implement HiDPI support for Skia/Mac (tdf#144214)

The basic idea is the same as the 'aqua' backend, simply set up
a scaling matrix for all drawing. That will take care of the basic
drawing everything twice as large, which is twice the resolution.
And then blit this data to the window, which expects data this way.

Converting back from backing surface needs explicit coordinate
conversions, and when converting to a bitmap the bitmap needs
to be scaled down in order to appear normally sized. Fortunately
I've already implemented delayed scaling, which means that if
the bitmap is drawn later again without any modifications, no
data would be lost (to be done in a follow-up commit).

Unittests occassionally need special handling, as such scaling
down to bitmap not being smoothed, because they expect exact
color values.

Change-Id: Ieadf2c3693f7c9676c31c7394d46299addf7880c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/125060
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/vcl/backendtest/outputdevice/common.cxx b/vcl/backendtest/outputdevice/common.cxx
index 21a32635ab85..80408fac70fe 100644
--- a/vcl/backendtest/outputdevice/common.cxx
+++ b/vcl/backendtest/outputdevice/common.cxx
@@ -1370,7 +1370,7 @@ TestResult OutputDeviceTestCommon::checkRadialGradient(Bitmap& bitmap)
     int nNumberOfErrors = 0;
     // The default VCL implementation is off-center in the direction to the top-left.
     // This means not all corners will be pure white => quirks.
-    checkValue(pAccess, 1, 1, COL_WHITE, nNumberOfQuirks, nNumberOfErrors, 255 / 10, 255 / 3);
+    checkValue(pAccess, 1, 1, COL_WHITE, nNumberOfQuirks, nNumberOfErrors, 255 / 10, 255 / 2);
     checkValue(pAccess, 1, 10, COL_WHITE, nNumberOfQuirks, nNumberOfErrors, 255 / 10, 255 / 5);
     checkValue(pAccess, 10, 1, COL_WHITE, nNumberOfQuirks, nNumberOfErrors, 255 / 10, 255 / 5);
     checkValue(pAccess, 10, 10, COL_WHITE, nNumberOfQuirks, nNumberOfErrors, 255 / 10, 255 / 5);