Add override_url_template_prefix setting to segmentation plan.

This allows the url template used in the IFT font to be customized.

Author: garretrieger

ift/common/font_helper.h

@@ -43,6 +43,7 @@ struct CompareTableOffsets {
 class FontHelper {
  public:
   constexpr static hb_tag_t kIFT = HB_TAG('I', 'F', 'T', ' ');
+  constexpr static hb_tag_t kIFTX = HB_TAG('I', 'F', 'T', 'X');
   constexpr static hb_tag_t kLoca = HB_TAG('l', 'o', 'c', 'a');
   constexpr static hb_tag_t kGlyf = HB_TAG('g', 'l', 'y', 'f');
   constexpr static hb_tag_t kHead = HB_TAG('h', 'e', 'a', 'd');

ift/config/BUILD

@@ -149,6 +149,18 @@ cc_library(
     ]
 )
 
+cc_test(
+    name = "config_compiler_test",
+    size = "small",
+    srcs = [
+        "config_compiler_test.cc",
+    ],
+    deps = [
+        ":config_compiler",
+        "@googletest//:gtest_main",
+    ],
+)
+
 cc_test(
     name = "auto_segmenter_config_test",
     size = "small",

ift/config/config_compiler.cc

@@ -42,7 +42,8 @@ static StatusOr<design_space_t> ToDesignSpace(const DesignSpace& proto) {
   return result;
 }
 
-static ActivationCondition FromProto(const ActivationConditionProto& condition) {
+static ActivationCondition FromProto(
+    const ActivationConditionProto& condition) {
   // TODO(garretrieger): once glyph segmentation activation conditions can
   // support features copy those here.
   std::vector<SegmentSet> groups;
@@ -150,6 +151,16 @@ Status ConfigCompiler::Configure(const SegmentationPlan& plan,
   }
   compiler.SetUsePrefetchLists(plan.use_prefetch_lists());
 
+  if (plan.has_advanced_settings()) {
+    const auto& advanced = plan.advanced_settings();
+    if (!advanced.override_url_template_prefix().empty()) {
+      std::vector<uint8_t> prefix(
+          advanced.override_url_template_prefix().begin(),
+          advanced.override_url_template_prefix().end());
+      compiler.SetOverrideUrlTemplatePrefix(prefix);
+    }
+  }
+
   // Check for unsupported settings
   if (plan.include_all_segment_patches()) {
     return absl::UnimplementedError(

ift/config/config_compiler_test.cc

@@ -0,0 +1,28 @@
+#include "ift/config/config_compiler.h"
+
+#include <cstdint>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "ift/config/segmentation_plan.pb.h"
+#include "ift/encoder/compiler.h"
+
+using ift::encoder::Compiler;
+
+namespace ift::config {
+
+TEST(ConfigCompilerTest, ConfigureOverrideUrlTemplatePrefix) {
+  Compiler compiler;
+  SegmentationPlan plan;
+  std::string prefix_str = "https://example.com/";
+  plan.mutable_advanced_settings()->set_override_url_template_prefix(
+      prefix_str);
+
+  absl::Status status = ConfigCompiler::Configure(plan, compiler);
+  ASSERT_TRUE(status.ok()) << status;
+
+  std::vector<uint8_t> expected(prefix_str.begin(), prefix_str.end());
+  EXPECT_EQ(compiler.override_url_template_prefix(), expected);
+}
+
+}  // namespace ift::config

ift/config/segmentation_plan.proto

@@ -152,7 +152,27 @@ message SegmentationPlan {
   // for in a single jump.
   repeated DesignSpace non_glyph_design_space_segmentation = 15;
 
-  // next = 17
+  // These settings are for advanced usage and typically shouldn't need to be configured.
+  AdvancedSettings advanced_settings = 17;
+
+  // next = 18
+}
+
+message AdvancedSettings {
+  // In the output font the URL template byte string is replaced with these bytes.
+  //
+  // The template bytes should not include the patch file extension (.ift_tk, .ift_gk),
+  // as that will be added automatically during compilation based on the type of patch.
+  //
+  // If unset the compiler uses the byte string [128] as the URL template based which sets the
+  // patch file name to the id32 value for each patch.
+  //
+  // URL template specification: https://w3c.github.io/IFT/Overview.html#url-templates
+  // It's up to the caller to ensure the provided byte string is a valid URL template.
+  //
+  // Note: patches will be output to directory specified by the provided template.
+  // it's up to the caller to ensure the location exists.
+  bytes override_url_template_prefix = 1;
 }
 
 // Activated when at least one set in every group is matched and all required_features match.

ift/dep_graph/dependency_graph_test.cc

@@ -523,7 +523,8 @@ TEST_F(DependencyGraphTest, StronglyConnectedComponents_TopologicalSorting) {
   EXPECT_LT(liga_f, gffi);
 }
 
-TEST_F(DependencyGraphTest, StronglyConnectedComponents_TopologicalSorting_InitFontFilter) {
+TEST_F(DependencyGraphTest,
+       StronglyConnectedComponents_TopologicalSorting_InitFontFilter) {
   SubsetDefinition liga;
   liga.feature_tags = {HB_TAG('l', 'i', 'g', 'a')};
   SubsetDefinition dlig;
@@ -550,7 +551,8 @@ TEST_F(DependencyGraphTest, StronglyConnectedComponents_TopologicalSorting_InitF
                                    Node::Feature(HB_TAG('d', 'l', 'i', 'g'))));
 }
 
-TEST_F(DependencyGraphTest, StronglyConnectedComponents_TopologicalSorting_InitFontFeatures) {
+TEST_F(DependencyGraphTest,
+       StronglyConnectedComponents_TopologicalSorting_InitFontFeatures) {
   Reconfigure(WithDefaultFeatures({}),
               {
                   /* 0 */ {{'a'}, ProbabilityBound::Zero()},
@@ -599,10 +601,8 @@ TEST_F(DependencyGraphTest,
   uint32_t num_cycles = 0;
   for (const auto& scc : *sccs_or) {
     if (scc.size() > 1) {
-      EXPECT_THAT(scc, UnorderedElementsAre(
-        Node::Glyph(129 /* AE */),
-        Node::Glyph(811 /* AEacute */)
-      ));
+      EXPECT_THAT(scc, UnorderedElementsAre(Node::Glyph(129 /* AE */),
+                                            Node::Glyph(811 /* AEacute */)));
       num_cycles++;
     }
   }

ift/encoder/compiler.h

@@ -58,6 +58,14 @@ class Compiler {
 
   void SetWoff2Encode(bool value) { this->woff2_encode_ = value; }
 
+  void SetOverrideUrlTemplatePrefix(const std::vector<uint8_t>& prefix) {
+    override_url_template_prefix_ = prefix;
+  }
+
+  const std::vector<uint8_t>& override_url_template_prefix() const {
+    return override_url_template_prefix_;
+  }
+
   /*
    * Adds a segmentation of glyph data.
    *
@@ -247,15 +255,19 @@ class Compiler {
     constexpr uint8_t insert_id_op_code = 128;
 
     std::vector<uint8_t> out;
+    if (!override_url_template_prefix_.empty()) {
+      out = override_url_template_prefix_;
+    } else {
+      out.push_back(insert_id_op_code);
+    }
+
     if (patch_set_id == 0) {
       // patch_set_id 0 is always used for table keyed patches
-      out.push_back(insert_id_op_code);
       AppendLiteralToTemplate(".ift_tk", out);
       return out;
     }
 
     // All other ids are for glyph keyed.
-    out.push_back(insert_id_op_code);
     AppendLiteralToTemplate(absl::StrCat(".", patch_set_id, ".ift_gk"), out);
     return out;
   }
@@ -363,6 +375,7 @@ class Compiler {
   uint32_t next_id_ = 0;
   bool use_prefetch_lists_ = false;
   bool woff2_encode_ = false;
+  std::vector<uint8_t> override_url_template_prefix_;
 
   struct ProcessingContext {
     ProcessingContext(uint32_t next_id)

ift/encoder/compiler_test.cc

@@ -1000,4 +1000,34 @@ TEST_F(CompilerTest, RoundTripWoff2_Fails) {
   ASSERT_TRUE(absl::IsInternal(ttf.status())) << ttf.status();
 }
 
+TEST_F(CompilerTest, UrlTemplateOverride) {
+  Compiler compiler;
+  hb_face_t* face = font.reference_face();
+  compiler.SetFace(face);
+
+  auto s = compiler.SetInitSubset(IntSet{'a', 'd'});
+  ASSERT_TRUE(s.ok()) << s;
+  compiler.AddNonGlyphDataSegment(IntSet{'b', 'c'});
+
+  // 3 (length) + 'p' + 'r' + 'e' + 128 (id opcode)
+  std::vector<uint8_t> prefix = {3, 'p', 'r', 'e', 133};
+  compiler.SetOverrideUrlTemplatePrefix(prefix);
+
+  auto encoding = compiler.Compile();
+  hb_face_destroy(face);
+
+  ASSERT_TRUE(encoding.ok()) << encoding.status();
+  auto encoded_face = encoding->init_font.face();
+
+  auto ift_table = FontHelper::TableData(encoded_face.get(), FontHelper::kIFT);
+  if (ift_table.empty()) {
+    ift_table = FontHelper::TableData(encoded_face.get(), FontHelper::kIFTX);
+  }
+  ASSERT_FALSE(ift_table.empty());
+
+  std::string expected_template = {3,   'p', 'r', 'e', (char)133, 7,  '.',
+                                   'i', 'f', 't', '_', 't',       'k'};
+  ASSERT_TRUE(ift_table.str().find(expected_template) != std::string::npos);
+}
+
 }  // namespace ift::encoder

ift/encoder/dependency_closure_test.cc

@@ -317,9 +317,10 @@ TEST_F(DependencyClosureTest, ExtractAllGlyphConditions_FullFont) {
   uint32_t parenleft = cp_to_seg.at('(');
   uint32_t parenright = cp_to_seg.at(')');
 
-  EXPECT_EQ(conditions->at(12 /* parenleft */).ToString(),
-    // '(' is accesible from either '(' or ')' due to unicode mirroring.
-    absl::StrCat("if ((s", parenleft, " OR s", parenright,")) then p0"));
+  EXPECT_EQ(
+      conditions->at(12 /* parenleft */).ToString(),
+      // '(' is accesible from either '(' or ')' due to unicode mirroring.
+      absl::StrCat("if ((s", parenleft, " OR s", parenright, ")) then p0"));
 
   // small caps AE is accesible via numerous pathways and forms a complex
   // composite condition (smcp, c2sc, and glyph component substitutions)
@@ -329,12 +330,12 @@ TEST_F(DependencyClosureTest, ExtractAllGlyphConditions_FullFont) {
   uint32_t aeacute = cp_to_seg.at(0x1FD);
   uint32_t smcp = layout_to_seg.at(HB_TAG('s', 'm', 'c', 'p'));
   uint32_t c2sc = layout_to_seg.at(HB_TAG('c', '2', 's', 'c'));
-  EXPECT_EQ(conditions->at(627 /* small caps AE */).ToString(),
-  absl::StrCat(
-    "if ((s", AE, " OR s", ae," OR s", AEacute, " OR s", aeacute, ") ",
-    "AND (s", AE, " OR s", AEacute, " OR s", smcp, ") ",
-    "AND (s", ae," OR s", aeacute," OR s", c2sc,") ",
-    "AND (s", c2sc," OR s", smcp, ")) then p0"));
+  EXPECT_EQ(
+      conditions->at(627 /* small caps AE */).ToString(),
+      absl::StrCat("if ((s", AE, " OR s", ae, " OR s", AEacute, " OR s",
+                   aeacute, ") ", "AND (s", AE, " OR s", AEacute, " OR s", smcp,
+                   ") ", "AND (s", ae, " OR s", aeacute, " OR s", c2sc, ") ",
+                   "AND (s", c2sc, " OR s", smcp, ")) then p0"));
 }
 
 TEST_F(DependencyClosureTest, ExtractAllGlyphConditions_PhaseCycle) {

ift/integration_test.cc

@@ -1800,4 +1800,55 @@ TEST_F(IntegrationTest, MixedMode_Cff2) {
             FontHelper::Cff2Data(desubroutinized_face.get(), 35).span());
 }
 
+TEST_F(IntegrationTest, UrlTemplateOverride) {
+  Compiler compiler;
+  auto init_gids = InitEncoderForMixedMode(compiler);
+  ASSERT_TRUE(init_gids.ok()) << init_gids.status();
+
+  auto face = noto_sans_jp_.face();
+  auto segment_0 = FontHelper::GidsToUnicodes(face.get(), *init_gids);
+  auto segment_1 = FontHelper::GidsToUnicodes(face.get(), TestSegment1());
+
+  auto sc = compiler.SetInitSubset(segment_0);
+  compiler.AddNonGlyphDataSegment(segment_1);
+  sc.Update(compiler.AddGlyphDataPatchCondition(
+      PatchMap::Entry(segment_1, 1, PatchEncoding::GLYPH_KEYED)));
+  ASSERT_TRUE(sc.ok()) << sc;
+
+  // 4 (length) + 'p' + 'a' + 't' + 'h' + 128 (id opcode)
+  std::vector<uint8_t> prefix = {4, 'p', 'a', 't', 'h', 128};
+  compiler.SetOverrideUrlTemplatePrefix(prefix);
+
+  auto encoding = compiler.Compile();
+  ASSERT_TRUE(encoding.ok()) << encoding.status();
+
+  // Verify the keys in the patches map.
+  for (const auto& [uri, data] : encoding->patches) {
+    EXPECT_THAT(uri, testing::StartsWith("path"));
+  }
+
+  // Request codepoint extension
+  btree_set<std::string> fetched_uris;
+  auto extended = ExtendWithDesignSpace(*encoding, {chunk1_cp}, {}, {},
+                                        &fetched_uris, 1, 2);
+  ASSERT_TRUE(extended.ok()) << extended.status();
+
+  // Should have fetched one table keyed and one glyph keyed patch.
+  // Table keyed: path<id>.ift_tk
+  // Glyph keyed: path<id>.ift_gk
+  ASSERT_EQ(fetched_uris.size(), 2);
+  bool found_tk = false;
+  bool found_gk = false;
+  for (const std::string& uri : fetched_uris) {
+    EXPECT_THAT(uri, testing::StartsWith("path"));
+    if (uri.find(".ift_tk") != std::string::npos) {
+      found_tk = true;
+    } else if (uri.find(".ift_gk") != std::string::npos) {
+      found_gk = true;
+    }
+  }
+  EXPECT_TRUE(found_tk);
+  EXPECT_TRUE(found_gk);
+}
+
 }  // namespace ift