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jaganjan/WrapLayoutManager

Last active Nov 26, 2015
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Linear Layout Manager which supports WRAP_CONTENT C# ported version
/*
* Ported by Jagadeesh Govindaraj (@jaganjan)
*Copyright 2015 serso aka se.solovyev
*
* 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.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Contact details
*
* Email: se.solovyev @gmail.com
* Site: http://se.solovyev.org
*/
using Android.Content;
using Android.Graphics;
using Android.Support.V4.View;
using Android.Support.V7.Widget;
using Android.Util;
using Android.Views;
using Java.Lang;
using Java.Lang.Reflect;
using System;
using Math = Java.Lang.Math;
namespace Droid.Helper
{
public class WrapLayoutManager : LinearLayoutManager
{
private const int DefaultChildSize = 100;
private static readonly Rect TmpRect = new Rect();
private int _childSize = DefaultChildSize;
private static bool _canMakeInsetsDirty = true;
private static readonly int[] ChildDimensions = new int[2];
private const int ChildHeight = 1;
private const int ChildWidth = 0;
private static bool _hasChildSize;
private static Field InsetsDirtyField = null;
private static int _overScrollMode = ViewCompat.OverScrollAlways;
private static RecyclerView _view;
public WrapLayoutManager(Context context, int orientation, bool reverseLayout)
: base(context, orientation, reverseLayout)
{
_view = null;
}
public WrapLayoutManager(Context context) : base(context)
{
_view = null;
}
public WrapLayoutManager(RecyclerView view) : base(view.Context)
{
_view = view;
_overScrollMode = ViewCompat.GetOverScrollMode(view);
}
public WrapLayoutManager(RecyclerView view, int orientation, bool reverseLayout)
: base(view.Context, orientation, reverseLayout)
{
_view = view;
_overScrollMode = ViewCompat.GetOverScrollMode(view);
}
public void SetOverScrollMode(int overScrollMode)
{
if (overScrollMode < ViewCompat.OverScrollAlways || overScrollMode > ViewCompat.OverScrollNever)
throw new ArgumentException("Unknown overscroll mode: " + overScrollMode);
if (_view == null) throw new ArgumentNullException(nameof(_view));
_overScrollMode = overScrollMode;
ViewCompat.SetOverScrollMode(_view, overScrollMode);
}
public static int MakeUnspecifiedSpec()
{
return View.MeasureSpec.MakeMeasureSpec(0, MeasureSpecMode.Unspecified);
}
public override void OnMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec,
int heightSpec)
{
var widthMode = View.MeasureSpec.GetMode(widthSpec);
var heightMode = View.MeasureSpec.GetMode(heightSpec);
var widthSize = View.MeasureSpec.GetSize(widthSpec);
var heightSize = View.MeasureSpec.GetSize(heightSpec);
var hasWidthSize = widthMode != MeasureSpecMode.Unspecified;
var hasHeightSize = heightMode != MeasureSpecMode.Unspecified;
var exactWidth = widthMode == MeasureSpecMode.Exactly;
var exactHeight = heightMode == MeasureSpecMode.Exactly;
var unspecified = MakeUnspecifiedSpec();
if (exactWidth && exactHeight)
{
// in case of exact calculations for both dimensions let's use default "onMeasure" implementation
base.OnMeasure(recycler, state, widthSpec, heightSpec);
return;
}
var vertical = Orientation == Vertical;
InitChildDimensions(widthSize, heightSize, vertical);
var width = 0;
var height = 0;
// it's possible to get scrap views in recycler which are bound to old (invalid) adapter
// entities. This happens because their invalidation happens after "onMeasure" method.
// As a workaround let's clear the recycler now (it should not cause any performance
// issues while scrolling as "onMeasure" is never called whiles scrolling)
recycler.Clear();
var stateItemCount = state.ItemCount;
var adapterItemCount = ItemCount;
// adapter always contains actual data while state might contain old data (f.e. data
// before the animation is done). As we want to measure the view with actual data we
// must use data from the adapter and not from the state
for (var i = 0; i < adapterItemCount; i++)
{
if (vertical)
{
if (!_hasChildSize)
{
if (i < stateItemCount)
{
// we should not exceed state count, otherwise we'll get
// IndexOutOfBoundsException. For such items we will use previously
// calculated dimensions
MeasureChild(recycler, i, widthSize, unspecified, ChildDimensions);
}
else
{
LogMeasureWarning(i);
}
}
height += ChildDimensions[ChildHeight];
if (i == 0)
{
width = ChildDimensions[ChildWidth];
}
if (hasHeightSize && height >= heightSize)
{
break;
}
}
else
{
if (!_hasChildSize)
{
if (i < stateItemCount)
{
// we should not exceed state count, otherwise we'll get
// IndexOutOfBoundsException. For such items we will use previously
// calculated dimensions
MeasureChild(recycler, i, unspecified, heightSize, ChildDimensions);
}
else
{
LogMeasureWarning(i);
}
}
width += ChildDimensions[ChildWidth];
if (i == 0)
{
height = ChildDimensions[ChildHeight];
}
if (hasWidthSize && width >= widthSize)
{
break;
}
}
}
if (exactWidth)
{
width = widthSize;
}
else
{
width += PaddingLeft + PaddingRight;
if (hasWidthSize)
{
width = Math.Min(width, widthSize);
}
}
if (exactHeight)
{
height = heightSize;
}
else
{
height += PaddingTop + PaddingBottom;
if (hasHeightSize)
{
height = Math.Min(height, heightSize);
}
}
SetMeasuredDimension(width, height);
if (_view == null || _overScrollMode != ViewCompat.OverScrollIfContentScrolls) return;
var fit = (vertical && (!hasHeightSize || height < heightSize))
|| (!vertical && (!hasWidthSize || width < widthSize));
ViewCompat.SetOverScrollMode(_view, fit ? ViewCompat.OverScrollNever : ViewCompat.OverScrollAlways);
}
private void LogMeasureWarning(int child)
{
#if DEBUG
Log.WriteLine(LogPriority.Warn, "LinearLayoutManager",
"Can't measure child #" + child + ", previously used dimensions will be reused." +
"To remove this message either use #SetChildSize() method or don't run RecyclerView animations");
#endif
}
private void InitChildDimensions(int width, int height, bool vertical)
{
if (ChildDimensions[ChildWidth] != 0 || ChildDimensions[ChildHeight] != 0)
{
// already initialized, skipping
return;
}
if (vertical)
{
ChildDimensions[ChildWidth] = width;
ChildDimensions[ChildHeight] = _childSize;
}
else
{
ChildDimensions[ChildWidth] = _childSize;
ChildDimensions[ChildHeight] = height;
}
}
public void ClearChildSize()
{
_hasChildSize = false;
SetChildSize(DefaultChildSize);
}
public void SetChildSize(int size)
{
_hasChildSize = true;
if (_childSize == size) return;
_childSize = size;
RequestLayout();
}
private void MeasureChild(RecyclerView.Recycler recycler, int position, int widthSize, int heightSize,
int[] dimensions)
{
View child = null;
try
{
child = recycler.GetViewForPosition(position);
}
catch (IndexOutOfRangeException e)
{
Log.WriteLine(LogPriority.Warn, "LinearLayoutManager",
"LinearLayoutManager doesn't work well with animations. Consider switching them off", e);
}
if (child != null)
{
var p = (RecyclerView.LayoutParams) child.LayoutParameters;
var hPadding = PaddingLeft + PaddingRight;
var vPadding = PaddingTop + PaddingBottom;
var hMargin = p.LeftMargin + p.RightMargin;
var vMargin = p.TopMargin + p.BottomMargin;
// we must make insets dirty in order calculateItemDecorationsForChild to work
MakeInsetsDirty(p);
// this method should be called before any getXxxDecorationXxx() methods
CalculateItemDecorationsForChild(child, TmpRect);
var hDecoration = GetRightDecorationWidth(child) + GetLeftDecorationWidth(child);
var vDecoration = GetTopDecorationHeight(child) + GetBottomDecorationHeight(child);
var childWidthSpec = GetChildMeasureSpec(widthSize, hPadding + hMargin + hDecoration, p.Width,
CanScrollHorizontally());
var childHeightSpec = GetChildMeasureSpec(heightSize, vPadding + vMargin + vDecoration, p.Height,
CanScrollVertically());
child.Measure(childWidthSpec, childHeightSpec);
dimensions[ChildWidth] = GetDecoratedMeasuredWidth(child) + p.LeftMargin + p.RightMargin;
dimensions[ChildHeight] = GetDecoratedMeasuredHeight(child) + p.BottomMargin + p.TopMargin;
// as view is recycled let's not keep old measured values
MakeInsetsDirty(p);
}
recycler.RecycleView(child);
}
private static void MakeInsetsDirty(RecyclerView.LayoutParams p)
{
if (!_canMakeInsetsDirty)
{
return;
}
try
{
if (InsetsDirtyField == null)
{
var klass = Java.Lang.Class.FromType (typeof (RecyclerView.LayoutParams));
InsetsDirtyField = klass.GetDeclaredField("mInsetsDirty");
InsetsDirtyField.Accessible = true;
}
InsetsDirtyField.Set(p, true);
}
catch (NoSuchFieldException e)
{
OnMakeInsertDirtyFailed();
}
catch (IllegalAccessException e)
{
OnMakeInsertDirtyFailed();
}
}
private static void OnMakeInsertDirtyFailed()
{
_canMakeInsetsDirty = false;
#if DEBUG
Log.Warn("LinearLayoutManager",
"Can't make LayoutParams insets dirty, decorations measurements might be incorrect");
#endif
}
}
}
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