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Diffstat (limited to 'core/java/android/text/TextLine.java')
| -rw-r--r-- | core/java/android/text/TextLine.java | 1053 |
1 files changed, 1053 insertions, 0 deletions
diff --git a/core/java/android/text/TextLine.java b/core/java/android/text/TextLine.java new file mode 100644 index 0000000..8ab481b --- /dev/null +++ b/core/java/android/text/TextLine.java @@ -0,0 +1,1053 @@ +/* + * Copyright (C) 2010 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package android.text; + +import com.android.internal.util.ArrayUtils; + +import android.graphics.Bitmap; +import android.graphics.Canvas; +import android.graphics.Paint; +import android.graphics.RectF; +import android.graphics.Paint.FontMetricsInt; +import android.icu.text.ArabicShaping; +import android.text.Layout.Directions; +import android.text.style.CharacterStyle; +import android.text.style.MetricAffectingSpan; +import android.text.style.ReplacementSpan; +import android.text.style.TabStopSpan; +import android.util.Log; + +/** + * Represents a line of styled text, for measuring in visual order and + * for rendering. + * + * <p>Get a new instance using obtain(), and when finished with it, return it + * to the pool using recycle(). + * + * <p>Call set to prepare the instance for use, then either draw, measure, + * metrics, or caretToLeftRightOf. + * + * @hide + */ +class TextLine { + private TextPaint mPaint; + private CharSequence mText; + private int mStart; + private int mLen; + private int mDir; + private Directions mDirections; + private boolean mHasTabs; + private TabStopSpan[] mTabs; + + private char[] mChars; + private boolean mCharsValid; + private Spanned mSpanned; + private TextPaint mWorkPaint = new TextPaint(); + private int mPreppedIndex; + private int mPreppedLimit; + + private static TextLine[] cached = new TextLine[3]; + + /** + * Returns a new TextLine from the shared pool. + * + * @return an uninitialized TextLine + */ + static TextLine obtain() { + TextLine tl; + synchronized (cached) { + for (int i = cached.length; --i >= 0;) { + if (cached[i] != null) { + tl = cached[i]; + cached[i] = null; + return tl; + } + } + } + tl = new TextLine(); + Log.e("TLINE", "new: " + tl); + return tl; + } + + /** + * Puts a TextLine back into the shared pool. Do not use this TextLine once + * it has been returned. + * @param tl the textLine + * @return null, as a convenience from clearing references to the provided + * TextLine + */ + static TextLine recycle(TextLine tl) { + tl.mText = null; + tl.mPaint = null; + tl.mDirections = null; + if (tl.mLen < 250) { + synchronized(cached) { + for (int i = 0; i < cached.length; ++i) { + if (cached[i] == null) { + cached[i] = tl; + break; + } + } + } + } + return null; + } + + /** + * Initializes a TextLine and prepares it for use. + * + * @param paint the base paint for the line + * @param text the text, can be Styled + * @param start the start of the line relative to the text + * @param limit the limit of the line relative to the text + * @param dir the paragraph direction of this line + * @param directions the directions information of this line + * @param hasTabs true if the line might contain tabs or emoji + * @param spans array of paragraph-level spans, of which only TabStopSpans + * are used. Can be null. + */ + void set(TextPaint paint, CharSequence text, int start, int limit, int dir, + Directions directions, boolean hasTabs, Object[] spans) { + mPaint = paint; + mText = text; + mStart = start; + mLen = limit - start; + mDir = dir; + mDirections = directions; + mHasTabs = hasTabs; + mSpanned = null; + mPreppedIndex = 0; + mPreppedLimit = 0; + + boolean hasReplacement = false; + if (text instanceof Spanned) { + mSpanned = (Spanned) text; + hasReplacement = mSpanned.getSpans(start, limit, + ReplacementSpan.class).length > 0; + } + + mCharsValid = hasReplacement || hasTabs || + directions != Layout.DIRS_ALL_LEFT_TO_RIGHT; + + if (mCharsValid) { + if (mChars == null || mChars.length < mLen) { + mChars = new char[ArrayUtils.idealCharArraySize(mLen)]; + } + TextUtils.getChars(text, start, limit, mChars, 0); + + if (hasTabs) { + TabStopSpan[] tabs = mTabs; + int tabLen = 0; + if (mSpanned != null && spans == null) { + TabStopSpan[] newTabs = mSpanned.getSpans(start, limit, + TabStopSpan.class); + if (tabs == null || tabs.length < newTabs.length) { + tabs = newTabs; + } else { + for (int i = 0; i < newTabs.length; ++i) { + tabs[i] = newTabs[i]; + } + } + tabLen = newTabs.length; + } else if (spans != null) { + if (tabs == null || tabs.length < spans.length) { + tabs = new TabStopSpan[spans.length]; + } + for (int i = 0; i < spans.length; ++i) { + if (spans[i] instanceof TabStopSpan) { + tabs[tabLen++] = (TabStopSpan) spans[i]; + } + } + } + + if (tabs != null && tabLen < tabs.length){ + tabs[tabLen] = null; + } + mTabs = tabs; + } + } + } + + /** + * Renders the TextLine. + * + * @param c the canvas to render on + * @param x the leading margin position + * @param top the top of the line + * @param y the baseline + * @param bottom the bottom of the line + */ + void draw(Canvas c, float x, int top, int y, int bottom) { + if (!mHasTabs) { + if (mDirections == Layout.DIRS_ALL_LEFT_TO_RIGHT) { + drawRun(c, 0, 0, mLen, false, x, top, y, bottom, false); + return; + } + if (mDirections == Layout.DIRS_ALL_RIGHT_TO_LEFT) { + drawRun(c, 0, 0, mLen, true, x, top, y, bottom, false); + return; + } + } + + float h = 0; + int[] runs = mDirections.mDirections; + RectF emojiRect = null; + + int lastRunIndex = runs.length - 2; + 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; + char[] chars = mChars; + for (int j = mHasTabs ? runStart : runLimit; j <= runLimit; j++) { + int codept = 0; + Bitmap bm = null; + + if (mHasTabs && j < runLimit) { + codept = mChars[j]; + if (codept >= 0xd800 && codept < 0xdc00 && j + 1 < runLimit) { + codept = Character.codePointAt(mChars, j); + if (codept >= Layout.MIN_EMOJI && codept <= Layout.MAX_EMOJI) { + bm = Layout.EMOJI_FACTORY.getBitmapFromAndroidPua(codept); + } else if (codept > 0xffff) { + ++j; + continue; + } + } + } + + if (j == runLimit || codept == '\t' || bm != null) { + h += drawRun(c, i, segstart, j, runIsRtl, x+h, top, y, bottom, + i != lastRunIndex || j != mLen); + + if (codept == '\t') { + h = mDir * nextTab(h * mDir); + } else if (bm != null) { + float bmAscent = ascent(j); + float bitmapHeight = bm.getHeight(); + float scale = -bmAscent / bitmapHeight; + float width = bm.getWidth() * scale; + + if (emojiRect == null) { + emojiRect = new RectF(); + } + emojiRect.set(x + h, y + bmAscent, + x + h + width, y); + c.drawBitmap(bm, null, emojiRect, mPaint); + h += width; + j++; + } + segstart = j + 1; + } + } + } + } + + /** + * Returns metrics information for the entire line. + * + * @param fmi receives font metrics information, can be null + * @return the signed width of the line + */ + float metrics(FontMetricsInt fmi) { + return measure(mLen, false, fmi); + } + + /** + * Returns information about a position on the line. + * + * @param offset the line-relative character offset, between 0 and the + * line length, inclusive + * @param trailing true to measure the trailing edge of the character + * before offset, false to measure the leading edge of the character + * at offset. + * @param fmi receives metrics information about the requested + * character, can be null. + * @return the signed offset from the leading margin to the requested + * character edge. + */ + float measure(int offset, boolean trailing, FontMetricsInt fmi) { + int target = trailing ? offset - 1 : offset; + if (target < 0) { + return 0; + } + + float h = 0; + + if (!mHasTabs) { + if (mDirections == Layout.DIRS_ALL_LEFT_TO_RIGHT) { + return measureRun( 0, 0, target, mLen, false, fmi); + } + if (mDirections == Layout.DIRS_ALL_RIGHT_TO_LEFT) { + return measureRun(0, 0, target, mLen, true, fmi); + } + } + + 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; + Bitmap bm = null; + + if (mHasTabs && j < runLimit) { + codept = chars[j]; + if (codept >= 0xd800 && codept < 0xdc00 && j + 1 < runLimit) { + codept = Character.codePointAt(chars, j); + if (codept >= Layout.MIN_EMOJI && codept <= Layout.MAX_EMOJI) { + bm = Layout.EMOJI_FACTORY.getBitmapFromAndroidPua(codept); + } else if (codept > 0xffff) { + ++j; + continue; + } + } + } + + if (j == runLimit || codept == '\t' || bm != null) { + boolean inSegment = target >= segstart && target < j; + + boolean advance = (mDir == Layout.DIR_RIGHT_TO_LEFT) == runIsRtl; + if (inSegment && advance) { + return h += measureRun(i, segstart, offset, j, runIsRtl, fmi); + } + + float w = measureRun(i, segstart, j, j, runIsRtl, fmi); + h += advance ? w : -w; + + if (inSegment) { + return h += measureRun(i, segstart, offset, j, runIsRtl, null); + } + + if (codept == '\t') { + if (offset == j) { + return h; + } + h = mDir * nextTab(h * mDir); + if (target == j) { + return h; + } + } + + if (bm != null) { + float bmAscent = ascent(j); + float wid = bm.getWidth() * -bmAscent / bm.getHeight(); + h += mDir * wid; + j++; + } + + segstart = j + 1; + } + } + } + + return h; + } + + /** + * Draws a unidirectional (but possibly multi-styled) run of text. + * + * @param c the canvas to draw on + * @param runIndex the index of this directional run + * @param start the line-relative start + * @param limit the line-relative limit + * @param runIsRtl true if the run is right-to-left + * @param x the position of the run that is closest to the leading margin + * @param top the top of the line + * @param y the baseline + * @param bottom the bottom of the line + * @param needWidth true if the width value is required. + * @return the signed width of the run, based on the paragraph direction. + * Only valid if needWidth is true. + */ + private float drawRun(Canvas c, int runIndex, int start, + int limit, boolean runIsRtl, float x, int top, int y, int bottom, + boolean needWidth) { + + if ((mDir == Layout.DIR_LEFT_TO_RIGHT) == runIsRtl) { + float w = -measureRun(runIndex, start, limit, limit, runIsRtl, null); + handleRun(runIndex, start, limit, limit, runIsRtl, c, x + w, top, + y, bottom, null, false, PREP_NONE); + return w; + } + + return handleRun(runIndex, start, limit, limit, runIsRtl, c, x, top, + y, bottom, null, needWidth, PREP_NEEDED); + } + + /** + * Measures a unidirectional (but possibly multi-styled) run of text. + * + * @param runIndex the run index + * @param start the line-relative start of the run + * @param offset the offset to measure to, between start and limit inclusive + * @param limit the line-relative limit of the run + * @param runIsRtl true if the run is right-to-left + * @param fmi receives metrics information about the requested + * run, can be null. + * @return the signed width from the start of the run to the leading edge + * of the character at offset, based on the run (not paragraph) direction + */ + private float measureRun(int runIndex, int start, + int offset, int limit, boolean runIsRtl, FontMetricsInt fmi) { + return handleRun(runIndex, start, offset, limit, runIsRtl, null, + 0, 0, 0, 0, fmi, true, PREP_NEEDED); + } + + /** + * Prepares a run for measurement or rendering. This ensures that any + * required shaping of the text in the run has been performed so that + * measurements reflect the shaped text. + * + * @param runIndex the run index + * @param start the line-relative start of the run + * @param limit the line-relative limit of the run + * @param runIsRtl true if the run is right-to-left + */ + private void prepRun(int runIndex, int start, int limit, + boolean runIsRtl) { + handleRun(runIndex, start, limit, limit, runIsRtl, null, 0, 0, 0, + 0, null, false, PREP_ONLY); + } + + /** + * Walk the cursor through this line, skipping conjuncts and + * zero-width characters. + * + * <p>This function cannot properly walk the cursor off the ends of the line + * since it does not know about any shaping on the previous/following line + * that might affect the cursor position. Callers must either avoid these + * situations or handle the result specially. + * + * <p>The paint is required because the region around the cursor might not + * have been formatted yet, and the valid positions can depend on the glyphs + * used to render the text, which in turn depends on the paint. + * + * @param paint the base paint of the line + * @param cursor the starting position of the cursor, between 0 and the + * length of the line, inclusive + * @param toLeft true if the caret is moving to the left. + * @return the new offset. If it is less than 0 or greater than the length + * of the line, the previous/following line should be examined to get the + * actual offset. + */ + int getOffsetToLeftRightOf(int cursor, boolean toLeft) { + // 1) The caret marks the leading edge of a character. The character + // logically before it might be on a different level, and the active caret + // position is on the character at the lower level. If that character + // was the previous character, the caret is on its trailing edge. + // 2) Take this character/edge and move it in the indicated direction. + // This gives you a new character and a new edge. + // 3) This position is between two visually adjacent characters. One of + // these might be at a lower level. The active position is on the + // character at the lower level. + // 4) If the active position is on the trailing edge of the character, + // the new caret position is the following logical character, else it + // is the character. + + int lineStart = 0; + int lineEnd = mLen; + boolean paraIsRtl = mDir == -1; + int[] runs = mDirections.mDirections; + + int runIndex, runLevel = 0, runStart = lineStart, runLimit = lineEnd, newCaret = -1; + boolean trailing = false; + + if (cursor == lineStart) { + runIndex = -2; + } else if (cursor == lineEnd) { + runIndex = runs.length; + } else { + // First, get information about the run containing the character with + // the active caret. + for (runIndex = 0; runIndex < runs.length; runIndex += 2) { + runStart = lineStart + runs[runIndex]; + if (cursor >= runStart) { + runLimit = runStart + (runs[runIndex+1] & Layout.RUN_LENGTH_MASK); + if (runLimit > lineEnd) { + runLimit = lineEnd; + } + if (cursor < runLimit) { + runLevel = (runs[runIndex+1] >>> Layout.RUN_LEVEL_SHIFT) & + Layout.RUN_LEVEL_MASK; + if (cursor == runStart) { + // The caret is on a run boundary, see if we should + // use the position on the trailing edge of the previous + // logical character instead. + int prevRunIndex, prevRunLevel, prevRunStart, prevRunLimit; + int pos = cursor - 1; + for (prevRunIndex = 0; prevRunIndex < runs.length; prevRunIndex += 2) { + prevRunStart = lineStart + runs[prevRunIndex]; + if (pos >= prevRunStart) { + prevRunLimit = prevRunStart + + (runs[prevRunIndex+1] & Layout.RUN_LENGTH_MASK); + if (prevRunLimit > lineEnd) { + prevRunLimit = lineEnd; + } + if (pos < prevRunLimit) { + prevRunLevel = (runs[prevRunIndex+1] >>> Layout.RUN_LEVEL_SHIFT) + & Layout.RUN_LEVEL_MASK; + if (prevRunLevel < runLevel) { + // Start from logically previous character. + runIndex = prevRunIndex; + runLevel = prevRunLevel; + runStart = prevRunStart; + runLimit = prevRunLimit; + trailing = true; + break; + } + } + } + } + } + break; + } + } + } + + // caret might be == lineEnd. This is generally a space or paragraph + // separator and has an associated run, but might be the end of + // text, in which case it doesn't. If that happens, we ran off the + // end of the run list, and runIndex == runs.length. In this case, + // we are at a run boundary so we skip the below test. + if (runIndex != runs.length) { + boolean runIsRtl = (runLevel & 0x1) != 0; + boolean advance = toLeft == runIsRtl; + if (cursor != (advance ? runLimit : runStart) || advance != trailing) { + // Moving within or into the run, so we can move logically. + prepRun(runIndex, runStart, runLimit, runIsRtl); + newCaret = getOffsetBeforeAfter(runIndex, cursor, advance); + // If the new position is internal to the run, we're at the strong + // position already so we're finished. + if (newCaret != (advance ? runLimit : runStart)) { + return newCaret; + } + } + } + } + + // If newCaret is -1, we're starting at a run boundary and crossing + // into another run. Otherwise we've arrived at a run boundary, and + // need to figure out which character to attach to. Note we might + // need to run this twice, if we cross a run boundary and end up at + // another run boundary. + while (true) { + boolean advance = toLeft == paraIsRtl; + int otherRunIndex = runIndex + (advance ? 2 : -2); + if (otherRunIndex >= 0 && otherRunIndex < runs.length) { + int otherRunStart = lineStart + runs[otherRunIndex]; + int otherRunLimit = otherRunStart + + (runs[otherRunIndex+1] & Layout.RUN_LENGTH_MASK); + if (otherRunLimit > lineEnd) { + otherRunLimit = lineEnd; + } + int otherRunLevel = (runs[otherRunIndex+1] >>> Layout.RUN_LEVEL_SHIFT) & + Layout.RUN_LEVEL_MASK; + boolean otherRunIsRtl = (otherRunLevel & 1) != 0; + + advance = toLeft == otherRunIsRtl; + if (newCaret == -1) { + prepRun(otherRunIndex, otherRunStart, otherRunLimit, + otherRunIsRtl); + newCaret = getOffsetBeforeAfter(otherRunIndex, + advance ? otherRunStart : otherRunLimit, advance); + if (newCaret == (advance ? otherRunLimit : otherRunStart)) { + // Crossed and ended up at a new boundary, + // repeat a second and final time. + runIndex = otherRunIndex; + runLevel = otherRunLevel; + continue; + } + break; + } + + // The new caret is at a boundary. + if (otherRunLevel < runLevel) { + // The strong character is in the other run. + newCaret = advance ? otherRunStart : otherRunLimit; + } + break; + } + + if (newCaret == -1) { + // We're walking off the end of the line. The paragraph + // level is always equal to or lower than any internal level, so + // the boundaries get the strong caret. + newCaret = getOffsetBeforeAfter(-1, cursor, advance); + break; + } + + // Else we've arrived at the end of the line. That's a strong position. + // We might have arrived here by crossing over a run with no internal + // breaks and dropping out of the above loop before advancing one final + // time, so reset the caret. + // Note, we use '<=' below to handle a situation where the only run + // on the line is a counter-directional run. If we're not advancing, + // we can end up at the 'lineEnd' position but the caret we want is at + // the lineStart. + if (newCaret <= lineEnd) { + newCaret = advance ? lineEnd : lineStart; + } + break; + } + + return newCaret; + } + + /** + * Returns the next valid offset within this directional run, skipping + * conjuncts and zero-width characters. This should not be called to walk + * off the end of the run. + * + * @param runIndex the run index + * @param offset the offset + * @param after true if the new offset should logically follow the provided + * offset + * @return the new offset + */ + private int getOffsetBeforeAfter(int runIndex, int offset, boolean after) { + // XXX note currently there is no special handling of zero-width + // combining marks, since the only analysis involves mock shaping. + + boolean offEnd = offset == (after ? mLen : 0); + if (runIndex >= 0 && !offEnd && mCharsValid) { + char[] chars = mChars; + if (after) { + int cp = Character.codePointAt(chars, offset, mLen); + if (cp >= 0x10000) { + ++offset; + } + while (++offset < mLen && chars[offset] == '\ufeff'){} + } else { + while (--offset >= 0 && chars[offset] == '\ufeff'){} + int cp = Character.codePointBefore(chars, offset + 1); + if (cp >= 0x10000) { + --offset; + } + } + return offset; + } + + if (after) { + return TextUtils.getOffsetAfter(mText, offset + mStart) - mStart; + } + return TextUtils.getOffsetBefore(mText, offset + mStart) - mStart; + } + + /** + * Utility function for measuring and rendering text. The text must + * not include a tab or emoji. + * + * @param wp the working paint + * @param start the start of the text + * @param limit the limit of the text + * @param runIsRtl true if the run is right-to-left + * @param c the canvas, can be null if rendering is not needed + * @param x the edge of the run closest to the leading margin + * @param top the top of the line + * @param y the baseline + * @param bottom the bottom of the line + * @param fmi receives metrics information, can be null + * @param needWidth true if the width of the run is needed + * @return the signed width of the run based on the run direction; only + * valid if needWidth is true + */ + private float handleText(TextPaint wp, int start, int limit, + boolean runIsRtl, Canvas c, float x, int top, int y, int bottom, + FontMetricsInt fmi, boolean needWidth) { + + float ret = 0; + + int runLen = limit - start; + if (needWidth || (c != null && (wp.bgColor != 0 || runIsRtl))) { + if (mCharsValid) { + ret = wp.measureText(mChars, start, runLen); + } else { + ret = wp.measureText(mText, mStart + start, + mStart + start + runLen); + } + } + + if (fmi != null) { + wp.getFontMetricsInt(fmi); + } + + if (c != null) { + if (runIsRtl) { + x -= ret; + } + + if (wp.bgColor != 0) { + int color = wp.getColor(); + Paint.Style s = wp.getStyle(); + wp.setColor(wp.bgColor); + wp.setStyle(Paint.Style.FILL); + + c.drawRect(x, top, x + ret, bottom, wp); + + wp.setStyle(s); + wp.setColor(color); + } + + drawTextRun(c, wp, start, limit, runIsRtl, x, y + wp.baselineShift); + } + + return runIsRtl ? -ret : ret; + } + + /** + * Utility function for measuring and rendering a replacement. + * + * @param replacement the replacement + * @param wp the work paint + * @param runIndex the run index + * @param start the start of the run + * @param limit the limit of the run + * @param runIsRtl true if the run is right-to-left + * @param c the canvas, can be null if not rendering + * @param x the edge of the replacement closest to the leading margin + * @param top the top of the line + * @param y the baseline + * @param bottom the bottom of the line + * @param fmi receives metrics information, can be null + * @param needWidth true if the width of the replacement is needed + * @param prepFlags one of PREP_NONE, PREP_REQUIRED, or PREP_ONLY + * @return the signed width of the run based on the run direction; only + * valid if needWidth is true + */ + private float handleReplacement(ReplacementSpan replacement, TextPaint wp, + int runIndex, int start, int limit, boolean runIsRtl, Canvas c, + float x, int top, int y, int bottom, FontMetricsInt fmi, + boolean needWidth, int prepFlags) { + + float ret = 0; + + // Preparation replaces the first character of the series with the + // object-replacement character and the remainder with zero width + // non-break space aka BOM. Cursor movement code skips over the BOMs + // so that the replacement character is the only character 'seen'. + if (prepFlags != PREP_NONE && limit > start && + (runIndex > mPreppedIndex || + (runIndex == mPreppedIndex && start >= mPreppedLimit))) { + char[] chars = mChars; + chars[start] = '\ufffc'; + for (int i = start + 1; i < limit; ++i) { + chars[i] = '\ufeff'; // used as ZWNBS, marks positions to skip + } + mPreppedIndex = runIndex; + mPreppedLimit = limit; + } + + if (prepFlags != PREP_ONLY) { + int textStart = mStart + start; + int textLimit = mStart + limit; + + if (needWidth || (c != null && runIsRtl)) { + ret = replacement.getSize(wp, mText, textStart, textLimit, fmi); + } + + if (c != null) { + if (runIsRtl) { + x -= ret; + } + replacement.draw(c, mText, textStart, textLimit, + x, top, y, bottom, wp); + } + } + + return runIsRtl ? -ret : ret; + } + + /** + * Utility function for handling a unidirectional run. The run must not + * contain tabs or emoji but can contain styles. + * + * @param p the base paint + * @param runIndex the run index + * @param start the line-relative start of the run + * @param offset the offset to measure to, between start and limit inclusive + * @param limit the limit of the run + * @param runIsRtl true if the run is right-to-left + * @param c the canvas, can be null + * @param x the end of the run closest to the leading margin + * @param top the top of the line + * @param y the baseline + * @param bottom the bottom of the line + * @param fmi receives metrics information, can be null + * @param needWidth true if the width is required + * @param prepFlags one of PREP_NONE, PREP_REQUIRED, or PREP_ONLY + * @return the signed width of the run based on the run direction; only + * valid if needWidth is true + */ + private float handleRun(int runIndex, int start, int offset, + int limit, boolean runIsRtl, Canvas c, float x, int top, int y, + int bottom, FontMetricsInt fmi, boolean needWidth, int prepFlags) { + + // Shaping needs to take into account context up to metric boundaries, + // but rendering needs to take into account character style boundaries. + // So we iterate through metric runs, shape using the initial + // paint (the same typeface is used up to the next metric boundary), + // then within each metric run iterate through character style runs. + float ox = x; + for (int i = start, inext; i < offset; i = inext) { + TextPaint wp = mWorkPaint; + wp.set(mPaint); + + int mnext; + if (mSpanned == null) { + inext = limit; + mnext = offset; + } else { + inext = mSpanned.nextSpanTransition(mStart + i, mStart + limit, + MetricAffectingSpan.class) - mStart; + + mnext = inext < offset ? inext : offset; + MetricAffectingSpan[] spans = mSpanned.getSpans(mStart + i, + mStart + mnext, MetricAffectingSpan.class); + + if (spans.length > 0) { + ReplacementSpan replacement = null; + for (int j = 0; j < spans.length; j++) { + MetricAffectingSpan span = spans[j]; + if (span instanceof ReplacementSpan) { + replacement = (ReplacementSpan)span; + } else { + span.updateDrawState(wp); // XXX or measureState? + } + } + + if (replacement != null) { + x += handleReplacement(replacement, wp, runIndex, i, + mnext, runIsRtl, c, x, top, y, bottom, fmi, + needWidth || mnext < offset, prepFlags); + continue; + } + } + } + + if (prepFlags != PREP_NONE) { + handlePrep(wp, runIndex, i, inext, runIsRtl); + } + + if (prepFlags != PREP_ONLY) { + if (mSpanned == null || c == null) { + x += handleText(wp, i, mnext, runIsRtl, c, x, top, + y, bottom, fmi, needWidth || mnext < offset); + } else { + for (int j = i, jnext; j < mnext; j = jnext) { + jnext = mSpanned.nextSpanTransition(mStart + j, + mStart + mnext, CharacterStyle.class) - mStart; + + CharacterStyle[] spans = mSpanned.getSpans(mStart + j, + mStart + jnext, CharacterStyle.class); + + wp.set(mPaint); + for (int k = 0; k < spans.length; k++) { + CharacterStyle span = spans[k]; + span.updateDrawState(wp); + } + + x += handleText(wp, j, jnext, runIsRtl, c, x, + top, y, bottom, fmi, needWidth || jnext < offset); + } + } + } + } + + return x - ox; + } + + private static final int PREP_NONE = 0; + private static final int PREP_NEEDED = 1; + private static final int PREP_ONLY = 2; + + /** + * Prepares text for measuring or rendering. + * + * @param paint the paint used to shape the text + * @param runIndex the run index + * @param start the start of the text to prepare + * @param limit the limit of the text to prepare + * @param runIsRtl true if the run is right-to-left + */ + private void handlePrep(TextPaint paint, int runIndex, int start, int limit, + boolean runIsRtl) { + + // The current implementation 'prepares' text by manipulating the + // character array. In order to keep track of what ranges have + // already been prepared, it uses the runIndex and the limit of + // the prepared text within that run. This index is required + // since operations that prepare the text always proceed in visual + // order and the limit itself does not let us know which runs have + // been processed and which have not. + // + // This bookkeeping is an attempt to let us process a line partially, + // for example, by only shaping up to the cursor position. This may + // not make sense if we can reuse the line, say by caching repeated + // accesses to the same line for both measuring and drawing, since in + // those cases we'd always prepare the entire line. At the + // opposite extreme, we might shape and then immediately discard only + // the run of text we're working with at the moment, instead of retaining + // the results of shaping (as the chars array is). In this case as well + // we would not need to do the index/limit bookkeeping. + // + // Technically, the only reason for bookkeeping is so that we don't + // re-mirror already-mirrored glyphs, since the shaping and object + // replacement operations will not change already-processed text. + + if (runIndex > mPreppedIndex || + (runIndex == mPreppedIndex && start >= mPreppedLimit)) { + if (runIsRtl) { + int runLen = limit - start; + AndroidCharacter.mirror(mChars, start, runLen); + ArabicShaping.SHAPER.shape(mChars, start, runLen); + + // Note: tweaked MockShaper to put '\ufeff' in place of + // alef when it forms lam-alef ligatures, so no extra + // processing is necessary here. + } + mPreppedIndex = runIndex; + mPreppedLimit = limit; + } + } + + /** + * Render a text run with the set-up paint. + * + * @param c the canvas + * @param wp the paint used to render the text + * @param start the run start + * @param limit the run limit + * @param runIsRtl true if the run is right-to-left + * @param x the x position of the left edge of the run + * @param y the baseline of the run + */ + private void drawTextRun(Canvas c, TextPaint wp, int start, int limit, + boolean runIsRtl, float x, int y) { + + // Since currently skia only renders text left-to-right, we need to + // put the shaped characters into visual order before rendering. + // Since we might want to re-render the line again, we swap them + // back when we're done. If we left them swapped, measurement + // would be broken since it expects the characters in logical order. + if (runIsRtl) { + swapRun(start, limit); + } + if (mCharsValid) { + c.drawText(mChars, start, limit - start, x, y, wp); + } else { + c.drawText(mText, mStart + start, mStart + limit, x, y, wp); + } + if (runIsRtl) { + swapRun(start, limit); + } + } + + /** + * Reverses the order of characters in the chars array between start and + * limit, used by drawTextRun. + * @param start the start of the run to reverse + * @param limit the limit of the run to reverse + */ + private void swapRun(int start, int limit) { + // First we swap all the characters one for one, then we + // do another pass looking for surrogate pairs and swapping them + // back into their logical order. + char[] chars = mChars; + for (int s = start, e = limit - 1; s < e; ++s, --e) { + char ch = chars[s]; chars[s] = chars[e]; chars[e] = ch; + } + + for (int s = start, e = limit - 1; s < e; ++s) { + char c1 = chars[s]; + if (c1 >= 0xdc00 && c1 < 0xe000) { + char c2 = chars[s+1]; + if (c2 >= 0xd800 && c2 < 0xdc00) { + chars[s++] = c2; + chars[s] = c1; + } + } + } + } + + /** + * Returns the ascent of the text at start. This is used for scaling + * emoji. + * + * @param pos the line-relative position + * @return the ascent of the text at start + */ + float ascent(int pos) { + if (mSpanned == null) { + return mPaint.ascent(); + } + + pos += mStart; + MetricAffectingSpan[] spans = mSpanned.getSpans(pos, pos + 1, + MetricAffectingSpan.class); + if (spans.length == 0) { + return mPaint.ascent(); + } + + TextPaint wp = mWorkPaint; + wp.set(mPaint); + for (MetricAffectingSpan span : spans) { + span.updateMeasureState(wp); + } + return wp.ascent(); + } + + /** + * Returns the next tab position. + * + * @param h the (unsigned) offset from the leading margin + * @return the (unsigned) tab position after this offset + */ + float nextTab(float h) { + float nh = Float.MAX_VALUE; + boolean alltabs = false; + + if (mHasTabs && mTabs != null) { + TabStopSpan[] tabs = mTabs; + for (int i = 0; i < tabs.length && tabs[i] != null; ++i) { + int where = tabs[i].getTabStop(); + if (where < nh && where > h) { + nh = where; + } + } + if (nh != Float.MAX_VALUE) { + return nh; + } + } + + return ((int) ((h + TAB_INCREMENT) / TAB_INCREMENT)) * TAB_INCREMENT; + } + + private static final int TAB_INCREMENT = 20; +} |