Add better scrolling (alamkanak#145)

* Fix crash in sample app on APIs below 24

* Make firstVisibleDate and lastVisibleDate non-nullable

* Add smooth vertical and horizontal scrolling

* Fix issue in TimeColumnDrawer where the wrong hours where displayed

Author: thellmund

core/src/main/java/com/alamkanak/weekview/CalendarExtensions.kt

@@ -25,11 +25,17 @@ internal inline class Millis(val millis: Int) : Duration {
         get() = millis
 }
 
-internal val Calendar.hour: Int
+internal var Calendar.hour: Int
     get() = get(Calendar.HOUR_OF_DAY)
+    set(value) {
+        set(Calendar.HOUR_OF_DAY, value)
+    }
 
-internal val Calendar.minute: Int
+internal var Calendar.minute: Int
     get() = get(Calendar.MINUTE)
+    set(value) {
+        set(Calendar.MINUTE, value)
+    }
 
 internal val Calendar.dayOfWeek: Int
     get() = get(Calendar.DAY_OF_WEEK)
@@ -258,3 +264,13 @@ internal fun Calendar.format(
     val sdf = SimpleDateFormat.getDateInstance(format)
     return sdf.format(time)
 }
+
+internal fun Calendar.limitBy(minTime: Calendar, maxTime: Calendar) {
+    if (this < minTime) {
+        hour = minTime.hour
+        minute = 0
+    } else if (this > maxTime) {
+        hour = maxTime.hour
+        minute = 0
+    }
+}

core/src/main/java/com/alamkanak/weekview/PublicApi.kt

@@ -0,0 +1,3 @@
+package com.alamkanak.weekview
+
+annotation class PublicApi

core/src/main/java/com/alamkanak/weekview/SavedState.kt

@@ -8,22 +8,22 @@ import java.util.Calendar
 internal class SavedState : BaseSavedState {
 
     var numberOfVisibleDays: Int = 0
-    var firstVisibleDate: Calendar? = null
+    var firstVisibleDate: Calendar = today()
 
     constructor(superState: Parcelable) : super(superState)
 
     constructor(
         superState: Parcelable,
         numberOfVisibleDays: Int,
-        firstVisibleDate: Calendar?
+        firstVisibleDate: Calendar
     ) : super(superState) {
         this.numberOfVisibleDays = numberOfVisibleDays
         this.firstVisibleDate = firstVisibleDate
     }
 
     constructor(source: Parcel) : super(source) {
         numberOfVisibleDays = source.readInt()
-        firstVisibleDate = source.readSerializable() as? Calendar
+        firstVisibleDate = source.readSerializable() as Calendar
     }
 
     override fun writeToParcel(out: Parcel, flags: Int) {

core/src/main/java/com/alamkanak/weekview/ScaleGestureDetector.kt

@@ -0,0 +1,39 @@
+package com.alamkanak.weekview
+
+import android.content.Context
+import android.view.MotionEvent
+import android.view.ScaleGestureDetector as AndroidScaleGestureDetector
+
+internal class ScaleGestureDetector(
+    context: Context,
+    private val config: WeekViewConfigWrapper,
+    private val valueAnimator: ValueAnimator,
+    private val onInvalidation: () -> Unit
+) {
+
+    private val listener = object : AndroidScaleGestureDetector.OnScaleGestureListener {
+
+        override fun onScaleBegin(
+            detector: AndroidScaleGestureDetector
+        ): Boolean = !valueAnimator.isRunning
+
+        override fun onScale(detector: AndroidScaleGestureDetector): Boolean {
+            val hourHeight = config.hourHeight
+            config.newHourHeight = hourHeight * detector.scaleFactor
+            onInvalidation()
+            return true
+        }
+
+        override fun onScaleEnd(detector: AndroidScaleGestureDetector) {
+            onInvalidation()
+        }
+    }
+
+    private val detector = AndroidScaleGestureDetector(context, listener)
+
+    fun onTouchEvent(event: MotionEvent) {
+        if (!valueAnimator.isRunning) {
+            detector.onTouchEvent(event)
+        }
+    }
+}

core/src/main/java/com/alamkanak/weekview/TimeColumnDrawer.kt

@@ -15,8 +15,8 @@ internal class TimeColumnDrawer(
     }
 
     private fun cacheTimeLabels() = with(config) {
-        for (hour in startHour until hoursPerDay step timeColumnHoursInterval) {
-            timeLabelCache.put(hour, dateTimeInterpreter.interpretTime(hour + minHour))
+        for (hour in timeRange step timeColumnHoursInterval) {
+            timeLabelCache.put(hour, dateTimeInterpreter.interpretTime(hour))
         }
     }
 
@@ -32,8 +32,8 @@ internal class TimeColumnDrawer(
         val hourLines = FloatArray(hoursPerDay * 4)
         val hourStep = timeColumnHoursInterval
 
-        for (hour in startHour until hoursPerDay step hourStep) {
-            val heightOfHour = (hourHeight * hour)
+        for (hour in timeRange step hourStep) {
+            val heightOfHour = hourHeight * (hour - minHour)
             topMargin = headerHeight + currentOrigin.y + heightOfHour
 
             val isOutsideVisibleArea = topMargin > bottom
@@ -49,7 +49,9 @@ internal class TimeColumnDrawer(
                 y += timeTextHeight / 2 + hourSeparatorPaint.strokeWidth + timeColumnPadding
             }
 
-            canvas.drawText(timeLabelCache[hour], x, y, timeTextPaint)
+            if (hour in timeLabelCache) {
+                canvas.drawText(timeLabelCache[hour], x, y, timeTextPaint)
+            }
 
             if (showTimeColumnHourSeparator && hour > 0) {
                 val j = hour - 1
@@ -77,3 +79,5 @@ internal class TimeColumnDrawer(
         cacheTimeLabels()
     }
 }
+
+private operator fun <E> SparseArray<E>.contains(key: Int): Boolean = indexOfKey(key) >= 0

core/src/main/java/com/alamkanak/weekview/ValueAnimator.kt

@@ -0,0 +1,53 @@
+package com.alamkanak.weekview
+
+import android.animation.Animator
+import android.animation.ValueAnimator as AndroidValueAnimator
+import android.view.animation.DecelerateInterpolator
+
+internal class ValueAnimator {
+
+    private var valueAnimator: AndroidValueAnimator? = null
+
+    val isRunning: Boolean
+        get() = valueAnimator?.isStarted ?: false
+
+    fun animate(
+        fromValue: Float,
+        toValue: Float,
+        duration: Long = 300,
+        onUpdate: (Float) -> Unit,
+        onEnd: () -> Unit = {}
+    ) {
+        valueAnimator?.cancel()
+
+        valueAnimator = AndroidValueAnimator.ofFloat(fromValue, toValue).apply {
+            setDuration(duration)
+            interpolator = DecelerateInterpolator()
+
+            addUpdateListener {
+                val value = it.animatedValue as Float
+                onUpdate(value)
+            }
+
+            addEndListener { onEnd() }
+
+            start()
+        }
+    }
+
+    fun stop() {
+        valueAnimator?.cancel()
+    }
+}
+
+private fun AndroidValueAnimator.addEndListener(listener: (AndroidValueAnimator) -> Unit) {
+    addListener(object : Animator.AnimatorListener {
+        override fun onAnimationStart(animator: Animator) {
+            listener(animator as AndroidValueAnimator)
+        }
+
+        override fun onAnimationEnd(animator: Animator) = Unit
+        override fun onAnimationCancel(animator: Animator) = Unit
+        override fun onAnimationRepeat(animator: Animator) = Unit
+    })
+}