Implement overlays for the DRM/KMS preview

Signed-off-by: David Plowman <[email protected]>

Author: davidplowman

picamera2/previews/drm_preview.py

@@ -1,7 +1,10 @@
 import picamera2.picamera2
 import pykms
+import mmap
+import numpy as np
 from picamera2.previews.null_preview import *
 
+dd = None
 
 class DrmPreview(NullPreview):
     FMT_MAP = {
@@ -36,6 +39,20 @@ def init_drm(self, x, y, width, height):
         self.drmfbs = {}
         self.current = None
         self.window = (x, y, width, height)
+        self.overlay_plane = None
+        self.overlay_fb = None
+        self.overlay_new_fb = None
+
+    def set_overlay(self, overlay):
+        if overlay is None:
+            self.overlay_new_fb = None
+        else:
+            h, w, channels = overlay.shape
+            # Should I be recycling these instead of making new ones all the time?
+            new_fb = pykms.DumbFramebuffer(self.card, w, h, "AB24")
+            with mmap.mmap(new_fb.fd(0), w * h * 4, mmap.MAP_SHARED, mmap.PROT_WRITE) as mm:
+                mm.write(np.ascontiguousarray(overlay).data)
+            self.overlay_new_fb = new_fb
 
     def render_drm(self, picam2, completed_request):
         if picam2.display_stream_name is None:
@@ -55,9 +72,14 @@ def render_drm(self, picam2, completed_request):
             fmt = self.FMT_MAP[cfg.pixelFormat]
             if self.plane is None:
                 self.plane = self.resman.reserve_overlay_plane(self.crtc, fmt)
-                if picam2.verbose_console:
-                    print("Got plane", self.plane, "for format", fmt)
-                assert(self.plane)
+                if self.plane is None:
+                    raise RuntimeError("Failed to reserve DRM plane")
+                # The second plane we ask for will go on top of the first.
+                self.overlay_plane = self.resman.reserve_overlay_plane(self.crtc, pykms.PixelFormat.ABGR8888)
+                if self.overlay_plane is None:
+                    raise RuntimeError("Failed to reserve DRM overlay plane")
+                # Want "coverage" mode, not pre-multiplied alpha.
+                self.overlay_plane.set_prop("pixel blend mode", 1)
             fd = fb.fd(0)
             stride = cfg.stride
             if cfg.pixelFormat in ("YUV420", "YVU420"):
@@ -77,6 +99,21 @@ def render_drm(self, picam2, completed_request):
         drmfb = self.drmfbs[fb]
         x, y, w, h = self.window
         self.crtc.set_plane(self.plane, drmfb, x, y, w, h, 0, 0, width, height)
+        # An "atomic commit" would probably be better, but I can't get this to work...
+        # ctx = pykms.AtomicReq(self.card)
+        # ctx.add(self.plane, {"FB_ID": drmfb.id, "CRTC_ID": self.crtc.id,
+        #                      "SRC_W": width << 16, "SRC_H": height << 16,
+        #                      "CRTC_X": x, "CRTC_Y": y, "CRTC_W": w, "CRTC_H": h})
+        # ctx.commit()
+
+        overlay_new_fb = self.overlay_new_fb
+        if overlay_new_fb != self.overlay_fb:
+            overlay_old_fb = self.overlay_fb  # Must hang on to this momentarily to avoid a "wink"
+            self.overlay_fb = overlay_new_fb
+        if self.overlay_fb is not None:
+            width, height = self.overlay_fb.width, self.overlay_fb.height
+            self.crtc.set_plane(self.overlay_plane, self.overlay_fb, x, y, w, h, 0, 0, width, height)
+        overlay_old_fb = None  # The new one has been sent so it's safe to let this go now
 
         if self.current:
             self.current.release()
@@ -86,6 +123,8 @@ def stop(self):
         super().stop()
         # Seem to need some of this in order to be able to create another DrmPreview.
         self.drmfbs = {}
+        self.overlay_new_fb = None
+        self.overlay_fb = None
         self.crtc = None
         self.resman = None
         self.card = None