在平台上绘制形状笔划的问题 Android

Question

I am new to Android app development using Delphi 11 and FMX framework.

I wanted to use a rectangle with frame as a style for a panel and wonder about how the frames of rectangles with rounded corners and other shapes are drawn on platform Android (see image). On Windows everything works as expected. For fills, I have not been able to find any drawing error on Android so far.

With rectangles, the corners are deformed and the frame is sometimes not closed.

Generally, for all shapes ( TCircle , TArc ) no gradient is drawn for the frame and drawing is done without antialiasing.

Since I am new, it is difficult for me to assess the problem. Is this a known and unsolvable problem of the FMX framework? Or is this a special problem of Delphi 11? Is there any other drawing problem especially on Android?

Is there an alternative to draw a rectangle with rounded corners under Android? I can only think of bitmaps here.

I would be very grateful if an experienced Delphi FMX developer could say something on the subject.

Create a new blank multi-device FMX app using Delphi 11. Drag a TRectangle onto the form. Paste the following code into the form:

procedure TForm13.FormCreate(Sender: TObject);
begin
  Rectangle.Fill.Kind:=TBrushKind.None;
  Rectangle.XRadius:=10;
  Rectangle.YRadius:=10;
  Rectangle.Stroke.Kind:=TBrushKind.Gradient;
  Rectangle.Stroke.Thickness:=10;
  Rectangle.Stroke.Gradient.Color:=TAlphaColors.Black;
  Rectangle.Stroke.Gradient.Color1:=TAlphaColors.White;
end;

Launch the app on platform Windows and on an Android tablet. Take a screenshot on both systems. Why is the graphical representation different?

Answer 1

As of Delphi 11 gradient brushes in strokes are not supported for Android. This is not an official statement from Embarcadero but can be observed by browsing the source code responsible for rendering shapes on Android. By looking at FMX.StrokeBuilder.pas you will find no use of Gradient property of Brush and it uses the solid color always. This was already reported on Embarcadero offical bug tracker but seems like there is not enough demand to have this fixed/implemented.

As for the deformed rounded corners this is another issue with how FMX renders curved lines on Android. This was also already reported and is waiting for solution.

Answer 2

Late but I am a newbie here. I ran in this problem long time ago and use RadiantShapes.TRadiantRectangle instead of TRectangle. Another solution is to use TPath (FMX.Objects one)