From 2894e0dadba1a5e65dbca35ac44781ed7b2bf5b5 Mon Sep 17 00:00:00 2001 From: gedoor Date: Sat, 27 Mar 2021 23:30:59 +0800 Subject: [PATCH] =?UTF-8?q?=E4=BC=98=E5=8C=96?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../app/ui/widget/page2/FrameLayoutNS.kt | 96 +++++++++++++++++++ .../app/ui/widget/page2/LinearLayoutNS.kt | 96 +++++++++++++++++++ 2 files changed, 192 insertions(+) create mode 100644 app/src/main/java/io/legado/app/ui/widget/page2/FrameLayoutNS.kt create mode 100644 app/src/main/java/io/legado/app/ui/widget/page2/LinearLayoutNS.kt diff --git a/app/src/main/java/io/legado/app/ui/widget/page2/FrameLayoutNS.kt b/app/src/main/java/io/legado/app/ui/widget/page2/FrameLayoutNS.kt new file mode 100644 index 000000000..050b4286f --- /dev/null +++ b/app/src/main/java/io/legado/app/ui/widget/page2/FrameLayoutNS.kt @@ -0,0 +1,96 @@ +package io.legado.app.ui.widget.page2 + +import android.content.Context +import android.util.AttributeSet +import android.view.MotionEvent +import android.view.View +import android.view.ViewConfiguration +import android.widget.FrameLayout +import androidx.viewpager2.widget.ViewPager2 +import androidx.viewpager2.widget.ViewPager2.ORIENTATION_HORIZONTAL +import kotlin.math.absoluteValue +import kotlin.math.sign + +/** + * Layout to wrap a scrollable component inside a ViewPager2. Provided as a solution to the problem + * where pages of ViewPager2 have nested scrollable elements that scroll in the same direction as + * ViewPager2. The scrollable element needs to be the immediate and only child of this host layout. + * + * This solution has limitations when using multiple levels of nested scrollable elements + * (e.g. a horizontal RecyclerView in a vertical RecyclerView in a horizontal ViewPager2). + */ +class FrameLayoutNS : FrameLayout { + constructor(context: Context) : super(context) + constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) + + private var touchSlop = 0 + private var initialX = 0f + private var initialY = 0f + private val parentViewPager: ViewPager2? + get() { + var v: View? = parent as? View + while (v != null && v !is ViewPager2) { + v = v.parent as? View + } + return v as? ViewPager2 + } + + private val child: View? get() = if (childCount > 0) getChildAt(0) else null + + init { + touchSlop = ViewConfiguration.get(context).scaledTouchSlop + } + + private fun canChildScroll(orientation: Int, delta: Float): Boolean { + val direction = -delta.sign.toInt() + return when (orientation) { + 0 -> child?.canScrollHorizontally(direction) ?: false + 1 -> child?.canScrollVertically(direction) ?: false + else -> throw IllegalArgumentException() + } + } + + override fun onInterceptTouchEvent(e: MotionEvent): Boolean { + handleInterceptTouchEvent(e) + return super.onInterceptTouchEvent(e) + } + + private fun handleInterceptTouchEvent(e: MotionEvent) { + val orientation = parentViewPager?.orientation ?: return + + // Early return if child can't scroll in same direction as parent + if (!canChildScroll(orientation, -1f) && !canChildScroll(orientation, 1f)) { + return + } + + if (e.action == MotionEvent.ACTION_DOWN) { + initialX = e.x + initialY = e.y + parent.requestDisallowInterceptTouchEvent(true) + } else if (e.action == MotionEvent.ACTION_MOVE) { + val dx = e.x - initialX + val dy = e.y - initialY + val isVpHorizontal = orientation == ORIENTATION_HORIZONTAL + + // assuming ViewPager2 touch-slop is 2x touch-slop of child + val scaledDx = dx.absoluteValue * if (isVpHorizontal) .5f else 1f + val scaledDy = dy.absoluteValue * if (isVpHorizontal) 1f else .5f + + if (scaledDx > touchSlop || scaledDy > touchSlop) { + if (isVpHorizontal == (scaledDy > scaledDx)) { + // Gesture is perpendicular, allow all parents to intercept + parent.requestDisallowInterceptTouchEvent(false) + } else { + // Gesture is parallel, query child if movement in that direction is possible + if (canChildScroll(orientation, if (isVpHorizontal) dx else dy)) { + // Child can scroll, disallow all parents to intercept + parent.requestDisallowInterceptTouchEvent(true) + } else { + // Child cannot scroll, allow all parents to intercept + parent.requestDisallowInterceptTouchEvent(false) + } + } + } + } + } +} \ No newline at end of file diff --git a/app/src/main/java/io/legado/app/ui/widget/page2/LinearLayoutNS.kt b/app/src/main/java/io/legado/app/ui/widget/page2/LinearLayoutNS.kt new file mode 100644 index 000000000..b82baa455 --- /dev/null +++ b/app/src/main/java/io/legado/app/ui/widget/page2/LinearLayoutNS.kt @@ -0,0 +1,96 @@ +package io.legado.app.ui.widget.page2 + +import android.content.Context +import android.util.AttributeSet +import android.view.MotionEvent +import android.view.View +import android.view.ViewConfiguration +import android.widget.LinearLayout +import androidx.viewpager2.widget.ViewPager2 +import androidx.viewpager2.widget.ViewPager2.ORIENTATION_HORIZONTAL +import kotlin.math.absoluteValue +import kotlin.math.sign + +/** + * Layout to wrap a scrollable component inside a ViewPager2. Provided as a solution to the problem + * where pages of ViewPager2 have nested scrollable elements that scroll in the same direction as + * ViewPager2. The scrollable element needs to be the immediate and only child of this host layout. + * + * This solution has limitations when using multiple levels of nested scrollable elements + * (e.g. a horizontal RecyclerView in a vertical RecyclerView in a horizontal ViewPager2). + */ +class LinearLayoutNS : LinearLayout { + constructor(context: Context) : super(context) + constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) + + private var touchSlop = 0 + private var initialX = 0f + private var initialY = 0f + private val parentViewPager: ViewPager2? + get() { + var v: View? = parent as? View + while (v != null && v !is ViewPager2) { + v = v.parent as? View + } + return v as? ViewPager2 + } + + private val child: View? get() = if (childCount > 0) getChildAt(0) else null + + init { + touchSlop = ViewConfiguration.get(context).scaledTouchSlop + } + + private fun canChildScroll(orientation: Int, delta: Float): Boolean { + val direction = -delta.sign.toInt() + return when (orientation) { + 0 -> child?.canScrollHorizontally(direction) ?: false + 1 -> child?.canScrollVertically(direction) ?: false + else -> throw IllegalArgumentException() + } + } + + override fun onInterceptTouchEvent(e: MotionEvent): Boolean { + handleInterceptTouchEvent(e) + return super.onInterceptTouchEvent(e) + } + + private fun handleInterceptTouchEvent(e: MotionEvent) { + val orientation = parentViewPager?.orientation ?: return + + // Early return if child can't scroll in same direction as parent + if (!canChildScroll(orientation, -1f) && !canChildScroll(orientation, 1f)) { + return + } + + if (e.action == MotionEvent.ACTION_DOWN) { + initialX = e.x + initialY = e.y + parent.requestDisallowInterceptTouchEvent(true) + } else if (e.action == MotionEvent.ACTION_MOVE) { + val dx = e.x - initialX + val dy = e.y - initialY + val isVpHorizontal = orientation == ORIENTATION_HORIZONTAL + + // assuming ViewPager2 touch-slop is 2x touch-slop of child + val scaledDx = dx.absoluteValue * if (isVpHorizontal) .5f else 1f + val scaledDy = dy.absoluteValue * if (isVpHorizontal) 1f else .5f + + if (scaledDx > touchSlop || scaledDy > touchSlop) { + if (isVpHorizontal == (scaledDy > scaledDx)) { + // Gesture is perpendicular, allow all parents to intercept + parent.requestDisallowInterceptTouchEvent(false) + } else { + // Gesture is parallel, query child if movement in that direction is possible + if (canChildScroll(orientation, if (isVpHorizontal) dx else dy)) { + // Child can scroll, disallow all parents to intercept + parent.requestDisallowInterceptTouchEvent(true) + } else { + // Child cannot scroll, allow all parents to intercept + parent.requestDisallowInterceptTouchEvent(false) + } + } + } + } + } +} \ No newline at end of file