Implement right-to-left text rendering in Pepper.

ppapi/tests/test_browser_font.cc

 // Copyright (c) 2012 The Chromium 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 "ppapi/tests/test_browser_font.h"
 
-#include <stdio.h>// ERASEME
-
 #include "ppapi/tests/test_utils.h"
 #include "ppapi/tests/testing_instance.h"
 #include "ppapi/cpp/image_data.h"
 #include "ppapi/cpp/trusted/browser_font_trusted.h"
 
 REGISTER_TEST_CASE(BrowserFont);
 
 bool TestBrowserFont::Init() {
   return true;
 }
 
 void TestBrowserFont::RunTests(const std::string& filter) {
   RUN_TEST(FontFamilies, filter);
   RUN_TEST(Measure, filter);
+  RUN_TEST(MeasureRTL, filter);
   RUN_TEST(CharPos, filter);
   RUN_TEST(Draw, filter);

[viettrungluu, 2012/06/27 20:34:28]

You forgot CharPosRTL.

 }
 
 // Just tests that GetFontFamilies is hooked up & returns something.
 std::string TestBrowserFont::TestFontFamilies() {
   // This function is only supported out-of-process.
   const PPB_Testing_Dev* testing_interface = GetTestingInterface();
   if (testing_interface && !testing_interface->IsOutOfProcess())
     PASS();
 
   pp::Var families = pp::BrowserFont_Trusted::GetFontFamilies(instance_);
@@ skipping 12 matching lines @@
   pp::BrowserFont_Trusted font(instance_, desc);
 
   int32_t length1 = font.MeasureText(pp::BrowserFontTextRun("WWW"));
   ASSERT_TRUE(length1 > 0);
   int32_t length2 = font.MeasureText(pp::BrowserFontTextRun("WWWWWWWW"));
 
   ASSERT_TRUE(length2 >= length1 * 2);
   PASS();
 }
 
+std::string TestBrowserFont::TestMeasureRTL() {
+  pp::BrowserFontDescription desc;
+  pp::BrowserFont_Trusted font(instance_, desc);
+
+  // Mixed string, two chars of LTR, two of RTL, than two of LTR.

[viettrungluu, 2012/06/27 20:33:58]

s/than/then/

+  // Note this is in UTF-8 so has more than 6 bytes.
+  std::string mixed("AB\xd7\x94\xd7\x97ZZ");
+  const int kNumChars = 6;
+  pp::BrowserFontTextRun run(mixed);
+
+  // Note that since this is UTF8, the two RTL chars are two bytes each.

[viettrungluu, 2012/06/27 20:33:58]

Nit: "UTF8" or "UTF-8"?

+  int32_t len[kNumChars];
+  len[0] = font.PixelOffsetForCharacter(run, 0);
+  len[1] = font.PixelOffsetForCharacter(run, 1);
+  len[2] = font.PixelOffsetForCharacter(run, 2);
+  len[3] = font.PixelOffsetForCharacter(run, 3);
+  len[4] = font.PixelOffsetForCharacter(run, 4);
+  len[5] = font.PixelOffsetForCharacter(run, 5);
+
+  // First three chars should be increasing.
+  ASSERT_TRUE(len[0] >= 0);
+  ASSERT_TRUE(len[1] > len[0]);
+  ASSERT_TRUE(len[2] > len[1]);

[viettrungluu, 2012/06/27 20:33:58]

Instead of this convoluted logic, I don't see why you don't just do:

I don't see why you don't just continue:

// Visually, left-to-write, the characters occur in the order:
// 0, 1, 3, 2, 4, 5.

ASSERT_TRUE(len[0] >= 0);
ASSERT_TRUE(len[1] > len[0]);
ASSERT_TRUE(len[3] > len[1]);
ASSERT_TRUE(len[2] > len[3]);
ASSERT_TRUE(len[4] > len[2]);
ASSERT_TRUE(len[5] > len[4]);

(You also forgot to look at len[5].)

+
+  // Next char should be between the previous two (since it's going RTL).
+  ASSERT_TRUE(len[3] < len[2] && len[3] > len[1]);
+
+  // Last two chars should be increasing again.
+  ASSERT_TRUE(len[4] > len[2] && len[4] > len[3]);
+  ASSERT_TRUE(len[4] > len[3]);
+
+  // Test the same sequence with force LTR. The offsets should appear in
+  // sequence.
+  pp::BrowserFontTextRun forced_run(mixed, false, true);
+  len[0] = font.PixelOffsetForCharacter(forced_run, 0);
+  len[1] = font.PixelOffsetForCharacter(forced_run, 1);
+  len[2] = font.PixelOffsetForCharacter(forced_run, 2);
+  len[3] = font.PixelOffsetForCharacter(forced_run, 3);
+  len[4] = font.PixelOffsetForCharacter(forced_run, 4);
+  len[5] = font.PixelOffsetForCharacter(forced_run, 5);
+  for (int i = 1; i < kNumChars; i++)
+    ASSERT_TRUE(len[i] > len[i - 1]);
+
+  PASS();
+}
+
 // Tests that the character/pixel offset functions correctly round-trip.
 std::string TestBrowserFont::TestCharPos() {
   pp::BrowserFontDescription desc;
   pp::BrowserFont_Trusted font(instance_, desc);
 
   pp::BrowserFontTextRun run("Hello, world");
   uint32_t original_char = 3;
   uint32_t pixel_offset = font.PixelOffsetForCharacter(run, original_char);
   ASSERT_TRUE(pixel_offset > 0);
 
   uint32_t computed_char = font.CharacterOffsetForPixel(
       run, static_cast<int32_t>(pixel_offset));
   ASSERT_TRUE(computed_char == original_char);
 
   PASS();
 }
 
+// Tests that we can get character positions in a mixed LTR/RTL run.
+std::string TestBrowserFont::TestCharPosRTL() {
+  pp::BrowserFontDescription desc;
+  pp::BrowserFont_Trusted font(instance_, desc);
+
+  // Mixed string, two chars of LTR, two of RTL, than two of LTR.
+  // Note this is in UTF-8 so has more than 6 bytes.
+  std::string mixed("AB\xd7\x94\xd7\x97ZZ");
+
+  pp::BrowserFontTextRun run(mixed);
+  static const int kNumChars = 6;
+  int expected_char_sequence[kNumChars] = { 0, 1, 3, 2, 4, 5 };
+
+  // Check that the characters appear in the order we expect.
+  int pixel_width = font.MeasureText(pp::BrowserFontTextRun(mixed));
+  int last_sequence = 0;  // Index into expected_char_sequence.
+  for (int x = 0; x < pixel_width; x++) {
+    int cur_char = font.CharacterOffsetForPixel(run, x);
+    if (cur_char != expected_char_sequence[cur_char]) {
+      // This pixel has a different character. It should be the next one in
+      // the sequence for it to be correct.
+      last_sequence++;
+      ASSERT_TRUE(last_sequence < kNumChars);
+      ASSERT_TRUE(cur_char == expected_char_sequence[last_sequence]);
+    }
+  }
+
+  // Try the same string with force LTR. The characters should all appear in
+  // sequence.
+  pp::BrowserFontTextRun forced_run(mixed, false, true);
+  int last_forced_char = 0;  // Char index into the forced sequence.
+  for (int x = 0; x < pixel_width; x++) {
+    int cur_char = font.CharacterOffsetForPixel(forced_run, x);
+    if (cur_char != last_forced_char) {
+      last_forced_char++;
+      ASSERT_TRUE(cur_char == last_forced_char);
+    }
+  }
+
+  PASS();
+}
+
 // Tests that drawing some text produces "some" output.
 std::string TestBrowserFont::TestDraw() {
   pp::BrowserFontDescription desc;
   desc.set_size(100);
   pp::BrowserFont_Trusted font(instance_, desc);
 
   const int kSize = 256;
   pp::ImageData image(instance_, pp::ImageData::GetNativeImageDataFormat(),
                       pp::Size(kSize, kSize), true);
   ASSERT_TRUE(!image.is_null());
 
   const uint32_t kColor = 0xFFFFFFFF;
   font.DrawSimpleText(&image, "Hello", pp::Point(0, 0), kColor, false);
 
   // Expect that some pixel is nonzero. Due to blending, there may be rounding
   // errors and checking for exact white may not be correct.
   bool found = false;
   for (int y = 0; y < kSize; y++) {
     for (int x = 0; x < kSize; x++) {
       if (*image.GetAddr32(pp::Point(x, y)) != 0) {
         found = true;
         break;
       }
     }
   }
   ASSERT_TRUE(found);
   PASS();
 }