[Windows] Ignore case optionally in AXPlatformNodeTextRangeProviderWin::FindText (flutter#39922)

When `ignore_case` is `true`, convert needle and haystack strings to
lowercase before performing search,

flutter/flutter#117013

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Author: yaakovschectman

third_party/accessibility/ax/BUILD.gn

@@ -106,7 +106,10 @@ source_set("ax") {
       "oleacc.lib",
       "uiautomationcore.lib",
     ]
-    deps = [ "//flutter/fml:string_conversion" ]
+    deps = [
+      "//flutter/fml:fml",
+      "//third_party/icu:icui18n",
+    ]
   }
 
   public_deps = [

third_party/accessibility/ax/platform/ax_platform_node_textrangeprovider_win.cc

@@ -6,6 +6,7 @@
 
 #include <UIAutomation.h>
 #include <wrl/client.h>
+#include <string_view>
 
 #include "ax/ax_action_data.h"
 #include "ax/ax_range.h"
@@ -14,6 +15,7 @@
 #include "ax/platform/ax_platform_tree_manager.h"
 #include "base/win/variant_vector.h"
 #include "flutter/fml/platform/win/wstring_conversion.h"
+#include "third_party/icu/source/i18n/unicode/usearch.h"
 
 #define UIA_VALIDATE_TEXTRANGEPROVIDER_CALL()                  \
   if (!GetOwner() || !GetOwner()->GetDelegate() || !start() || \
@@ -433,28 +435,63 @@ HRESULT AXPlatformNodeTextRangeProviderWin::FindAttributeRange(
   return S_OK;
 }
 
-static bool StringSearch(const std::u16string& search_string,
-                         const std::u16string& find_in,
-                         size_t* find_start,
-                         size_t* find_length,
-                         bool ignore_case,
-                         bool backwards) {
-  // TODO(schectman) Respect ignore_case/i18n.
-  // https://github.com/flutter/flutter/issues/117013
-  size_t match_pos;
-  if (backwards) {
-    match_pos = find_in.rfind(search_string);
-  } else {
-    match_pos = find_in.find(search_string);
-  }
-  if (match_pos == std::u16string::npos) {
+static bool StringSearchBasic(const std::u16string_view search_string,
+                              const std::u16string_view find_in,
+                              size_t* find_start,
+                              size_t* find_length,
+                              bool backwards) {
+  size_t index =
+      backwards ? find_in.rfind(search_string) : find_in.find(search_string);
+  if (index == std::u16string::npos) {
     return false;
   }
-  *find_start = match_pos;
-  *find_length = search_string.length();
+  *find_start = index;
+  *find_length = search_string.size();
   return true;
 }
 
+bool StringSearch(std::u16string_view search_string,
+                  std::u16string_view find_in,
+                  size_t* find_start,
+                  size_t* find_length,
+                  bool ignore_case,
+                  bool backwards) {
+  UErrorCode status = U_ZERO_ERROR;
+  UCollator* col = ucol_open(uloc_getDefault(), &status);
+  UStringSearch* search = usearch_openFromCollator(
+      search_string.data(), search_string.size(), find_in.data(),
+      find_in.size(), col, nullptr, &status);
+  if (!U_SUCCESS(status)) {
+    if (search) {
+      usearch_close(search);
+    }
+    return StringSearchBasic(search_string, find_in, find_start, find_length,
+                             backwards);
+  }
+  UCollator* collator = usearch_getCollator(search);
+  ucol_setStrength(collator, ignore_case ? UCOL_PRIMARY : UCOL_TERTIARY);
+  usearch_reset(search);
+  status = U_ZERO_ERROR;
+  usearch_setText(search, find_in.data(), find_in.size(), &status);
+  if (!U_SUCCESS(status)) {
+    if (search) {
+      usearch_close(search);
+    }
+    return StringSearchBasic(search_string, find_in, find_start, find_length,
+                             backwards);
+  }
+  int32_t index = backwards ? usearch_last(search, &status)
+                            : usearch_first(search, &status);
+  bool match = false;
+  if (U_SUCCESS(status) && index != USEARCH_DONE) {
+    match = true;
+    *find_start = static_cast<size_t>(index);
+    *find_length = static_cast<size_t>(usearch_getMatchedLength(search));
+  }
+  usearch_close(search);
+  return match;
+}
+
 HRESULT AXPlatformNodeTextRangeProviderWin::FindText(
     BSTR string,
     BOOL backwards,

third_party/accessibility/ax/platform/ax_platform_node_textrangeprovider_win.h

@@ -280,6 +280,16 @@ class AX_EXPORT __declspec(uuid("3071e40d-a10d-45ff-a59f-6e8e1138e2c1"))
   TextRangeEndpoints endpoints_;
 };
 
+// Optionally case-insensitive or reverse string search.
+//
+// Exposed as non-static for use in testing.
+bool StringSearch(std::u16string_view search_string,
+                  std::u16string_view find_in,
+                  size_t* find_start,
+                  size_t* find_length,
+                  bool ignore_case,
+                  bool backwards);
+
 }  // namespace ui
 
 #endif  // UI_ACCESSIBILITY_PLATFORM_AX_PLATFORM_NODE_TEXTRANGEPROVIDER_WIN_H_

third_party/accessibility/ax/platform/ax_platform_node_textrangeprovider_win_unittest.cc

@@ -7,6 +7,7 @@
 #include <UIAutomationClient.h>
 #include <UIAutomationCoreApi.h>
 
+#include <filesystem>
 #include <memory>
 #include <utility>
 
@@ -17,6 +18,8 @@
 #include "base/win/scoped_bstr.h"
 #include "base/win/scoped_safearray.h"
 #include "base/win/scoped_variant.h"
+#include "flutter/fml/icu_util.h"
+#include "third_party/icu/source/common/unicode/putil.h"
 
 using Microsoft::WRL::ComPtr;
 
@@ -144,25 +147,25 @@ namespace ui {
     EXPECT_STREQ(expected_content, provider_content.Get()); \
   }
 
-#define EXPECT_UIA_FIND_TEXT(text_range_provider, search_term, ignore_case,  \
-                             owner)                                          \
-  {                                                                          \
-    base::win::ScopedBstr find_string(search_term);                          \
-    ComPtr<ITextRangeProvider> text_range_provider_found;                    \
-    EXPECT_HRESULT_SUCCEEDED(text_range_provider->FindText(                  \
-        find_string.Get(), false, ignore_case, &text_range_provider_found)); \
-    if (text_range_provider_found == nullptr) {                              \
-      EXPECT_TRUE(false);                                                    \
-    } else {                                                                 \
-      SetOwner(owner, text_range_provider_found.Get());                      \
-      base::win::ScopedBstr found_content;                                   \
-      EXPECT_HRESULT_SUCCEEDED(                                              \
-          text_range_provider_found->GetText(-1, found_content.Receive()));  \
-      if (ignore_case)                                                       \
-        EXPECT_EQ(0, _wcsicmp(found_content.Get(), find_string.Get()));      \
-      else                                                                   \
-        EXPECT_EQ(0, wcscmp(found_content.Get(), find_string.Get()));        \
-    }                                                                        \
+#define EXPECT_UIA_FIND_TEXT(text_range_provider, search_term, ignore_case,    \
+                             owner)                                            \
+  {                                                                            \
+    base::win::ScopedBstr find_string(search_term);                            \
+    ComPtr<ITextRangeProvider> text_range_provider_found;                      \
+    EXPECT_HRESULT_SUCCEEDED(text_range_provider->FindText(                    \
+        find_string.Get(), false, ignore_case, &text_range_provider_found));   \
+    if (text_range_provider_found == nullptr) {                                \
+      EXPECT_TRUE(false);                                                      \
+    } else {                                                                   \
+      SetOwner(owner, text_range_provider_found.Get());                        \
+      base::win::ScopedBstr found_content;                                     \
+      EXPECT_HRESULT_SUCCEEDED(                                                \
+          text_range_provider_found->GetText(-1, found_content.Receive()));    \
+      if (ignore_case)                                                         \
+        EXPECT_TRUE(StringCompareICU(found_content.Get(), find_string.Get())); \
+      else                                                                     \
+        EXPECT_EQ(0, wcscmp(found_content.Get(), find_string.Get()));          \
+    }                                                                          \
   }
 
 #define EXPECT_UIA_FIND_TEXT_NO_MATCH(text_range_provider, search_term,      \
@@ -209,6 +212,16 @@ namespace ui {
 
 #define DCHECK_EQ(a, b) BASE_DCHECK((a) == (b))
 
+static bool StringCompareICU(BSTR left, BSTR right) {
+  size_t start, length;
+  if (!StringSearch(reinterpret_cast<char16_t*>(left),
+                    reinterpret_cast<char16_t*>(right), &start, &length, true,
+                    false)) {
+    return false;
+  }
+  return start == 0 && length == wcslen(left);
+}
+
 static AXNodePosition::AXPositionInstance CreateTextPosition(
     const AXNode& anchor,
     int text_offset,
@@ -5094,9 +5107,20 @@ TEST_F(AXPlatformNodeTextRangeProviderTest,
   selection.Reset();
 }
 
-// TODO(schectman) Find text cannot ignore case yet.
 TEST_F(AXPlatformNodeTextRangeProviderTest, TestITextRangeProviderFindText) {
-  Init(BuildTextDocument({"some text", "more text"},
+  // Initialize the ICU data from the icudtl.dat file, if it exists.
+  wchar_t buffer[MAX_PATH];
+  GetModuleFileName(nullptr, buffer, MAX_PATH);
+  std::filesystem::path exec_path(buffer);
+  exec_path.remove_filename();
+  exec_path.append("icudtl.dat");
+  const std::string icudtl_path = exec_path.string();
+  if (std::filesystem::exists(icudtl_path)) {
+    fml::icu::InitializeICU(icudtl_path);
+  }
+
+  // \xC3\xA9 are the UTF8 bytes for codepoint 0xE9 - accented lowercase e.
+  Init(BuildTextDocument({"some text", "more text", "resum\xC3\xA9"},
                          false /* build_word_boundaries_offsets */,
                          true /* place_text_on_one_line */));
 
@@ -5109,24 +5133,29 @@ TEST_F(AXPlatformNodeTextRangeProviderTest, TestITextRangeProviderFindText) {
   // Test Leaf kStaticText search.
   GetTextRangeProviderFromTextNode(range, root_node->children()[0]);
   EXPECT_UIA_FIND_TEXT(range, L"some text", false, owner);
-  // Some expectations like the one below are currently skipped until we can
-  // implement ignoreCase in FindText.
-  // EXPECT_UIA_FIND_TEXT(range, L"SoMe TeXt", false, owner);
+  EXPECT_UIA_FIND_TEXT(range, L"SoMe TeXt", true, owner);
   GetTextRangeProviderFromTextNode(range, root_node->children()[1]);
   EXPECT_UIA_FIND_TEXT(range, L"more", false, owner);
-  // EXPECT_UIA_FIND_TEXT(range, L"MoRe", true, owner);
+  EXPECT_UIA_FIND_TEXT(range, L"MoRe", true, owner);
 
   // Test searching for leaf content from ancestor.
   GetTextRangeProviderFromTextNode(range, root_node);
   EXPECT_UIA_FIND_TEXT(range, L"some text", false, owner);
-  // EXPECT_UIA_FIND_TEXT(range, L"SoMe TeXt", true, owner);
+  EXPECT_UIA_FIND_TEXT(range, L"SoMe TeXt", true, owner);
   EXPECT_UIA_FIND_TEXT(range, L"more text", false, owner);
-  // EXPECT_UIA_FIND_TEXT(range, L"MoRe TeXt", true, owner);
+  EXPECT_UIA_FIND_TEXT(range, L"MoRe TeXt", true, owner);
   EXPECT_UIA_FIND_TEXT(range, L"more", false, owner);
+  // Accented lowercase e.
+  EXPECT_UIA_FIND_TEXT(range, L"resum\xE9", false, owner);
+  // Accented uppercase +e.
+  EXPECT_UIA_FIND_TEXT(range, L"resum\xC9", true, owner);
+  EXPECT_UIA_FIND_TEXT(range, L"resume", true, owner);
+  EXPECT_UIA_FIND_TEXT(range, L"resumE", true, owner);
   // Test finding text that crosses a node boundary.
   EXPECT_UIA_FIND_TEXT(range, L"textmore", false, owner);
   // Test no match.
   EXPECT_UIA_FIND_TEXT_NO_MATCH(range, L"no match", false, owner);
+  EXPECT_UIA_FIND_TEXT_NO_MATCH(range, L"resume", false, owner);
 
   // Test if range returned is in expected anchor node.
   GetTextRangeProviderFromTextNode(range, root_node->children()[1]);