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Merge pull request #170 from rubensousa/text_scrolling
Add support for scrollbars & discrete scrolling
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153 changes: 153 additions & 0 deletions
153
dpadrecyclerview/src/main/java/com/rubensousa/dpadrecyclerview/DpadScroller.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,153 @@ | ||
| /* | ||
| * Copyright 2023 Rúben Sousa | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package com.rubensousa.dpadrecyclerview | ||
|
|
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| import android.view.KeyEvent | ||
| import android.view.ViewGroup | ||
| import androidx.recyclerview.widget.RecyclerView | ||
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| /** | ||
| * A helper class that allows scrolling a [DpadRecyclerView] based on specific scroll distances, | ||
| * ignoring the default alignment behavior. | ||
| * | ||
| * A typical use case for this class is a terms & conditions page, | ||
| * where a large amount of text is displayed, which the user isn't expected to interact with | ||
| */ | ||
| class DpadScroller( | ||
| private val calculator: ScrollDistanceCalculator = DefaultScrollDistanceCalculator(), | ||
| ) { | ||
|
|
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| private var recyclerView: DpadRecyclerView? = null | ||
| private val keyListener = KeyListener() | ||
| private var smoothScrollEnabled = true | ||
|
|
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| /** | ||
| * Attaches this [DpadScroller] to a new [DpadRecyclerView] to start observing key events. | ||
| * If you no longer need this behavior, call [detach] | ||
| * | ||
| * @param recyclerView The RecyclerView that will be scrolled discretely | ||
| */ | ||
| fun attach(recyclerView: DpadRecyclerView) { | ||
| detach() | ||
| this.recyclerView = recyclerView | ||
| recyclerView.descendantFocusability = ViewGroup.FOCUS_BLOCK_DESCENDANTS | ||
| recyclerView.setOnKeyInterceptListener(keyListener) | ||
| } | ||
|
|
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| /** | ||
| * Stops observing key events to scroll the current attached [DpadRecyclerView], if any exists | ||
| */ | ||
| fun detach() { | ||
| recyclerView?.descendantFocusability = ViewGroup.FOCUS_AFTER_DESCENDANTS | ||
| recyclerView?.setOnKeyInterceptListener(null) | ||
| recyclerView = null | ||
| } | ||
|
|
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| /** | ||
| * Enables or disables smooth scrolling on key events | ||
| */ | ||
| fun setSmoothScrollEnabled(enabled: Boolean) { | ||
| smoothScrollEnabled = enabled | ||
| } | ||
|
|
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| private inner class KeyListener : DpadRecyclerView.OnKeyInterceptListener { | ||
|
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| override fun onInterceptKeyEvent(event: KeyEvent): Boolean { | ||
| val currentRecyclerView = recyclerView ?: return false | ||
| when (event.action) { | ||
| KeyEvent.ACTION_DOWN -> { | ||
| return if (currentRecyclerView.getOrientation() == RecyclerView.VERTICAL) { | ||
| scrollVertically(currentRecyclerView, event) | ||
| } else { | ||
| scrollHorizontally(currentRecyclerView, event) | ||
| } | ||
| } | ||
| } | ||
| return false | ||
| } | ||
|
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| private fun scrollVertically(recyclerView: DpadRecyclerView, event: KeyEvent): Boolean { | ||
| val scrollDistance = calculator.calculateScrollDistance(recyclerView, event) | ||
| when (event.keyCode) { | ||
| KeyEvent.KEYCODE_DPAD_DOWN -> { | ||
| if (smoothScrollEnabled) { | ||
| recyclerView.smoothScrollBy(0, scrollDistance) | ||
| } else { | ||
| recyclerView.scrollBy(0, scrollDistance) | ||
| } | ||
| return true | ||
| } | ||
|
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| KeyEvent.KEYCODE_DPAD_UP -> { | ||
| if (smoothScrollEnabled) { | ||
| recyclerView.smoothScrollBy(0, -scrollDistance) | ||
| } else { | ||
| recyclerView.scrollBy(0, -scrollDistance) | ||
| } | ||
| return true | ||
| } | ||
| } | ||
| return false | ||
| } | ||
|
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| private fun scrollHorizontally(recyclerView: DpadRecyclerView, event: KeyEvent): Boolean { | ||
| val scrollDistance = calculator.calculateScrollDistance(recyclerView, event) | ||
| when (event.keyCode) { | ||
| KeyEvent.KEYCODE_DPAD_RIGHT -> { | ||
| if (smoothScrollEnabled) { | ||
| recyclerView.smoothScrollBy(0, scrollDistance) | ||
| } else { | ||
| recyclerView.scrollBy(0, scrollDistance) | ||
| } | ||
| return true | ||
| } | ||
|
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| KeyEvent.KEYCODE_DPAD_LEFT -> { | ||
| if (smoothScrollEnabled) { | ||
| recyclerView.smoothScrollBy(0, -scrollDistance) | ||
| } else { | ||
| recyclerView.scrollBy(0, -scrollDistance) | ||
| } | ||
| return true | ||
| } | ||
| } | ||
| return false | ||
| } | ||
|
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| } | ||
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| interface ScrollDistanceCalculator { | ||
| /** | ||
| * @return the number of pixels we should scroll for this [event] | ||
| */ | ||
| fun calculateScrollDistance(recyclerView: DpadRecyclerView, event: KeyEvent): Int | ||
| } | ||
|
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| private class DefaultScrollDistanceCalculator : ScrollDistanceCalculator { | ||
| override fun calculateScrollDistance( | ||
| recyclerView: DpadRecyclerView, | ||
| event: KeyEvent | ||
| ): Int { | ||
| return if (recyclerView.getOrientation() == RecyclerView.VERTICAL) { | ||
| recyclerView.height / 4 | ||
| } else { | ||
| recyclerView.width / 4 | ||
| } | ||
| } | ||
| } | ||
|
|
||
| } |
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