工具类如下
class ToolsBox(w: WeakReference<Any>) {
private val zis = (w as WeakReference<Activity>).get()
fun dp2px(dp:Int):Int?{
return zis?.resources?.displayMetrics?.density?.let {
(dp * it + 0.5).toInt()}
}
fun px2dp(px:Int):Int?{
return zis?.resources?.displayMetrics?.density?.let {
(px.toDouble() / it + 0.5).toInt()}
}
private fun root(a:Double, b:Double, c:Double):List<Double>?{
val d = b*b - 4.0 * a * c
if(d < 0) return null
val sd = sqrt(d)
val x1 = (-b + sd)/(2.0 * a)
val x2 = (-b - sd)/(2.0 * a)
return listOf(x1, x2)
}
fun calcWidthFromDp(marginLeftDp:Int, widthDp:Int):List<Int>{
val margin = marginLeftDp.toDouble()
val marginPx = dp2px(marginLeftDp)?:16
val root = root(margin, widthDp.toDouble(), -((px2dp(zis?.resources?.displayMetrics?.widthPixels?:1080))?:400).toDouble())
val numPerRow = root?.let {
(it[0]+0.5).toInt()}?:3
val w = ((zis?.resources?.displayMetrics?.widthPixels?:1080)-marginPx*(numPerRow+1))/numPerRow
val totalWidth = ((zis?.resources?.displayMetrics?.widthPixels?:1080)-marginPx)/numPerRow
return listOf(numPerRow, w, totalWidth)
}
}
使用方法
val t = ToolsBox(WeakReference(this))
val px = t.dp2px(1)
val dp = t.px2dp(px)
另外calcWidthFromDp
函数还可以根据想设定的dp宽度自动计算与之最相近的能够容纳整数个控件的px宽度。