Add support for additional drawers

Additional drawers allow users to customize the appearance of the calendar by drawing additional items on any layer (background, on top of the grid, on top of everything, etc). This allows supporting customization use-cases that are too uncommon to implement and support in the base library.
thellmund · Nov 28, 2020 · 2308e3b · 2308e3b
1 parent 88638dc
commit 2308e3b
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Showing 5 changed files with 94 additions and 27 deletions.
diff --git a/core/src/main/java/com/alamkanak/weekview/CalendarRenderer.kt b/core/src/main/java/com/alamkanak/weekview/CalendarRenderer.kt
@@ -5,12 +5,13 @@ import android.graphics.Paint
 import android.graphics.RectF
 import android.text.StaticLayout
 import androidx.collection.ArrayMap
+import com.alamkanak.weekview.WeekView.DrawBase
 import java.util.Calendar
 import kotlin.math.max
 import kotlin.math.min
 
 internal class CalendarRenderer(
-    viewState: ViewState,
+    private val viewState: ViewState,
     eventChipsCacheProvider: EventChipsCacheProvider
 ) : Renderer {
 
@@ -29,9 +30,21 @@ internal class CalendarRenderer(
     override fun render(canvas: Canvas) {
         eventsUpdater.update()
 
+        drawAdditional(canvas, DrawBase.CANVAS)
         for (drawer in drawers) {
-            drawer.draw(canvas)
+            drawer.draw(canvas, viewState)
+            drawAdditional(canvas, drawer.base)
         }
+        drawAdditional(canvas, DrawBase.TOP)
+    }
+
+    private fun drawAdditional(canvas: Canvas, base: DrawBase) {
+        val drawers = viewState.additionalDrawers[base]
+        if (drawers.isNullOrEmpty()) return
+
+        val saveCount = canvas.save()
+        drawers.forEach { it.draw(canvas, viewState) }
+        canvas.restoreToCount(saveCount)
     }
 }
 
@@ -107,9 +120,10 @@ private class SingleEventsUpdater(
 
 private class DayBackgroundDrawer(
     private val viewState: ViewState
-) : Drawer {
+) : WeekView.Drawer {
+    override val base = DrawBase.BACKGROUND
 
-    override fun draw(canvas: Canvas) {
+    override fun draw(canvas: Canvas, bounds: WeekView.DrawBounds) {
         canvas.drawInBounds(viewState.calendarGridBounds) {
             viewState.dateRangeWithStartPixels.forEach { (date, startPixel) ->
                 drawDayBackground(date, startPixel, canvas)
@@ -167,9 +181,10 @@ private class DayBackgroundDrawer(
 
 private class BackgroundGridDrawer(
     private val viewState: ViewState
-) : Drawer {
+) : WeekView.Drawer {
+    override val base = DrawBase.GRID
 
-    override fun draw(canvas: Canvas) {
+    override fun draw(canvas: Canvas, bounds: WeekView.DrawBounds) {
         canvas.drawInBounds(viewState.calendarGridBounds) {
             if (viewState.showHourSeparators) {
                 drawHourLines()
@@ -201,7 +216,7 @@ private class BackgroundGridDrawer(
     private fun Canvas.drawHourLine(hour: Int) {
         val heightOfHour = (viewState.hourHeight * (hour - viewState.minHour))
         val verticalOffset = viewState.headerHeight + viewState.currentOrigin.y + heightOfHour
-        val horizontalOffset = if (viewState.isLtr) viewState.timeColumnWidth else 0f
+        val horizontalOffset = viewState.calendarGridBounds.left
 
         drawHorizontalLine(
             verticalOffset = verticalOffset,
@@ -216,11 +231,12 @@ private class SingleEventsDrawer(
     private val viewState: ViewState,
     private val chipsCacheProvider: EventChipsCacheProvider,
     private val eventLabels: ArrayMap<String, StaticLayout>
-) : Drawer {
+) : WeekView.Drawer {
+    override val base = DrawBase.EVENTS
 
     private val eventChipDrawer = EventChipDrawer(viewState)
 
-    override fun draw(canvas: Canvas) {
+    override fun draw(canvas: Canvas, bounds: WeekView.DrawBounds) {
         canvas.drawInBounds(viewState.calendarGridBounds) {
             for (date in viewState.dateRange) {
                 drawEventsForDate(date)
@@ -241,9 +257,10 @@ private class SingleEventsDrawer(
 
 private class NowLineDrawer(
     private val viewState: ViewState
-) : Drawer {
+) : WeekView.Drawer {
+    override val base = DrawBase.NOWLINE
 
-    override fun draw(canvas: Canvas) {
+    override fun draw(canvas: Canvas, bounds: WeekView.DrawBounds) {
         if (viewState.showNowLine.not()) {
             return
         }

diff --git a/core/src/main/java/com/alamkanak/weekview/HeaderRenderer.kt b/core/src/main/java/com/alamkanak/weekview/HeaderRenderer.kt
@@ -136,7 +136,7 @@ private class HeaderUpdater(
 private class DateLabelsDrawer(
     private val viewState: ViewState,
     private val dateLabelLayouts: SparseArray<StaticLayout>
-) : Drawer {
+) : DrawerInternal {
 
     override fun draw(canvas: Canvas) {
         canvas.drawInBounds(viewState.headerBounds) {
@@ -240,7 +240,7 @@ private class AllDayEventsUpdater(
 internal class AllDayEventsDrawer(
     private val viewState: ViewState,
     private val allDayEventLayouts: ArrayMap<EventChip, StaticLayout>
-) : Drawer {
+) : DrawerInternal {
 
     private val eventChipDrawer = EventChipDrawer(viewState)
 
@@ -319,7 +319,7 @@ internal class AllDayEventsDrawer(
 private class HeaderDrawer(
     context: Context,
     private val viewState: ViewState
-) : Drawer {
+) : DrawerInternal {
 
     private val upArrow: Drawable by lazy {
         checkNotNull(ContextCompat.getDrawable(context, R.drawable.ic_arrow_up))

diff --git a/core/src/main/java/com/alamkanak/weekview/Renderers.kt b/core/src/main/java/com/alamkanak/weekview/Renderers.kt
@@ -6,7 +6,7 @@ internal interface Updater {
     fun update()
 }
 
-internal interface Drawer {
+internal interface DrawerInternal {
     fun draw(canvas: Canvas)
 }
 

diff --git a/core/src/main/java/com/alamkanak/weekview/ViewState.kt b/core/src/main/java/com/alamkanak/weekview/ViewState.kt
@@ -8,21 +8,21 @@ import android.graphics.Typeface
 import android.os.Build
 import android.text.TextPaint
 import android.view.View
-import java.util.Calendar
+import java.util.*
 import kotlin.math.ceil
 import kotlin.math.max
 import kotlin.math.min
 
 typealias DateFormatter = (Calendar) -> String
 typealias TimeFormatter = (Int) -> String
 
-internal class ViewState {
+internal class ViewState : WeekView.DrawBounds {
 
     // View
-    var viewWidth: Int = 0
-    var viewHeight: Int = 0
+    override var viewWidth: Int = 0
+    override var viewHeight: Int = 0
 
-    var isLtr: Boolean = true
+    override var isLtr: Boolean = true
 
     // Calendar state
     var firstVisibleDate: Calendar = today()
@@ -38,7 +38,7 @@ internal class ViewState {
     val dateRangeWithStartPixels: MutableList<Pair<Calendar, Float>> = mutableListOf()
 
     // Calendar configuration
-    var numberOfVisibleDays: Int = 3
+    override var numberOfVisibleDays: Int = 3
     var restoreNumberOfVisibleDays: Boolean = true
     var showFirstDayOfWeekFirst: Boolean = false
     var showCurrentTimeFirst: Boolean = false
@@ -64,7 +64,7 @@ internal class ViewState {
     var eventMarginVertical: Int = 0
     var singleDayHorizontalPadding: Int = 0
 
-    var hourHeight: Float = 0f
+    override var hourHeight: Float = 0f
     var minHourHeight: Float = 0f
     var maxHourHeight: Float = 0f
     var effectiveMinHourHeight: Float = 0f
@@ -90,11 +90,13 @@ internal class ViewState {
     @Deprecated("No longer used")
     var scrollDuration: Int = 0
 
-    var minHour: Int = 0
-    var maxHour: Int = 24
+    override var minHour: Int = 0
+    override var maxHour: Int = 24
 
     var typeface: Typeface = Typeface.DEFAULT
 
+    var additionalDrawers: Map<WeekView.DrawBase, List<WeekView.Drawer>> = emptyMap()
+
     var timeColumnWidth: Float = 0f
     var timeColumnTextHeight: Float = 0f
 
@@ -134,13 +136,13 @@ internal class ViewState {
 
     // In LTR: Dates in the past have origin.x > 0, dates in the future have origin.x < 0
     // In RTL: Dates in the past have origin.x < 0, dates in the future have origin.x > 0
-    var currentOrigin = PointF(0f, 0f)
+    override var currentOrigin = PointF(0f, 0f)
 
     val headerBackgroundPaint = Paint()
 
     val headerBackgroundWithShadowPaint = Paint()
 
-    val dayWidth: Float
+    override val dayWidth: Float
         get() = (viewWidth - timeColumnWidth) / numberOfVisibleDays
 
     val drawableDayWidth: Float
@@ -237,7 +239,7 @@ internal class ViewState {
 
     private val _calendarGridBounds: RectF = RectF()
 
-    val calendarGridBounds: RectF
+    override val calendarGridBounds: RectF
         get() = _calendarGridBounds.apply {
             left = if (isLtr) timeColumnWidth else 0f
             top = headerHeight

diff --git a/core/src/main/java/com/alamkanak/weekview/WeekView.kt b/core/src/main/java/com/alamkanak/weekview/WeekView.kt
@@ -4,6 +4,7 @@ import android.annotation.SuppressLint
 import android.content.Context
 import android.content.res.Configuration
 import android.graphics.Canvas
+import android.graphics.PointF
 import android.graphics.RectF
 import android.graphics.Typeface
 import android.os.Parcelable
@@ -1339,6 +1340,53 @@ class WeekView @JvmOverloads constructor(
             invalidate()
         }
 
+    /*
+     ***********************************************************************************************
+     *
+     *   Custom drawers
+     *
+     ***********************************************************************************************
+     */
+
+    /**
+     * Bounds available to [Drawer] to draw on the [Canvas] during rendering.
+     */
+    @PublicApi
+    interface DrawBounds {
+        val calendarGridBounds: RectF
+        val currentOrigin: PointF
+        val viewWidth: Int
+        val viewHeight: Int
+        val dayWidth: Float
+        val hourHeight: Float
+        val isLtr: Boolean
+    }
+
+    @PublicApi
+    enum class DrawBase {
+        CANVAS, BACKGROUND, GRID, EVENTS, NOWLINE, TOP;
+    }
+
+    @PublicApi
+    interface Drawer {
+        fun draw(canvas: Canvas, bounds: DrawBounds)
+        val base: DrawBase
+    }
+
+    /**
+     * Additional drawers that will be draw on the view during rendering.
+     *
+     * Each drawer will draw on top of the layer specified by [Drawer.base]. Drawers with the same
+     * base will draw in the order specified in the list.
+     */
+    @PublicApi
+    var additionalDrawers: List<Drawer>
+        get() = viewState.additionalDrawers.values.flatten()
+        set(value) {
+            viewState.additionalDrawers = value.groupBy { it.base }
+            invalidate()
+        }
+
     /*
      ***********************************************************************************************
      *