Add FlTextInputPlugin (#18314)

* Add FlTextInputPlugin

Author: robert-ancell

ci/licenses_golden/licenses_flutter

@@ -1230,6 +1230,8 @@ FILE: ../../../flutter/shell/platform/linux/fl_standard_method_codec.cc
 FILE: ../../../flutter/shell/platform/linux/fl_standard_method_codec_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_string_codec.cc
 FILE: ../../../flutter/shell/platform/linux/fl_string_codec_test.cc
+FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin.cc
+FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin.h
 FILE: ../../../flutter/shell/platform/linux/fl_value.cc
 FILE: ../../../flutter/shell/platform/linux/fl_value_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view.cc

shell/platform/common/cpp/BUILD.gn

@@ -30,12 +30,28 @@ source_set("common_cpp_library_headers") {
   configs += [ ":desktop_library_implementation" ]
 }
 
+source_set("common_cpp_input") {
+  public = [
+    "text_input_model.h",
+  ]
+
+  sources = [
+    "text_input_model.cc",
+  ]
+
+  configs += [ ":desktop_library_implementation" ]
+
+  if (is_win) {
+    # For wstring_conversion. See issue #50053.
+    defines = [ "_SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING" ]
+  }
+}
+
 source_set("common_cpp") {
   public = [
     "incoming_message_dispatcher.h",
     "json_message_codec.h",
     "json_method_codec.h",
-    "text_input_model.h",
   ]
 
   # TODO: Refactor flutter_glfw.cc to move the implementations corresponding
@@ -44,7 +60,6 @@ source_set("common_cpp") {
     "incoming_message_dispatcher.cc",
     "json_message_codec.cc",
     "json_method_codec.cc",
-    "text_input_model.cc",
   ]
 
   configs += [ ":desktop_library_implementation" ]
@@ -59,11 +74,6 @@ source_set("common_cpp") {
     ":common_cpp_core",
     "//third_party/rapidjson",
   ]
-
-  if (is_win) {
-    # For wstring_conversion. See issue #50053.
-    defines = [ "_SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING" ]
-  }
 }
 
 # The portion of common_cpp that has no dependencies on the public/
@@ -117,6 +127,7 @@ executable("common_cpp_unittests") {
   deps = [
     ":common_cpp",
     ":common_cpp_fixtures",
+    ":common_cpp_input",
     "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
     "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper_library_stubs",
     "//flutter/testing",

shell/platform/common/cpp/text_input_model.cc

@@ -85,6 +85,12 @@ void TextInputModel::AddText(const std::u16string& text) {
   selection_base_ = selection_extent_;
 }
 
+void TextInputModel::AddText(const std::string& text) {
+  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t>
+      utf16_converter;
+  AddText(utf16_converter.from_bytes(text));
+}
+
 bool TextInputModel::Backspace() {
   if (selection_base_ != selection_extent_) {
     DeleteSelected();
@@ -113,6 +119,46 @@ bool TextInputModel::Delete() {
   return false;
 }
 
+bool TextInputModel::DeleteSurrounding(int offset_from_cursor, int count) {
+  auto start = selection_extent_;
+  if (offset_from_cursor < 0) {
+    for (int i = 0; i < -offset_from_cursor; i++) {
+      // If requested start is before the available text then reduce the
+      // number of characters to delete.
+      if (start == text_.begin()) {
+        count = i;
+        break;
+      }
+      start -= IsTrailingSurrogate(*(start - 1)) ? 2 : 1;
+    }
+  } else {
+    for (int i = 0; i < offset_from_cursor && start != text_.end(); i++) {
+      start += IsLeadingSurrogate(*start) ? 2 : 1;
+    }
+  }
+
+  auto end = start;
+  for (int i = 0; i < count && end != text_.end(); i++) {
+    end += IsLeadingSurrogate(*start) ? 2 : 1;
+  }
+
+  if (start == end) {
+    return false;
+  }
+
+  auto new_base = text_.erase(start, end);
+
+  // Cursor moves only if deleted area is before it.
+  if (offset_from_cursor <= 0) {
+    selection_base_ = new_base;
+  }
+
+  // Clear selection.
+  selection_extent_ = selection_base_;
+
+  return true;
+}
+
 bool TextInputModel::MoveCursorToBeginning() {
   if (selection_base_ == text_.begin() && selection_extent_ == text_.begin())
     return false;
@@ -172,4 +218,13 @@ std::string TextInputModel::GetText() const {
   return utf8_converter.to_bytes(text_);
 }
 
+int TextInputModel::GetCursorOffset() const {
+  // Measure the length of the current text up to the cursor.
+  // There is probably a much more efficient way of doing this.
+  auto leading_text = text_.substr(0, selection_extent_ - text_.begin());
+  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t>
+      utf8_converter;
+  return utf8_converter.to_bytes(leading_text).size();
+}
+
 }  // namespace flutter

shell/platform/common/cpp/text_input_model.h

@@ -33,12 +33,18 @@ class TextInputModel {
   // code point.
   void AddCodePoint(char32_t c);
 
-  // Adds a UTF-16 text.
+  // Adds UTF-16 text.
   //
   // Either appends after the cursor (when selection base and extent are the
   // same), or deletes the selected text, replacing it with the given text.
   void AddText(const std::u16string& text);
 
+  // Adds UTF-8 text.
+  //
+  // Either appends after the cursor (when selection base and extent are the
+  // same), or deletes the selected text, replacing it with the given text.
+  void AddText(const std::string& text);
+
   // Deletes either the selection, or one character ahead of the cursor.
   //
   // Deleting one character ahead of the cursor occurs when the selection base
@@ -47,6 +53,17 @@ class TextInputModel {
   // Returns true if any deletion actually occurred.
   bool Delete();
 
+  // Deletes text near the cursor.
+  //
+  // A section is made starting at @offset code points past the cursor (negative
+  // values go before the cursor). @count code points are removed. The selection
+  // may go outside the bounds of the text and will result in only the part
+  // selection that covers the available text being deleted. The existing
+  // selection is ignored and removed after this operation.
+  //
+  // Returns true if any deletion actually occurred.
+  bool DeleteSurrounding(int offset_from_cursor, int count);
+
   // Deletes either the selection, or one character behind the cursor.
   //
   // Deleting one character behind the cursor occurs when the selection base
@@ -77,9 +94,13 @@ class TextInputModel {
   // Returns true if the cursor could be moved.
   bool MoveCursorToEnd();
 
-  // Get the current text
+  // Gets the current text as UTF-8.
   std::string GetText() const;
 
+  // Gets the cursor position as a byte offset in UTF-8 string returned from
+  // GetText().
+  int GetCursorOffset() const;
+
   // The position of the cursor
   int selection_base() const {
     return static_cast<int>(selection_base_ - text_.begin());

shell/platform/common/cpp/text_input_model_unittests.cc

@@ -103,8 +103,8 @@ TEST(TextInputModel, AddCodePointSelectionWideCharacter) {
 TEST(TextInputModel, AddText) {
   auto model = std::make_unique<TextInputModel>("", "");
   model->AddText(u"ABCDE");
-  model->AddText(u"😄");
-  model->AddText(u"FGHIJ");
+  model->AddText("😄");
+  model->AddText("FGHIJ");
   EXPECT_EQ(model->selection_base(), 12);
   EXPECT_EQ(model->selection_extent(), 12);
   EXPECT_STREQ(model->GetText().c_str(), "ABCDE😄FGHIJ");
@@ -113,7 +113,7 @@ TEST(TextInputModel, AddText) {
 TEST(TextInputModel, AddTextSelection) {
   auto model = std::make_unique<TextInputModel>("", "");
   EXPECT_TRUE(model->SetEditingState(1, 4, "ABCDE"));
-  model->AddText(u"xy");
+  model->AddText("xy");
   EXPECT_EQ(model->selection_base(), 3);
   EXPECT_EQ(model->selection_extent(), 3);
   EXPECT_STREQ(model->GetText().c_str(), "AxyE");
@@ -173,6 +173,96 @@ TEST(TextInputModel, DeleteSelection) {
   EXPECT_STREQ(model->GetText().c_str(), "AE");
 }
 
+TEST(TextInputModel, DeleteSurroundingAtCursor) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(0, 1));
+  EXPECT_EQ(model->selection_base(), 2);
+  EXPECT_EQ(model->selection_extent(), 2);
+  EXPECT_STREQ(model->GetText().c_str(), "ABDE");
+}
+
+TEST(TextInputModel, DeleteSurroundingAtCursorAll) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(0, 3));
+  EXPECT_EQ(model->selection_base(), 2);
+  EXPECT_EQ(model->selection_extent(), 2);
+  EXPECT_STREQ(model->GetText().c_str(), "AB");
+}
+
+TEST(TextInputModel, DeleteSurroundingAtCursorGreedy) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(0, 4));
+  EXPECT_EQ(model->selection_base(), 2);
+  EXPECT_EQ(model->selection_extent(), 2);
+  EXPECT_STREQ(model->GetText().c_str(), "AB");
+}
+
+TEST(TextInputModel, DeleteSurroundingBeforeCursor) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(-1, 1));
+  EXPECT_EQ(model->selection_base(), 1);
+  EXPECT_EQ(model->selection_extent(), 1);
+  EXPECT_STREQ(model->GetText().c_str(), "ACDE");
+}
+
+TEST(TextInputModel, DeleteSurroundingBeforeCursorAll) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(-2, 2));
+  EXPECT_EQ(model->selection_base(), 0);
+  EXPECT_EQ(model->selection_extent(), 0);
+  EXPECT_STREQ(model->GetText().c_str(), "CDE");
+}
+
+TEST(TextInputModel, DeleteSurroundingBeforeCursorGreedy) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(-3, 3));
+  EXPECT_EQ(model->selection_base(), 0);
+  EXPECT_EQ(model->selection_extent(), 0);
+  EXPECT_STREQ(model->GetText().c_str(), "CDE");
+}
+
+TEST(TextInputModel, DeleteSurroundingAfterCursor) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(1, 1));
+  EXPECT_EQ(model->selection_base(), 2);
+  EXPECT_EQ(model->selection_extent(), 2);
+  EXPECT_STREQ(model->GetText().c_str(), "ABCE");
+}
+
+TEST(TextInputModel, DeleteSurroundingAfterCursorAll) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(1, 2));
+  EXPECT_EQ(model->selection_base(), 2);
+  EXPECT_EQ(model->selection_extent(), 2);
+  EXPECT_STREQ(model->GetText().c_str(), "ABC");
+}
+
+TEST(TextInputModel, DeleteSurroundingAfterCursorGreedy) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 2, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(1, 3));
+  EXPECT_EQ(model->selection_base(), 2);
+  EXPECT_EQ(model->selection_extent(), 2);
+  EXPECT_STREQ(model->GetText().c_str(), "ABC");
+}
+
+TEST(TextInputModel, DeleteSurroundingSelection) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(2, 3, "ABCDE");
+  EXPECT_TRUE(model->DeleteSurrounding(0, 1));
+  EXPECT_EQ(model->selection_base(), 3);
+  EXPECT_EQ(model->selection_extent(), 3);
+  EXPECT_STREQ(model->GetText().c_str(), "ABCE");
+}
+
 TEST(TextInputModel, BackspaceStart) {
   auto model = std::make_unique<TextInputModel>("", "");
   EXPECT_TRUE(model->SetEditingState(0, 0, "ABCDE"));
@@ -380,4 +470,25 @@ TEST(TextInputModel, MoveCursorToEndSelection) {
   EXPECT_STREQ(model->GetText().c_str(), "ABCDE");
 }
 
+TEST(TextInputModel, GetCursorOffset) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  // These characters take 1, 2, 3 and 4 bytes in UTF-8.
+  model->SetEditingState(0, 0, "$¢€𐍈");
+  EXPECT_EQ(model->GetCursorOffset(), 0);
+  EXPECT_TRUE(model->MoveCursorForward());
+  EXPECT_EQ(model->GetCursorOffset(), 1);
+  EXPECT_TRUE(model->MoveCursorForward());
+  EXPECT_EQ(model->GetCursorOffset(), 3);
+  EXPECT_TRUE(model->MoveCursorForward());
+  EXPECT_EQ(model->GetCursorOffset(), 6);
+  EXPECT_TRUE(model->MoveCursorForward());
+  EXPECT_EQ(model->GetCursorOffset(), 10);
+}
+
+TEST(TextInputModel, GetCursorOffsetSelection) {
+  auto model = std::make_unique<TextInputModel>("", "");
+  model->SetEditingState(1, 4, "ABCDE");
+  EXPECT_EQ(model->GetCursorOffset(), 4);
+}
+
 }  // namespace flutter

shell/platform/glfw/BUILD.gn

@@ -53,6 +53,7 @@ source_set("flutter_glfw") {
     ":flutter_glfw_headers",
     "//build/secondary/third_party/glfw",
     "//flutter/shell/platform/common/cpp:common_cpp",
+    "//flutter/shell/platform/common/cpp:common_cpp_input",
     "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
     "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
     "//flutter/shell/platform/glfw/client_wrapper:client_wrapper_glfw",

shell/platform/linux/BUILD.gn

@@ -94,6 +94,7 @@ source_set("flutter_linux") {
     "fl_standard_message_codec.cc",
     "fl_standard_method_codec.cc",
     "fl_string_codec.cc",
+    "fl_text_input_plugin.cc",
     "fl_value.cc",
     "fl_view.cc",
   ]
@@ -108,6 +109,7 @@ source_set("flutter_linux") {
   defines = [ "FLUTTER_LINUX_COMPILATION" ]
 
   deps = [
+    "//flutter/shell/platform/common/cpp:common_cpp_input",
     "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
     "//third_party/rapidjson",
   ]