freetype: fix MDRP/MIRP Set-RP0 bit and fix normalize rounding.

Also make phantom point delta-X adjustment.

Also make print-glyph-points require Freetype version >= 2.5, which is
the latest version, at the time of writing.

R=bsiegert
CC=golang-dev, remyoudompheng
https://codereview.appspot.com/18370043

cmd/print-glyph-points/main.c

@@ -7,7 +7,7 @@ gcc main.c -I/usr/include/freetype2 -lfreetype && ./a.out 12 ../../testdata/luxi
 #include FT_FREETYPE_H
 
 void usage(char** argv) {
-	printf("usage: %s font_size font_file [with_hinting|sans_hinting]\n", argv[0]);
+	fprintf(stderr, "usage: %s font_size font_file [with_hinting|sans_hinting]\n", argv[0]);
 }
 
 int main(int argc, char** argv) {
@@ -15,6 +15,7 @@ int main(int argc, char** argv) {
 	FT_Library library;
 	FT_Face face;
 	FT_Outline* o;
+	FT_Int major, minor, patch;
 	int i, j, font_size, no_hinting;
 
 	if (argc != 4) {
@@ -23,7 +24,7 @@ int main(int argc, char** argv) {
 	}
 	font_size = atoi(argv[1]);
 	if (font_size <= 0) {
-		printf("invalid font_size\n");
+		fprintf(stderr, "invalid font_size\n");
 		usage(argv);
 		return 1;
 	}
@@ -32,33 +33,40 @@ int main(int argc, char** argv) {
 	} else if (!strcmp(argv[3], "sans_hinting")) {
 		no_hinting = 1;
 	} else {
-		printf("neither \"with_hinting\" nor \"sans_hinting\"\n");
+		fprintf(stderr, "neither \"with_hinting\" nor \"sans_hinting\"\n");
 		usage(argv);
 		return 1;
 	};
 	error = FT_Init_FreeType(&library);
 	if (error) {
-		printf("FT_Init_FreeType: error #%d\n", error);
+		fprintf(stderr, "FT_Init_FreeType: error #%d\n", error);
+		return 1;
+	}
+	FT_Library_Version(library, &major, &minor, &patch);
+	if ((major < 2) || ((major == 2) && (minor < 5))) {
+		fprintf(stderr, "%s needs freetype version >= 2.5.\n"
+			"Try setting LD_LIBRARY_PATH=/path/to/freetype_built_from_src/objs/.libs/\n",
+			argv[0]);
 		return 1;
 	}
 	error = FT_New_Face(library, argv[2], 0, &face);
 	if (error) {
-		printf("FT_New_Face: error #%d\n", error);
+		fprintf(stderr, "FT_New_Face: error #%d\n", error);
 		return 1;
 	}
 	error = FT_Set_Char_Size(face, 0, font_size*64, 0, 0);
 	if (error) {
-		printf("FT_Set_Char_Size: error #%d\n", error);
+		fprintf(stderr, "FT_Set_Char_Size: error #%d\n", error);
 		return 1;
 	}
 	for (i = 0; i < face->num_glyphs; i++) {
 		error = FT_Load_Glyph(face, i, no_hinting ? FT_LOAD_NO_HINTING : FT_LOAD_DEFAULT);
 		if (error) {
-			printf("FT_Load_Glyph: glyph %d: error #%d\n", i, error);
+			fprintf(stderr, "FT_Load_Glyph: glyph %d: error #%d\n", i, error);
 			return 1;
 		}
 		if (face->glyph->format != FT_GLYPH_FORMAT_OUTLINE) {
-			printf("glyph format for glyph %d is not FT_GLYPH_FORMAT_OUTLINE\n", i);
+			fprintf(stderr, "glyph format for glyph %d is not FT_GLYPH_FORMAT_OUTLINE\n", i);
 			return 1;
 		}
 		o = &face->glyph->outline;

freetype/truetype/glyph.go

@@ -171,6 +171,11 @@ func (g *GlyphBuf) load(recursion int32, i Index, useMyMetrics bool) (err error)
 		if g.hinter != nil {
 			g.InFontUnits = g.InFontUnits[:len(g.InFontUnits)-4]
 			g.Unhinted = g.Unhinted[:len(g.Unhinted)-4]
+			if dx := ((pp1x + 32) &^ 63) - pp1x; dx != 0 {
+				for i := np0; i < len(g.Point); i++ {
+					g.Point[i].X += dx
+				}
+			}
 		}
 		if np0 != 0 {
 			// The hinting program expects the []End values to be indexed relative

freetype/truetype/hint.go

@@ -989,11 +989,11 @@ func (h *Hinter) run(program []byte, pCurrent, pUnhinted, pInFontUnits []Point,
 			}
 
 			// Set-RP0 bit.
+			h.gs.rp[1] = h.gs.rp[0]
+			h.gs.rp[2] = i
 			if opcode&0x10 != 0 {
 				h.gs.rp[0] = i
 			}
-			h.gs.rp[1] = h.gs.rp[0]
-			h.gs.rp[2] = i
 
 			// Move the point.
 			oldDist = dotProduct(f26dot6(p.X-ref.X), f26dot6(p.Y-ref.Y), h.gs.pv)
@@ -1068,11 +1068,11 @@ func (h *Hinter) run(program []byte, pCurrent, pUnhinted, pInFontUnits []Point,
 			}
 
 			// Set-RP0 bit.
+			h.gs.rp[1] = h.gs.rp[0]
+			h.gs.rp[2] = i
 			if opcode&0x10 != 0 {
 				h.gs.rp[0] = i
 			}
-			h.gs.rp[1] = h.gs.rp[0]
-			h.gs.rp[2] = i
 
 			// Move the point.
 			h.move(p, distance-curDist, true)
@@ -1438,13 +1438,20 @@ type f2dot14 int16
 
 func normalize(x, y f2dot14) [2]f2dot14 {
 	fx, fy := float64(x), float64(y)
-	l := math.Hypot(fx, fy)
-	fx /= l
-	fy /= l
-	return [2]f2dot14{
-		f2dot14(fx * 0x4000),
-		f2dot14(fy * 0x4000),
+	l := 0x4000 / math.Hypot(fx, fy)
+	fx *= l
+	if fx >= 0 {
+		fx += 0.5
+	} else {
+		fx -= 0.5
 	}
+	fy *= l
+	if fy >= 0 {
+		fy += 0.5
+	} else {
+		fy -= 0.5
+	}
+	return [2]f2dot14{f2dot14(fx), f2dot14(fy)}
 }
 
 // f26dot6 is a 26.6 fixed point number.

freetype/truetype/hint_test.go

@@ -583,6 +583,8 @@ func TestBytecode(t *testing.T) {
 	}
 }
 
+// TestMove tests that the Hinter.move method matches the output of the C
+// Freetype implementation.
 func TestMove(t *testing.T) {
 	h, p := Hinter{}, Point{}
 	testCases := []struct {
@@ -642,3 +644,30 @@ func TestMove(t *testing.T) {
 		}
 	}
 }
+
+// TestNormalize tests that the normalize function matches the output of the C
+// Freetype implementation.
+func TestNormalize(t *testing.T) {
+	testCases := [][2]f2dot14{
+		{-15895, 3974},
+		{-15543, 5181},
+		{-14654, 7327},
+		{-11585, 11585},
+		{0, 16384},
+		{11585, 11585},
+		{14654, 7327},
+		{15543, 5181},
+		{15895, 3974},
+		{16066, 3213},
+		{16161, 2694},
+		{16219, 2317},
+		{16257, 2032},
+		{16284, 1809},
+	}
+	for i, want := range testCases {
+		got := normalize(f2dot14(i)-4, 1)
+		if got != want {
+			t.Errorf("i=%d: got %v, want %v", i, got, want)
+		}
+	}
+}

freetype/truetype/truetype_test.go

@@ -253,7 +253,7 @@ var scalingTestCases = []struct {
 }{
 	{"luxisr", 12, -1},
 	{"x-arial-bold", 11, 0},
-	{"x-deja-vu-sans-oblique", 17, 14},
+	{"x-deja-vu-sans-oblique", 17, 229},
 	{"x-droid-sans-japanese", 9, 0},
 	{"x-times-new-roman", 13, 0},
 }