Font Sizes in the attrs.xml File of a Xamarin.Android Compound Control

Question

I am creating a compound control in Xamarin.Android compound control. Some of the properties that I need to include in attrs.xml are used to specify font sizes. I used format="float" for these properties in attrs.xml. In the Android Designer, this looks great and works fine when I use values like 22dp, but when I run the debugger, it complains about values with dp. However, using straightforward values like 22 do not display the correct size. What is the best way to include a property that will be used to specify a font size when creating a compound control?

Answer 1

Hello,​

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If you want to set the fontsize with a float property. I used the following way.

Firstly, I add a float property called fontScale in the attrs.xml.

   <?xml version="1.0" encoding="utf-8" ?>  
   <resources>  
     <declare-styleable name="test">  
       <attr name="text" format="string" />  
       <attr name="testAttr" format="integer" />  
       <attr name = "fontScale" format = "float" />  
     </declare-styleable>  
   </resources>  

Then I set it in the XML.

   <App55.MyTextView  
          android:layout_width="200dp"  
          android:layout_height="200dp"  
          app:testAttr="520"  
          app:text="helloworld"   
          app:fontScale="11.5"  
          android:text="TestTestTestTestTestTestTestTestTestTestTestTestTestTest"  
       />  

We can get the value app:fontScale then set it to the custom control.

   public class MyTextView : TextView  
       {  
           protected MyTextView(IntPtr javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)  
           {  
           }  
     
           public MyTextView(Context context) : base(context)  
           {  
               Initialize(context);  
           }  
           
               public MyTextView(Context context, IAttributeSet attrs) : base(context, attrs)  
           {  
               Initialize(context, attrs);  
           }  
     
           public MyTextView(Context context, IAttributeSet attrs, int defStyleAttr) : base(context, attrs, defStyleAttr)  
           {  
               Initialize(context, attrs);  
           }  
     
           public MyTextView(Context context, IAttributeSet attrs, int defStyleAttr, int defStyleRes) : base(context, attrs, defStyleAttr, defStyleRes)  
           {  
               Initialize(context, attrs);  
           }  
     
           float ontScale;  
           private void Initialize(Context context, IAttributeSet attrs = null)  
           {  
               if (attrs != null)  
               {  
                   TypedArray ta = context.ObtainStyledAttributes(attrs, Resource.Styleable.test);  
                   string text = ta.GetString(Resource.Styleable.test_text);  
                   int textAttr = ta.GetInt(Resource.Styleable.test_testAttr, 0);  
                   ontScale = ta.GetFloat(Resource.Styleable.test_fontScale, 0);  
     
                   //set float value to the custom control‘s TextSize  
                   this.TextSize = ontScale;  
                   ta.Recycle();  
               }  
           }  
     }  
   }  

Here is running screenshot.

Best Regards,

Leon Lu

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