Android实现雷达View效果的示例代码

样式效果

  还是先来看效果:

  这是一个仿雷达扫描的效果,是之前在做地图sdk接入时就想实现的效果,但之前由于赶着毕业设计,就没有亲手去实现,不过现在自己撸一个发现还是挺简单的。

  这里主要分享一下我的做法。

目录

主体轮廓的实现(雷达的结构)

动画的实现(雷达扫描的效果)

目标点的加入(图片/点)

主体轮廓实现

  

  不难分析得出,这个View主要由外部的一个圆,中间的锚点圆以及扇形旋转区域组成。而且每个部分理应由不同的Paint去绘制,以方便去定制各部分的样式。

  外部圆以及锚点圆的绘制较为简单,主要的点还是要对整个View的宽高进行一定的限制,例如宽高必须相等且在某种模式下,取小的那个值来限定整个RadarView的最大值。那么该如何去控制呢?

onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int)

  由于我们继承自View,在onMeasure方法中,我们可以根据两个参数来获取Mode,并且根据Mode来指定宽/高对应的值,再通过setMeasuredDimension去指定控件主体的宽高即可。

override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec)

val vWidth = measureDimension(widthMeasureSpec)

val vHeight = measureDimension(heightMeasureSpec)

val size = min(vWidth, vHeight)

setMeasuredDimension(size, size)

}

private fun measureDimension(spec: Int) = when (MeasureSpec.getMode(spec)) {

MeasureSpec.EXACTLY -> {

// exactly number or match_parent

MeasureSpec.getSize(spec)

}

MeasureSpec.AT_MOST -> {

// wrap_content

min(mDefaultSize, MeasureSpec.getSize(spec))

}

else -> {

mDefaultSize

}

}

  测量工作完成了,我们自然可以去绘制了。为了不让中间的小圆看起来那么突兀(偏大或偏小),这里设置了一个scaleFactor的缩放因子,使其能根据外圆的尺寸来进行缩放。

override fun onDraw(canvas: Canvas?) {

super.onDraw(canvas)

// draw outside circle (background)

canvas?.drawCircle(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2, measuredWidth.toFloat() / 2, mOutlinePaint)

if (mBorderWidth > 0F && mOutlinePaint.shader == null) {

drawBorder(canvas)

}

// mOutlineRect = Rect(0, 0, measuredWidth, measuredHeight)

canvas?.drawArc(mOutlineRect.toRectF(), mStartAngle, mSweepAngle, true, mSweepPaint)

// draw center circle

// scaleFactor = 30F

canvas?.drawCircle(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2, measuredWidth.toFloat() / 2 / mScaleFactor, mPaint)

}

private fun drawBorder(canvas: Canvas?) {

Log.i("RadarView", "drawBorder")

mOutlinePaint.style = Paint.Style.STROKE

mOutlinePaint.color = mBorderColor

mOutlinePaint.strokeWidth = mBorderWidth

canvas?.drawCircle(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2,

(measuredWidth.toFloat() - mBorderWidth) / 2, mOutlinePaint)

// 还原

mOutlinePaint.style = Paint.Style.FILL_AND_STROKE

mOutlinePaint.color = mBackgroundColor

}

  绘制了基准圆以后,要实现雷达扫描时那种渐变的效果,我们可以通过SweepGradient来操作。通过指定中心点,渐变颜色,以及颜色的分布,来定制扫描渐变的样式,默认的即时开头时gif展示的那种。由于这里是从第一象限开始旋转,因此将旋转的起点通过matrix逆时针旋转90度,从而达到由浅入深的效果。

private fun setShader(size: Int) {

val shader = SweepGradient(size.toFloat() / 2, size.toFloat() / 2,

mScanColors?: mDefaultScanColors, // 可通过setScanColors()来定制颜色

floatArrayOf(0F, 0.5F, 1F)) // 这里默认走平均分布

val matrix = Matrix()

// 逆时针旋转90度

matrix.setRotate(-90F, size.toFloat() / 2, size.toFloat() / 2)

shader.setLocalMatrix(matrix)

mSweepPaint.shader = shader

}

  这里完成了测量与绘制的工作,那么我们在布局里引用以后,就会看到这样的效果:

  这时,由于我们之前在测量的时候,将宽高最小值作为绘制的基准大小给予了RadarView,因此measuredWidth和measuredHeight是相等的,但是由于在布局中指定了match_parent属性,那么实际的控件宽高还是和父布局一致(在这里即占满屏幕宽高,由于宽比高小,所以看到绘制的图形会偏向上方;如果设置了高比宽小,那么绘制的图形就会位于左侧)。一般的雷达控件应该都是居中显示的,所以我在这里也重写了onLayout方法,来实现居中的效果。

override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {

// 设置默认居中

var l = left

var r = right

var t = top

var b = bottom

when {

width > height -> {

// 宽度比高度大 那么要设置默认居中就得把left往右移 right往左移

l = (width - measuredWidth) / 2

r = width - l

layout(l, t, r, b)

}

height > width -> {

// 高度比宽度大 那么要设置默认居中就得把top往下移 bottom往上移

t = (height - measuredHeight) / 2

b = height - t

layout(l, t, r, b)

}

else -> super.onLayout(changed, left, top, right, bottom)

}

}

动画的实现

  完成了绘制,接下来就是思考该如何让他动起来了。由绘制的代码不难想到,我这里考虑的是通过mStartAngle的变化来控制绘制的角度旋转,而ValueAnimator则正好能获取到每次更新时value的值,因此这里我选用了这个方案。

fun start() {

Log.i("RadarView", "animation start")

mIsAnimating = true

mAnimator.duration = 2000

mAnimator.repeatCount = ValueAnimator.INFINITE

mAnimator.addUpdateListener {

val angle = it.animatedValue as Float

mStartAngle = angle

// Log.i("RadarView", "mStartAngle = $mStartAngle and curValue = ${it.animatedValue}")

postInvalidate()

}

mAnimator.start()

}

  坑

  这里就需要注意一个点,就是canvas在绘制时,后绘制的会覆盖在前绘制的图像上,所以需要注意绘制的顺序。当然,这里也可以把mOutlineRect的宽高设置为measuredWidth - mBorderWidth,那么就能保证绘制填充角度时,不会把边界覆盖。

  至此,动画的效果便完成了。

目标点的加入

  首先,前两点已经能满足大多的雷达扫描需求了。这里这个添加目标点(target)纯粹是我自己想加入的功能,因为觉得可以结合地图sdk的MapView来共同使用,目前也只是开发阶段,扩展性可能考虑得还不是特别充足,也还没应用到具体项目中。但是,总觉得自己想的功能也该试着去实践一下~

  这里主要运用的圆的计算公式:

  x^{2} + y^{2} = r^2

  由于Android的坐标系的原点是在左上角,y轴过顶点向下延伸。由我们的绘制可知,此绘制图像在坐标系中的位置大概如下图所示:

  那么,对应的公式就为:

(x - cx)^{2} + (y - cy)^{2} < r^2

  要注意的是,这里r的计算会根据图/点的设置来动态计算,具体例子通过代码来进行分析。

// 随机落点

fun addTarget(size: Int, type: TYPE = TYPE.RANDOM) {

val list = ArrayList<PointF>()

val r = measuredWidth.toFloat() / 2

val innerRect = Rect((r - r / mScaleFactor).toInt(), (r - r / mScaleFactor).toInt(),

(r + r / mScaleFactor).toInt(), (r + r / mScaleFactor).toInt())

// 圆的中心点

val circle = PointF(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2)

while (list.size < size) {

val ranX = Random.nextDouble(0.0, r * 2.0).toFloat()

val ranY = Random.nextDouble(0.0, r * 2.0).toFloat()

val ranPointF = PointF(ranX, ranY)

if (innerRect.contains(ranPointF.toPoint())) {

continue

}

// 圆公式

if (!mNeedBitmap &&

(ranX - circle.x).pow(2) + (ranY - circle.y).pow(2) <

(r - mTargetRadius - mBorderWidth).toDouble().pow(2.0)) {

// 普通点

addTargetFromType(type, list, ranX, ranY, r, ranPointF)

} else if (mNeedBitmap &&

(ranX - circle.x).pow(2) + (ranY - circle.y).pow(2) <

(r - mBorderWidth - max(mBitmap.width, mBitmap.height) / 2).toDouble().pow(2)) {

// 图

addTargetFromType(type, list, ranX, ranY, r, ranPointF)

} else {

continue

}

}

mTargetList = list

for (target in list) {

Log.i("RadarView", "target = [${target.x}, ${target.y}]")

}

invalidate()

}

  可以看到,当target为普通点时,r的计算还要减去targetRadius,即目标点的半径,同时还要减去边界的宽度,如图所示:

  

  当target为图时,由于宽高不定,故除了边界外,还要减去大的边,那么r的计算则为:

  同时为了避免图片的尺寸过大,这里同样采取了一个默认值与一个缩放因子,从而保证图的完整性以及避免过大而引起的视觉丑化。

  关于落点的位置,目前采取的是随机落点,如果应用到地图扫点的话,可以通过地图sdk内的距离计算工具再与RadarView的坐标做一个比例转换,从而达到雷达内显示该点具体方位。

  关于落点的分布,目前提供了5种类型:分别是全象限随机、第一象限、第二象限、第三象限与第四象限随机。

Github

  若须直接调用,可移步至 https://github.com/CarsonWoo/RadarView

完整代码

class RadarView : View {

enum class TYPE { RANDOM, FIRST, SECOND, THIRD, FOURTH }

private val mPaint by lazy { Paint(Paint.ANTI_ALIAS_FLAG) }

private val mSweepPaint by lazy { Paint(Paint.ANTI_ALIAS_FLAG) }

private val mOutlinePaint by lazy { Paint(Paint.ANTI_ALIAS_FLAG) }

private val mTargetPaint by lazy { Paint(Paint.ANTI_ALIAS_FLAG) }

private val mDefaultSize = 120// px

// limit the size of bitmap

private var mBitmapMaxSize = 0F

private var mBitmapWHRatio = 0F

private val mScaleFactor = 30F

private var mStartAngle = 0F

private val mSweepAngle = -60F

private var mScanColors: IntArray? = null

private val mDefaultScanColors = intArrayOf(Color.parseColor("#0F7F7F7F"),

Color.parseColor("#7F7F7F7F"),

Color.parseColor("#857F7F7F"))

private val mDefaultBackgroundColor = Color.WHITE

private var mBackgroundColor: Int = mDefaultBackgroundColor

private var mBorderColor: Int = Color.BLACK

private var mBorderWidth = 0F

private var mTargetColor: Int = Color.RED

private var mTargetRadius = 10F

private lateinit var mOutlineRect: Rect

private val mAnimator = ValueAnimator.ofFloat(0F, 360F)

private var mTargetList: ArrayList<PointF>? = null

private var mIsAnimating = false

private var mNeedBitmap = false

private var mBitmap = BitmapFactory.decodeResource(resources, R.mipmap.ic_launcher)

constructor(context: Context): this(context, null)

constructor(context: Context, attributeSet: AttributeSet?) : super(context, attributeSet)

init {

mPaint.color = Color.GRAY

mPaint.strokeWidth = 10F

mPaint.style = Paint.Style.FILL_AND_STROKE

mPaint.strokeJoin = Paint.Join.ROUND

mPaint.strokeCap = Paint.Cap.ROUND

mSweepPaint.style = Paint.Style.FILL

mOutlinePaint.style = Paint.Style.FILL_AND_STROKE

mOutlinePaint.color = mBackgroundColor

mTargetPaint.style = Paint.Style.FILL

mTargetPaint.color = mTargetColor

mTargetPaint.strokeWidth = 10F

}

override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec)

val vWidth = measureDimension(widthMeasureSpec)

val vHeight = measureDimension(heightMeasureSpec)

val size = min(vWidth, vHeight)

setShader(size)

setMeasuredDimension(size, size)

setParamUpdate()

}

override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {

// 设置默认居中

var l = left

var r = right

var t = top

var b = bottom

when {

width > height -> {

// 宽度比高度大 那么要设置默认居中就得把left往右移 right往左移

l = (width - measuredWidth) / 2

r = width - l

layout(l, t, r, b)

}

height > width -> {

// 高度比宽度大 那么要设置默认居中就得把top往下移 bottom往上移

t = (height - measuredHeight) / 2

b = height - t

layout(l, t, r, b)

}

else -> super.onLayout(changed, left, top, right, bottom)

}

}

private fun setShader(size: Int) {

val shader = SweepGradient(size.toFloat() / 2, size.toFloat() / 2,

mScanColors?: mDefaultScanColors,

floatArrayOf(0F, 0.5F, 1F))

val matrix = Matrix()

matrix.setRotate(-90F, size.toFloat() / 2, size.toFloat() / 2)

shader.setLocalMatrix(matrix)

mSweepPaint.shader = shader

}

fun setScanColors(colors: IntArray) {

this.mScanColors = colors

setShader(measuredWidth)

invalidate()

}

fun setRadarColor(@ColorInt color: Int) {

this.mBackgroundColor = color

this.mOutlinePaint.color = color

invalidate()

}

fun setRadarColor(colorString: String) {

if (!colorString.startsWith("#") || colorString.length != 7 || colorString.length != 9) {

Log.e("RadarView", "colorString parse error, please check your enter param")

return

}

val color = Color.parseColor(colorString)

setRadarColor(color)

}

fun setBorderColor(@ColorInt color: Int) {

this.mBorderColor = color

invalidate()

}

fun setBorderColor(colorString: String) {

if (!colorString.startsWith("#") || colorString.length != 7 || colorString.length != 9) {

Log.e("RadarView", "colorString parse error, please check your enter param")

return

}

val color = Color.parseColor(colorString)

setBorderColor(color)

}

fun setRadarGradientColor(colors: IntArray) {

val shader = SweepGradient(measuredWidth.toFloat() / 2,

measuredHeight.toFloat() / 2, colors, null)

mOutlinePaint.shader = shader

invalidate()

}

fun setBorderWidth(width: Float) {

this.mBorderWidth = width

invalidate()

}

private fun setParamUpdate() {

mOutlineRect = Rect(0, 0, measuredWidth, measuredHeight)

mBitmapMaxSize = measuredWidth.toFloat() / mScaleFactor

}

private fun measureDimension(spec: Int) = when (MeasureSpec.getMode(spec)) {

MeasureSpec.EXACTLY -> {

// exactly number or match_parent

MeasureSpec.getSize(spec)

}

MeasureSpec.AT_MOST -> {

// wrap_content

min(mDefaultSize, MeasureSpec.getSize(spec))

}

else -> {

mDefaultSize

}

}

override fun setBackground(background: Drawable?) {

// 取消传统背景设置

// super.setBackground(background)

}

override fun onDraw(canvas: Canvas?) {

super.onDraw(canvas)

// draw outside circle (background)

canvas?.drawCircle(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2, measuredWidth.toFloat() / 2, mOutlinePaint)

if (mBorderWidth > 0F && mOutlinePaint.shader == null) {

drawBorder(canvas)

}

canvas?.drawArc(mOutlineRect.toRectF(), mStartAngle, mSweepAngle, true, mSweepPaint)

if (!mTargetList.isNullOrEmpty() && !mIsAnimating) {

drawTarget(canvas)

}

// draw center circle

canvas?.drawCircle(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2, measuredWidth.toFloat() / 2 / mScaleFactor, mPaint)

}

private fun drawBorder(canvas: Canvas?) {

Log.i("RadarView", "drawBorder")

mOutlinePaint.style = Paint.Style.STROKE

mOutlinePaint.color = mBorderColor

mOutlinePaint.strokeWidth = mBorderWidth

canvas?.drawCircle(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2,

(measuredWidth.toFloat() - mBorderWidth) / 2, mOutlinePaint)

// 还原

mOutlinePaint.style = Paint.Style.FILL_AND_STROKE

mOutlinePaint.color = mBackgroundColor

}

private fun drawTarget(canvas: Canvas?) {

mTargetList?.let {

Log.e("RadarView", "draw target")

for (target in it) {

if (mNeedBitmap) {

canvas?.drawBitmap(mBitmap, target.x - mBitmap.width / 2,

target.y - mBitmap.height / 2, mTargetPaint)

} else {

canvas?.drawCircle(target.x, target.y, mTargetRadius, mTargetPaint)

}

}

}

}

fun setBitmapEnabled(enabled: Boolean, drawable: Drawable) {

// 这里是为了防止界面还未获取到宽高时 会导致onMeasure走不到 那么maxSize就会为0

post {

this.mNeedBitmap = enabled

this.mBitmapWHRatio = drawable.intrinsicWidth.toFloat() / drawable.intrinsicHeight.toFloat()

mBitmap = if (mBitmapWHRatio >= 1) {

// 宽比高大

drawable.toBitmap(

width = min(mBitmapMaxSize, drawable.intrinsicWidth.toFloat()).toInt(),

height = (min(mBitmapMaxSize, drawable.intrinsicWidth.toFloat()) / mBitmapWHRatio).toInt(),

config = Bitmap.Config.ARGB_8888)

} else {

// 高比宽大

drawable.toBitmap(

height = min(mBitmapMaxSize, drawable.intrinsicHeight.toFloat()).toInt(),

width = (min(mBitmapMaxSize, drawable.intrinsicHeight.toFloat()) * mBitmapWHRatio).toInt(),

config = Bitmap.Config.ARGB_8888

)

}

}

}

// 随机落点

fun addTarget(size: Int, type: TYPE = TYPE.RANDOM) {

val list = ArrayList<PointF>()

val r = measuredWidth.toFloat() / 2

val innerRect = Rect((r - r / mScaleFactor).toInt(), (r - r / mScaleFactor).toInt(),

(r + r / mScaleFactor).toInt(), (r + r / mScaleFactor).toInt())

// 圆的中心点

val circle = PointF(measuredWidth.toFloat() / 2, measuredHeight.toFloat() / 2)

while (list.size < size) {

val ranX = Random.nextDouble(0.0, r * 2.0).toFloat()

val ranY = Random.nextDouble(0.0, r * 2.0).toFloat()

val ranPointF = PointF(ranX, ranY)

if (innerRect.contains(ranPointF.toPoint())) {

continue

}

// 圆公式

if (!mNeedBitmap &&

(ranX - circle.x).pow(2) + (ranY - circle.y).pow(2) <

(r - mTargetRadius - mBorderWidth).toDouble().pow(2.0)) {

// 在圆内

addTargetFromType(type, list, ranX, ranY, r, ranPointF)

} else if (mNeedBitmap &&

(ranX - circle.x).pow(2) + (ranY - circle.y).pow(2) <

(r - mBorderWidth - max(mBitmap.width, mBitmap.height) / 2).toDouble().pow(2)) {

addTargetFromType(type, list, ranX, ranY, r, ranPointF)

} else {

continue

}

}

mTargetList = list

for (target in list) {

Log.i("RadarView", "target = [${target.x}, ${target.y}]")

}

invalidate()

}

private fun addTargetFromType(type: TYPE, list: ArrayList<PointF>, ranX: Float, ranY: Float,

r: Float, ranPointF: PointF) {

when (type) {

TYPE.RANDOM -> {

list.add(ranPointF)

}

TYPE.FOURTH -> {

if (ranX in r.toDouble()..2 * r.toDouble() && ranY in r.toDouble()..2 * r.toDouble()) {

list.add(ranPointF)

}

}

TYPE.THIRD -> {

if (ranX in 0.0..r.toDouble() && ranY in r.toDouble()..2 * r.toDouble()) {

list.add(ranPointF)

}

}

TYPE.SECOND -> {

if (ranX in 0.0..r.toDouble() && ranY in 0.0..r.toDouble()) {

list.add(ranPointF)

}

}

TYPE.FIRST -> {

if (ranX in r.toDouble()..2 * r.toDouble() && ranY in 0.0..r.toDouble()) {

list.add(ranPointF)

}

}

}

}

fun start() {

Log.i("RadarView", "animation start")

mIsAnimating = true

mAnimator.duration = 2000

mAnimator.repeatCount = ValueAnimator.INFINITE

mAnimator.addUpdateListener {

val angle = it.animatedValue as Float

mStartAngle = angle

Log.i("RadarView", "mStartAngle = $mStartAngle and curValue = ${it.animatedValue}")

postInvalidate()

}

mAnimator.start()

}

fun start(startVal: Float, endVal: Float) {

mIsAnimating = true

mAnimator.setFloatValues(startVal, endVal)

mAnimator.duration = 2000

mAnimator.repeatCount = ValueAnimator.INFINITE

mAnimator.addUpdateListener {

mStartAngle = it.animatedValue as Float

Log.i("RadarView", "mStartAngle = $mStartAngle and curValue = ${it.animatedValue}")

postInvalidate()

}

mAnimator.start()

}

fun stop() {

mIsAnimating = false

if (mAnimator.isRunning) {

mAnimator.cancel()

mAnimator.removeAllListeners()

}

mStartAngle = 0F

}

}

调用方式

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

setContentView(R.layout.activity_main)

radar_view.setBorderWidth(5F)

radar_view.setRadarColor(Color.TRANSPARENT)

radar_view.setBitmapEnabled(true, resources.getDrawable(R.mipmap.ic_launcher_round))

// radar_view.setScanColors(intArrayOf(Color.RED, Color.LTGRAY, Color.CYAN))

// radar_view.setRadarGradientColor(intArrayOf(Color.RED, Color.GREEN, Color.BLUE))

btn_start.setOnClickListener {

radar_view.start()

// workThreadAndCallback()

}

btn_stop.setOnClickListener {

radar_view.stop()

radar_view.addTarget(7)

}

}

总结

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