[lensoverlay] Add message plumbing for rendering text fragments in PDF.

The parsing, searching, and rendering of the text fragments will take
place in follow-up CLs. This message is currently a no-op.

Change-Id: I2e1b2ce5eb5bd3bb638d1ceb8acd14a59a0d5684
Bug: 383575917
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6166811
Reviewed-by: Andy Phan <andyphan@chromium.org>
Commit-Queue: Juan Mojica <juanmojica@google.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1406772}

chrome/browser/resources/pdf/controller.ts

@@ -339,6 +339,13 @@ export class PluginController implements ContentController {
     this.postMessage_({type: 'selectAll'});
   }
 
+  highlightTextFragments(textFragments: string[]) {
+    this.postMessage_({
+      type: 'highlightTextFragments',
+      textFragments,
+    });
+  }
+
   getSelectedText(): Promise<{selectedText: string}> {
     return this.postMessageWithReply_({type: 'getSelectedText'});
   }

chrome/browser/resources/pdf/open_pdf_params_parser.ts

@@ -29,6 +29,8 @@ export enum ViewMode {
   XYZ = 'xyz',
 }
 
+const FRAGMENT_DIRECTIVE_DELIMITER = ':~:';
+
 type GetNamedDestinationCallback = (name: string) =>
     Promise<NamedDestinationMessageData>;
 
@@ -306,6 +308,26 @@ export class OpenPdfParamsParser {
     return navpanes === '1';
   }
 
+  /**
+   * Fetch text fragment directives that appear in the PDF URL if any.
+   *
+   * @param url that needs to be parsed.
+   * @return The text fragment directives or an empty array if they do not
+   *     exist.
+   */
+  getTextFragments(url: string): string[] {
+    const hash = new URL(url).hash;
+    // Handle the case of text directives included in the URL.
+    if (!hash.includes(FRAGMENT_DIRECTIVE_DELIMITER)) {
+      return [];
+    }
+
+    // Splitting the hash by the delimiter should always have at least two
+    // items since there was already a check for if the delimiter existed.
+    return new URLSearchParams(hash.split(FRAGMENT_DIRECTIVE_DELIMITER)[1])
+        .getAll('text');
+  }
+
   /**
    * Parse PDF url parameters. These parameters are mentioned in the url
    * and specify actions to be performed when opening pdf files.

chrome/browser/resources/pdf/pdf_viewer.ts

@@ -741,6 +741,12 @@ export class PdfViewerElement extends PdfViewerBaseElement {
       this.loadProgress_ = progress;
     }
     super.updateProgress(progress);
+
+    // Text fragment directives should be handled after the document is set to
+    // finished loading.
+    if (progress === 100) {
+      this.maybeRenderTextDirectiveHighlights_();
+    }
   }
 
   protected onErrorDialog_() {
@@ -1268,6 +1274,18 @@ export class PdfViewerElement extends PdfViewerBaseElement {
   }
   // </if>
 
+  /**
+   * Sends a message to the PDF plugin to highlight the provided text
+   * directives if any.
+   */
+  private maybeRenderTextDirectiveHighlights_() {
+    assert(this.paramsParser);
+    const textDirectives = this.paramsParser.getTextFragments(this.originalUrl);
+    if (textDirectives.length > 0) {
+      this.pluginController_.highlightTextFragments(textDirectives);
+    }
+  }
+
   /**
    * Saves the current PDF document to disk.
    */

chrome/test/data/pdf/params_parser_test.ts

@@ -502,6 +502,40 @@ chrome.test.runTests([
     chrome.test.assertEq(300, params.boundingBox.height);
     chrome.test.assertEq(100, params.viewPosition);
 
+    chrome.test.succeed();
+  },
+  function testParamsGetTextFragments() {
+    const paramsParser = getParamsParser();
+
+    // Checking single text fragment.
+    let fragments = paramsParser.getTextFragments(`${URL}#:~:text=apples`);
+    chrome.test.assertEq(fragments.length, 1);
+    chrome.test.assertEq(fragments[0], 'apples');
+
+    // Checking multiple text fragments.
+    fragments = paramsParser.getTextFragments(
+        `${URL}#:~:text=apples&text=oranges&text=hello-,world,there,-world`);
+    chrome.test.assertEq(fragments.length, 3);
+    chrome.test.assertEq(fragments[0], 'apples');
+    chrome.test.assertEq(fragments[1], 'oranges');
+    chrome.test.assertEq(fragments[2], 'hello-,world,there,-world');
+
+    // Checking case where no text fragments are present.
+    fragments = paramsParser.getTextFragments(`${URL}#page=3`);
+    chrome.test.assertEq(fragments.length, 0);
+
+    // Check case where only delimiter is present.
+    fragments = paramsParser.getTextFragments(`${URL}#:~:`);
+    chrome.test.assertEq(fragments.length, 0);
+
+    // Check case where there are other viewport parameters before the text
+    // fragments.
+    fragments = paramsParser.getTextFragments(
+        `${URL}#page=3&view=FitBV:~:text=foo&text=bar`);
+    chrome.test.assertEq(fragments.length, 2);
+    chrome.test.assertEq(fragments[0], 'foo');
+    chrome.test.assertEq(fragments[1], 'bar');
+
     chrome.test.succeed();
   },
 ]);

pdf/pdf_view_web_plugin.cc

@@ -19,6 +19,7 @@
 #include "base/compiler_specific.h"
 #include "base/containers/fixed_flat_map.h"
 #include "base/containers/queue.h"
+#include "base/containers/span.h"
 #include "base/debug/crash_logging.h"
 #include "base/feature_list.h"
 #include "base/functional/bind.h"
@@ -1595,6 +1596,8 @@ void PdfViewWebPlugin::OnMessage(const base::Value::Dict& message) {
            &PdfViewWebPlugin::HandleGetPasswordCompleteMessage},
           {"getSelectedText", &PdfViewWebPlugin::HandleGetSelectedTextMessage},
           {"getThumbnail", &PdfViewWebPlugin::HandleGetThumbnailMessage},
+          {"highlightTextFragments",
+           &PdfViewWebPlugin::HandleHighlightTextFragmentsMessage},
           {"print", &PdfViewWebPlugin::HandlePrintMessage},
           {"loadPreviewPage", &PdfViewWebPlugin::HandleLoadPreviewPageMessage},
           {"resetPrintPreviewMode",
@@ -1703,6 +1706,17 @@ void PdfViewWebPlugin::HandleGetThumbnailMessage(
                      weak_factory_.GetWeakPtr(), std::move(reply), page_index));
 }
 
+void PdfViewWebPlugin::HandleHighlightTextFragmentsMessage(
+    const base::Value::Dict& message) {
+  const auto* text_fragment_value_list = message.FindList("textFragments");
+  std::vector<std::string> text_fragments;
+  text_fragments.reserve(text_fragment_value_list->size());
+  for (const base::Value& fragment : *text_fragment_value_list) {
+    text_fragments.push_back(fragment.GetString());
+  }
+  engine_->HighlightTextFragments(text_fragments);
+}
+
 void PdfViewWebPlugin::HandlePrintMessage(
     const base::Value::Dict& /*message*/) {
   Print();

pdf/pdf_view_web_plugin.h

@@ -547,6 +547,7 @@ class PdfViewWebPlugin final : public PDFiumEngineClient,
   void HandleGetPasswordCompleteMessage(const base::Value::Dict& message);
   void HandleGetSelectedTextMessage(const base::Value::Dict& message);
   void HandleGetThumbnailMessage(const base::Value::Dict& message);
+  void HandleHighlightTextFragmentsMessage(const base::Value::Dict& message);
   void HandlePrintMessage(const base::Value::Dict& /*message*/);
   void HandleRotateClockwiseMessage(const base::Value::Dict& /*message*/);
   void HandleRotateCounterclockwiseMessage(

pdf/pdf_view_web_plugin_unittest.cc

@@ -1866,6 +1866,20 @@ TEST_F(PdfViewWebPluginTest, OnHasSearchifyText) {
   plugin_->OnHasSearchifyText();
 }
 
+TEST_F(PdfViewWebPluginTest, HighlightTextFragments) {
+  base::Value::List fragments;
+  fragments.Append("hello-,world");
+  fragments.Append("world,-hello");
+
+  base::Value::Dict message;
+  message.Set("type", "highlightTextFragments");
+  message.Set("textFragments", std::move(fragments));
+
+  EXPECT_CALL(*engine_ptr_, HighlightTextFragments(
+                                ElementsAre("hello-,world", "world,-hello")));
+  plugin_->OnMessage(message);
+}
+
 class PdfViewWebPluginWithDocInfoTest : public PdfViewWebPluginTest {
  public:
   void SetUp() override {

pdf/pdfium/pdfium_engine.cc

@@ -992,6 +992,12 @@ void PDFiumEngine::SetFormHighlight(bool enable_form) {
   KillFormFocus();
 }
 
+void PDFiumEngine::HighlightTextFragments(
+    base::span<const std::string> text_fragments) {
+  // TODO(crbug.com/383575917): Implement parsing, searching, and rendering of
+  // text fragments.
+}
+
 void PDFiumEngine::ClearTextSelection() {
   SelectionChangeInvalidator selection_invalidator(this);
   selection_.clear();

pdf/pdfium/pdfium_engine.h

@@ -492,6 +492,12 @@ class PDFiumEngine : public DocumentLoader::Client, public IFSDK_PAUSE {
   // Sets whether form highlight should be enabled or cleared.
   virtual void SetFormHighlight(bool enable_form);
 
+  // Attempts to render highlights for all of the fragments provided in
+  // `text_fragments`. If a fragment is not found, it is skipped and the
+  // engine will attempt to find and highlight the next fragment in the list.
+  virtual void HighlightTextFragments(
+      base::span<const std::string> text_fragments);
+
  private:
   // This helper class is used to detect the difference in selection between
   // construction and destruction.  At destruction, it invalidates all the

pdf/test/test_pdfium_engine.h

@@ -128,6 +128,11 @@ class TestPDFiumEngine : public PDFiumEngine {
 
   MOCK_METHOD(void, SetFormHighlight, (bool), (override));
 
+  MOCK_METHOD(void,
+              HighlightTextFragments,
+              (const base::span<const std::string>),
+              (override));
+
   MOCK_METHOD(void, ClearTextSelection, (), (override));
 
  protected: