X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=effect_chain.h;h=b51c2bb56cc0d97222ddf7ca99c98d5d8988df38;hp=6ceb0c361f80e4b1d94db6d5db1a5a775979f925;hb=f6ccf310656ba0c218574654fbf8e794041efeaf;hpb=a616ded3842994840ce0cfa365d259f602493779

diff --git a/effect_chain.h b/effect_chain.h
index 6ceb0c3..b51c2bb 100644
--- a/effect_chain.h
+++ b/effect_chain.h
@@ -11,6 +11,21 @@
 class EffectChain;
 class Phase;
 
+// For internal use within Node.
+enum AlphaType {
+	ALPHA_INVALID = -1,
+	ALPHA_BLANK,
+	ALPHA_PREMULTIPLIED,
+	ALPHA_POSTMULTIPLIED,
+};
+
+// Whether you want pre- or postmultiplied alpha in the output
+// (see effect.h for a discussion of pre- versus postmultiplied alpha).
+enum OutputAlphaFormat {
+	OUTPUT_ALPHA_PREMULTIPLIED,
+	OUTPUT_ALPHA_POSTMULTIPLIED,
+};
+
 // A node in the graph; basically an effect and some associated information.
 class Node {
 public:
@@ -42,6 +57,7 @@ private:
 	// Used during the building of the effect chain.
 	Colorspace output_color_space;
 	GammaCurve output_gamma_curve;
+	AlphaType output_alpha_type;
 
 	friend class EffectChain;
 };
@@ -89,7 +105,7 @@ public:
 	}
 	Effect *add_effect(Effect *effect, const std::vector<Effect *> &inputs);
 
-	void add_output(const ImageFormat &format);
+	void add_output(const ImageFormat &format, OutputAlphaFormat alpha_format);
 
 	// Set number of output bits, to scale the dither.
 	// 8 is the right value for most outputs.
@@ -163,11 +179,21 @@ private:
 	// Some of the graph algorithms assume that the nodes array is sorted
 	// topologically (inputs are always before outputs), but some operations
 	// (like graph rewriting) can change that. This function restores that order.
-	void sort_nodes_topologically();
-	void topological_sort_visit_node(Node *node, std::set<Node *> *visited_nodes, std::vector<Node *> *sorted_list);
+	void sort_all_nodes_topologically();
+
+	// Do the actual topological sort. <nodes> must be a connected, acyclic subgraph;
+	// links that go to nodes not in the set will be ignored.
+	std::vector<Node *> topological_sort(const std::vector<Node *> &nodes);
+
+	// Utility function used by topological_sort() to do a depth-first search.
+	// The reason why we store nodes left to visit instead of a more conventional
+	// list of nodes to visit is that we want to be able to limit ourselves to
+	// a subgraph instead of all nodes. The set thus serves a dual purpose.
+	void topological_sort_visit_node(Node *node, std::set<Node *> *nodes_left_to_visit, std::vector<Node *> *sorted_list);
 
 	// Used during finalize().
 	void find_color_spaces_for_inputs();
+	void propagate_alpha();
 	void propagate_gamma_and_color_space();
 	Node *find_output_node();
 
@@ -175,6 +201,10 @@ private:
 	void fix_internal_color_spaces();
 	void fix_output_color_space();
 
+	bool node_needs_alpha_fix(Node *node);
+	void fix_internal_alpha(unsigned step);
+	void fix_output_alpha();
+
 	bool node_needs_gamma_fix(Node *node);
 	void fix_internal_gamma_by_asking_inputs(unsigned step);
 	void fix_internal_gamma_by_inserting_nodes(unsigned step);
@@ -183,6 +213,7 @@ private:
 
 	float aspect_nom, aspect_denom;
 	ImageFormat output_format;
+	OutputAlphaFormat output_alpha_format;
 
 	std::vector<Node *> nodes;
 	std::map<Effect *, Node *> node_map;