[Solved] Saving Window position and High DPI

[lainz]

Hi,

I'm with this problem, I can't solve.

I store the properties of the Form with JSONPropStorage. I store left, top, width and height.

I'm using Lazarus trunk, and I set Use LCL Scaling (hi-dpi) to true in the options.

The problem is that every time I open the window, it gets bigger.

As I understand the problem, it loads the stored values and then scales it. The next time does the same, loads the stored values and scales them.

How I can prevent this to happen?

I've set the properties to store (left, top, width, height) with the object inspector (SessionProperties).

I don't know how I can solve it. The DPI can be changed also, I'm running now at 120%, but when I switch to another mode for any reason, It will stop working as well.

[balazsszekely]

Did you try to scale with MulDiv from LCLType?

Code: Pascal  [Select][+][-]

1. WidthX% := MulDiv(Width100%, Screen.PixelsPerInch, 96);

Where Width100% is the default value at 96 DPI. So one possible solution is to always store the width in 96 DPI equivalent, then scale it whenever is needed.

[lainz]

Thanks. Yes, I need to change the automatic saving and try with your code.
The problem of the automatic saving / loading, is that I can't change nothing.

[balazsszekely]

Plese try something like this:

1. Save
Width96 := MulDiv(CurWidth, 96,  Screen.PixelsPerInch);
Save Width96 to json.

2. Load
Load Width96 from JSON:
CurWidth  := MulDiv(Width96,  Screen.PixelsPerInch, 96);

[lainz]

Thanks GetMem, it works.

Code: Pascal  [Select][+][-]

1. procedure TfrmTimeEntry.JSONPropStorage1RestoreProperties(Sender: TObject);
2. begin
3.   Width := MulDiv(Width, 96, Screen.PixelsPerInch);
4.   Height := MulDiv(Height, 96, Screen.PixelsPerInch);    
5. end;

It's only needed on restore.