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-rw-r--r--core/java/android/text/Layout.java169
-rw-r--r--core/java/android/text/TextLine.java92
2 files changed, 255 insertions, 6 deletions
diff --git a/core/java/android/text/Layout.java b/core/java/android/text/Layout.java
index 0bd5071b6ea4..c94e489f89cf 100644
--- a/core/java/android/text/Layout.java
+++ b/core/java/android/text/Layout.java
@@ -824,6 +824,32 @@ public abstract class Layout {
return TextUtils.packRangeInLong(0, getLineEnd(line));
}
+ /**
+ * Checks if the trailing BiDi level should be used for an offset
+ *
+ * This method is useful when the offset is at the BiDi level transition point and determine
+ * which run need to be used. For example, let's think about following input: (L* denotes
+ * Left-to-Right characters, R* denotes Right-to-Left characters.)
+ * Input (Logical Order): L1 L2 L3 R1 R2 R3 L4 L5 L6
+ * Input (Display Order): L1 L2 L3 R3 R2 R1 L4 L5 L6
+ *
+ * Then, think about selecting the range (3, 6). The offset=3 and offset=6 are ambiguous here
+ * since they are at the BiDi transition point. In Android, the offset is considered to be
+ * associated with the trailing run if the BiDi level of the trailing run is higher than of the
+ * previous run. In this case, the BiDi level of the input text is as follows:
+ *
+ * Input (Logical Order): L1 L2 L3 R1 R2 R3 L4 L5 L6
+ * BiDi Run: [ Run 0 ][ Run 1 ][ Run 2 ]
+ * BiDi Level: 0 0 0 1 1 1 0 0 0
+ *
+ * Thus, offset = 3 is part of Run 1 and this method returns true for offset = 3, since the BiDi
+ * level of Run 1 is higher than the level of Run 0. Similarly, the offset = 6 is a part of Run
+ * 1 and this method returns false for the offset = 6 since the BiDi level of Run 1 is higher
+ * than the level of Run 2.
+ *
+ * @returns true if offset is at the BiDi level transition point and trailing BiDi level is
+ * higher than previous BiDi level. See above for the detail.
+ */
private boolean primaryIsTrailingPrevious(int offset) {
int line = getLineForOffset(offset);
int lineStart = getLineStart(line);
@@ -874,6 +900,41 @@ public abstract class Layout {
}
/**
+ * Computes in linear time the results of calling
+ * #primaryIsTrailingPrevious for all offsets on a line.
+ * @param line The line giving the offsets we compute the information for
+ * @return The array of results, indexed from 0, where 0 corresponds to the line start offset
+ */
+ private boolean[] primaryIsTrailingPreviousAllLineOffsets(int line) {
+ int lineStart = getLineStart(line);
+ int lineEnd = getLineEnd(line);
+ int[] runs = getLineDirections(line).mDirections;
+
+ boolean[] trailing = new boolean[lineEnd - lineStart + 1];
+
+ byte[] level = new byte[lineEnd - lineStart + 1];
+ for (int i = 0; i < runs.length; i += 2) {
+ int start = lineStart + runs[i];
+ int limit = start + (runs[i + 1] & RUN_LENGTH_MASK);
+ if (limit > lineEnd) {
+ limit = lineEnd;
+ }
+ level[limit - lineStart - 1] =
+ (byte) ((runs[i + 1] >>> RUN_LEVEL_SHIFT) & RUN_LEVEL_MASK);
+ }
+
+ for (int i = 0; i < runs.length; i += 2) {
+ int start = lineStart + runs[i];
+ byte currentLevel = (byte) ((runs[i + 1] >>> RUN_LEVEL_SHIFT) & RUN_LEVEL_MASK);
+ trailing[start - lineStart] = currentLevel > (start == lineStart
+ ? (getParagraphDirection(line) == 1 ? 0 : 1)
+ : level[start - lineStart - 1]);
+ }
+
+ return trailing;
+ }
+
+ /**
* Get the primary horizontal position for the specified text offset.
* This is the location where a new character would be inserted in
* the paragraph's primary direction.
@@ -953,6 +1014,60 @@ public abstract class Layout {
}
/**
+ * Computes in linear time the results of calling
+ * #getHorizontal for all offsets on a line.
+ * @param line The line giving the offsets we compute information for
+ * @param clamped Whether to clamp the results to the width of the layout
+ * @param primary Whether the results should be the primary or the secondary horizontal
+ * @return The array of results, indexed from 0, where 0 corresponds to the line start offset
+ */
+ private float[] getLineHorizontals(int line, boolean clamped, boolean primary) {
+ int start = getLineStart(line);
+ int end = getLineEnd(line);
+ int dir = getParagraphDirection(line);
+ boolean hasTab = getLineContainsTab(line);
+ Directions directions = getLineDirections(line);
+
+ TabStops tabStops = null;
+ if (hasTab && mText instanceof Spanned) {
+ // Just checking this line should be good enough, tabs should be
+ // consistent across all lines in a paragraph.
+ TabStopSpan[] tabs = getParagraphSpans((Spanned) mText, start, end, TabStopSpan.class);
+ if (tabs.length > 0) {
+ tabStops = new TabStops(TAB_INCREMENT, tabs); // XXX should reuse
+ }
+ }
+
+ TextLine tl = TextLine.obtain();
+ tl.set(mPaint, mText, start, end, dir, directions, hasTab, tabStops);
+ boolean[] trailings = primaryIsTrailingPreviousAllLineOffsets(line);
+ if (!primary) {
+ for (int offset = 0; offset < trailings.length; ++offset) {
+ trailings[offset] = !trailings[offset];
+ }
+ }
+ float[] wid = tl.measureAllOffsets(trailings, null);
+ TextLine.recycle(tl);
+
+ if (clamped) {
+ for (int offset = 0; offset <= wid.length; ++offset) {
+ if (wid[offset] > mWidth) {
+ wid[offset] = mWidth;
+ }
+ }
+ }
+ int left = getParagraphLeft(line);
+ int right = getParagraphRight(line);
+
+ int lineStartPos = getLineStartPos(line, left, right);
+ float[] horizontal = new float[end - start + 1];
+ for (int offset = 0; offset < horizontal.length; ++offset) {
+ horizontal[offset] = lineStartPos + wid[offset];
+ }
+ return horizontal;
+ }
+
+ /**
* Get the leftmost position that should be exposed for horizontal
* scrolling on the specified line.
*/
@@ -1167,6 +1282,8 @@ public abstract class Layout {
// XXX: we don't care about tabs as we just use TextLine#getOffsetToLeftRightOf here.
tl.set(mPaint, mText, lineStartOffset, lineEndOffset, getParagraphDirection(line), dirs,
false, null);
+ final HorizontalMeasurementProvider horizontal =
+ new HorizontalMeasurementProvider(line, primary);
final int max;
if (line == getLineCount() - 1) {
@@ -1176,7 +1293,7 @@ public abstract class Layout {
!isRtlCharAt(lineEndOffset - 1)) + lineStartOffset;
}
int best = lineStartOffset;
- float bestdist = Math.abs(getHorizontal(best, primary) - horiz);
+ float bestdist = Math.abs(horizontal.get(lineStartOffset) - horiz);
for (int i = 0; i < dirs.mDirections.length; i += 2) {
int here = lineStartOffset + dirs.mDirections[i];
@@ -1192,7 +1309,7 @@ public abstract class Layout {
guess = (high + low) / 2;
int adguess = getOffsetAtStartOf(guess);
- if (getHorizontal(adguess, primary) * swap >= horiz * swap)
+ if (horizontal.get(adguess) * swap >= horiz * swap)
high = guess;
else
low = guess;
@@ -1205,9 +1322,9 @@ public abstract class Layout {
int aft = tl.getOffsetToLeftRightOf(low - lineStartOffset, isRtl) + lineStartOffset;
low = tl.getOffsetToLeftRightOf(aft - lineStartOffset, !isRtl) + lineStartOffset;
if (low >= here && low < there) {
- float dist = Math.abs(getHorizontal(low, primary) - horiz);
+ float dist = Math.abs(horizontal.get(low) - horiz);
if (aft < there) {
- float other = Math.abs(getHorizontal(aft, primary) - horiz);
+ float other = Math.abs(horizontal.get(aft) - horiz);
if (other < dist) {
dist = other;
@@ -1222,7 +1339,7 @@ public abstract class Layout {
}
}
- float dist = Math.abs(getHorizontal(here, primary) - horiz);
+ float dist = Math.abs(horizontal.get(here) - horiz);
if (dist < bestdist) {
bestdist = dist;
@@ -1230,7 +1347,7 @@ public abstract class Layout {
}
}
- float dist = Math.abs(getHorizontal(max, primary) - horiz);
+ float dist = Math.abs(horizontal.get(max) - horiz);
if (dist <= bestdist) {
bestdist = dist;
@@ -1242,6 +1359,46 @@ public abstract class Layout {
}
/**
+ * Responds to #getHorizontal queries, by selecting the better strategy between:
+ * - calling #getHorizontal explicitly for each query
+ * - precomputing all #getHorizontal measurements, and responding to any query in constant time
+ * The first strategy is used for LTR-only text, while the second is used for all other cases.
+ * The class is currently only used in #getOffsetForHorizontal, so reuse with care in other
+ * contexts.
+ */
+ private class HorizontalMeasurementProvider {
+ private final int mLine;
+ private final boolean mPrimary;
+
+ private float[] mHorizontals;
+ private int mLineStartOffset;
+
+ HorizontalMeasurementProvider(final int line, final boolean primary) {
+ mLine = line;
+ mPrimary = primary;
+ init();
+ }
+
+ private void init() {
+ final Directions dirs = getLineDirections(mLine);
+ if (dirs == DIRS_ALL_LEFT_TO_RIGHT) {
+ return;
+ }
+
+ mHorizontals = getLineHorizontals(mLine, false, mPrimary);
+ mLineStartOffset = getLineStart(mLine);
+ }
+
+ float get(final int offset) {
+ if (mHorizontals == null) {
+ return getHorizontal(offset, mPrimary);
+ } else {
+ return mHorizontals[offset - mLineStartOffset];
+ }
+ }
+ }
+
+ /**
* Return the text offset after the last character on the specified line.
*/
public final int getLineEnd(int line) {
diff --git a/core/java/android/text/TextLine.java b/core/java/android/text/TextLine.java
index 2a52961984f7..79333563af1d 100644
--- a/core/java/android/text/TextLine.java
+++ b/core/java/android/text/TextLine.java
@@ -339,6 +339,98 @@ class TextLine {
}
/**
+ * @see #measure(int, boolean, FontMetricsInt)
+ * @return The measure results for all possible offsets
+ */
+ float[] measureAllOffsets(boolean[] trailing, FontMetricsInt fmi) {
+ float[] measurement = new float[mLen + 1];
+
+ int[] target = new int[mLen + 1];
+ for (int offset = 0; offset < target.length; ++offset) {
+ target[offset] = trailing[offset] ? offset - 1 : offset;
+ }
+ if (target[0] < 0) {
+ measurement[0] = 0;
+ }
+
+ float h = 0;
+
+ if (!mHasTabs) {
+ if (mDirections == Layout.DIRS_ALL_LEFT_TO_RIGHT) {
+ for (int offset = 0; offset <= mLen; ++offset) {
+ measurement[offset] = measureRun(0, offset, mLen, false, fmi);
+ }
+ return measurement;
+ }
+ if (mDirections == Layout.DIRS_ALL_RIGHT_TO_LEFT) {
+ for (int offset = 0; offset <= mLen; ++offset) {
+ measurement[offset] = measureRun(0, offset, mLen, true, fmi);
+ }
+ return measurement;
+ }
+ }
+
+ char[] chars = mChars;
+ int[] runs = mDirections.mDirections;
+ for (int i = 0; i < runs.length; i += 2) {
+ int runStart = runs[i];
+ int runLimit = runStart + (runs[i + 1] & Layout.RUN_LENGTH_MASK);
+ if (runLimit > mLen) {
+ runLimit = mLen;
+ }
+ boolean runIsRtl = (runs[i + 1] & Layout.RUN_RTL_FLAG) != 0;
+
+ int segstart = runStart;
+ for (int j = mHasTabs ? runStart : runLimit; j <= runLimit; ++j) {
+ int codept = 0;
+ if (mHasTabs && j < runLimit) {
+ codept = chars[j];
+ if (codept >= 0xD800 && codept < 0xDC00 && j + 1 < runLimit) {
+ codept = Character.codePointAt(chars, j);
+ if (codept > 0xFFFF) {
+ ++j;
+ continue;
+ }
+ }
+ }
+
+ if (j == runLimit || codept == '\t') {
+ float oldh = h;
+ boolean advance = (mDir == Layout.DIR_RIGHT_TO_LEFT) == runIsRtl;
+ float w = measureRun(segstart, j, j, runIsRtl, fmi);
+ h += advance ? w : -w;
+
+ float baseh = advance ? oldh : h;
+ FontMetricsInt crtfmi = advance ? fmi : null;
+ for (int offset = segstart; offset <= j && offset <= mLen; ++offset) {
+ if (target[offset] >= segstart && target[offset] < j) {
+ measurement[offset] =
+ baseh + measureRun(segstart, offset, j, runIsRtl, crtfmi);
+ }
+ }
+
+ if (codept == '\t') {
+ if (target[j] == j) {
+ measurement[j] = h;
+ }
+ h = mDir * nextTab(h * mDir);
+ if (target[j + 1] == j) {
+ measurement[j + 1] = h;
+ }
+ }
+
+ segstart = j + 1;
+ }
+ }
+ }
+ if (target[mLen] == mLen) {
+ measurement[mLen] = h;
+ }
+
+ return measurement;
+ }
+
+ /**
* Draws a unidirectional (but possibly multi-styled) run of text.
*
*
generated by cgit v1.2.3-59-g8ed1b (git 2.39.0) at 2025-12-08 03:25:35 +0000