[PATCH] Mirroing mode

[Leslie Zhai]

Hi Pekka,

Thanks for your reply!

It is not easy to use Google "thanks to" G.F.W. blocked it ;-(
Could you paste the URL links for me please? thanks a lot!

It is not the issue - whether or not able to do partial (or full 
repaint) updates, but owing to:
1. different mode such as different width x height resolution
2. different scale, maybe output VGA1 is often called "HiDPI" or 
"retina" display

The screenshot 
https://twitter.com/xiangzhai/status/587827576665587713/photo/1
The overlap of outputs (LVDS1 and VGA1) is not in the SAME coordinate 
system: different X and Y axes, so even do a full repaint, it is not 
able to fix the issue!

But what about Xinerama http://en.wikipedia.org/wiki/Xinerama like the 
father of Xrandr.
I am learning how Xinerama do the coordinate matrix transform for the 
X11, hope to inspire me for weston ;-)

On 2015年04月10日 21:05, Pekka Paalanen wrote:
> On Fri, 10 Apr 2015 15:36:36 +0800
> Leslie Zhai <xiang.zhai at i-soft.com.cn> wrote:
>
>> Hi Pekka,
>>
>> I am reading src/compositor-drm.c in create_outputs(...) function, it
>> uses drmModeGetResources to get count_connectors,
>> then update the X position in a for loop shown as below:
>>
>> ```
>> x += container_of(ec->base.output_list.prev,
>>                         struct weston_output,
>>                         link)->width;
>> ```
>>
>> so it is absolutely extend mode by default, "draw" count_connectors`
>> create_output_for_connector(...) rectangles with DIFFERENT X position,
>> if take a screenshot, it should be
>> https://twitter.com/xiangzhai/status/586061869279883266/photo/1
>>
>> But if add mirror to drm_options (shown as below patch) it is able to
>> run weston --mirror with the SAME X position,
>> the screenshot
>> https://twitter.com/xiangzhai/status/586428721533288449/photo/1
>>
> I have a huge deja vu experience here. I warmly suggest you dig up the
> previous discussions from the mailing list archives when this kind of
> simple (too stupid to work for more than 2 outputs) mirroring was
> proposed.
>
>> diff --git a/src/compositor-drm.c b/src/compositor-drm.c
>> index 153ca5d..d28a32e 100644
>> --- a/src/compositor-drm.c
>> +++ b/src/compositor-drm.c
>> @@ -216,6 +216,7 @@ struct drm_parameters {
>>        int tty;
>>        int use_pixman;
>>        const char *seat_id;
>> +    int mirror;
>>    };
>>
>>    static struct gl_renderer_interface *gl_renderer;
>> @@ -2327,7 +2328,7 @@ destroy_sprites(struct drm_compositor *compositor)
>>
>>    static int
>>    create_outputs(struct drm_compositor *ec, uint32_t option_connector,
>> -           struct udev_device *drm_device)
>> +           struct udev_device *drm_device, int mirror_mode)
>>    {
>>        drmModeConnector *connector;
>>        drmModeRes *resources;
>> @@ -2370,9 +2371,12 @@ create_outputs(struct drm_compositor *ec,
>> uint32_t option_connector,
>>                    continue;
>>                }
>>
>> -            x += container_of(ec->base.output_list.prev,
>> +            /* FIXME: mirroring mode */
>> +            if (!mirror_mode) {
>> +                x += container_of(ec->base.output_list.prev,
>>                          struct weston_output,
>>                          link)->width;
>> +            }
>>            }
>>
>>            drmModeFreeConnector(connector);
>> @@ -2936,7 +2940,7 @@ drm_compositor_create(struct wl_display *display,
>>            goto err_sprite;
>>        }
>>
>> -    if (create_outputs(ec, param->connector, drm_device) < 0) {
>> +    if (create_outputs(ec, param->connector, drm_device, param->mirror)
>> < 0) {
>>            weston_log("failed to create output for %s\n", path);
>>            goto err_udev_input;
>>        }
>> @@ -3021,6 +3025,7 @@ backend_init(struct wl_display *display, int
>> *argc, char *argv[],
>>            { WESTON_OPTION_INTEGER, "tty", 0, &param.tty },
>>            { WESTON_OPTION_BOOLEAN, "current-mode", 0,
>> &option_current_mode },
>>            { WESTON_OPTION_BOOLEAN, "use-pixman", 0, &param.use_pixman },
>> +        { WESTON_OPTION_BOOLEAN, "mirror", 0, &param.mirror }
>>        };
>>
>>        param.seat_id = default_seat;
>> diff --git a/src/compositor.c b/src/compositor.c
>> index 6fbb8e8..d29cabc 100644
>> --- a/src/compositor.c
>> +++ b/src/compositor.c
>> @@ -5043,7 +5043,8 @@ usage(int error_code)
>>            "  --seat=SEAT\t\tThe seat that weston should run on\n"
>>            "  --tty=TTY\t\tThe tty to use\n"
>>            "  --use-pixman\t\tUse the pixman (CPU) renderer\n"
>> -        "  --current-mode\tPrefer current KMS mode over EDID preferred
>> mode\n\n");
>> +        "  --current-mode\tPrefer current KMS mode over EDID preferred
>> mode\n"
>> +        "  --mirror\t\tUse mirroring mode\n\n");
>>    #endif
>>
>>    #if defined(BUILD_FBDEV_COMPOSITOR)
>>
>>
>>
>> It is a monkey patch ;-) there are a lot of things I have to fix or
>> learn, such as:
>> 1. how to "draw" the SAME "rectangle" to different outputs, what do I
>> need to hack for recent weston`s architecture?
>> 2. xrandr utility will choose the SAME mode for different outputs, for
>> example, 1024x768, I have not implemented it for mirroring mode!
> Like I said, a simple test does not guarantee that weston's damage
> tracking can cope with it. You have to ensure the renderer/backend can
> do partial updates, and then watch for glitches when causing partial
> repaints.
>
> The answer to your question about rectangles involves understanding the
> damage tracking system and making sure it works also for overlapping
> outputs. After that, it should just work. I cannot explain it off-hand,
> it is so complex that it would take a good while for me to study and
> understand again how it works.
>
> Screenshooting forces a full repaint IIRC, so that would immediately
> hide any glitches you might see.
>
>
> Thanks,
> pq
>

-- 
Regards,
Leslie Zhai