Merge "Optimise the hit test algorithm" into pi-dev (32ea362e) · Commits · e / os / android_frameworks_base

core/java/android/text/Layout.java

+163 −6

Original line number	Diff line number	Diff line
		@@ -1004,6 +1004,32 @@ 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);
		@@ -1053,6 +1079,41 @@ public abstract class Layout {
		return levelBefore < levelAt;
		}

		/**
		* 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
		@@ -1132,6 +1193,60 @@ public abstract class Layout {
		return getLineStartPos(line, left, right) + wid;
		}

		/**
		* 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.
		@@ -1360,6 +1475,8 @@ 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) {
		@@ -1369,7 +1486,7 @@ 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];
		@@ -1385,7 +1502,7 @@ 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;
		@@ -1399,9 +1516,9 @@ 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;
		@@ -1416,7 +1533,7 @@ 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;
		@@ -1424,7 +1541,7 @@ public abstract class Layout {
		}
		}

		float dist = Math.abs(getHorizontal(max, primary) - horiz);
		float dist = Math.abs(horizontal.get(max) - horiz);

		if (dist <= bestdist) {
		best = max;
		@@ -1434,6 +1551,46 @@ public abstract class Layout {
		return best;
		}

		/**
		* 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.
		*/

core/java/android/text/TextLine.java

+92 −0

Original line number	Diff line number	Diff line
		@@ -387,6 +387,98 @@ public class TextLine {
		return h;
		}

		/**
		* @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.
		*