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backends: Calculate output scale correctly on vertical transforms

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The code calculating the output scale involves calculations around pixel
and mm sizes, however we do compare post-transformation pixel sizes to
untransformed mm sizes, which breaks the DPI calculations. Fix this by
transforming back pixel sizes back to untransformed.

While we're at it, actually compare the output height to HIDPI_MIN_HEIGHT
instead of its width, it seems right according to the #define name and
comment.

https://bugzilla.gnome.org/show_bug.cgi?id=777687
This commit is contained in:
Carlos Garnacho 2017-01-24 10:48:43 +01:00
parent ac813d5285
commit 70a4f59960
1 changed files with 19 additions and 5 deletions
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24
src/backends/native/meta-monitor-manager-kms.c
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@ -498,18 +498,31 @@ find_output_by_id (MetaOutput *outputs,
static int
compute_scale (MetaOutput *output)
{
int scale = 1;
int scale = 1, width, height;
if (!output->crtc)
goto out;
width = output->crtc->rect.width;
height = output->crtc->rect.height;
/* Swap values on rotated transforms, so pixel and mm sizes
* from the same axes is compared.
*/
if (meta_monitor_transform_is_rotated (output->crtc->transform))
{
int tmp = width;
width = height;
height = tmp;
}
/* Scaling makes no sense */
if (output->crtc->rect.width < HIDPI_MIN_HEIGHT)
if (height < HIDPI_MIN_HEIGHT)
goto out;
/* 4K TV */
if (output->name != NULL && strstr(output->name, "HDMI") != NULL &&
output->crtc->rect.width >= SMALLEST_4K_WIDTH)
width >= SMALLEST_4K_WIDTH)
goto out;
/* Somebody encoded the aspect ratio (16/9 or 16/10)
@ -523,8 +536,9 @@ compute_scale (MetaOutput *output)
if (output->width_mm > 0 && output->height_mm > 0)
{
double dpi_x, dpi_y;
dpi_x = (double)output->crtc->rect.width / (output->width_mm / 25.4);
dpi_y = (double)output->crtc->rect.height / (output->height_mm / 25.4);
dpi_x = (double)width / (output->width_mm / 25.4);
dpi_y = (double)height / (output->height_mm / 25.4);
/* We don't completely trust these values so both
must be high, and never pick higher ratio than
2 automatically */