Set font size automatically depending on display size

[stewag64 8]

I develop a smartphone app with a tabcontrol with several tabs for some years already.

 

In order to size controls I use TGridPanelLayouts but in order to also scale font-sizes, I am still using various layout packages.

That is because I realized that the "standard" font-size is often too small on larger devices.

 

Layout packages have two drawbacks:

1. There is a bunch of layouts to update for every change in the app

2. You can never catch all existing Android display sizes, as I realize when I look at my app at other person's smartphones.

 

That is why I want to get rid of layout packages and find an algorithm that allows me to set font-sizes for labels, buttons and memos, depending on screen.width (or other device parameter).

 

Is there a general approach for this?

Does it also respect different device's dpi?

 

Thanks for any advice 

Steffen  

    

[stewag64 8]

This is my solution. I iterate font size until it fits the control.

Not sure if it works for high-dpi screens. Would it?

 

function SetFontSize(LongestText: String; MaxWidth: Single; MarginPerc: Integer): Integer;
{LongestText: string to be adapted
 MaxWidth: width of tab, button or label
 MarginPerc: side-margin in percent}
var
  i: Integer;
  bmp: TBitmap;
  TextWidth: Single;
begin
  Result := 10;
  bmp := TBitmap.Create(1, 1);
  try
    for i := 10 to 50 do
    begin
      bmp.Canvas.Font.Size := i;
      bmp.Canvas.Font.Style := []; // optional, bold
      bmp.Canvas.Fill.Kind := TBrushKind.Solid;
      bmp.Canvas.Fill.Color := TAlphaColorRec.Black;

      TextWidth := bmp.Canvas.TextWidth(LongestText);
      TextWidth := TextWidth * (1 + MarginPerc / 100);

      if TextWidth > MaxWidth then
      begin
        Result := i;
        Break;
      end;
    end;
  finally
    bmp.Free;
  end;
end;

 

Edited 17 hours ago by stewag64