Yes, it can be done. Although not very straightforward or even convenient.
First, let me plunge a bit into the RadialProgressView drawing RadialProgressView (as shown in the Xamarin Studio Assembly Browser):
protected override void OnDraw(Canvas canvas) { // ... there more stuff here, but you get the idea canvas.DrawCircle(this.bgCx, this.bgCy, this.radius, this.bgCirclePaint); canvas.DrawCircle(this.bgCx, this.bgCy, this.innerLineRadius, this.bgBorderPaint); canvas.DrawText(this.valueText, this.textX, this.textY, this.textPaint); }
We notice several colors here, for example bgCirclePaint and bgBorderPaint . If we can change the value of these variables, we can change the color with which the ProgressView will be colored.
The problem is that RadialProgressView does not expose fields - they are all private, so just inheriting from RadialProgressView will not allow us to set them to a new value.
However, we can use reflection to change these private fields, for example:
var textPaintMember = typeof(RadialProgressView).GetField("textPaint", BindingFlags.Instance | BindingFlags.NonPublic); textPaintMember.SetValue(Instance, MyNewSuperCoolColorPaint);
By combining the two, we can create a new custom class as follows:
public class CustomizableRadialProgressView : RadialProgressView { public CustomizableRadialProgressView(Context context) : base(context) { } public void SetTextColor(Color color) { var paint = new Paint(); paint.SetTypeface(Typeface.DefaultBold); paint.Color = color; paint.AntiAlias = true; var textPaintMember = typeof(RadialProgressView).GetField("textPaint", BindingFlags.Instance | BindingFlags.NonPublic); textPaintMember.SetValue(this, paint); } public void SetCircleColor(Color color) { var paint = new Paint(); paint.SetStyle(Paint.Style.Fill); paint.Color = color; paint.AntiAlias = true; var circlePaintMember = typeof(RadialProgressView).GetField("bgCirclePaint", BindingFlags.Instance | BindingFlags.NonPublic); circlePaintMember.SetValue(this, paint); } public void SetBorderColor(Color color) { var paint = new Paint(); paint.SetStyle(Paint.Style.Stroke); paint.Color = color; paint.AntiAlias = true; var circlePaintMember = typeof(RadialProgressView).GetField("bgBorderPaint", BindingFlags.Instance | BindingFlags.NonPublic); circlePaintMember.SetValue(this, paint); } public void SetProgressPackgroundColor(Color color) { var paint = new Paint(); paint.SetStyle(Paint.Style.Stroke); paint.Color = color; paint.AntiAlias = true; var circlePaintMember = typeof(RadialProgressView).GetField("bgProgressPaint", BindingFlags.Instance | BindingFlags.NonPublic); circlePaintMember.SetValue(this, paint); } }
This will give us the result we will accomplish:
Note. It is probably wise to notice that we are making improper use of private fields: we manipulate them from outside the class in which they live. If Xamarin ever decides to change the way RadialProgressView , or even just renames one of the private variables, our code will not work at run time. The best way to approach this problem would probably be to simply ask Xamarin to provide the getters / setters you need. But hey it's so much cooler;)