子吧

我正在参加「兔了个兔」创意投稿大赛，详情请看：「兔了个兔」创意投稿大赛,今年已经来到了兔年，记得去年的时候，看到过不少开发者用Compose画过老虎，各种各样的老虎都有，那既然已经是兔年了，忽然也想着用Compose来画只兔子试试看，顺便练练手，毕竟也好久没碰Compose了

准备工作

兔子主要还是画在画布上面，所以我们首先得生成个Canvas，然后确定Canvas的宽高跟画笔颜色

val drawColor = colorResource(id = R.color.color_EC4126)
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {

}
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宽高这边只是写死的两个数值，我们也可以用系统api来获取真实的屏幕宽高，画笔颜色选用偏红的颜色，毕竟要过年了，喜庆点～，接下去开始准备画兔子

脑袋

脑袋其实就是个椭圆，我们用canvas的drawPath方法去绘制，我们需要做的就是确定这个椭圆的中心点坐标，以及绘制这个椭圆的左上坐标以及右下坐标

val startX = screenWidth() / 4
val startY = screenHeight() / 3
val headPath = Path()
headPath.moveTo(screenWidth() / 2, screenHeight() / 2)
headPath.addOval(Rect(startX, startY, screenWidth() - startX, screenHeight() - startY))
headPath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = headPath, color = drawColor, style = Stroke(width = 12f))
}

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脑袋的中心点坐标x轴跟y轴分别就是画布宽高的一半，左上的x坐标就是画布宽的四分之一，y坐标就是画布高的三分之一，右下的x坐标就是画布宽减去左上的x坐标，右下的y坐标就是减去左上的y坐标，最终在Canvas里面将这个椭圆的path绘制出来，我们看下效果图

耳朵

画完脑袋我们接着画耳朵，两只耳朵其实也就是两个椭圆，分别以中心线左右对称，绘制思路同画脑袋一样，确定两个path的中心点坐标，以及各自左上跟右下的xy坐标

val leftEarPath = Path()
val leftEarPathX = screenWidth() * 3 / 8
val leftEarPathY = screenHeight() / 6
leftEarPath.moveTo(leftEarPathX, leftEarPathY)
leftEarPath.addOval(
    Rect(
        leftEarPathX - 60f,
        leftEarPathY / 2,
        leftEarPathX + 60f,
        startY + 30f
    )
)
leftEarPath.close()

val rightEarPath = Path()
val rightEarPathX = screenWidth() * 5 / 8
val rightEarPathY = screenHeight() / 6
rightEarPath.moveTo(rightEarPathX, rightEarPathY)
rightEarPath.addOval(
    Rect(
        rightEarPathX - 60f,
        rightEarPathY / 2,
        rightEarPathX + 60f,
        startY + 30f
    )
)
rightEarPath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = leftEarPath, color = drawColor, style = Stroke(width = 10f))
    drawPath(path = rightEarPath, color = drawColor, style = Stroke(width = 10f))
}
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看下效果图

内耳

这样感觉耳朵不是很立体，看起来有点平面，毕竟兔耳朵会有点往里凹的感觉，所以我们给这副耳朵加个内耳增加点立体感，内耳其实很简单，道理同外面的耳朵一样，只是中心点跟左上点，右下点的xy坐标会小一点，我们稍微改一下外耳的path就可以了

val leftEarSubPath = Path()
val leftEarSubPathX = screenWidth() * 3 / 8
val leftEarSubPathY = screenHeight() / 4
leftEarSubPath.moveTo(leftEarSubPathX, leftEarSubPathY)
leftEarSubPath.addOval(
    Rect(
        leftEarSubPathX - 30f,
        screenHeight() / 6,
        leftEarSubPathX + 30f,
        startY + 30f
    )
)
leftEarSubPath.close()

val rightEarSubPath = Path()
val rightEarSubPathX = screenWidth() * 5 / 8
val rightEarSubPathY = screenHeight() / 4
rightEarSubPath.moveTo(rightEarSubPathX, rightEarSubPathY)
rightEarSubPath.addOval(
    Rect(
        rightEarSubPathX - 30f,
        screenHeight() / 6,
        rightEarSubPathX + 30f,
        startY + 30f
    )
)
rightEarSubPath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = leftEarSubPath, color = drawColor, style = Stroke(width = 6f))
    drawPath(path = rightEarSubPath, color = drawColor, style = Stroke(width = 6f))
}
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看下效果图

有内味儿了，内耳的画笔粗细稍微调小了一点，为了突出个近大远小嘛哈哈哈，我们接着下一步

眼睛

画完耳朵我们开始画眼睛了，眼睛也很好画，主要是先找到中心点位置就好，中心点的x坐标其实跟耳朵的x坐标是一样的，y坐标在脑袋中心点y坐标稍微靠上一点的位置

val leftEyePath = Path()
val leftEyePathX = screenWidth() * 3 / 8
val leftEyePathY = screenHeight() * 11 / 24
leftEyePath.moveTo(leftEyePathX, leftEyePathY)
leftEyePath.addOval(
    Rect(
        leftEyePathX - 35f,
        leftEyePathY - 35f,
        leftEyePathX + 35f,
        leftEyePathY + 35f
    )
)
leftEyePath.close()

val rightEyePath = Path()
val rightEyePathX = screenWidth() * 5 / 8
val rightEyePathY = screenHeight() * 11 / 24
rightEyePath.moveTo(rightEyePathX, rightEyePathY)
rightEyePath.addOval(
    Rect(
        rightEyePathX - 35f,
        rightEyePathY - 35f,
        rightEyePathX + 35f,
        rightEyePathY + 35f
    )
)
rightEyePath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = leftEyePath, color = drawColor, style = Stroke(width = 10f))
    drawPath(path = rightEyePath, color = drawColor, style = Stroke(width = 10f))
}

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效果图如下

眼神有点空洞，无神是不，缺个眼珠子，那我们再给小兔子画上眼珠吧，眼珠就在眼睛的中心点位置，画一个圆点，圆点就要用到drawCircle，它有这些属性

fun drawCircle(
    color: Color,
    radius: Float = size.minDimension / 2.0f,
    center: Offset = this.center,
    /*@FloatRange(from = 0.0, to = 1.0)*/
    alpha: Float = 1.0f,
    style: DrawStyle = Fill,
    colorFilter: ColorFilter? = null,
    blendMode: BlendMode = DefaultBlendMode
)
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我们不需要用到全部，只需要用到颜色color，也就是红色，圆点半径radius，肯定要比眼睛的半径要小一点，我们就设置为10f,圆点中心坐标center,就是眼睛的中心点坐标，知道了以后我们开始绘制眼珠

Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) { 
    drawCircle(color = drawColor, radius = 10f, center = Offset(leftEyePathX,leftEyePathY))
    drawCircle(color = drawColor, radius = 10f, center = Offset(rightEyePathX,rightEyePathY))
}
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我们再看下效果图

鼻子

接下去我们画鼻子，鼻子肯定在脑袋的中间，所以中心点x坐标就是脑袋中心点的x坐标，那鼻子的y坐标就设置成比中心点y坐标稍微高一点的位置，代码如下

val nosePath = Path()
val nosePathX = screenWidth() / 2
val nosePathY = screenHeight() * 13 / 24
nosePath.moveTo(nosePathX, nosePathY)
nosePath.addOval(Rect(nosePathX - 15f, nosePathY - 15f, nosePathX + 15f, nosePathY + 15f))
nosePath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) { 
    drawPath(path = nosePath, color = drawColor, style = Stroke(width = 10f))
}

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我们看下效果图

兔唇

兔子的样子逐渐出来了，画完鼻子我们接着画啥呢？没错，兔子最有特点的位置也就是兔唇，我们脑补下兔唇长啥样子，首先位置肯定是在鼻子的下面，然后从鼻子开始往两边分叉，也就是两个扇形，扇形怎么画呢，我们也有现成的api，drawArc,我们看下drawArc都提供了哪些属性

fun drawArc(
    color: Color,
    startAngle: Float,
    sweepAngle: Float,
    useCenter: Boolean,
    topLeft: Offset = Offset.Zero,
    size: Size = this.size.offsetSize(topLeft),
    /*@FloatRange(from = 0.0, to = 1.0)*/
    alpha: Float = 1.0f,
    style: DrawStyle = Fill,
    colorFilter: ColorFilter? = null,
    blendMode: BlendMode = DefaultBlendMode
)
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我们需要用到的就是颜色color,这个扇形起始角度startAngle,扇形终止的角度sweepAngle,是否扇形两端跟中心点连接起来的布尔值useCenter,扇形的左上位置topLeft以及扇形的大小size也就是设置半径，知道这些以后我们开始逐个代入参数吧

Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) { 
    drawArc(
        color = drawColor,
        0f,
        120f,
        style = Stroke(width = 10f),
        useCenter = false,
        size = Size(120f, 120f),
        topLeft = Offset(nosePathX - 120f, nosePathY)
    )

    drawArc(
        color = drawColor,
        180f,
        -120f,
        style = Stroke(width = 10f),
        useCenter = false,
        size = Size(120f, 120f),
        topLeft = Offset(nosePathX + 10f, nosePathY)
    )
}
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画兔唇的时候其实就是在鼻子的两端各画一个坐标轴，左边的兔唇起始角度就是从x轴开始也就是0度，顺时针旋转120度，左上位置的x坐标刚好离开鼻子一个半径的位置，右边的兔唇刚好相反，逆时针旋转120度，起始角度是180度，左上位置的x坐标刚好在鼻子的位置那里，稍微加个10f让兔唇可以对称一些，我们看下效果图

胡须

脸上好像空了点，兔子的胡须还没有呢，胡须其实就是两边各画三条线，用drawLine这个api,起始位置的x坐标跟眼睛中心点的x坐标一样，中间胡须起始位置的y坐标跟鼻子的y坐标一样，上下胡须的y坐标各减去一定的数值

Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) { 
    drawLine(
        color = drawColor,
        start = Offset(leftEyePathX, nosePathY - 60f),
        end = Offset(leftEyePathX - 250f, nosePathY - 90f),
        strokeWidth = 5f,
        cap = StrokeCap.Round
    )
    drawLine(
        color = drawColor,
        start = Offset(leftEyePathX, nosePathY),
        end = Offset(leftEyePathX - 250f, nosePathY),
        strokeWidth = 5f,
        cap = StrokeCap.Round
    )
    drawLine(
        color = drawColor,
        start = Offset(leftEyePathX, nosePathY + 60f),
        end = Offset(leftEyePathX - 250f, nosePathY + 90f),
        strokeWidth = 5f,
        cap = StrokeCap.Round
    )

    drawLine(
        color = drawColor,
        start = Offset(rightEyePathX, nosePathY - 60f),
        end = Offset(rightEyePathX + 250f, nosePathY - 90f),
        strokeWidth = 5f,
        cap = StrokeCap.Round
    )
    drawLine(
        color = drawColor,
        start = Offset(rightEyePathX, nosePathY),
        end = Offset(rightEyePathX + 250f, nosePathY),
        strokeWidth = 5f,
        cap = StrokeCap.Round
    )
    drawLine(
        color = drawColor,
        start = Offset(rightEyePathX, nosePathY + 60f),
        end = Offset(rightEyePathX + 250f, nosePathY + 90f),
        strokeWidth = 5f,
        cap = StrokeCap.Round
    )
}
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很简单的画了六条线，线的粗细也稍微设置的小一点，毕竟胡须还是比较细的，我们看下效果图

就这样兔子脑袋部分所有元素都画完了，我们接着给兔子画身体

身体

身体其实也是个椭圆，位置刚好在画布下方三分之一的位置，左上x坐标比脑袋左上x坐标大一点，y坐标就是画布三分之二的位置处，右下x坐标比脑袋右下x坐标稍微小一点，y坐标就是画布的底端，知道以后我们就仿照着脑袋画身体

val bodyPath = Path()
val bodyPathX = screenWidth() / 2
val bodyPathY = screenHeight() * 5 / 6
bodyPath.moveTo(bodyPathX, bodyPathY)
bodyPath.addOval(
    Rect(
        startX + 50f,
        screenHeight() * 2 / 3,
        screenWidth() - startX - 50f,
        screenHeight()
    )
)
bodyPath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = bodyPath, color = drawColor, style = Stroke(width = 10f))
}
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效果图如下

双爪

画完身体我们再画兔子的双爪，双爪其实也是画两个椭圆，椭圆中心点的x坐标同两只眼睛的x坐标一样，y坐标在画布六分之五的位置

val leftHandPath = Path()
val leftHandPathX = screenWidth() * 3 / 8
val leftHandPathY = screenHeight() * 5 / 6
leftHandPath.moveTo(leftHandPathX, leftHandPathY)
leftHandPath.addOval(
    Rect(
        leftHandPathX - 35f,
        leftHandPathY - 90f,
        leftHandPathX + 35f,
        leftHandPathY + 90f
    )
)
leftHandPath.close()

val rightHandPath = Path()
val rightHandPathX = screenWidth() * 5 / 8
val rightHandPathY = screenHeight() * 5 / 6
rightHandPath.moveTo(rightHandPathX, rightHandPathY)
rightHandPath.addOval(
    Rect(
        rightHandPathX - 35f,
        rightHandPathY - 90f,
        rightHandPathX + 35f,
        rightHandPathY + 90f
    )
)
rightHandPath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = leftHandPath, color = drawColor, style = Stroke(width = 10f))
    drawPath(path = rightHandPath, color = drawColor, style = Stroke(width = 10f))
}
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我们看下效果图

尾巴

还差最后一步，我们给兔子画上尾巴，尾巴的中心点x坐标就是画布宽度减去脑袋右边x轴坐标，尾巴中心点的y坐标就是画布高度减去一定的数值，我们看下代码

val tailPath = Path()
val tailPathX = screenWidth() - startX
val tailPathY = screenHeight() - 200f
tailPath.moveTo(tailPathX, tailPathY)
tailPath.addOval(Rect(tailPathX - 60f, tailPathY - 90f, tailPathX + 60f, tailPathY + 90f))
tailPath.close()
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawPath(path = tailPath, color = drawColor, style = Stroke(width = 10f))
}
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就这样一只兔子画完了，我们看下最终效果图

看起来像那么回事了，我们再稍微点缀下，背景我们发现还有点单调，毕竟是过年了嘛，虽然多地不让放烟花，但我们看看还是可以的，网上找张烟花图片给兔子当背景吧，刚好也有drawImage这样的api可以将图片绘制到画布上，代码如下

val bgBitmap = ImageBitmap.imageResource(id = R.drawable.firework_night)
Canvas(
    modifier = Modifier
        .size(screenWidth().dp, screenHeight().dp)
        .background(color = Color.White)
) {
    drawImage(image = bgBitmap,
        srcOffset = IntOffset(0,0),
        srcSize = IntSize(bgBitmap.width,bgBitmap.height),
        dstSize = IntSize(screenWidth().toInt()*5/4,screenHeight().toInt()*5/4),
        dstOffset = IntOffset(0,0)
    )
}
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我们来看下效果怎么样

嗯～～大功告成～～好像也不是很好看哈哈哈，不过重点咱也不是为了美观，而是一个过年了图个寓意，另一个就是用下Compose里面Canvas这些api，毕竟随着kotlin逐步成熟，个人感觉Compose很有可能成为Android以后主流的UI开发模式

最后给大家拜个早年了，祝大家兔年大吉，“兔”飞猛进～～