Hello,
Sorry for the late rep= ly=2E

I am using cairo for drawing and pango for the text=2E I am cr= eating a window with xcb and using cairo_xcb_surface=2E

I can easily= extract the dpi information from the xrandr api calls=2E Now that I have t= his ratio, I have to use it somewhere to scale my canvas appropriately=2E
I will try using cairo_scale, and should I also scale the size of the= xcb_surface by the same ratio?

Anyway my main concern about antiali= sing is that since I am making layered shapes (think buttons) the border an= d the background will not match up pixel perfect (which is something that I= have seen in other project using cairo)=2E

Does what I described ab= out scaling the surface makes sense or am I misinterpreting cairo_scale?
Regards

Ps:
I will soon try and post the results

On March 18, 2024 1:46:= 54 PM GMT+01:00, Dov Grobgeld <dov=2Egrobgeld@gmail=2Ecom> wrote:

I think that you should describe in detail what you ex= pect=2E

In pure vector graphics a contour may cut thro= ugh a pixel and partially obscure it, and it is then the responsibility of = the graphics engine to create anti-aliased graphics by mixing the colors of= the background and the foreground=2E As a user you typically don't need to= concern yourself with that as it is done automatically=2E

However, e=2Eg=2E for text this may cause "fuzzy" characters and the = engine will then fallback to moving the contours and scale the font so that= the glyphs fall on whole pixels=2E

Note that the use = of anti-aliased graphics is less needed, and less visible, for an HDPI devi= ce=2E

In any case all that you will typically need is = cairo_scale() as Uli Shlachter already described=2E

=
Try it!

Regards,
On Sun, Mar 17, = 2024 at 12:46=E2=80=AFPM Federico Angelilli <list@fedang=2Enet> wrote:
Hi

Will cairo_sc= ale make a pixel perfect image for non integer scales? To my understanding = the scale matrix will be multiplied to all the coordinates scaling the coor= dinates appropriately=2E Should I also scale the whole surface by that same= factor?

Regards
On March 16, 2024 6:27:56 PM GMT+01:00, Uli Schlachter <psychon@znc=2Ein> wro= te:
Hi

Am 14=2E03=2E24 um 16:34 schrieb fedang:<=
br>
Hello all,

I am writing a small X11 app using cairo as the drawi=
ng backend=2E I was wondering if and how to implement
fractional scaling=
 to accommodate high dpi screens=2E After searching online I found almost n=
othing, so here I am=2E

Can someone give me some pointers on what to=
 do? I can get a scale factor for the screens (depending on the size)
bu=
t I have no idea how to actually use it in the draw code=2E

I'm not sure if I understand the question=2E Y=
ou can use cairo_scale() to set a scale factor for all drawing=2E So I woul=
d say that you can just apply the scale factor with cairo_scale() before dr=
awing=2E

Of course, this assumes that you don't use cairo_identity_m=
atrix() or cairo_set_matrix() in your drawing=2E Instead, cairo_save() and =
cairo_restore() should be used around temporary modifications of the transf=
ormations=2E

Cheers,
Uli
=

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