[PATCH] Mirroing mode

[Leslie Zhai]

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



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!

-- 
Regards,
Leslie Zhai