A little bit of sleep and reflection suggested that the use of
device_offset_[xy] was confusing and clone_offset_[xy] more consistent
with the function naming.
Previously the rule for clone_similar() was that the returned surface
had exactly the same size as the original, but only the contents within
the region of interest needed to be copied. This caused failures for very
large images in the xlib-backend (see test/large-source).
The obvious solution to allow cloning only the region of interest seemed
to be to simply set the device offset on the cloned surface. However, this
fails as a) nothing respects the device offset on the surface at that
layer in the compositing stack and b) possibly returning references to the
original source surface provides further confusion by mixing in another
source of device offset.
The second method was to add extra out parameters so that the
device offset could be returned separately and, for example, mixed into
the pattern matrix. Not as elegant, a couple of extra warts to the
interface, but it works - one less XFAIL...
This reverts commit 919bea6dbb.
Sadly as Behdad points out some backends do modify the glyph array and,
for example cairo-xlib-surface, hide this from the compiler with some
evil casts.
Skip the memory duplication of the incoming glyphs if we do not need
to transform them into the backend coordinate system.
As a consequence we need to constify the glyphs passed to the backend
functions.
The rule is: cairo_glyph_t* is always passed as const for measurement
purposes. This was not reflected in our public api previously. Fixed
Showing glyphs used to have cairo_glyph_t* always as const. With this
changed, it is only const on cairo_t and cairo_gstate_t operations.
cairo_surface_t, cairo_scaled_font_t, and individual backends receive
cairo_glyph_t* as non-const. The desired semantics is that they may modify
the contents of the array as long as they do not return
CAIRO_STATUS_UNSUPPORTED. This makes it possible to avoid copying the glyph
array again and again, and edit it in-place. Backends are in fact free to use
the array as a generic buffer as they see fit.
This rectangle has regular integer values, not fixed-point values.
So the old name was horribly wrong and misleading, (and yes I think
it was even I that had suggested it).
