Create a custom Grid Item in Xamarin

问题

I have a GridLayout in my Xamarin.Forms App and I would like each element in the grid shown here:

to be an instance of something like this:

Where each element (brand, picture, price, seller etc.) is set by getting a value from an array and placing that value into the cell.

For example, if I am only using the brand and the picture (in the form of strings) for now, and I have just retrieved data from my SQL database in the form of two lists: (pseudocode)

brand = ["supreme","louisvuitton","addidas","addidas","bape"]
picture = ["hoodie","tshirt","tracksuit","trainers","jacket"]

How can I create a class/content page that will take the next string from each list and add an item to the grid with these strings on it. So far I have tried creating a c# class like so:

class Item
{
    public string brand { get; set; }
    public string picture { get; set; }

    Button Background = new Button
    {
        BackgroundColor = Color.FromHex("#EEEEEE"),
    };
    Label label = new Label
    {
        Text = brand
    };
    Label label2 = new Label
    {
        Text = picture
    };

I am aware that I have to add the Button and Labels to a Layout of some sort but I don't know how to get my item onto the grid in the first place. I am using xaml for the page with the grid on it btw. Any help would be appreciated :)

回答1:

You can create a custom grid view item using a ContentView.

Doing the UI with the XAML previewer can be a little messy as you will see the view in the context of the phone screen (not as nice as using xib's in iOS for instance).

Start by creating a new XAML file with codebehind.

public partial class MyCustomGridCell : ContentView
{
}

You will need to change the XAML to also be a ContentView

<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="NAMESPACEHERE">
    <ContentView.Content>
        <!-- Your View here, This is done the same as any other UI-->
    </ContentView.Content>
</ContentView>

Now you have a custom class that you can add to your grid view. In the view that you want this custom object you can import it in the following ways:

XAML:

xmlns:custom="clr-namespace:YOUR_CUSTOM_VIEW_NAMESPACE_HERE"

CS:

using YOUR_CUSTOM_VIEW_NAMESPACE_HERE;

Now you can access your custom view in your ContentPage. You can add it to your view by the following:

XAML:

<custom: MyCustomGridCell VerticalOptions="FillAndExpand" BackgroundColor="Gray" Padding="2,0,2,2"/>

CS:

//Dont forget to add this to your view (Foo.Children.Add(customView);
MyCustomGridCell customView = new MyCustomGridCell();

If you want to add properties to your custom view, thats not an issue.

If you are using XAML for the UI (which I recommend) you should add the x:name property to your control:

<Image x:Name="MainImageView"/>

Now add a new public property to your class, and add a setter:

public ImageSource MainImage
{
    set
    {
        MainImageView.Source = value;
    }
}

Now when creating your custom view you can call MyCustomGridCell.MainImage = Foo;

By doing your UI this way you make everything super maintainable, you can reuse this view anywhere in your app and only have to make changes to this file once.

I am currently working on an app where I have built my own date picker control (soon to be open sourced). I used this exact approach (I have written this answer from my code) to reuse a view many times (in a loop). Here is a little preview of what I was able to achieve with this method:

来源：https://stackoverflow.com/questions/49439199/create-a-custom-grid-item-in-xamarin

标签

class

Xamarin

xamarin.forms

grid