优化主题色选择

app/src/main/java/io/legado/app/ui/config/ThemeConfigFragment.kt

@@ -80,12 +80,38 @@ class ThemeConfigFragment : BasePreferenceFragment(),
         }
         findPreference<ColorPreference>(PreferKey.cAccent)?.let {
             it.onSaveColor = { color ->
-                false
+                val background =
+                    getPrefInt(PreferKey.cBackground, getCompatColor(R.color.md_grey_100))
+                val textColor = getCompatColor(R.color.tv_text_default)
+                when {
+                    ColorUtils.getColorDifference(color, background) <= 60 -> {
+                        toast("强调色不能和背景颜色相似")
+                        true
+                    }
+                    ColorUtils.getColorDifference(color, textColor) <= 60 -> {
+                        toast("强调色不能和文字颜色相似")
+                        true
+                    }
+                    else -> false
+                }
             }
         }
         findPreference<ColorPreference>(PreferKey.cNAccent)?.let {
             it.onSaveColor = { color ->
-                false
+                val background =
+                    getPrefInt(PreferKey.cNBackground, getCompatColor(R.color.md_grey_900))
+                val textColor = getCompatColor(R.color.tv_text_default)
+                when {
+                    ColorUtils.getColorDifference(color, background) <= 60 -> {
+                        toast("强调色不能和背景颜色相似")
+                        true
+                    }
+                    ColorUtils.getColorDifference(color, textColor) <= 60 -> {
+                        toast("强调色不能和文字颜色相似")
+                        true
+                    }
+                    else -> false
+                }
             }
         }
     }

app/src/main/java/io/legado/app/utils/ColorUtils.kt

@@ -5,9 +5,7 @@ import android.graphics.Color
 import androidx.annotation.ColorInt
 import androidx.annotation.FloatRange
 import java.util.*
-import kotlin.math.max
-import kotlin.math.min
-import kotlin.math.roundToInt
+import kotlin.math.*
 
 @Suppress("unused")
 object ColorUtils {
@@ -83,7 +81,6 @@ object ColorUtils {
         return Color.argb(a.toInt(), r.toInt(), g.toInt(), b.toInt())
     }
 
-
     /**
      * 按条件的到随机颜色
      *
@@ -161,4 +158,95 @@ object ColorUtils {
         }
     }
 
+    fun argb(R: Int, G: Int, B: Int): Int {
+        return argb(Byte.MAX_VALUE.toInt(), R, G, B)
+    }
+
+    fun argb(A: Int, R: Int, G: Int, B: Int): Int {
+        val colorByteArr =
+            byteArrayOf(A.toByte(), R.toByte(), G.toByte(), B.toByte())
+        return byteArrToInt(colorByteArr)
+    }
+
+    fun rgb(argb: Int): IntArray? {
+        return intArrayOf(argb shr 16 and 0xFF, argb shr 8 and 0xFF, argb and 0xFF)
+    }
+
+    fun byteArrToInt(colorByteArr: ByteArray): Int {
+        return ((colorByteArr[0].toInt() shl 24) + (colorByteArr[1].toInt() and 0xFF shl 16)
+                + (colorByteArr[2].toInt() and 0xFF shl 8) + (colorByteArr[3].toInt() and 0xFF))
+    }
+
+    fun rgb2lab(R: Int, G: Int, B: Int): IntArray {
+        val x: Float
+        val y: Float
+        val z: Float
+        val fx: Float
+        val fy: Float
+        val fz: Float
+        val xr: Float
+        val yr: Float
+        val zr: Float
+        val ls: Float
+        val `as`: Float
+        val bs: Float
+        val eps = 216f / 24389f
+        val k = 24389f / 27f
+        val xr1 = 0.964221f // reference white D50
+        val yr1 = 1.0f
+        val zr1 = 0.825211f
+
+        // RGB to XYZ
+        var r: Float = R / 255f //R 0..1
+        var g: Float = G / 255f //G 0..1
+        var b: Float = B / 255f //B 0..1
+
+        // assuming sRGB (D65)
+        r = if (r <= 0.04045) r / 12 else ((r + 0.055) / 1.055).pow(2.4).toFloat()
+        g = if (g <= 0.04045) g / 12 else ((g + 0.055) / 1.055).pow(2.4).toFloat()
+        b = if (b <= 0.04045) b / 12 else ((b + 0.055) / 1.055).pow(2.4).toFloat()
+        x = 0.436052025f * r + 0.385081593f * g + 0.143087414f * b
+        y = 0.222491598f * r + 0.71688606f * g + 0.060621486f * b
+        z = 0.013929122f * r + 0.097097002f * g + 0.71418547f * b
+
+        // XYZ to Lab
+        xr = x / xr1
+        yr = y / yr1
+        zr = z / zr1
+        fx = if (xr > eps) xr.toDouble().pow(1 / 3.0)
+            .toFloat() else ((k * xr + 16.0) / 116.0).toFloat()
+        fy = if (yr > eps) yr.toDouble().pow(1 / 3.0)
+            .toFloat() else ((k * yr + 16.0) / 116.0).toFloat()
+        fz = if (zr > eps) zr.toDouble().pow(1 / 3.0)
+            .toFloat() else ((k * zr + 16.0) / 116).toFloat()
+        ls = 116 * fy - 16
+        `as` = 500 * (fx - fy)
+        bs = 200 * (fy - fz)
+        val lab = IntArray(3)
+        lab[0] = (2.55 * ls + .5).toInt()
+        lab[1] = (`as` + .5).toInt()
+        lab[2] = (bs + .5).toInt()
+        return lab
+    }
+
+    /**
+     * Computes the difference between two RGB colors by converting them to the L*a*b scale and
+     * comparing them using the CIE76 algorithm { http://en.wikipedia.org/wiki/Color_difference#CIE76}
+     */
+    fun getColorDifference(a: Int, b: Int): Double {
+        val r1: Int = Color.red(a)
+        val g1: Int = Color.green(a)
+        val b1: Int = Color.blue(a)
+        val r2: Int = Color.red(b)
+        val g2: Int = Color.green(b)
+        val b2: Int = Color.blue(b)
+        val lab1 = rgb2lab(r1, g1, b1)
+        val lab2 = rgb2lab(r2, g2, b2)
+        return sqrt(
+            (lab2[0] - lab1[0].toDouble())
+                .pow(2.0) + (lab2[1] - lab1[1].toDouble())
+                .pow(2.0) + (lab2[2] - lab1[2].toDouble())
+                .pow(2.0)
+        )
+    }
 }