These tests check that we round glyph positions to integral device
pixel coordinates when hinting is enabled, and to device subpixel
positions if it isn't.
Enforce the following rules:
- No hinting or subpixel positioning in transformed context
- glyph-align determines if we use integral or fractional
device pixel positions
- For hinting, always use an integral y position (the hinter
assumes integral positions, and only operates vertically).
When we get an unhinted font for text node extents, don't change
the antialiasing setting. It doesn't affect the extents we get
here, but if we later need an unhinted font for rendering, the
one we create this way will be the right one, so it will already
exist.
We want to test subpixel positioning, so turn off hinting, since
hinting and subpixel positioning are opposing forces.
This does not currently change test outcomes, but it will prevent
the tests from breaking in the future when we make changes to
improve hinting.
Accessible text attributes come in two flavours:
- the run attributes, which apply to a text from a given offset
- the default attributes, which apply to the whole text
The default attributes are used to gather the initial values for every
text attribute, while the run attributes operate additively.
We currently have a getter for the former, but we lack one for the
latter.
The glyph in this test has extents that will be made smaller
by hinting, which poses some challenge for our renderers.
The scaled glyph rendering is too big for the 'small texture'
text setup, so we allow the test to fail there.
The goal is to fix all the context that influences the rendering
of text nodes in the node file. This will help with better font
testing.
The newly accepted properties are
hint-style: none/slight/full
antialias: none/gray
We are omitting font options and values that aren't supported
in GSK or have no influence on the rendering.
Note that these settings will get incorporated in the PangoFont
that gets set on the resulting text node.
Parser tests included.
We need precise bounds. And while hinting might shift the rendering
around from these bounds by a fraction of a pixel, we account for
this in the places where it matters: when determining diff regions,
when sizing offscreens, and when determining the size of atlas
regions for glyphs.
Add a function to change the cairo font options of a font to
to the given values while keeping everything else the same.
We use pango api for this if available.
Note that this is not a fully general api, but tailored to the
needs of GSK. We don't allow setting hint-metrics (because it
only influences layout, not rendering) or subpixel-mode (since
we don't have component alpha available).
