I have a map and a list of items underneath.
I want to move the list up (while maintaining the position of the map) until the user reaches the last element of the list. In that case, the list shouldn't move up anymore.
The problem is that the list continues to move upwards even after the last element has been shown living a white background.
template:
<GridLayout rows="*, *, 0" columns="*">
<MapView row="0" col="0"> ...
<GridLayout #list rows="*, 0" columns="*" #list row="1" col="0">
<GridLayout row="0" col="0" class="m-15"
rows="..." (pan)="onPan($event)">
...
</GridLayout>
</GridLayout>
<GridLayout #ref row="2" col="0">...
component.ts
onPan(args: PanGestureEventData) {
switch (args.state) {
case 1:
break;
case 2:
const diff = this.ref.nativeElement.getLocationRelativeTo(this.list.nativeElement);
if (diff > 1400) return; // I used 1400 seems based on various devices sizes, it seems like a good number.
this.dragContainer.translateY += args.deltaY - this.prevDeltaY;
this.prevDeltaY = args.deltaY;
break;
case 3:
default:
break;
}
}
**Expected: **
- I expect that when the last element in the list has been shown, the list is not able to move up anymore
**Actual: **
- The list continues to move upward leaving a white background.
I have created a demo on nativescript playground here https://play.nativescript.org/?template=play-ng&id=rB4H2M
I finally was able to find an example which basically does what I needed. The effect I was trying to achieve is called Parallax and here is an example of Nativescript Demo Samples
https://play.nativescript.org/?template=play-ng&id=b9hyJh&v=2
Related
How can I view image two columns per row with nativescript-vue by using RadListView, as picture below:
Like Monoj answered in the comment here a little example:
<RadListView ref="mylistView"
for="item in items"
layout="grid"
gridSpanCount="2">
<v-template>
...
</v-template>
</RadListView>
I need to use an AbsoluteLayout for other controls on the page not listed here. How do I layout a common senerio where I have a SearchBar at the top, then a ListView which fills the rest of the screen.
I tried this, but the ListView goes incorrectly under the SearchBar
<AbsoluteLayout VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
<SearchBar></SearchBar>
<ListView
AbsoluteLayout.LayoutFlags="All"
AbsoluteLayout.LayoutBounds="0,0,1,1">
</ListView>
</AbsoluteLayout>
Part of the problem is AbsoluteLayoutFlags you have set on the listview.
when you set it to all, you are telling the layout to start at 0,0 and go all the way to 1,1. Which is why the listview is appearing on the searchbar.
<AbsoluteLayout VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
<SearchBar AbsoluteLayout.LayoutBounds="0,0,1,40"
AbsoluteLayout.LayoutFlags="WidthProportional,PositionProportional"/>
<ListView
AbsoluteLayout.LayoutFlags="XProportional,SizeProportional"
AbsoluteLayout.LayoutBounds="0,40,1,1">
<ListView.ItemsSource>
<x:Array Type="{x:Type x:String}">
<x:String>mono</x:String>
<x:String>monodroid</x:String>
<x:String>monotouch</x:String>
<x:String>monorail</x:String>
<x:String>monodevelop</x:String>
<x:String>monotone</x:String>
<x:String>monopoly</x:String>
<x:String>monomodal</x:String>
<x:String>mononucleosis</x:String>
</x:Array>
</ListView.ItemsSource>
</ListView>
</AbsoluteLayout>
Xamarin Documentation
I am sure you were referencing the documentation. I linked it here and quoting part of it. Hopefully it helps.
Proportional values define a relationship between a layout and a view.
This relationship defines a child view's position or scale value as a
proportion of the corresponding value of the parent layout. These
values are expressed as doubles with values between 0 and 1.
Proportional values are used to position and size views within the
layout. So, when a view's width is set as a proportion, the resultant
width value is the proportion multiplied by the AbsoluteLayout's
width. For example, with an AbsoluteLayout of width 500 and a view set
to have a proportional width of .5, the rendered width of the view
will be 250 (500 x .5).
I don't understand why is there so much space before the end of the screen(photo attached, platform - Android).
It looks like AbsoluteLayout fills not all the space of the screen, but it's not true.Where are also spaces between 'White' buttons(one button should take 20% of the screen; first starts after 4% from the left edge of the screen, second - after 28%: 28% - 4% -20% = 4% free space between buttons)????
Here is xaml code:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="PokerCalculator.OutsCalculator"
BackgroundColor="#131313">
<AbsoluteLayout BackgroundColor="HotPink">
<Label Text="Number of outs:"
FontSize="Medium"
AbsoluteLayout.LayoutBounds="0.04,0,0.3,0.18"
AbsoluteLayout.LayoutFlags="SizeProportional, PositionProportional"
BackgroundColor="Aqua"/>
<Label x:Name="lblOutNumber"
Text="15"
AbsoluteLayout.LayoutBounds="0.35,0,0.18,0.18"
AbsoluteLayout.LayoutFlags="SizeProportional, PositionProportional"
BackgroundColor="Azure"/>
<Button x:Name="btnBack"
Text="BACK"
Clicked="btnBack_Clicked"
AbsoluteLayout.LayoutBounds="0.7,0,0.28,0.18"
AbsoluteLayout.LayoutFlags="SizeProportional, PositionProportional"
BackgroundColor="Fuchsia"/>
<Button BackgroundColor="White"
AbsoluteLayout.LayoutBounds="0.04,0.2,0.20,0.28"
AbsoluteLayout.LayoutFlags="All"/>
<Button BackgroundColor="White"
AbsoluteLayout.LayoutBounds="0.28,0.2,0.20,0.28"
AbsoluteLayout.LayoutFlags="All"/>
<Button BackgroundColor="White"
AbsoluteLayout.LayoutBounds="0.52,0.2,0.20,0.28"
AbsoluteLayout.LayoutFlags="All"/>
<Button BackgroundColor="White"
AbsoluteLayout.LayoutBounds="0.76,0.2,0.20,0.28"
AbsoluteLayout.LayoutFlags="All"/>
</AbsoluteLayout>
</ContentPage>
photo
Photo(mockup)
As discussed on here forum
Absolute layout proportional does not work/calculated as what you expect. Your intention can be achieved using the relativelayout instead.
Lets say that you set X = 0.5 and Width = 0.5.
With your intention you might be expecting the element's X to start from the center and filling the second right half of the absolutelayout bound? No.
The answer is that the element will be 50% width of the layout bound and be right in the center. Making the X position such as (0.5 * absolutelayoutWidth) - (0.5 * elementWidth) (formula is something like this i guess?)
I suggest using relativelayout
As a late answer, I've put a nuget package with a fork of AbsoluteLayout but working in a more predictable way.
Install nuget package SmartMachines.AbsoluteLayout, add namespace xmlns:sm="clr-namespace:SmartMachines;assembly=AbsoluteLayout" and you will have exactly same AbsoluteLayout as native Xamarin, but with expected Proportional alignment behavior.
Hope that will save other people several hours on googling and debugging.
I have a FlatList inside of a Modal in my application the Flatlist is filled with ListItem components from 'react-native-elements'.
The ListItems just have a title and an onPress method and nothing else, but the list has 250-300 items. The list is very laggy. I understand that is going to happen with a lot of items, but with the list I cant scroll to the bottom immediately. I can scroll a certain distance then it loads up the next few items then scroll a bit more then load a bit etc. This makes picking an item lower on the list or at the bottom incredibly slow.
My data is an array of { imgnames: "imglink" } objects and the list is sorted alphabetically.
I was wondering if this performance issue is going to happen no matter what because of the amount of items, or if its because it is inside of the module.
I just want to be able to scroll the entire length of the list immediately, so I can scroll to the 'M' or 'P' sections straightaway and then have a small delay while the list renders.
What would be the best list implementation for this.
FlatList Code:
<FlatList
data={this.props.list}
renderItem={
({item}) => <ListItem hideChevron = {true} onPress={() => this._setImage(item.imgLink)} title={item.key} removeClippedSubviews = {true} initialNumToRender={5}/>
}/>
Setting initailRenderNum and removeClipping props should help with the performance problems of the FlatList.
Example:
<FlatList
data={this.props.list}
removeClippedSubviews={true}
initialNumToRender={5}
renderItem={
({item}) => <ListItem hideChevron={true} onPress={() => this._setImage(item.imgLink)} title={item.key} />
}/>
In the NativeScript StackLayout, I have three elements A, B and C. I want the middle element B to take up all the available space. This is what i want:
|ABBBBBBBBBBBBC|
I'm trying with this simplified code. A and C are labels with a fixed width, B is a progress bar.
<StackLayout orientation="horizontal" verticalAlignment="center">
<Label text="1" width="50"></Label>
<Progress value="50" maxValue="100"></Progress>
<Label text="1" width="50"></Label>
</StackLayout>
What happens is that the progress bar fills up the remaining space of the StackLayout, leaving no space for the last label. Only the first label and the Progress bar itself are drawn on the screen, like this:
|ABBBBBBBBBBBBB|C
So the C elements is drawn beyond the screen.
If I place the 2 labels in front, sizing looks ok.
What am I doing wrong here?
Use a GridLayout.
<GridLayout columns="50, *, 50">
<Label text="1" col="0"></Label>
<Progress value="50" maxValue="100" col="1"></Progress>
<Label text="1" col="2"></Label>
</GridLayout>