On Thu, 12 Apr 2018 09:31:48 +0200 Johan Klokkhammer Helsing <johan.hels...@qt.io> wrote:
> Some clients rely on the physical size to determine the physical DPI. With the
> previous implementation, we would report 1px==1mm, which is a DPI of 25.4,
> which is incredibly low.
>
> The problem is solved by setting a physical size so the DPI is close to 72
> instead. If the output is scaled, the DPI is set to the corresponding multiple
> of 72.
>
> This makes the headless backend more usable for automated testing of DPI
> sensitive functionality such as point sized fonts.
>
> Signed-off-by: Johan Klokkhammer Helsing <johan.hels...@qt.io>
> ---
> libweston/compositor-headless.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
Hi,
this is a good idea, but could you rebase this patch to master?
Thanks,
pq
>
> diff --git a/libweston/compositor-headless.c b/libweston/compositor-headless.c
> index 9307a36a..9f1a1a72 100644
> --- a/libweston/compositor-headless.c
> +++ b/libweston/compositor-headless.c
> @@ -180,12 +180,19 @@ err_malloc:
> return -1;
> }
>
> +static int
> +physical_size_for_dpi(int pixels, int dpi)
> +{
> + static const float mm_per_inch = 25.4;
> + return pixels * mm_per_inch / dpi;
> +}
> +
> static int
> headless_output_set_size(struct weston_output *base,
> int width, int height)
> {
> struct headless_output *output = to_headless_output(base);
> - int output_width, output_height;
> + int output_width, output_height, output_dpi;
>
> /* We can only be called once. */
> assert(!output->base.current_mode);
> @@ -207,9 +214,10 @@ headless_output_set_size(struct weston_output *base,
> output->base.make = "weston";
> output->base.model = "headless";
>
> - /* XXX: Calculate proper size. */
> - output->base.mm_width = width;
> - output->base.mm_height = height;
> + /* XXX: Make this configurable */
> + output_dpi = 72 * output->base.scale;
> + output->base.mm_width = physical_size_for_dpi(output_width, output_dpi);
> + output->base.mm_height = physical_size_for_dpi(output_height,
> output_dpi);
>
> output->base.start_repaint_loop = headless_output_start_repaint_loop;
> output->base.repaint = headless_output_repaint;
pgpqclHCu7dK2.pgp
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