+void BlurEffect::rewrite_graph(EffectChain *graph, Node *self)
+{
+ Node *hpass_node = graph->add_node(hpass);
+ Node *vpass_node = graph->add_node(vpass);
+ graph->connect_nodes(hpass_node, vpass_node);
+ graph->replace_receiver(self, hpass_node);
+ graph->replace_sender(self, vpass_node);
+ self->disabled = true;
+}
+
+// We get this information forwarded from the first blur pass,
+// since we are not part of the chain ourselves.
+void BlurEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
+{
+ assert(input_num == 0);
+ assert(width != 0);
+ assert(height != 0);
+ input_width = width;
+ input_height = height;
+ update_radius();
+}
+
+void BlurEffect::update_radius()
+{
+ // We only have 16 taps to work with on each side, and we want that to
+ // reach out to about 2.5*sigma. Bump up the mipmap levels (giving us
+ // box blurs) until we have what we need.
+ unsigned mipmap_width = input_width, mipmap_height = input_height;
+ float adjusted_radius = radius;
+ while ((mipmap_width > 1 || mipmap_height > 1) && adjusted_radius * 1.5f > num_taps / 2) {
+ // Find the next mipmap size (round down, minimum 1 pixel).
+ mipmap_width = max(mipmap_width / 2, 1u);
+ mipmap_height = max(mipmap_height / 2, 1u);
+
+ // Approximate when mipmap sizes are odd, but good enough.
+ adjusted_radius = radius * float(mipmap_width) / float(input_width);
+ }
+
+ bool ok = hpass->set_float("radius", adjusted_radius);
+ ok |= hpass->set_int("width", mipmap_width);
+ ok |= hpass->set_int("height", mipmap_height);
+ ok |= hpass->set_int("virtual_width", mipmap_width);
+ ok |= hpass->set_int("virtual_height", mipmap_height);
+ ok |= hpass->set_int("num_taps", num_taps);
+
+ ok |= vpass->set_float("radius", adjusted_radius);
+ ok |= vpass->set_int("width", mipmap_width);
+ ok |= vpass->set_int("height", mipmap_height);
+ ok |= vpass->set_int("virtual_width", input_width);
+ ok |= vpass->set_int("virtual_height", input_height);
+ ok |= vpass->set_int("num_taps", num_taps);
+
+ assert(ok);
+}