I have set list border using trigger according to my requirement but when I scroll up the listview and selected view cell is gone than I scroll down when ViewCell is appearing on screen than selected border is gone
To prevent this I also created frame renderer but still ViewCell border gone. Attached image here
class FrameHighLightRenderer : VisualElementRenderer<Frame>
{
ACanvas _canvas = null;
private FrameDrawable _frameDrawable;
protected override void OnElementChanged(ElementChangedEventArgs<Frame> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
if (_frameDrawable != null && e.NewElement.ClassId != null) //This block execute while any cell appearing in scroll time up/dowm
{ // I added classId =10 to identify colored/selected cell
if (e.NewElement.ClassId=="10")
{
e.NewElement.OutlineColor = Xamarin.Forms.Color.Red;
this.Invalidate();
}
else
{
e.NewElement.BackgroundColor = Xamarin.Forms.Color.TransParent;
}
}
else
{
UpdateBackground();
}
}
}
void UpdateBackground()
{
_frameDrawable = new FrameDrawable(Element, Context.ToPixels);
this.SetBackground(_frameDrawable);
}
class FrameDrawable : Drawable
{
readonly Frame _frame;
readonly Func<double, float> _convertToPixels;
public ACanvas _canvas;
bool _isDisposed;
Bitmap _normalBitmap;
public FrameDrawable(Frame frame, Func<double, float> convertToPixels)
{
_frame = frame;
_convertToPixels = convertToPixels;
frame.PropertyChanged += FrameOnPropertyChanged;
}
public override bool IsStateful
{
get { return false; }
}
public override int Opacity
{
get { return 0; }
}
public override void Draw(ACanvas canvas)
{
SetBorderColorandWidth(canvas);
}
private void SetBorderColorandWidth(ACanvas canvas)
{
int width = Bounds.Width();
int height = Bounds.Height();
if (width <= 0 || height <= 0)
{
if (_normalBitmap != null)
{
_normalBitmap.Dispose();
_normalBitmap = null;
}
return;
}
if (_normalBitmap == null || _normalBitmap.Height != height || _normalBitmap.Width != width)
{
_normalBitmap = CreateBitmap(false, width, height);
}
Bitmap bitmap = _normalBitmap;
// if(canvas)
if (InspectionQAPage._highlight_color)
{
using (var paint = new Paint { AntiAlias = true })
using (var path = new Path())
using (Path.Direction direction = Path.Direction.Cw)
using (Paint.Style style = Paint.Style.Stroke)
using (var rect = new RectF(0, 0, width, height))
{
float rx = Forms.Context.ToPixels(4);
float ry = Forms.Context.ToPixels(4);
path.AddRoundRect(rect, rx, ry, direction);
if (this._frame.OutlineColor == Xamarin.Forms.Color.Red)
{
paint.Color = Android.Graphics.Color.Red;
this._frame.ClassId = "10";
// this._frame.BackgroundColor = Xamarin.Forms.Color.Red;
// paint.SetStyle = (Paint.Style)(Resource.Style.WithBorder);
}
else
{
// paint.Reset();
paint.Color = Android.Graphics.Color.Transparent;
// this._frame.BackgroundColor = Xamarin.Forms.Color.Transparent;
}
paint.StrokeWidth = 10f; //set outline stroke
paint.SetStyle(style);
canvas.DrawPath(path, paint);
}
InspectionQAPage._highlight_color = false;
}
else
{
using (var paint = new Paint())
canvas.DrawBitmap(bitmap, 0, 0, paint);
}
// InvalidateSelf();
}
public override void SetAlpha(int alpha)
{
}
public override void SetColorFilter(ColorFilter cf)
{
}
protected override void Dispose(bool disposing)
{
if (disposing && !_isDisposed)
{
if (_normalBitmap != null)
{
_normalBitmap.Dispose();
_normalBitmap = null;
}
_isDisposed = true;
}
base.Dispose(disposing);
}
protected override bool OnStateChange(int[] state)
{
return false;
}
Bitmap CreateBitmap(bool pressed, int width, int height)
{
Bitmap bitmap;
using (Bitmap.Config config = Bitmap.Config.Argb8888)
if (width <= 0 || height <= 0)
{
return null;
}
else
bitmap = Bitmap.CreateBitmap(width, height, config);
using (var canvas = new ACanvas(bitmap))
{
// DrawCanvas(canvas, width, height, pressed);
}
return bitmap;
}
void FrameOnPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == VisualElement.BackgroundColorProperty.PropertyName ||
e.PropertyName == Frame.OutlineColorProperty.PropertyName ||
e.PropertyName == Frame.CornerRadiusProperty.PropertyName)
{
try
{
if (_normalBitmap == null)
return;
int width = Bounds.Width();
int height = Bounds.Height();
if (width <= 0 || height <= 0)
{
return;
}
if (_canvas == null)
{
var canvas = new ACanvas(_normalBitmap);
_canvas = canvas;
_canvas.DrawColor(global::Android.Graphics.Color.Red, PorterDuff.Mode.Clear);
DrawCanvas(_canvas, width, height, false, sender);
}
else
{
_canvas.DrawColor(global::Android.Graphics.Color.Red, PorterDuff.Mode.Clear);
DrawCanvas(_canvas, width, height, false, sender);
}
InvalidateSelf();
}
catch (Exception ex)
{
Console.WriteLine(">>>>>>>>>>>>>>>>>>>>>>>>>>" + ex);
throw;
}
}
}
public void DrawCanvas(ACanvas canvas, int width, int height, bool pressed, object sender)
{
using (var paint = new Paint { AntiAlias = true })
using (var path = new Path())
using (Path.Direction direction = Path.Direction.Cw)
using (Paint.Style style = Paint.Style.Stroke)
using (var rect = new RectF(0, 0, width, height))
{
float rx = Forms.Context.ToPixels(4);
float ry = Forms.Context.ToPixels(4);
path.AddRoundRect(rect, rx, ry, direction);
if (((Frame)sender).OutlineColor == Xamarin.Forms.Color.Red)
{
paint.Color = Android.Graphics.Color.Red;
((Frame)sender).ClassId = "10";
}
else
{
((Frame)sender).BackgroundColor = Xamarin.Forms.Color.Transparent;
}
paint.StrokeWidth = 10f; //set outline stroke
paint.SetStyle(style);
canvas.DrawPath(path, paint);
}
}
}
}
}
