Implement right-to-left text rendering in Pepper.

ppapi/tests/test_browser_font.cc

Index: ppapi/tests/test_browser_font.cc
diff --git a/ppapi/tests/test_browser_font.cc b/ppapi/tests/test_browser_font.cc
index 9f3a2e07044d742670063a50c36f5e56ab4356eb..7c6614662254a023af1c467b876affa655079935 100644
--- a/ppapi/tests/test_browser_font.cc
+++ b/ppapi/tests/test_browser_font.cc
@@ -4,8 +4,6 @@
 
 #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"
@@ -20,6 +18,7 @@ bool TestBrowserFont::Init() {
 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.

 }
@@ -54,6 +53,52 @@ std::string TestBrowserFont::TestMeasure() {
   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;
@@ -71,6 +116,48 @@ std::string TestBrowserFont::TestCharPos() {
   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;