Provide background+text color combinations for calendar screen

app/src/main/java/com/mensinator/app/calendar/CalendarScreen.kt

@@ -14,11 +14,11 @@ import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.kizitonwose.calendar.compose.VerticalCalendar
 import com.kizitonwose.calendar.compose.rememberCalendarState
 import com.kizitonwose.calendar.core.CalendarDay
@@ -30,7 +30,10 @@ import com.mensinator.app.business.IPeriodDatabaseHelper
 import com.mensinator.app.calendar.CalendarViewModel.UiAction
 import com.mensinator.app.data.ColorSource
 import com.mensinator.app.extensions.stringRes
+import com.mensinator.app.settings.ColorSetting
 import com.mensinator.app.ui.navigation.displayCutoutExcludingStatusBarsPadding
+import com.mensinator.app.ui.theme.Black
+import com.mensinator.app.ui.theme.DarkGrey
 import com.mensinator.app.ui.theme.isDarkMode
 import kotlinx.collections.immutable.*
 import org.koin.androidx.compose.koinViewModel
@@ -48,7 +51,12 @@ fun CalendarScreen(
     modifier: Modifier,
     viewModel: CalendarViewModel = koinViewModel()
 ) {
-    val state = viewModel.viewState.collectAsState()
+    val state = viewModel.viewState.collectAsStateWithLifecycle()
+
+    val isDarkMode = isDarkMode()
+    LaunchedEffect(isDarkMode) {
+        viewModel.updateDarkModeStatus(isDarkMode)
+    }
 
     val context = LocalContext.current
     val notificationScheduler: INotificationScheduler = koinInject()
@@ -297,7 +305,7 @@ fun Day(
     val state = viewState.value
 
     val colorMap = ColorSource.getColorMap(isDarkMode())
-    val calendarColors = state.calendarColors
+    val calendarColorMap = state.calendarColorMap
     val dbHelper: IPeriodDatabaseHelper = koinInject()
 
     if (day.position != DayPosition.MonthDate) {
@@ -308,22 +316,22 @@ fun Day(
         return
     }
 
-    val backgroundColor = when {
-        day.date in state.selectedDays -> colorMap[calendarColors?.selectedColorName]
-            ?: colorMap["LightGray"]
-        day.date in state.periodDates.keys -> colorMap[calendarColors?.periodColorName]
-            ?: colorMap["Red"]
-        state.periodPredictionDate?.isEqual(day.date) == true -> colorMap[calendarColors?.nextPeriodColorName]
-            ?: colorMap["Yellow"]
-        day.date in state.ovulationDates -> colorMap[calendarColors?.ovulationColorName]
-            ?: colorMap["Blue"]
-        state.ovulationPredictionDate?.isEqual(day.date) == true -> colorMap[calendarColors?.nextOvulationColorName]
-            ?: colorMap["Magenta"]
+    val fallbackColors = if (isDarkMode()) {
+        ColorCombination(DarkGrey, Color.White)
+    } else {
+        ColorCombination(Color.Transparent, Black)
+    }
+    val dayColors = when {
+        day.date in state.selectedDays -> calendarColorMap[ColorSetting.SELECTION]
+        day.date in state.periodDates.keys -> calendarColorMap[ColorSetting.PERIOD]
+        state.periodPredictionDate?.isEqual(day.date) == true -> calendarColorMap[ColorSetting.EXPECTED_PERIOD]
+        day.date in state.ovulationDates -> calendarColorMap[ColorSetting.OVULATION]
+        state.ovulationPredictionDate?.isEqual(day.date) == true -> calendarColorMap[ColorSetting.EXPECTED_OVULATION]
         else -> null
-    } ?: Color.Transparent
+    } ?: fallbackColors
 
     val border = if (day.date.isEqual(LocalDate.now())) {
-        BorderStroke(1.dp, Color.DarkGray)
+        BorderStroke(1.5.dp, Color.DarkGray)
     } else null
 
     val fontStyleType = when {
@@ -335,11 +343,12 @@ fun Day(
     val isSelected = day.date in state.selectedDays
     val hasSymptomDate = day.date in state.symptomDates
 
+    val shape = MaterialTheme.shapes.small
     Surface(
         modifier = Modifier
             .aspectRatio(1f) // This ensures the cells remain square.
             .padding(2.dp)
-            .clip(MaterialTheme.shapes.small)
+            .clip(shape)
             .clickable {
                 val newSelectedDates = if (isSelected) {
                     state.selectedDays - day.date
@@ -348,15 +357,15 @@ fun Day(
                 }.toPersistentSet()
                 onAction(UiAction.SelectDays(newSelectedDates))
             },
-        shape = MaterialTheme.shapes.small,
-        color = backgroundColor,
+        shape = shape,
+        color = dayColors.backgroundColor,
         border = border
     ) {
         Box(contentAlignment = Alignment.Center) {
             Text(
                 text = day.date.dayOfMonth.toString(),
                 fontWeight = fontStyleType,
-                color = if (isSelected) MaterialTheme.colorScheme.onPrimary else MaterialTheme.colorScheme.onSurface
+                color = dayColors.textColor
             )
 
             // Add symptom circles
@@ -383,19 +392,15 @@ fun Day(
             if (state.showCycleNumbers) {
                 val cycleNumber = calculateCycleNumber(day.date, dbHelper)
                 if (cycleNumber > 0) {
-                    Box(
-                        modifier = Modifier
-                            .size(18.dp)
-                            .background(Color.Transparent)
-                            .align(Alignment.TopStart)
+                    Surface(
+                        shape = shape,
+                        color = Color.Transparent,
+                        modifier = Modifier.align(Alignment.TopStart)
                     ) {
                         Text(
                             text = cycleNumber.toString(),
-                            style = TextStyle(
-                                fontSize = 8.sp,
-                                textAlign = TextAlign.Left
-                            ),
-                            modifier = Modifier.padding(4.dp)
+                            fontSize = 8.sp,
+                            modifier = Modifier.padding(horizontal = 4.dp)
                         )
                     }
                 }

app/src/main/java/com/mensinator/app/calendar/CalendarViewModel.kt

@@ -8,11 +8,16 @@ import com.mensinator.app.business.IOvulationPrediction
 import com.mensinator.app.business.IPeriodDatabaseHelper
 import com.mensinator.app.business.IPeriodPrediction
 import com.mensinator.app.business.PeriodId
+import com.mensinator.app.data.ColorSource
 import com.mensinator.app.data.Symptom
 import com.mensinator.app.data.isActive
+import com.mensinator.app.extensions.pickBestContrastTextColorForThisBackground
+import com.mensinator.app.settings.ColorSetting
 import com.mensinator.app.settings.IntSetting
 import com.mensinator.app.settings.StringSetting
 import com.mensinator.app.ui.ResourceMapper
+import com.mensinator.app.ui.theme.Black
+import com.mensinator.app.ui.theme.DarkGrey
 import kotlinx.collections.immutable.*
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -29,6 +34,7 @@ class CalendarViewModel(
     private val periodPrediction: IPeriodPrediction,
     private val ovulationPrediction: IOvulationPrediction,
 ) : ViewModel() {
+
     private val _viewState = MutableStateFlow(
         ViewState()
     )
@@ -65,12 +71,20 @@ class CalendarViewModel(
                     activeSymptoms = dbHelper.getAllSymptoms().filter { it.isActive }
                         .toPersistentSet(),
                     periodMessageText = periodMessageText,
-                    calendarColors = getCalendarColors()
                 )
             }
         }
     }
 
+    fun updateDarkModeStatus(isDarkMode: Boolean) {
+        _viewState.update {
+            it.copy(
+                isDarkMode = isDarkMode,
+                calendarColorMap = getCalendarColorMap(isDarkMode)
+            )
+        }
+    }
+
     fun onAction(uiAction: UiAction): Unit = when (uiAction) {
         is UiAction.UpdateFocusedYearMonth -> {
             _viewState.update {
@@ -121,17 +135,25 @@ class CalendarViewModel(
         }
     }
 
-    private fun getCalendarColors(): CalendarColors {
-        return CalendarColors(
-            periodColorName = dbHelper.getSettingByKey("period_color")?.value,
-            selectedColorName = dbHelper.getSettingByKey("selection_color")?.value,
-            nextPeriodColorName = dbHelper.getSettingByKey("expected_period_color")?.value,
-            ovulationColorName = dbHelper.getSettingByKey("ovulation_color")?.value,
-            nextOvulationColorName = dbHelper.getSettingByKey("expected_ovulation_color")?.value,
-        )
+    private fun getCalendarColorMap(isDarkMode: Boolean): Map<ColorSetting, ColorCombination> {
+        return ColorSetting.entries.associate {
+            val backgroundColor = ColorSource.getColor(
+                isDarkMode,
+                dbHelper.getSettingByKey(it.settingDbKey)?.value ?: "LightGray"
+            )
+            val textColor = backgroundColor.pickBestContrastTextColorForThisBackground(
+                isDarkMode,
+                DarkGrey,
+                Black
+            )
+
+            it to ColorCombination(backgroundColor, textColor)
+        }
     }
 
     data class ViewState(
+        val isDarkMode: Boolean = false,
+
         val showCycleNumbers: Boolean = false,
         val focusedYearMonth: YearMonth = YearMonth.now(),
         val periodPredictionDate: LocalDate? = null,
@@ -144,7 +166,7 @@ class CalendarViewModel(
         val periodMessageText: String? = null,
         val selectedDays: PersistentSet<LocalDate> = persistentSetOf(),
         val activeSymptomIdsForLatestSelectedDay: PersistentSet<Int> = persistentSetOf(),
-        val calendarColors: CalendarColors? = null
+        val calendarColorMap: Map<ColorSetting, ColorCombination> = mapOf()
     )
 
     sealed class UiAction {

app/src/main/java/com/mensinator/app/calendar/ColorCombination.kt

@@ -0,0 +1,8 @@
+package com.mensinator.app.calendar
+
+import androidx.compose.ui.graphics.Color
+
+data class ColorCombination(
+    val backgroundColor: Color,
+    val textColor: Color,
+)

app/src/main/java/com/mensinator/app/extensions/ColorExtensions.kt

@@ -0,0 +1,32 @@
+package com.mensinator.app.extensions
+
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.luminance
+
+// Pick the text color with the best contrast against this background color.
+fun Color.pickBestContrastTextColorForThisBackground(
+    isDarkMode: Boolean,
+    textColor1: Color,
+    textColor2: Color
+): Color {
+    fun calculateContrastRatio(color1: Color, color2: Color): Double {
+        val lum1 = color1.luminance()
+        val lum2 = color2.luminance()
+
+        val lighter = maxOf(lum1, lum2)
+        val darker = minOf(lum1, lum2)
+
+        return (lighter + 0.05) / (darker + 0.05) // +0.05 to avoid null division
+    }
+
+    val safeBackground = when {
+        Color.Transparent == this && isDarkMode -> Color.Black
+        Color.Transparent == this -> Color.White
+        else -> this
+    }
+
+    val contrast1 = calculateContrastRatio(safeBackground, textColor1)
+    val contrast2 = calculateContrastRatio(safeBackground, textColor2)
+
+    return if (contrast1 >= contrast2) textColor1 else textColor2
+}

app/src/main/java/com/mensinator/app/settings/SettingsViewModel.kt

@@ -7,9 +7,9 @@ import android.util.Log
 import android.widget.Toast
 import androidx.compose.ui.graphics.Color
 import androidx.lifecycle.ViewModel
+import com.mensinator.app.R
 import com.mensinator.app.business.IExportImport
 import com.mensinator.app.business.IPeriodDatabaseHelper
-import com.mensinator.app.R
 import com.mensinator.app.data.ColorSource
 import com.mensinator.app.settings.ColorSetting.*
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -30,7 +30,6 @@ class SettingsViewModel(
             periodColor = Color.Yellow,
             selectionColor = Color.Yellow,
             expectedPeriodColor = Color.Yellow,
-            periodSelectionColor = Color.Yellow,
             ovulationColor = Color.Yellow,
             expectedOvulationColor = Color.Yellow,
             openColorPickerForSetting = null,
@@ -64,7 +63,6 @@ class SettingsViewModel(
         val periodColor: Color,
         val selectionColor: Color,
         val expectedPeriodColor: Color,
-        val periodSelectionColor: Color,
         val ovulationColor: Color,
         val expectedOvulationColor: Color,
         val openColorPickerForSetting: ColorSetting? = null,
@@ -106,7 +104,6 @@ class SettingsViewModel(
                 periodColor = getColor(isDarkMode, PERIOD.settingDbKey),
                 selectionColor = getColor(isDarkMode, SELECTION.settingDbKey),
                 expectedPeriodColor = getColor(isDarkMode, EXPECTED_PERIOD.settingDbKey),
-                periodSelectionColor = getColor(isDarkMode, PERIOD_SELECTION.settingDbKey),
                 ovulationColor = getColor(isDarkMode, OVULATION.settingDbKey),
                 expectedOvulationColor = getColor(isDarkMode, EXPECTED_OVULATION.settingDbKey),
 
@@ -238,10 +235,9 @@ class SettingsViewModel(
 }
 
 enum class ColorSetting(val stringResId: Int, val settingDbKey: String) {
-    PERIOD(R.string.period_color, "period_color"),
     SELECTION(R.string.selection_color, "selection_color"),
+    PERIOD(R.string.period_color, "period_color"),
     EXPECTED_PERIOD(R.string.expected_period_color, "expected_period_color"),
-    PERIOD_SELECTION(R.string.period_selection_color, "period_selection_color"),
     OVULATION(R.string.ovulation_color, "ovulation_color"),
     EXPECTED_OVULATION(R.string.expected_ovulation_color, "expected_ovulation_color"),
 }

app/src/main/java/com/mensinator/app/ui/theme/Color.kt

@@ -17,5 +17,6 @@ val PurpleGrey40 = Color(0xFF625B71)
 val Pink40 = Color(0xFF7D5260)
 
 
-val Black = Color(0xFF000000)
-val White = Color(0xFFC0C0C0)
+val Black = Color.Black
+val DarkGrey = Color(29, 27, 32)
+val White = Color.White