Add public APIs for undo / redo in forms.

Add FORM_CanUndo(), FORM_CanRedo(), FORM_Undo(), and FORM_Redo().

BUG=chromium:764260

Change-Id: I1d9ea67152d9b35d9b8e1d7ef7d019706fdfa30a
Reviewed-on: https://pdfium-review.googlesource.com/30872
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/fpdfsdk/fpdf_formfill_embeddertest.cpp b/fpdfsdk/fpdf_formfill_embeddertest.cpp
index 5dd4d1e1c1..09e0c200d3 100644
--- a/fpdfsdk/fpdf_formfill_embeddertest.cpp
+++ b/fpdfsdk/fpdf_formfill_embeddertest.cpp
@@ -134,6 +134,18 @@ class FPDFFormFillInteractiveEmbeddertest : public FPDFFormFillEmbeddertest {
     EXPECT_EQ(expected_string, WideString::FromUTF16LE(buf.data(), num_chars));
   }
 
+  void CheckCanUndo(bool expected_result) {
+    EXPECT_EQ(expected_result, !!FORM_CanUndo(form_handle(), page_));
+  }
+
+  void CheckCanRedo(bool expected_result) {
+    EXPECT_EQ(expected_result, !!FORM_CanRedo(form_handle(), page_));
+  }
+
+  void PerformUndo() { EXPECT_TRUE(FORM_Undo(form_handle(), page_)); }
+
+  void PerformRedo() { EXPECT_TRUE(FORM_Redo(form_handle(), page_)); }
+
  private:
   FPDF_PAGE page_ = nullptr;
 };
@@ -1544,3 +1556,68 @@ TEST_F(FPDFFormFillComboBoxFormEmbeddertest, FocusChanges) {
   SelectEditableFormOption(0);
   CheckFocusedFieldText(L"Foo");
 }
+
+TEST_F(FPDFFormFillTextFormEmbeddertest, UndoRedo) {
+  ClickOnFormFieldAtPoint(RegularFormBegin());
+  CheckFocusedFieldText(L"");
+  CheckCanUndo(false);
+  CheckCanRedo(false);
+
+  TypeTextIntoTextField(5, RegularFormBegin());
+  CheckFocusedFieldText(L"ABCDE");
+  CheckCanUndo(true);
+  CheckCanRedo(false);
+
+  PerformUndo();
+  CheckFocusedFieldText(L"ABCD");
+  CheckCanUndo(true);
+  CheckCanRedo(true);
+  PerformUndo();
+  CheckFocusedFieldText(L"ABC");
+  CheckCanUndo(true);
+  CheckCanRedo(true);
+
+  PerformRedo();
+  CheckFocusedFieldText(L"ABCD");
+  CheckCanUndo(true);
+  CheckCanRedo(true);
+  PerformRedo();
+  CheckFocusedFieldText(L"ABCDE");
+  CheckCanUndo(true);
+  CheckCanRedo(false);
+}
+
+TEST_F(FPDFFormFillComboBoxFormEmbeddertest, UndoRedo) {
+  ClickOnFormFieldAtPoint(NonEditableFormBegin());
+  CheckFocusedFieldText(L"Banana");
+  CheckCanUndo(false);
+  CheckCanRedo(false);
+
+  ClickOnFormFieldAtPoint(EditableFormBegin());
+  CheckFocusedFieldText(L"");
+  CheckCanUndo(false);
+  CheckCanRedo(false);
+
+  TypeTextIntoTextField(3, EditableFormBegin());
+  CheckFocusedFieldText(L"ABC");
+  CheckCanUndo(true);
+  CheckCanRedo(false);
+
+  PerformUndo();
+  CheckFocusedFieldText(L"AB");
+  CheckCanUndo(true);
+  CheckCanRedo(true);
+  PerformUndo();
+  CheckFocusedFieldText(L"A");
+  CheckCanUndo(true);
+  CheckCanRedo(true);
+  PerformUndo();
+  CheckFocusedFieldText(L"");
+  CheckCanUndo(false);
+  CheckCanRedo(true);
+
+  PerformRedo();
+  CheckFocusedFieldText(L"A");
+  CheckCanUndo(true);
+  CheckCanRedo(true);
+}