Add APIs for limited use of document tagged code.

fpdfsdk/fpdf_structtree_embeddertest.cpp

+// Copyright 2016 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/fxcrt/fx_string.h"
+#include "public/fpdf_structtree.h"
+#include "testing/embedder_test.h"
+#include "testing/test_support.h"
+
+class FPDFStructTreeEmbeddertest : public EmbedderTest, public TestSaver {};
+
+TEST_F(FPDFStructTreeEmbeddertest, GetAltText) {
+  ASSERT_TRUE(OpenDocument("tagged_alt_text.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  FPDF_STRUCTTREE struct_tree = FPDF_StructTree_GetForPage(page);
+  ASSERT_TRUE(struct_tree);
+  ASSERT_EQ(1, FPDF_StructTree_CountChildren(struct_tree));
+
+  FPDF_STRUCTELEMENT element = FPDF_StructTree_GetChildAtIndex(struct_tree, -1);
+  EXPECT_EQ(nullptr, element);
+  element = FPDF_StructTree_GetChildAtIndex(struct_tree, 1);
+  EXPECT_EQ(nullptr, element);
+  element = FPDF_StructTree_GetChildAtIndex(struct_tree, 0);
+  ASSERT_NE(nullptr, element);
+  EXPECT_EQ(0U, FPDF_StructElement_GetAltText(element, nullptr, 0));
+
+  ASSERT_EQ(1, FPDF_StructElement_CountChildren(element));
+  FPDF_STRUCTELEMENT child_element =
+      FPDF_StructElement_GetChildAtIndex(element, -1);
+  EXPECT_EQ(nullptr, child_element);
+  child_element = FPDF_StructElement_GetChildAtIndex(element, 1);
+  EXPECT_EQ(nullptr, child_element);
+  child_element = FPDF_StructElement_GetChildAtIndex(element, 0);
+  ASSERT_NE(nullptr, child_element);
+  EXPECT_EQ(0U, FPDF_StructElement_GetAltText(child_element, nullptr, 0));
+
+  ASSERT_EQ(1, FPDF_StructElement_CountChildren(child_element));
+  FPDF_STRUCTELEMENT gchild_element =
+      FPDF_StructElement_GetChildAtIndex(child_element, -1);
+  EXPECT_EQ(nullptr, gchild_element);
+  gchild_element = FPDF_StructElement_GetChildAtIndex(child_element, 1);
+  EXPECT_EQ(nullptr, gchild_element);
+  gchild_element = FPDF_StructElement_GetChildAtIndex(child_element, 0);
+  ASSERT_NE(nullptr, gchild_element);
+  ASSERT_EQ(24U, FPDF_StructElement_GetAltText(gchild_element, nullptr, 0));
+
+  unsigned short buffer[12];
+  memset(buffer, 0, sizeof(buffer));
+  // Deliberately pass in a small buffer size to make sure |buffer| remains
+  // untouched.
+  ASSERT_EQ(24U, FPDF_StructElement_GetAltText(gchild_element, buffer, 1));
+  for (size_t i = 0; i < FX_ArraySize(buffer); ++i)
+    EXPECT_EQ(0U, buffer[i]);
+
+  ASSERT_EQ(24U, FPDF_StructElement_GetAltText(gchild_element, buffer,
+                                               sizeof(buffer)));
+  const FX_WCHAR kExpected[] = L"Black Image";
+  EXPECT_EQ(CFX_WideString(kExpected),
+            CFX_WideString::FromUTF16LE(buffer, FXSYS_len(kExpected)));
+
+  ASSERT_EQ(1, FPDF_StructElement_CountChildren(gchild_element));
+  FPDF_STRUCTELEMENT ggchild_element =
+      FPDF_StructElement_GetChildAtIndex(gchild_element, 0);
+  EXPECT_EQ(nullptr, ggchild_element);
+
+  FPDF_StructTree_Close(struct_tree);
+  FPDF_ClosePage(page);
+}