xamarin ViewPager Android
本文关键字：Android ViewPager xamarin | 更新日期: 2023-09-27 18:05:07
我试图创建一个滑动标签布局。我遵循这个教程滑动标签布局它很棒，但是我想在每个TabView
我也想让每一个加载，当我选择它或滚动到它，就像facebook应用程序。
这样做的原因是为了不花太多时间来加载ViewPager中的每个视图还有类:
SlidingTabStrip
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Graphics;
using Android.Util;
namespace SlidingTabLayoutTutorial
{
public class SlidingTabStrip : LinearLayout
{
//Copy and paste from here................................................................
private const int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 0;
private const byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0X26;
private const int SELECTED_INDICATOR_THICKNESS_DIPS = 3;
private int[] INDICATOR_COLORS = { 0xffffff };
private int[] DIVIDER_COLORS = { 0xffffff };
private const int DEFAULT_DIVIDER_THICKNESS_DIPS = 1;
private const float DEFAULT_DIVIDER_HEIGHT = 0.5f;
//Bottom border
private int mBottomBorderThickness;
private Paint mBottomBorderPaint;
private int mDefaultBottomBorderColor;
//Indicator
private int mSelectedIndicatorThickness;
private Paint mSelectedIndicatorPaint;
//Divider
private Paint mDividerPaint;
private float mDividerHeight;
//Selected position and offset
private int mSelectedPosition;
private float mSelectionOffset;
//Tab colorizer
private SlidingTabScrollView.TabColorizer mCustomTabColorizer;
private SimpleTabColorizer mDefaultTabColorizer;
//Stop copy and paste here........................................................................
//Constructors
public SlidingTabStrip (Context context) : this(context, null)
{ }
public SlidingTabStrip (Context context, IAttributeSet attrs) : base(context, attrs)
{
SetWillNotDraw(false);
float density = Resources.DisplayMetrics.Density;
TypedValue outValue = new TypedValue();
context.Theme.ResolveAttribute(Android.Resource.Attribute.ColorForeground, outValue, true);
int themeForeGround = outValue.Data;
mDefaultBottomBorderColor = SetColorAlpha(themeForeGround, DEFAULT_BOTTOM_BORDER_COLOR_ALPHA);
mDefaultTabColorizer = new SimpleTabColorizer();
mDefaultTabColorizer.IndicatorColors = INDICATOR_COLORS;
mDefaultTabColorizer.DividerColors = DIVIDER_COLORS;
mBottomBorderThickness = (int)(DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density);
mBottomBorderPaint = new Paint();
mBottomBorderPaint.Color = GetColorFromInteger(0x1B729E); //Gray
mSelectedIndicatorThickness = (int)(SELECTED_INDICATOR_THICKNESS_DIPS * density);
mSelectedIndicatorPaint = new Paint();
mDividerHeight = DEFAULT_DIVIDER_HEIGHT;
mDividerPaint = new Paint();
mDividerPaint.StrokeWidth = (int)(DEFAULT_DIVIDER_THICKNESS_DIPS * density);
}
public SlidingTabScrollView.TabColorizer CustomTabColorizer
{
set
{
mCustomTabColorizer = value;
this.Invalidate();
}
}
public int [] SelectedIndicatorColors
{
set
{
mCustomTabColorizer = null;
mDefaultTabColorizer.IndicatorColors = value;
this.Invalidate();
}
}
public int [] DividerColors
{
set
{
mDefaultTabColorizer = null;
mDefaultTabColorizer.DividerColors = value;
this.Invalidate();
}
}
private Color GetColorFromInteger(int color)
{
return Color.Rgb(Color.GetRedComponent(color), Color.GetGreenComponent(color), Color.GetBlueComponent(color));
}
private int SetColorAlpha(int color, byte alpha)
{
return Color.Argb(alpha, Color.GetRedComponent(color), Color.GetGreenComponent(color), Color.GetBlueComponent(color));
}
public void OnViewPagerPageChanged(int position, float positionOffset)
{
mSelectedPosition = position;
mSelectionOffset = positionOffset;
this.Invalidate();
}
protected override void OnDraw(Canvas canvas)
{
int height = Height;
int tabCount = ChildCount;
int dividerHeightPx = (int)(Math.Min(Math.Max(0f, mDividerHeight), 1f) * height);
SlidingTabScrollView.TabColorizer tabColorizer = mCustomTabColorizer != null ? mCustomTabColorizer : mDefaultTabColorizer;
//Thick colored underline below the current selection
if (tabCount > 0)
{
View selectedTitle = GetChildAt(mSelectedPosition);
int left = selectedTitle.Left;
int right = selectedTitle.Right;
int color = tabColorizer.GetIndicatorColor(mSelectedPosition);
if (mSelectionOffset > 0f && mSelectedPosition < (tabCount - 1))
{
int nextColor = tabColorizer.GetIndicatorColor(mSelectedPosition + 1);
if (color != nextColor)
{
color = blendColor(nextColor, color, mSelectionOffset);
}
View nextTitle = GetChildAt(mSelectedPosition + 1);
left = (int)(mSelectionOffset * nextTitle.Left + (1.0f - mSelectionOffset) * left);
right = (int)(mSelectionOffset * nextTitle.Right + (1.0f - mSelectionOffset) * right);
}
mSelectedIndicatorPaint.Color = GetColorFromInteger(color);
canvas.DrawRect(left, height - mSelectedIndicatorThickness, right, height, mSelectedIndicatorPaint);
//Creat vertical dividers between tabs
int separatorTop = (height - dividerHeightPx) / 2;
for (int i = 0; i < ChildCount -1; i++)
{
View child = GetChildAt(i);
mDividerPaint.Color = GetColorFromInteger(tabColorizer.GetDividerColor(i));
canvas.DrawLine(child.Right, separatorTop, child.Right, separatorTop + dividerHeightPx, mDividerPaint);
}
canvas.DrawRect(0, height - mBottomBorderThickness, Width, height, mBottomBorderPaint);
}
}
private int blendColor(int color1, int color2, float ratio)
{
float inverseRatio = 1f - ratio;
float r = (Color.GetRedComponent(color1) * ratio) + (Color.GetRedComponent(color2) * inverseRatio);
float g = (Color.GetGreenComponent(color1) * ratio) + (Color.GetGreenComponent(color2) * inverseRatio);
float b = (Color.GetBlueComponent(color1) * ratio) + (Color.GetBlueComponent(color2) * inverseRatio);
return Color.Rgb((int)r, (int)g, (int)b);
}
private class SimpleTabColorizer : SlidingTabScrollView.TabColorizer
{
private int[] mIndicatorColors;
private int[] mDividerColors;
public int GetIndicatorColor(int position)
{
return mIndicatorColors[position % mIndicatorColors.Length];
}
public int GetDividerColor (int position)
{
return mDividerColors[position % mDividerColors.Length];
}
public int[] IndicatorColors
{
set { mIndicatorColors = value; }
}
public int[] DividerColors
{
set { mDividerColors = value; }
}
}
}
}
SlidingTabScrollView
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Support.V4.View;
using Android.Util;
using Android.Graphics;
namespace SlidingTabLayoutTutorial
{
public class SlidingTabScrollView : HorizontalScrollView
{
private const int TITLE_OFFSET_DIPS = 15;
private const int TAB_VIEW_PADDING_DIPS = 15;
private const int TAB_VIEW_TEXT_SIZE_SP = 20;
private int mTitleOffset;
//private int mTabViewLayoutID;
//private int mTabViewTextViewID;
private ViewPager mViewPager;
private ViewPager.IOnPageChangeListener mViewPagerPageChangeListener;
private static SlidingTabStrip mTabStrip;
private int mScrollState;
public interface TabColorizer
{
int GetIndicatorColor(int position);
int GetDividerColor(int position);
}
public SlidingTabScrollView(Context context) : this(context, null) { }
public SlidingTabScrollView(Context context, IAttributeSet attrs) : this(context, attrs, 0) { }
public SlidingTabScrollView (Context context, IAttributeSet attrs, int defaultStyle) : base(context, attrs, defaultStyle)
{
//Disable the scroll bar
HorizontalScrollBarEnabled = false;
//Make sure the tab strips fill the view
FillViewport = true;
this.SetBackgroundColor(Android.Graphics.Color.ParseColor("#0078FF")); //Gray color
mTitleOffset = (int)(TITLE_OFFSET_DIPS * Resources.DisplayMetrics.Density);
mTabStrip = new SlidingTabStrip(context);
mTabStrip.WeightSum = 3;
this.AddView(mTabStrip, LayoutParams.MatchParent, LayoutParams.MatchParent);
}
public TabColorizer CustomTabColorizer
{
set { mTabStrip.CustomTabColorizer = value; }
}
public int [] SelectedIndicatorColor
{
set { mTabStrip.SelectedIndicatorColors = value; }
}
public int [] DividerColors
{
set { mTabStrip.DividerColors = value; }
}
public ViewPager.IOnPageChangeListener OnPageListener
{
set { mViewPagerPageChangeListener = value; }
}
public ViewPager ViewPager
{
set
{
mTabStrip.RemoveAllViews();
mViewPager = value;
if (value != null)
{
value.PageSelected += value_PageSelected;
value.PageScrollStateChanged += value_PageScrollStateChanged;
value.PageScrolled += value_PageScrolled;
PopulateTabStrip();
}
}
}
void value_PageScrolled(object sender, ViewPager.PageScrolledEventArgs e)
{
int tabCount = mTabStrip.ChildCount;
if ((tabCount == 0) || (e.Position < 0) || (e.Position >= tabCount))
{
//if any of these conditions apply, return, no need to scroll
return;
}
mTabStrip.OnViewPagerPageChanged(e.Position, e.PositionOffset);
View selectedTitle = mTabStrip.GetChildAt(e.Position);
int extraOffset = (selectedTitle != null ? (int)(e.Position * selectedTitle.Width) : 0);
ScrollToTab(e.Position, extraOffset);
if (mViewPagerPageChangeListener != null)
{
mViewPagerPageChangeListener.OnPageScrolled(e.Position, e.PositionOffset, e.PositionOffsetPixels);
}
}
void value_PageScrollStateChanged(object sender, ViewPager.PageScrollStateChangedEventArgs e)
{
mScrollState = e.State;
if (mViewPagerPageChangeListener != null)
{
mViewPagerPageChangeListener.OnPageScrollStateChanged(e.State);
}
}
void value_PageSelected(object sender, ViewPager.PageSelectedEventArgs e)
{
if (mScrollState == ViewPager.ScrollStateIdle)
{
mTabStrip.OnViewPagerPageChanged(e.Position, 0f);
ScrollToTab(e.Position, 0);
}
if (mViewPagerPageChangeListener != null)
{
mViewPagerPageChangeListener.OnPageSelected(e.Position);
}
}
private void PopulateTabStrip()
{
PagerAdapter adapter = mViewPager.Adapter;
for (int i = 0; i < adapter.Count; i++)
{
TextView tabView = CreateDefaultTabView(Context);
tabView.Text = ((SlidingTabsFragment.SamplePagerAdapter)adapter).GetHeaderTitle(i);
tabView.SetTextColor(Android.Graphics.Color.White);
tabView.Tag = i;
tabView.Click += tabView_Click;
mTabStrip.AddView(tabView);
}
}
void tabView_Click(object sender, EventArgs e)
{
TextView clickTab = (TextView)sender;
int pageToScrollTo = (int)clickTab.Tag;
mViewPager.CurrentItem = pageToScrollTo;
}
private TextView CreateDefaultTabView(Android.Content.Context context )
{
TextView textView = new TextView(context);
textView.Gravity = GravityFlags.Center;
textView.SetTextSize(ComplexUnitType.Sp, TAB_VIEW_TEXT_SIZE_SP);
textView.Typeface = Android.Graphics.Typeface.Default;
textView.LayoutParameters = new LinearLayout.LayoutParams(0, LayoutParams.MatchParent, 1);
if (Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Honeycomb)
{
TypedValue outValue = new TypedValue();
Context.Theme.ResolveAttribute(Android.Resource.Attribute.SelectableItemBackground, outValue, false);
textView.SetBackgroundResource(outValue.ResourceId);
}
if (Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.IceCreamSandwich)
{
textView.SetAllCaps(true);
}
int padding = (int)(TAB_VIEW_PADDING_DIPS * Resources.DisplayMetrics.Density);
textView.SetPadding(padding, padding, padding, padding);
return textView;
}
protected override void OnAttachedToWindow()
{
base.OnAttachedToWindow();
if (mViewPager != null)
{
ScrollToTab(mViewPager.CurrentItem, 0);
}
}
private void ScrollToTab(int tabIndex, int extraOffset)
{
int tabCount = mTabStrip.ChildCount;
if (tabCount == 0 || tabIndex < 0 || tabIndex >= tabCount)
{
//No need to go further, dont scroll
return;
}
View selectedChild = mTabStrip.GetChildAt(tabIndex);
if (selectedChild != null)
{
int scrollAmountX = selectedChild.Left + extraOffset;
if (tabIndex >0 || extraOffset > 0)
{
scrollAmountX -= mTitleOffset;
}
this.ScrollTo(scrollAmountX, 0);
}
}
}
}
SlidingTabsFragment
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Util;
using Android.Views;
using Android.Widget;
using Android.Support.V4.View;
namespace SlidingTabLayoutTutorial
{
public class SlidingTabsFragment : Fragment
{
private SlidingTabScrollView mSlidingTabScrollView;
private ViewPager mViewPager;
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.Inflate(Resource.Layout.fragment_sample, container, false);
}
public override void OnViewCreated(View view, Bundle savedInstanceState)
{
mSlidingTabScrollView = view.FindViewById<SlidingTabScrollView>(Resource.Id.sliding_tabs);
mViewPager = view.FindViewById<ViewPager>(Resource.Id.viewpager);
mViewPager.Adapter = new SamplePagerAdapter();
mSlidingTabScrollView.ViewPager = mViewPager;
}
public class SamplePagerAdapter : PagerAdapter
{
List<string> items = new List<string>();
public SamplePagerAdapter() : base()
{
items.Add("Home");
items.Add("Sell");
items.Add("Rent");
}
public override int Count
{
get { return items.Count; }
}
public override bool IsViewFromObject(View view, Java.Lang.Object obj)
{
return view == obj;
}
public override Java.Lang.Object InstantiateItem(ViewGroup container, int position)
{
View view = LayoutInflater.From(container.Context).Inflate(Resource.Layout.pager_item, container, false);
container.AddView(view);
TextView txtTitle = view.FindViewById<TextView>(Resource.Id.item_title);
int pos = position + 1;
txtTitle.Text = pos.ToString();
return view;
}
public string GetHeaderTitle (int position)
{
return items[position];
}
public override void DestroyItem(ViewGroup container, int position, Java.Lang.Object obj)
{
container.RemoveView((View)obj);
}
}
}
}
MainActivity
using System;
using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using Android.Support.V4.View;
namespace SlidingTabLayoutTutorial
{
[Activity(Label = "Sliding Tab Layout", MainLauncher = true, Icon = "@drawable/xs")]
public class MainActivity : Activity
{
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Main);
FragmentTransaction transaction = FragmentManager.BeginTransaction();
SlidingTabsFragment fragment = new SlidingTabsFragment();
transaction.Replace(Resource.Id.sample_content_fragment, fragment);
transaction.Commit();
}
public override bool OnCreateOptionsMenu(IMenu menu)
{
MenuInflater.Inflate(Resource.Menu.actionbar_main, menu);
return base.OnCreateOptionsMenu(menu);
}
}
}
我认为你需要在你的代码中添加这样的东西:(在OnCreateView())
position =>来自适配器..
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
switch (position)
{
case 0:
view = (ViewGroup)inflater.Inflate(Resource.Layout.Page1, container, false);
break;
case 1:
view = (ViewGroup)inflater.Inflate(Resource.Layout.Page2, container, false);
btn_forexample = view.FindViewById<Button>(Resource.Id.btn_forexample);
break;
case 2:
view = (ViewGroup)inflater.Inflate(Resource.Layout.Page3, container, false);
break;
default:
view = (ViewGroup)inflater.Inflate(Resource.Layout.DefaultPage, container, false);
break;
}
return view;
}
希望有帮助;)