+// Propagate gamma and color space information as far as we can in the graph.
+// The rules are simple: Anything where all the inputs agree, get that as
+// output as well. Anything else keeps having *_INVALID.
+void EffectChain::propagate_gamma_and_color_space()
+{
+ // We depend on going through the nodes in order.
+ sort_all_nodes_topologically();
+
+ for (unsigned i = 0; i < nodes.size(); ++i) {
+ Node *node = nodes[i];
+ if (node->disabled) {
+ continue;
+ }
+ assert(node->incoming_links.size() == node->effect->num_inputs());
+ if (node->incoming_links.size() == 0) {
+ assert(node->output_color_space != COLORSPACE_INVALID);
+ assert(node->output_gamma_curve != GAMMA_INVALID);
+ continue;
+ }
+
+ Colorspace color_space = node->incoming_links[0]->output_color_space;
+ GammaCurve gamma_curve = node->incoming_links[0]->output_gamma_curve;
+ for (unsigned j = 1; j < node->incoming_links.size(); ++j) {
+ if (node->incoming_links[j]->output_color_space != color_space) {
+ color_space = COLORSPACE_INVALID;
+ }
+ if (node->incoming_links[j]->output_gamma_curve != gamma_curve) {
+ gamma_curve = GAMMA_INVALID;
+ }
+ }
+
+ // The conversion effects already have their outputs set correctly,
+ // so leave them alone.
+ if (node->effect->effect_type_id() != "ColorspaceConversionEffect") {
+ node->output_color_space = color_space;
+ }
+ if (node->effect->effect_type_id() != "GammaCompressionEffect" &&
+ node->effect->effect_type_id() != "GammaExpansionEffect") {
+ node->output_gamma_curve = gamma_curve;
+ }
+ }
+}
+
+// Propagate alpha information as far as we can in the graph.
+// Similar to propagate_gamma_and_color_space().
+void EffectChain::propagate_alpha()
+{
+ // We depend on going through the nodes in order.
+ sort_all_nodes_topologically();
+
+ for (unsigned i = 0; i < nodes.size(); ++i) {
+ Node *node = nodes[i];
+ if (node->disabled) {
+ continue;
+ }
+ assert(node->incoming_links.size() == node->effect->num_inputs());
+ if (node->incoming_links.size() == 0) {
+ assert(node->output_alpha_type != ALPHA_INVALID);
+ continue;
+ }
+
+ // The alpha multiplication/division effects are special cases.
+ if (node->effect->effect_type_id() == "AlphaMultiplicationEffect") {
+ assert(node->incoming_links.size() == 1);
+ assert(node->incoming_links[0]->output_alpha_type == ALPHA_POSTMULTIPLIED);
+ node->output_alpha_type = ALPHA_PREMULTIPLIED;
+ continue;
+ }
+ if (node->effect->effect_type_id() == "AlphaDivisionEffect") {
+ assert(node->incoming_links.size() == 1);
+ assert(node->incoming_links[0]->output_alpha_type == ALPHA_PREMULTIPLIED);
+ node->output_alpha_type = ALPHA_POSTMULTIPLIED;
+ continue;
+ }
+
+ // GammaCompressionEffect and GammaExpansionEffect are also a special case,
+ // because they are the only one that _need_ postmultiplied alpha.
+ if (node->effect->effect_type_id() == "GammaCompressionEffect" ||
+ node->effect->effect_type_id() == "GammaExpansionEffect") {
+ assert(node->incoming_links.size() == 1);
+ if (node->incoming_links[0]->output_alpha_type == ALPHA_BLANK) {
+ node->output_alpha_type = ALPHA_BLANK;
+ } else if (node->incoming_links[0]->output_alpha_type == ALPHA_POSTMULTIPLIED) {
+ node->output_alpha_type = ALPHA_POSTMULTIPLIED;
+ } else {
+ node->output_alpha_type = ALPHA_INVALID;
+ }
+ continue;
+ }
+
+ // Only inputs can have unconditional alpha output (OUTPUT_BLANK_ALPHA
+ // or OUTPUT_ALPHA_POSTMULTIPLIED), and they have already been
+ // taken care of above. Rationale: Even if you could imagine
+ // e.g. an effect that took in an image and set alpha=1.0
+ // unconditionally, it wouldn't make any sense to have it as
+ // e.g. OUTPUT_BLANK_ALPHA, since it wouldn't know whether it
+ // got its input pre- or postmultiplied, so it wouldn't know
+ // whether to divide away the old alpha or not.
+ Effect::AlphaHandling alpha_handling = node->effect->alpha_handling();
+ assert(alpha_handling == Effect::INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED ||
+ alpha_handling == Effect::DONT_CARE_ALPHA_TYPE);
+
+ // If the node has multiple inputs, check that they are all valid and
+ // the same.
+ bool any_invalid = false;
+ bool any_premultiplied = false;
+ bool any_postmultiplied = false;
+
+ for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+ switch (node->incoming_links[j]->output_alpha_type) {
+ case ALPHA_INVALID:
+ any_invalid = true;
+ break;
+ case ALPHA_BLANK:
+ // Blank is good as both pre- and postmultiplied alpha,
+ // so just ignore it.
+ break;
+ case ALPHA_PREMULTIPLIED:
+ any_premultiplied = true;
+ break;
+ case ALPHA_POSTMULTIPLIED:
+ any_postmultiplied = true;
+ break;
+ default:
+ assert(false);
+ }
+ }
+
+ if (any_invalid) {
+ node->output_alpha_type = ALPHA_INVALID;
+ continue;
+ }
+
+ // Inputs must be of the same type.
+ if (any_premultiplied && any_postmultiplied) {
+ node->output_alpha_type = ALPHA_INVALID;
+ continue;
+ }
+
+ if (alpha_handling == Effect::INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED) {
+ // If the effect has asked for premultiplied alpha, check that it has got it.
+ if (any_postmultiplied) {
+ node->output_alpha_type = ALPHA_INVALID;
+ } else {
+ // In some rare cases, it might be advantageous to say
+ // that blank input alpha yields blank output alpha.
+ // However, this would cause a more complex Effect interface
+ // an effect would need to guarantee that it doesn't mess with
+ // blank alpha), so this is the simplest.
+ node->output_alpha_type = ALPHA_PREMULTIPLIED;
+ }
+ } else {
+ // OK, all inputs are the same, and this effect is not going
+ // to change it.
+ assert(alpha_handling == Effect::DONT_CARE_ALPHA_TYPE);
+ if (any_premultiplied) {
+ node->output_alpha_type = ALPHA_PREMULTIPLIED;
+ } else if (any_postmultiplied) {
+ node->output_alpha_type = ALPHA_POSTMULTIPLIED;
+ } else {
+ node->output_alpha_type = ALPHA_BLANK;
+ }
+ }
+ }
+}
+
+bool EffectChain::node_needs_colorspace_fix(Node *node)
+{
+ if (node->disabled) {
+ return false;
+ }
+ if (node->effect->num_inputs() == 0) {
+ return false;
+ }
+
+ // propagate_gamma_and_color_space() has already set our output
+ // to COLORSPACE_INVALID if the inputs differ, so we can rely on that.
+ if (node->output_color_space == COLORSPACE_INVALID) {
+ return true;
+ }
+ return (node->effect->needs_srgb_primaries() && node->output_color_space != COLORSPACE_sRGB);
+}
+
+// Fix up color spaces so that there are no COLORSPACE_INVALID nodes left in
+// the graph. Our strategy is not always optimal, but quite simple:
+// Find an effect that's as early as possible where the inputs are of
+// unacceptable colorspaces (that is, either different, or, if the effect only
+// wants sRGB, not sRGB.) Add appropriate conversions on all its inputs,
+// propagate the information anew, and repeat until there are no more such
+// effects.
+void EffectChain::fix_internal_color_spaces()
+{
+ unsigned colorspace_propagation_pass = 0;
+ bool found_any;
+ do {
+ found_any = false;
+ for (unsigned i = 0; i < nodes.size(); ++i) {
+ Node *node = nodes[i];
+ if (!node_needs_colorspace_fix(node)) {
+ continue;
+ }
+
+ // Go through each input that is not sRGB, and insert
+ // a colorspace conversion before it.
+ for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+ Node *input = node->incoming_links[j];
+ assert(input->output_color_space != COLORSPACE_INVALID);
+ if (input->output_color_space == COLORSPACE_sRGB) {
+ continue;
+ }
+ Node *conversion = add_node(new ColorspaceConversionEffect());
+ CHECK(conversion->effect->set_int("source_space", input->output_color_space));
+ CHECK(conversion->effect->set_int("destination_space", COLORSPACE_sRGB));
+ conversion->output_color_space = COLORSPACE_sRGB;
+ insert_node_between(input, conversion, node);
+ }
+
+ // Re-sort topologically, and propagate the new information.
+ propagate_gamma_and_color_space();
+
+ found_any = true;
+ break;
+ }
+
+ char filename[256];
+ sprintf(filename, "step5-colorspacefix-iter%u.dot", ++colorspace_propagation_pass);
+ output_dot(filename);
+ assert(colorspace_propagation_pass < 100);
+ } while (found_any);
+
+ for (unsigned i = 0; i < nodes.size(); ++i) {
+ Node *node = nodes[i];
+ if (node->disabled) {
+ continue;
+ }
+ assert(node->output_color_space != COLORSPACE_INVALID);
+ }
+}
+
+bool EffectChain::node_needs_alpha_fix(Node *node)
+{
+ if (node->disabled) {
+ return false;
+ }
+
+ // propagate_alpha() has already set our output to ALPHA_INVALID if the
+ // inputs differ or we are otherwise in mismatch, so we can rely on that.
+ return (node->output_alpha_type == ALPHA_INVALID);
+}
+
+// Fix up alpha so that there are no ALPHA_INVALID nodes left in
+// the graph. Similar to fix_internal_color_spaces().
+void EffectChain::fix_internal_alpha(unsigned step)
+{
+ unsigned alpha_propagation_pass = 0;
+ bool found_any;
+ do {
+ found_any = false;
+ for (unsigned i = 0; i < nodes.size(); ++i) {
+ Node *node = nodes[i];
+ if (!node_needs_alpha_fix(node)) {
+ continue;
+ }
+
+ // If we need to fix up GammaExpansionEffect, then clearly something
+ // is wrong, since the combination of premultiplied alpha and nonlinear inputs
+ // is meaningless.
+ assert(node->effect->effect_type_id() != "GammaExpansionEffect");
+
+ AlphaType desired_type = ALPHA_PREMULTIPLIED;
+
+ // GammaCompressionEffect is special; it needs postmultiplied alpha.
+ if (node->effect->effect_type_id() == "GammaCompressionEffect") {
+ assert(node->incoming_links.size() == 1);
+ assert(node->incoming_links[0]->output_alpha_type == ALPHA_PREMULTIPLIED);
+ desired_type = ALPHA_POSTMULTIPLIED;
+ }
+
+ // Go through each input that is not premultiplied alpha, and insert
+ // a conversion before it.
+ for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+ Node *input = node->incoming_links[j];
+ assert(input->output_alpha_type != ALPHA_INVALID);
+ if (input->output_alpha_type == desired_type ||
+ input->output_alpha_type == ALPHA_BLANK) {
+ continue;
+ }
+ Node *conversion;
+ if (desired_type == ALPHA_PREMULTIPLIED) {
+ conversion = add_node(new AlphaMultiplicationEffect());
+ } else {
+ conversion = add_node(new AlphaDivisionEffect());
+ }
+ conversion->output_alpha_type = desired_type;
+ insert_node_between(input, conversion, node);
+ }
+
+ // Re-sort topologically, and propagate the new information.
+ propagate_gamma_and_color_space();
+ propagate_alpha();
+
+ found_any = true;
+ break;
+ }
+
+ char filename[256];
+ sprintf(filename, "step%u-alphafix-iter%u.dot", step, ++alpha_propagation_pass);
+ output_dot(filename);
+ assert(alpha_propagation_pass < 100);
+ } while (found_any);
+
+ for (unsigned i = 0; i < nodes.size(); ++i) {
+ Node *node = nodes[i];
+ if (node->disabled) {
+ continue;
+ }
+ assert(node->output_alpha_type != ALPHA_INVALID);
+ }
+}
+
+// Make so that the output is in the desired color space.
+void EffectChain::fix_output_color_space()
+{
+ Node *output = find_output_node();
+ if (output->output_color_space != output_format.color_space) {
+ Node *conversion = add_node(new ColorspaceConversionEffect());
+ CHECK(conversion->effect->set_int("source_space", output->output_color_space));
+ CHECK(conversion->effect->set_int("destination_space", output_format.color_space));
+ conversion->output_color_space = output_format.color_space;
+ connect_nodes(output, conversion);
+ propagate_alpha();
+ propagate_gamma_and_color_space();
+ }
+}
+
+// Make so that the output is in the desired pre-/postmultiplication alpha state.
+void EffectChain::fix_output_alpha()