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A fork of https://github.com/crosspoint-reader/crosspoint-reader
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13 kB · 381 lines
C++
at master
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#include "lib/EpdFont/EpdFont.h"#include "lib/EpdFont/EpdFontData.h"
static int testsPassed = 0;static int testsFailed = 0;
#define ASSERT_EQ(a, b) \ do { \ if ((a) != (b)) { \ fprintf(stderr, " FAIL: %s:%d: %s == %d, expected %d\n", __FILE__, __LINE__, #a, (a), (b)); \ testsFailed++; \ return; \ } \ } while (0)
#define ASSERT_TRUE(cond) \ do { \ if (!(cond)) { \ fprintf(stderr, " FAIL: %s:%d: %s\n", __FILE__, __LINE__, #cond); \ testsFailed++; \ return; \ } \ } while (0)
#define PASS() testsPassed++
// ============================================================================// Synthetic test font//// Glyphs: 'T' (0x54), 'a' (0x61), 'o' (0x6F), 'x' (0x78)// - 'x' advance is 136 FP (8.5px) -- frac = 8, exactly at the rounding// boundary where absolute vs differential snapping diverges for "oo".// - No U+FFFD replacement glyph, so unknown codepoints trigger the// null-glyph path in getTextBounds.//// Kern pairs (4.4 fixed-point):// T->a: -5 (-0.3125px) T->o: -7 (-0.4375px)// o->a: -2 (-0.125px) o->o: -3 (-0.1875px)// ============================================================================
// clang-format offstatic const EpdGlyph kGlyphs[] = { // idx width height advanceX left top dataLength dataOffset /* 0 'T' */ { 8, 12, 137, 0, 12, 0, 0 }, /* 1 'a' */ { 7, 8, 130, 0, 8, 0, 0 }, /* 2 'o' */ { 8, 8, 145, 0, 8, 0, 0 }, /* 3 'x' */ { 7, 8, 136, 0, 8, 0, 0 },};
static const EpdUnicodeInterval kIntervals[] = { { 0x54, 0x54, 0 }, // 'T' -> glyph[0] { 0x61, 0x61, 1 }, // 'a' -> glyph[1] { 0x6F, 0x6F, 2 }, // 'o' -> glyph[2] { 0x78, 0x78, 3 }, // 'x' -> glyph[3]};
static const EpdKernClassEntry kKernLeft[] = { { 0x54, 1 }, // 'T' -> left class 1 { 0x6F, 2 }, // 'o' -> left class 2};
static const EpdKernClassEntry kKernRight[] = { { 0x61, 1 }, // 'a' -> right class 1 { 0x6F, 2 }, // 'o' -> right class 2};
// Flat matrix: leftClassCount(2) x rightClassCount(2), 4.4 fixed-point// [L1,R1]=kern(T,a) [L1,R2]=kern(T,o) [L2,R1]=kern(o,a) [L2,R2]=kern(o,o)static const int8_t kKernMatrix[] = { -5, -7, -2, -3 };
static const EpdFontData kTestFontData = { .bitmap = nullptr, .glyph = kGlyphs, .intervals = kIntervals, .intervalCount = 4, .advanceY = 16, .ascender = 12, .descender = 0, .is2Bit = false, .groups = nullptr, .groupCount = 0, .glyphToGroup = nullptr, .kernLeftClasses = kKernLeft, .kernRightClasses = kKernRight, .kernMatrix = kKernMatrix, .kernLeftEntryCount = 2, .kernRightEntryCount = 2, .kernLeftClassCount = 2, .kernRightClassCount = 2, .ligaturePairs = nullptr, .ligaturePairCount = 0,};// clang-format on
static EpdFont testFont(&kTestFontData);
// Helper: return width from getTextDimensionsstatic int textWidth(const char* str) { int w = 0, h = 0; testFont.getTextDimensions(str, &w, &h); return w;}
static int textHeight(const char* str) { int w = 0, h = 0; testFont.getTextDimensions(str, &w, &h); return h;}
// ============================================================================// Part 1: Pure fp4 math tests// ============================================================================
// Simulate the old absolute-snap gap for comparisonstatic int absoluteGap(int32_t startFP, int32_t advanceFP, int32_t kernFP) { int32_t nextFP = startFP + advanceFP + kernFP; return fp4::toPixel(nextFP) - fp4::toPixel(startFP);}
void testFp4Basics() { printf("testFp4Basics...\n");
for (int px = 0; px < 500; px++) { ASSERT_EQ(fp4::toPixel(fp4::fromPixel(px)), px); }
ASSERT_EQ(fp4::toPixel(0), 0); ASSERT_EQ(fp4::toPixel(7), 0); // 0.4375 -> 0 ASSERT_EQ(fp4::toPixel(8), 1); // 0.5 -> 1 (round half up) ASSERT_EQ(fp4::toPixel(15), 1); // 0.9375 -> 1 ASSERT_EQ(fp4::toPixel(16), 1); // 1.0 -> 1 ASSERT_EQ(fp4::toPixel(24), 2); // 1.5 -> 2 ASSERT_EQ(fp4::toPixel(-8), 0); // -0.5 -> 0 ASSERT_EQ(fp4::toPixel(-9), -1); // -0.5625 -> -1 ASSERT_EQ(fp4::toPixel(-16), -1);
ASSERT_EQ(fp4::toPixel(137 + (-9)), 8); // 128 = 8.0 exact ASSERT_EQ(fp4::toPixel(137 + (-5)), 8); // 132 = 8.25 ASSERT_EQ(fp4::toPixel(137 + (-1)), 9); // 136 = 8.5 (half rounds up)
printf(" All fp4 basics passed\n"); PASS();}
void testOldApproachInconsistency() { printf("testOldApproachInconsistency...\n");
// 'oo' pair: advance=145 (9.0625px), kern=-3 (-0.1875px), combined=142 (8.875px) const int32_t advance = 145; const int32_t kern = -3;
int minGap = 999, maxGap = -999; for (int startPx = 0; startPx < 100; startPx++) { for (int frac = 0; frac < 16; frac++) { int32_t startFP = fp4::fromPixel(startPx) + frac; int gap = absoluteGap(startFP, advance, kern); if (gap < minGap) minGap = gap; if (gap > maxGap) maxGap = gap; } }
ASSERT_TRUE(maxGap - minGap >= 1); printf(" Old absolute gap range: [%d, %d] -- varies by %d px\n", minGap, maxGap, maxGap - minGap);
int diffStep = fp4::toPixel(advance + kern); printf(" Differential step: always %d px\n", diffStep); PASS();}
void testExhaustiveKernRange() { printf("testExhaustiveKernRange...\n");
const int32_t baseAdvance = 128; int checked = 0;
for (int advFrac = 0; advFrac < 16; advFrac++) { int32_t advance = baseAdvance + advFrac; for (int kern = -128; kern <= 127; kern++) { int step = fp4::toPixel(advance + static_cast<int32_t>(kern)); float idealPx = fp4::toFloat(advance + kern); if (std::abs(step - idealPx) >= 1.0f) { fprintf(stderr, " FAIL: advance=%d, kern=%d, step=%d, ideal=%.4f\n", advance, kern, step, idealPx); testsFailed++; return; } checked++; } }
printf(" Checked %d (advance, kern) combinations -- all within 1px of ideal\n", checked); PASS();}
// ============================================================================// Part 2: Integration tests using real EpdFont::getTextDimensions// ============================================================================
void testKernLookup() { printf("testKernLookup...\n");
ASSERT_EQ(testFont.getKerning('T', 'a'), -5); ASSERT_EQ(testFont.getKerning('T', 'o'), -7); ASSERT_EQ(testFont.getKerning('o', 'a'), -2); ASSERT_EQ(testFont.getKerning('o', 'o'), -3); ASSERT_EQ(testFont.getKerning('a', 'o'), 0); // 'a' has no left class ASSERT_EQ(testFont.getKerning('x', 'o'), 0); // 'x' has no left class ASSERT_EQ(testFont.getKerning('T', 'x'), 0); // 'x' has no right class ASSERT_EQ(testFont.getKerning('T', 'T'), 0); // 'T' has no right class
printf(" All kern lookups correct\n"); PASS();}
void testGlyphLookup() { printf("testGlyphLookup...\n");
ASSERT_TRUE(testFont.getGlyph('T') != nullptr); ASSERT_TRUE(testFont.getGlyph('a') != nullptr); ASSERT_TRUE(testFont.getGlyph('o') != nullptr); ASSERT_TRUE(testFont.getGlyph('x') != nullptr); ASSERT_EQ(testFont.getGlyph('T')->advanceX, 137); ASSERT_EQ(testFont.getGlyph('a')->advanceX, 130); ASSERT_EQ(testFont.getGlyph('o')->advanceX, 145); ASSERT_EQ(testFont.getGlyph('x')->advanceX, 136);
// No U+FFFD in font, so unknown codepoints return nullptr ASSERT_TRUE(testFont.getGlyph('Z') == nullptr); ASSERT_TRUE(testFont.getGlyph('b') == nullptr);
printf(" All glyph lookups correct\n"); PASS();}
// Known-value regression tests. Expected widths are computed by hand using// differential rounding. If someone reverts to absolute snapping, specific// test cases will fail.//// Layout trace for each string (all glyphs have left=0):// width = max glyph right edge = lastBaseX + glyph.width//// Differential step from glyph A to glyph B:// step = fp4::toPixel(advanceA + kern(A,B))void testKnownWidths() { printf("testKnownWidths...\n");
// "o": single glyph at x=0, width=8 // w = 0 + 8 = 8 ASSERT_EQ(textWidth("o"), 8);
// "oo": step = toPixel(145 + (-3)) = toPixel(142) = 9 // o1 at 0, o2 at 9. w = 9 + 8 = 17 ASSERT_EQ(textWidth("oo"), 17);
// "ooo": two steps of 9 // o1 at 0, o2 at 9, o3 at 18. w = 18 + 8 = 26 ASSERT_EQ(textWidth("ooo"), 26);
// "To": step = toPixel(137 + (-7)) = toPixel(130) = 8 // T at 0, o at 8. w = 8 + 8 = 16 ASSERT_EQ(textWidth("To"), 16);
// "Ta": step = toPixel(137 + (-5)) = toPixel(132) = 8 // T at 0, a at 8. w = 8 + 7 = 15 ASSERT_EQ(textWidth("Ta"), 15);
// "oa": step = toPixel(145 + (-2)) = toPixel(143) = 9 // o at 0, a at 9. w = 9 + 7 = 16 ASSERT_EQ(textWidth("oa"), 16);
// "Too": T at 0. // step T->o = toPixel(137 + (-7)) = 8. o1 at 8. // step o->o = toPixel(145 + (-3)) = 9. o2 at 17. // w = 17 + 8 = 25 ASSERT_EQ(textWidth("Too"), 25);
// "xo": step = toPixel(136 + 0) = toPixel(136) = 9 (no kern: x has no left class) // x at 0, o at 9. w = 9 + 8 = 17 ASSERT_EQ(textWidth("xo"), 17);
printf(" All known widths correct\n"); PASS();}
// "oo" pair consistency: the pixel gap between two o's must be the same// regardless of what prefix precedes them. This is THE key property of// differential rounding. With absolute snapping, "xoo" would produce a// different oo gap than "oo" because 'x' advance (136 FP) puts the first// 'o' at fractional phase 8, crossing the rounding boundary differently.void testPairConsistencyViaFont() { printf("testPairConsistencyViaFont...\n");
// The oo gap = width(prefix + "oo") - width(prefix + "o") // This isolates the pixel distance contributed by the second 'o'. const int oo_gap_bare = textWidth("oo") - textWidth("o"); const int oo_gap_after_x = textWidth("xoo") - textWidth("xo"); const int oo_gap_after_T = textWidth("Too") - textWidth("To"); const int oo_gap_after_o = textWidth("ooo") - textWidth("oo");
printf(" oo gap (bare): %d\n", oo_gap_bare); printf(" oo gap (after x): %d\n", oo_gap_after_x); printf(" oo gap (after T): %d\n", oo_gap_after_T); printf(" oo gap (after o): %d\n", oo_gap_after_o);
// All must be identical ASSERT_EQ(oo_gap_after_x, oo_gap_bare); ASSERT_EQ(oo_gap_after_T, oo_gap_bare); ASSERT_EQ(oo_gap_after_o, oo_gap_bare);
printf(" All oo gaps identical (%d px) regardless of prefix\n", oo_gap_bare); PASS();}
// Null-glyph handling: when a codepoint has no glyph (and no replacement// glyph), the pending advance from the previous glyph must still be flushed.// Without the flush fix, the glyph after the null would overlap the one before.void testNullGlyphAdvancePreserved() { printf("testNullGlyphAdvancePreserved...\n");
// 'Z' (0x5A) is not in our font and there's no U+FFFD, so getGlyph returns null. // "oZo" should lay out as: o1 at 0, Z skipped (advance flushed), o2 at 9. // toPixel(145) = 9 (o's advance, no kern since Z resets prevCp). // w = 9 + 8 = 17 int w = textWidth("oZo"); printf(" width(\"oZo\") = %d\n", w);
// Without the flush fix, o2 would land at 0 (overlapping o1), giving w = 8. ASSERT_TRUE(w > 8); ASSERT_EQ(w, 17);
// Multi-null: "oZZo" -- two consecutive nulls, advance still preserved. w = textWidth("oZZo"); printf(" width(\"oZZo\") = %d\n", w); ASSERT_EQ(w, 17);
// Null at start: "Zo" -- no pending advance to flush, o renders at 0. w = textWidth("Zo"); printf(" width(\"Zo\") = %d\n", w); ASSERT_EQ(w, 8);
printf(" Null-glyph advance correctly preserved\n"); PASS();}
void testHeightCalculation() { printf("testHeightCalculation...\n");
// 'T' is tallest: top=12, height=12 -> extent [0, 12) // 'o' and 'a': top=8, height=8 -> extent [0, 8) ASSERT_EQ(textHeight("o"), 8); ASSERT_EQ(textHeight("T"), 12); ASSERT_EQ(textHeight("To"), 12); ASSERT_EQ(textHeight("oo"), 8);
printf(" All heights correct\n"); PASS();}
int main() { printf("=== Differential Rounding Tests ===\n\n");
// Part 1: Pure fp4 math testFp4Basics(); testOldApproachInconsistency(); testExhaustiveKernRange();
// Part 2: Integration tests against real EpdFont testKernLookup(); testGlyphLookup(); testKnownWidths(); testPairConsistencyViaFont(); testNullGlyphAdvancePreserved(); testHeightCalculation();
printf("\n=== Results: %d passed, %d failed ===\n", testsPassed, testsFailed); return testsFailed > 0 ? 1 : 0;}