[PATCH wayland-protocols 1/2] stable: add viewporter draft
Pekka Paalanen
ppaalanen at gmail.com
Tue Apr 19 10:49:14 UTC 2016
On Mon, 18 Apr 2016 07:15:28 -0500
Yong Bakos <junk at humanoriented.com> wrote:
> On Apr 15, 2016, at 9:53 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> >
> > From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> >
> > This XML file has been copied verbatim from Weston 1.10.0 release,
> > protocol/scaler.xml.
> >
> > The interfaces still need renaming according to wayland-protocols
> > policy. Also a redundant request needs to be removed. These will be done
> > in a follow-up patch to clearly show the changes.
> >
> > Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
>
> There's one paragraph I think could use a rewriting, noted inline below,
> but since this is just a move, the writing and such is
> Reviewed-by: Yong Bakos <ybakos at humanoriented.com>
>
> yong
>
>
> > ---
> > stable/viewporter/README | 7 ++
> > stable/viewporter/viewporter.xml | 208 +++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 215 insertions(+)
> > create mode 100644 stable/viewporter/README
> > create mode 100644 stable/viewporter/viewporter.xml
> >
> > diff --git a/stable/viewporter/README b/stable/viewporter/README
> > new file mode 100644
> > index 0000000..e09057b
> > --- /dev/null
> > +++ b/stable/viewporter/README
> > @@ -0,0 +1,7 @@
> > +Viewporter: cropping and scaling extension for surface contents
> > +
> > +Previously known as wl_scaler.
> > +
> > +Maintainers:
> > +Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> > +
> > diff --git a/stable/viewporter/viewporter.xml b/stable/viewporter/viewporter.xml
> > new file mode 100644
> > index 0000000..0e482a6
> > --- /dev/null
> > +++ b/stable/viewporter/viewporter.xml
> > @@ -0,0 +1,208 @@
> > +<?xml version="1.0" encoding="UTF-8"?>
> > +<protocol name="scaler">
> > +
> > + <copyright>
> > + Copyright © 2013-2014 Collabora, Ltd.
> > +
> > + Permission is hereby granted, free of charge, to any person obtaining a
> > + copy of this software and associated documentation files (the "Software"),
> > + to deal in the Software without restriction, including without limitation
> > + the rights to use, copy, modify, merge, publish, distribute, sublicense,
> > + and/or sell copies of the Software, and to permit persons to whom the
> > + Software is furnished to do so, subject to the following conditions:
> > +
> > + The above copyright notice and this permission notice (including the next
> > + paragraph) shall be included in all copies or substantial portions of the
> > + Software.
> > +
> > + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > + IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> > + FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> > + THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> > + LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> > + FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> > + DEALINGS IN THE SOFTWARE.
> > + </copyright>
> > +
> > + <interface name="wl_scaler" version="2">
> > + <description summary="surface cropping and scaling">
> > + The global interface exposing surface cropping and scaling
> > + capabilities is used to instantiate an interface extension for a
> > + wl_surface object. This extended interface will then allow
> > + cropping and scaling the surface contents, effectively
> > + disconnecting the direct relationship between the buffer and the
> > + surface size.
> > + </description>
> > +
> > + <request name="destroy" type="destructor">
> > + <description summary="unbind from the cropping and scaling interface">
> > + Informs the server that the client will not be using this
> > + protocol object anymore. This does not affect any other objects,
> > + wl_viewport objects included.
> > + </description>
> > + </request>
> > +
> > + <enum name="error">
> > + <entry name="viewport_exists" value="0"
> > + summary="the surface already has a viewport object associated"/>
> > + </enum>
> > +
> > + <request name="get_viewport">
> > + <description summary="extend surface interface for crop and scale">
> > + Instantiate an interface extension for the given wl_surface to
> > + crop and scale its content. If the given wl_surface already has
> > + a wl_viewport object associated, the viewport_exists
> > + protocol error is raised.
> > + </description>
> > +
> > + <arg name="id" type="new_id" interface="wl_viewport"
> > + summary="the new viewport interface id"/>
> > + <arg name="surface" type="object" interface="wl_surface"
> > + summary="the surface"/>
> > + </request>
> > + </interface>
> > +
> > + <interface name="wl_viewport" version="2">
> > + <description summary="crop and scale interface to a wl_surface">
> > + An additional interface to a wl_surface object, which allows the
> > + client to specify the cropping and scaling of the surface
> > + contents.
> > +
> > + This interface allows to define the source rectangle (src_x,
> > + src_y, src_width, src_height) from where to take the wl_buffer
> > + contents, and scale that to destination size (dst_width,
> > + dst_height). This state is double-buffered, and is applied on the
> > + next wl_surface.commit.
>
> The first sentence of this paragraph is a bit cumbersome. Maybe:
>
> This interface defines a source rectangle of the wl_buffer
> contents (src_x, src_y, src_width, src_height), and a means of
> scaling the source rectangle to a destination size (dst_width,
> dst_height).
Right. We also need to be careful to not imply an incorrect coordinate
space. The src coordinates are not buffer coordinates. It is also a
source not for wl_buffer but from wl_buffer.
I've had lots of issues in writing this, because there are two concepts
of surface content: the one before wp_viewport, and the one after
wp_viewport.
The src coordinates are in surface local coordinates as if there was no
wp_viewport defined at all. This is explained further below.
So, what to write here... "allows to define" was to mean that simply
creating a wp_viewport does not change anything, but you could use it
to change things.
How about:
This interface works with two concepts: the source rectangle
(src_x, src_y, src_width, src_height), and the destination size
(dst_width, dst_height). The contents of the source rectangle
are scaled to the destination size, and content outside the
source rectangle is culled. This state is double-buffered, and
is applied on the next wl_surface.commit.
Maybe I should keep the argument names src_x, src_y, src_width,
src_height, dst_width, dst_height also in the wp_viewport.set_source
and wp_viewport.set_destination requests to make a clear connection to
this documentation?
Thanks,
pq
> > +
> > + The two parts of crop and scale state are independent: the source
> > + rectangle, and the destination size. Initially both are unset, that
> > + is, no scaling is applied. The whole of the current wl_buffer is
> > + used as the source, and the surface size is as defined in
> > + wl_surface.attach.
> > +
> > + If the destination size is set, it causes the surface size to become
> > + dst_width, dst_height. The source (rectangle) is scaled to exactly
> > + this size. This overrides whatever the attached wl_buffer size is,
> > + unless the wl_buffer is NULL. If the wl_buffer is NULL, the surface
> > + has no content and therefore no size. Otherwise, the size is always
> > + at least 1x1 in surface coordinates.
> > +
> > + If the source rectangle is set, it defines what area of the
> > + wl_buffer is taken as the source. If the source rectangle is set and
> > + the destination size is not set, the surface size becomes the source
> > + rectangle size rounded up to the nearest integer. If the source size
> > + is already exactly integers, this results in cropping without scaling.
> > +
> > + The coordinate transformations from buffer pixel coordinates up to
> > + the surface-local coordinates happen in the following order:
> > + 1. buffer_transform (wl_surface.set_buffer_transform)
> > + 2. buffer_scale (wl_surface.set_buffer_scale)
> > + 3. crop and scale (wl_viewport.set*)
> > + This means, that the source rectangle coordinates of crop and scale
> > + are given in the coordinates after the buffer transform and scale,
> > + i.e. in the coordinates that would be the surface-local coordinates
> > + if the crop and scale was not applied.
> > +
> > + If the source rectangle is partially or completely outside of the
> > + wl_buffer, then the surface contents are undefined (not void), and
> > + the surface size is still dst_width, dst_height.
> > +
> > + The x, y arguments of wl_surface.attach are applied as normal to
> > + the surface. They indicate how many pixels to remove from the
> > + surface size from the left and the top. In other words, they are
> > + still in the surface-local coordinate system, just like dst_width
> > + and dst_height are.
> > +
> > + If the wl_surface associated with the wl_viewport is destroyed,
> > + the wl_viewport object becomes inert.
> > +
> > + If the wl_viewport object is destroyed, the crop and scale
> > + state is removed from the wl_surface. The change will be applied
> > + on the next wl_surface.commit.
> > + </description>
> > +
> > + <request name="destroy" type="destructor">
> > + <description summary="remove scaling and cropping from the surface">
> > + The associated wl_surface's crop and scale state is removed.
> > + The change is applied on the next wl_surface.commit.
> > + </description>
> > + </request>
> > +
> > + <enum name="error">
> > + <entry name="bad_value" value="0"
> > + summary="negative or zero values in width or height"/>
> > + </enum>
> > +
> > + <request name="set">
> > + <description summary="set the crop and scale state">
> > + Set both source rectangle and destination size of the associated
> > + wl_surface. See wl_viewport for the description, and relation to
> > + the wl_buffer size.
> > +
> > + The bad_value protocol error is raised if src_width or
> > + src_height is negative, or if dst_width or dst_height is not
> > + positive.
> > +
> > + The crop and scale state is double-buffered state, and will be
> > + applied on the next wl_surface.commit.
> > +
> > + Arguments dst_x and dst_y do not exist here, use the x and y
> > + arguments to wl_surface.attach. The x, y, dst_width, and dst_height
> > + define the surface-local coordinate system irrespective of the
> > + attached wl_buffer size.
> > + </description>
> > +
> > + <arg name="src_x" type="fixed" summary="source rectangle x"/>
> > + <arg name="src_y" type="fixed" summary="source rectangle y"/>
> > + <arg name="src_width" type="fixed" summary="source rectangle width"/>
> > + <arg name="src_height" type="fixed" summary="source rectangle height"/>
> > + <arg name="dst_width" type="int" summary="surface width"/>
> > + <arg name="dst_height" type="int" summary="surface height"/>
> > + </request>
> > +
> > + <request name="set_source" since="2">
> > + <description summary="set the source rectangle for cropping">
> > + Set the source rectangle of the associated wl_surface. See
> > + wl_viewport for the description, and relation to the wl_buffer
> > + size.
> > +
> > + If width is -1.0 and height is -1.0, the source rectangle is unset
> > + instead. Any other pair of values for width and height that
> > + contains zero or negative values raises the bad_value protocol
> > + error.
> > +
> > + The crop and scale state is double-buffered state, and will be
> > + applied on the next wl_surface.commit.
> > + </description>
> > +
> > + <arg name="x" type="fixed" summary="source rectangle x"/>
> > + <arg name="y" type="fixed" summary="source rectangle y"/>
> > + <arg name="width" type="fixed" summary="source rectangle width"/>
> > + <arg name="height" type="fixed" summary="source rectangle height"/>
> > + </request>
> > +
> > + <request name="set_destination" since="2">
> > + <description summary="set the surface size for scaling">
> > + Set the destination size of the associated wl_surface. See
> > + wl_viewport for the description, and relation to the wl_buffer
> > + size.
> > +
> > + If width is -1 and height is -1, the destination size is unset
> > + instead. Any other pair of values for width and height that
> > + contains zero or negative values raises the bad_value protocol
> > + error.
> > +
> > + The crop and scale state is double-buffered state, and will be
> > + applied on the next wl_surface.commit.
> > +
> > + Arguments x and y do not exist here, use the x and y arguments to
> > + wl_surface.attach. The x, y, width, and height define the
> > + surface-local coordinate system irrespective of the attached
> > + wl_buffer size.
> > + </description>
> > +
> > + <arg name="width" type="int" summary="surface width"/>
> > + <arg name="height" type="int" summary="surface height"/>
> > + </request>
> > + </interface>
> > +</protocol>
> > --
> > 2.7.3
> >
> > _______________________________________________
> > wayland-devel mailing list
> > wayland-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/wayland-devel
>
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