Simplify ConvertToPdfOrigin() inside pdfium_searchify.cc and add tests

Expose the function as ConvertToPdfOriginForTesting() to add some unit
tests. Also remove the unused width parameter.

Change-Id: Iaa7242f138fbe1a132c58643652daac80cc03aac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5691718
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Chu-Hsuan Yang <chuhsuan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1325951}

pdf/BUILD.gn

@@ -477,6 +477,10 @@ if (enable_pdf) {
       ]
     }
 
+    if (enable_screen_ai_service) {
+      sources += [ "pdfium/pdfium_searchify_unittest.cc" ]
+    }
+
     if (v8_use_external_startup_data) {
       deps += [
         "//tools/v8_context_snapshot",

pdf/pdfium/pdfium_searchify.cc

@@ -47,20 +47,13 @@ std::vector<uint32_t> Utf8ToCharcodes(const std::string& string) {
   return charcodes;
 }
 
-struct BoundingBoxOrigin {
-  double x;
-  double y;
-  double theta;
-};
-
 // The coordinate systems between OCR and PDF are different. OCR's origin is at
 // top-left, so we need to convert them to PDF's bottom-left.
-BoundingBoxOrigin ConvertToPdfOrigin(int x,
-                                     int y,
-                                     int width,
-                                     int height,
-                                     double angle,
-                                     double coordinate_system_height) {
+SearchifyBoundingBoxOrigin ConvertToPdfOrigin(int x,
+                                              int y,
+                                              int height,
+                                              double angle,
+                                              double coordinate_system_height) {
   const double theta = base::DegToRad(angle);
   return {.x = x - (sin(theta) * height),
           .y = coordinate_system_height - (y + cos(theta) * height),
@@ -68,8 +61,9 @@ BoundingBoxOrigin ConvertToPdfOrigin(int x,
 }
 
 // Project the text object's origin to the baseline's origin.
-BoundingBoxOrigin ProjectToBaseline(const BoundingBoxOrigin& origin,
-                                    const BoundingBoxOrigin& baseline_origin) {
+SearchifyBoundingBoxOrigin ProjectToBaseline(
+    const SearchifyBoundingBoxOrigin& origin,
+    const SearchifyBoundingBoxOrigin& baseline_origin) {
   // The length between `origin` and `baseline_origin`.
   double length = (origin.x - baseline_origin.x) * cos(baseline_origin.theta) +
                   (origin.y - baseline_origin.y) * sin(baseline_origin.theta);
@@ -107,10 +101,10 @@ void AddTextOnImage(FPDF_DOCUMENT document,
   }
 
   for (const auto& line : annotation->lines) {
-    BoundingBoxOrigin baseline_origin = ConvertToPdfOrigin(
-        line->baseline_box.x(), line->baseline_box.y(),
-        line->baseline_box.width(), line->baseline_box.height(),
-        line->baseline_box_angle, image_rendered_height);
+    SearchifyBoundingBoxOrigin baseline_origin =
+        ConvertToPdfOrigin(line->baseline_box.x(), line->baseline_box.y(),
+                           line->baseline_box.height(),
+                           line->baseline_box_angle, image_rendered_height);
 
     for (const auto& word : line->words) {
       double width = word->bounding_box.width();
@@ -167,8 +161,8 @@ void AddTextOnImage(FPDF_DOCUMENT document,
       FPDFPageObj_Transform(text.get(), width_scale, 0, 0, height_scale, 0, 0);
 
       // Move text object to the corresponding text position on the full image.
-      BoundingBoxOrigin origin = ConvertToPdfOrigin(
-          word->bounding_box.x(), word->bounding_box.y(), width, height,
+      SearchifyBoundingBoxOrigin origin = ConvertToPdfOrigin(
+          word->bounding_box.x(), word->bounding_box.y(), height,
           word->bounding_box_angle, image_rendered_height);
       origin = ProjectToBaseline(origin, baseline_origin);
       double a = cos(origin.theta);
@@ -280,6 +274,15 @@ std::vector<uint8_t> PDFiumSearchify(
   return output_file_write.TakeBuffer();
 }
 
+SearchifyBoundingBoxOrigin ConvertToPdfOriginForTesting(
+    int x,
+    int y,
+    int height,
+    double angle,
+    double coordinate_system_height) {
+  return ConvertToPdfOrigin(x, y, height, angle, coordinate_system_height);
+}
+
 PdfiumProgressiveSearchifier::ScopedSdkInitializer::ScopedSdkInitializer() {
   // TODO(thestig): Check the default value of `use_skia`.
   InitializeSDK(false, false, FontMappingMode::kNoMapping);

pdf/pdfium/pdfium_searchify.h

@@ -18,11 +18,25 @@
 
 namespace chrome_pdf {
 
+struct SearchifyBoundingBoxOrigin {
+  double x;
+  double y;
+  double theta;
+};
+
 std::vector<uint8_t> PDFiumSearchify(
     base::span<const uint8_t> pdf_buffer,
     base::RepeatingCallback<screen_ai::mojom::VisualAnnotationPtr(
         const SkBitmap& bitmap)> perform_ocr_callback);
 
+// Internal function exposed for testing.
+SearchifyBoundingBoxOrigin ConvertToPdfOriginForTesting(
+    int x,
+    int y,
+    int height,
+    double angle,
+    double coordinate_system_height);
+
 class PdfiumProgressiveSearchifier : public PdfProgressiveSearchifier {
  public:
   PdfiumProgressiveSearchifier();

pdf/pdfium/pdfium_searchify_unittest.cc

@@ -0,0 +1,73 @@
+// Copyright 2024 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "pdf/pdfium/pdfium_searchify.h"
+
+#include <numbers>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace chrome_pdf {
+
+TEST(PdfiumSearchifyTest, ConvertToPdfOrigin) {
+  {
+    SearchifyBoundingBoxOrigin result = ConvertToPdfOriginForTesting(
+        /*x=*/100,
+        /*y=*/50,
+        /*height=*/30,
+        /*angle=*/0,
+        /*coordinate_system_height=*/792);
+    EXPECT_DOUBLE_EQ(100, result.x);
+    EXPECT_DOUBLE_EQ(712, result.y);
+    EXPECT_DOUBLE_EQ(0, result.theta);
+  }
+
+  {
+    SearchifyBoundingBoxOrigin result = ConvertToPdfOriginForTesting(
+        /*x=*/100,
+        /*y=*/50,
+        /*height=*/30,
+        /*angle=*/45,
+        /*coordinate_system_height=*/792);
+    EXPECT_DOUBLE_EQ(78.786796564403573, result.x);
+    EXPECT_DOUBLE_EQ(720.78679656440363, result.y);
+    EXPECT_DOUBLE_EQ(-std::numbers::pi / 4, result.theta);
+  }
+
+  {
+    SearchifyBoundingBoxOrigin result = ConvertToPdfOriginForTesting(
+        /*x=*/100,
+        /*y=*/50,
+        /*height=*/30,
+        /*angle=*/90,
+        /*coordinate_system_height=*/792);
+    EXPECT_DOUBLE_EQ(70, result.x);
+    EXPECT_DOUBLE_EQ(742, result.y);
+    EXPECT_DOUBLE_EQ(-std::numbers::pi / 2, result.theta);
+  }
+  {
+    SearchifyBoundingBoxOrigin result = ConvertToPdfOriginForTesting(
+        /*x=*/100,
+        /*y=*/50,
+        /*height=*/30,
+        /*angle=*/180,
+        /*coordinate_system_height=*/792);
+    EXPECT_DOUBLE_EQ(100, result.x);
+    EXPECT_DOUBLE_EQ(772, result.y);
+    EXPECT_DOUBLE_EQ(-std::numbers::pi, result.theta);
+  }
+  {
+    SearchifyBoundingBoxOrigin result = ConvertToPdfOriginForTesting(
+        /*x=*/100,
+        /*y=*/50,
+        /*height=*/30,
+        /*angle=*/-90,
+        /*coordinate_system_height=*/792);
+    EXPECT_DOUBLE_EQ(130, result.x);
+    EXPECT_DOUBLE_EQ(742, result.y);
+    EXPECT_DOUBLE_EQ(std::numbers::pi / 2, result.theta);
+  }
+}
+
+}  // namespace chrome_pdf