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Fix detailed-diff highlight clipping at end of trimmed diff string #2965

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Fix detailed-diff highlight clipping at end of trimmed diff string #2965

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27 changes: 11 additions & 16 deletions ...mpare/compare/org/eclipse/compare/unifieddiff/internal/UnifiedDiffCodeMiningProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@

import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffManager.error;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffManager.isOverlay;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.clampDetailedDiffLength;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.countLines;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.mapOffsetToTabExpanded;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.mergeStyleRanges;
Expand Down Expand Up @@ -759,12 +760,9 @@ static List<StyleRange> createDetailedDiffBackgroundRanges(UnifiedDiff diff, int
if (detailedDiffStr.trim().length() == 0) {
continue;
}
if (detailedDiffStart + detailedDiffLength >= trimmedDiffStr.length()) {
int delta = diffStr.length() - trimmedDiffStr.length();
if (detailedDiffLength <= delta) {
continue;
}
detailedDiffLength -= delta;
detailedDiffLength = clampDetailedDiffLength(detailedDiffStart, detailedDiffLength, trimmedDiffStr.length());
if (detailedDiffLength <= 0) {
continue;
}
int expandedStart = mapOffsetToTabExpanded(diffStr, detailedDiffStart, tabWidth);
int expandedEnd = mapOffsetToTabExpanded(diffStr, detailedDiffStart + detailedDiffLength, tabWidth);
Expand Down Expand Up @@ -940,7 +938,6 @@ private static List<DetailedDiffRange> computeDetailedDiffRanges(UnifiedDiff dif
|| diff.mode.equals(UnifiedDiffMode.REVERT_MODE);
String fullDiffStr = useRight ? diff.rightStr : diff.leftStr;
String diffStr = removeTrailingNewLines(fullDiffStr);
int diffStrDelta = fullDiffStr.length() - diffStr.length();
List<DetailedDiffRange> result = new ArrayList<>();
for (var detailedDiff : diff.detailedDiffs) {
String detailedDiffStr = useRight ? detailedDiff.rightStr : detailedDiff.leftStr;
Expand All @@ -949,11 +946,9 @@ private static List<DetailedDiffRange> computeDetailedDiffRanges(UnifiedDiff dif
if (detailedDiffStr.trim().length() == 0) {
continue;
}
if (detailedDiffStart + detailedDiffLength >= diffStr.length()) {
if (detailedDiffLength <= diffStrDelta) {
continue;
}
detailedDiffLength -= diffStrDelta;
detailedDiffLength = clampDetailedDiffLength(detailedDiffStart, detailedDiffLength, diffStr.length());
if (detailedDiffLength <= 0) {
continue;
}
// String#split drops trailing empty strings, so it must not be used to
// count lines: a prefix ending with \n starts the next line
Expand Down Expand Up @@ -1228,19 +1223,19 @@ private int getLineDelimiterLength(Document diffStrDoc, int middleLine) throws B
return delim.length();
}

private static class RangeInfo {
public static class RangeInfo {
int rangeIndex;
int offset;
Point position;

RangeInfo(int rangeIndex, int offset, Point position) {
public RangeInfo(int rangeIndex, int offset, Point position) {
this.rangeIndex = rangeIndex;
this.offset = offset;
this.position = position;
}
}

private Point getPositionForOffset(StyledText tw, GC gc, int offset, String str, List<StyleRange> ranges,
public Point getPositionForOffset(StyledText tw, GC gc, int offset, String str, List<StyleRange> ranges,
RangeInfo rangeInfo) {
String sub = str.substring(0, offset);
Point result = null;
Expand Down Expand Up @@ -1268,7 +1263,7 @@ private Point getPositionForOffset(StyledText tw, GC gc, int offset, String str,
}
}
int lfIdx = sub.lastIndexOf("\n"); //$NON-NLS-1$
if (lfIdx > 0) {
if (lfIdx >= 0) {
if (lfIdx == sub.length() - 1 && isLastForCurrentOffset(ranges, i, offset)) {
sub = sub.substring(0, lfIdx);
} else {
Expand Down
13 changes: 13 additions & 0 deletions ...org.eclipse.compare/compare/org/eclipse/compare/unifieddiff/internal/UnifiedDiffText.java
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Original file line number Diff line number Diff line change
Expand Up @@ -162,4 +162,17 @@ private static StyleRange createRange(StyleRange base, int start, int length, Co
}
return r;
}

/**
* Clamps {@code length} so that {@code start + length} does not exceed
* {@code trimmedEnd}. Returns the clamped length, or {@code <= 0} when the
* range falls entirely outside.
*/
public static int clampDetailedDiffLength(int start, int length, int trimmedEnd) {
int end = start + length;
if (end > trimmedEnd) {
length -= end - trimmedEnd;
}
return length;
}
}
97 changes: 97 additions & 0 deletions .../tests/org.eclipse.team.tests.core/src/org/eclipse/team/tests/ui/UnifiedDiffTextTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -13,21 +13,35 @@
*******************************************************************************/
package org.eclipse.team.tests.ui;

import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.clampDetailedDiffLength;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.countLines;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.mapOffsetToTabExpanded;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.mergeStyleRanges;
import static org.eclipse.compare.unifieddiff.internal.UnifiedDiffText.replaceTabWithSpaces;
import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertSame;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.List;

import org.eclipse.compare.unifieddiff.UnifiedDiffMode;
import org.eclipse.compare.unifieddiff.internal.UnifiedDiffCodeMiningProvider.UnifiedDiffLineHeaderCodeMining;
import org.eclipse.compare.unifieddiff.internal.UnifiedDiffCodeMiningProvider.UnifiedDiffLineHeaderCodeMining.RangeInfo;
import org.eclipse.compare.unifieddiff.internal.UnifiedDiffManager.UnifiedDiff;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.Position;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

/**
Expand All @@ -36,13 +50,35 @@
* painted, so an off-by-one here shows up as a misplaced highlight that is easy
* to miss in a manual test.
*/
@SuppressWarnings("restriction")
public class UnifiedDiffTextTest {

private static final Color BACKGROUND_1 = systemColor(SWT.COLOR_RED);
private static final Color BACKGROUND_2 = systemColor(SWT.COLOR_GREEN);
private static final Color FOREGROUND_1 = systemColor(SWT.COLOR_BLUE);
private static final Color FOREGROUND_2 = systemColor(SWT.COLOR_YELLOW);

private Shell shell;
private StyledText styledText;
private GC gc;

@BeforeEach
public void setUp() {
shell = new Shell(Display.getDefault());
styledText = new StyledText(shell, SWT.NONE);
gc = new GC(styledText);
}

@AfterEach
public void tearDown() {
if (gc != null && !gc.isDisposed()) {
gc.dispose();
}
if (shell != null && !shell.isDisposed()) {
shell.dispose();
}
}

// ---------------------------------------------------------------- countLines

/**
Expand Down Expand Up @@ -221,6 +257,59 @@ public void testMergeStyleRangesWithGapsBetweenForegrounds() {
assertTilesForegrounds(result, foregrounds);
}

// ------------------------------------------- clampDetailedDiffLength

@Test
public void testClampDetailedDiffLengthEndExactlyAtTrimmedEnd() {
// diff ends exactly at the last char of the trimmed string — must not clip
assertEquals(4, clampDetailedDiffLength(22, 4, 26));
}

@Test
public void testClampDetailedDiffLengthEndBeyondTrimmedEnd() {
// diff overshoots by 1 (e.g. includes a stripped trailing newline) — clip by 1
assertEquals(4, clampDetailedDiffLength(22, 5, 26));
}

@Test
public void testClampDetailedDiffLengthFullyOutside() {
// diff is entirely in the stripped region — result is <= 0
assertTrue(clampDetailedDiffLength(26, 1, 26) <= 0);
}

@Test
public void testClampDetailedDiffLengthNoOvershoot() {
// diff well within bounds — unchanged
assertEquals(3, clampDetailedDiffLength(5, 3, 20));
}

// ------------------------------------------- getPositionForOffset

@Test
public void testGetPositionForOffsetResetsXAfterNewlineAtRangeStart() throws Exception {
// Label: "abc\nxyz" — two lines, 3 chars each.
// Range [0, 3): "abc" — first line only, no newline.
// Range [3, 7): "\nxyz" — starts with \n at index 0 (lfIdx == 0).
// Querying the position of offset 7 (end of "xyz") must return x=width("xyz"),
// not x=width("abc")+width("xyz"), because the \n resets the x accumulator.
String str = "abc\nxyz";
List<StyleRange> ranges = List.of(styledRange(0, 3), styledRange(3, 4));

Document doc = new Document(str);
UnifiedDiff diff = new UnifiedDiff(doc, 0, str.length(), str, doc, 0, str.length(), str,
List.of(), UnifiedDiffMode.REPLACE_MODE);
UnifiedDiffLineHeaderCodeMining mining = new UnifiedDiffLineHeaderCodeMining(
new Position(0, 1), null, diff, 4, null, null, null);

gc.setFont(styledText.getFont());
Point result = mining.getPositionForOffset(styledText, gc, 7, str, ranges, new RangeInfo(-1, -1, null));

assertNotNull(result, "position must not be null");
Point expected = gc.stringExtent("xyz");
assertEquals(expected.x, result.x,
"x must equal the width of 'xyz' alone, not width('abc')+width('xyz')");
}

// ------------------------------------------------------------------ helpers

/**
Expand Down Expand Up @@ -292,4 +381,12 @@ private static StyleRange background(int start, int length, Color color) {
private static Color systemColor(int id) {
return Display.getDefault().getSystemColor(id);
}

private static StyleRange styledRange(int start, int length) {
StyleRange range = new StyleRange();
range.start = start;
range.length = length;
range.foreground = systemColor(SWT.COLOR_BLUE);
return range;
}
}
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