diff --git a/java/src/com/android/inputmethod/keyboard/ProximityInfo.java b/java/src/com/android/inputmethod/keyboard/ProximityInfo.java index 57d3fede4..0e86b051d 100644 --- a/java/src/com/android/inputmethod/keyboard/ProximityInfo.java +++ b/java/src/com/android/inputmethod/keyboard/ProximityInfo.java @@ -240,28 +240,121 @@ public class ProximityInfo { private void computeNearestNeighbors() { final int defaultWidth = mMostCommonKeyWidth; - final Key[] keys = mKeys; - final int thresholdBase = (int) (defaultWidth * SEARCH_DISTANCE); - final int threshold = thresholdBase * thresholdBase; + final int keyCount = mKeys.length; + final int gridSize = mGridNeighbors.length; + final int threshold = (int) (defaultWidth * SEARCH_DISTANCE); + final int thresholdSquared = threshold * threshold; // Round-up so we don't have any pixels outside the grid - final Key[] neighborKeys = new Key[keys.length]; - final int gridWidth = mGridWidth * mCellWidth; - final int gridHeight = mGridHeight * mCellHeight; - for (int x = 0; x < gridWidth; x += mCellWidth) { - for (int y = 0; y < gridHeight; y += mCellHeight) { - final int centerX = x + mCellWidth / 2; - final int centerY = y + mCellHeight / 2; - int count = 0; - for (final Key key : keys) { - if (key.isSpacer()) continue; - if (key.squaredDistanceToEdge(centerX, centerY) < threshold) { - neighborKeys[count++] = key; + final int fullGridWidth = mGridWidth * mCellWidth; + final int fullGridHeight = mGridHeight * mCellHeight; + + // For large layouts, 'neighborsFlatBuffer' is about 80k of memory: gridSize is usually 512, + // keycount is about 40 and a pointer to a Key is 4 bytes. This contains, for each cell, + // enough space for as many keys as there are on the keyboard. Hence, every + // keycount'th element is the start of a new cell, and each of these virtual subarrays + // start empty with keycount spaces available. This fills up gradually in the loop below. + // Since in the practice each cell does not have a lot of neighbors, most of this space is + // actually just empty padding in this fixed-size buffer. + final Key[] neighborsFlatBuffer = new Key[gridSize * keyCount]; + final int[] neighborCountPerCell = new int[gridSize]; + final int halfCellWidth = mCellWidth / 2; + final int halfCellHeight = mCellHeight / 2; + for (final Key key : mKeys) { + if (key.isSpacer()) continue; + +/* HOW WE PRE-SELECT THE CELLS (iterate over only the relevant cells, instead of all of them) + + We want to compute the distance for keys that are in the cells that are close enough to the + key border, as this method is performance-critical. These keys are represented with 'star' + background on the diagram below. Let's consider the Y case first. + + We want to select the cells which center falls between the top of the key minus the threshold, + and the bottom of the key plus the threshold. + topPixelWithinThreshold is key.mY - threshold, and bottomPixelWithinThreshold is + key.mY + key.mHeight + threshold. + + Then we need to compute the center of the top row that we need to evaluate, as we'll iterate + from there. + +(0,0)----> x +| .-------------------------------------------. +| | | | | | | | | | | | | +| |---+---+---+---+---+---+---+---+---+---+---| .- top of top cell (aligned on the grid) +| | | | | | | | | | | | | | +| |-----------+---+---+---+---+---+---+---+---|---' v +| | | | |***|***|*_________________________ topPixelWithinThreshold | yDeltaToGrid +| |---+---+---+-----^-+-|-+---+---+---+---+---| ^ +| | | | |***|*|*|*|*|***|***| | | | ______________________________________ +v |---+---+--threshold--|-+---+---+---+---+---| | + | | | |***|*|*|*|*|***|***| | | | | Starting from key.mY, we substract +y |---+---+---+---+-v-+-|-+---+---+---+---+---| | thresholdBase and get the top pixel + | | | |***|**########------------------- key.mY | within the threshold. We align that on + |---+---+---+---+--#+---+-#-+---+---+---+---| | the grid by computing the delta to the + | | | |***|**#|***|*#*|***| | | | | grid, and get the top of the top cell. + |---+---+---+---+--#+---+-#-+---+---+---+---| | + | | | |***|**########*|***| | | | | Adding half the cell height to the top + |---+---+---+---+---+-|-+---+---+---+---+---| | of the top cell, we get the middle of + | | | |***|***|*|*|***|***| | | | | the top cell (yMiddleOfTopCell). + |---+---+---+---+---+-|-+---+---+---+---+---| | + | | | |***|***|*|*|***|***| | | | | + |---+---+---+---+---+-|________________________ yEnd | Since we only want to add the key to + | | | | | | | (bottomPixelWithinThreshold) | the proximity if it's close enough to + |---+---+---+---+---+---+---+---+---+---+---| | the center of the cell, we only need + | | | | | | | | | | | | | to compute for these cells where + '---'---'---'---'---'---'---'---'---'---'---' | topPixelWithinThreshold is above the + (positive x,y) | center of the cell. This is the case + | when yDeltaToGrid is less than half + [Zoomed in diagram] | the height of the cell. + +-------+-------+-------+-------+-------+ | + | | | | | | | On the zoomed in diagram, on the right + | | | | | | | the topPixelWithinThreshold (represented + | | | | | | top of | with an = sign) is below and we can skip + +-------+-------+-------+--v----+-------+ .. top cell | this cell, while on the left it's above + | | = topPixelWT | | yDeltaToGrid | and we need to compute for this cell. + |..yStart.|.....|.......|..|....|.......|... y middle | Thus, if yDeltaToGrid is more than half + | (left)| | | ^ = | | of top cell | the height of the cell, we start the + +-------+-|-----+-------+----|--+-------+ | iteration one cell below the top cell, + | | | | | | | | | else we start it on the top cell. This + |.......|.|.....|.......|....|..|.....yStart (right) | is stored in yStart. + + Since we only want to go up to bottomPixelWithinThreshold, and we only iterate on the center + of the keys, we can stop as soon as the y value exceeds bottomPixelThreshold, so we don't + have to align this on the center of the key. Hence, we don't need a separate value for + bottomPixelWithinThreshold and call this yEnd right away. +*/ + final int topPixelWithinThreshold = key.mY - threshold; + final int yDeltaToGrid = topPixelWithinThreshold % mCellHeight; + final int yMiddleOfTopCell = topPixelWithinThreshold - yDeltaToGrid + halfCellHeight; + final int yStart = Math.max(halfCellHeight, + yMiddleOfTopCell + (yDeltaToGrid <= halfCellHeight ? 0 : mCellHeight)); + final int yEnd = Math.min(fullGridHeight, key.mY + key.mHeight + threshold); + + final int leftPixelWithinThreshold = key.mX - threshold; + final int xDeltaToGrid = leftPixelWithinThreshold % mCellWidth; + final int xMiddleOfLeftCell = leftPixelWithinThreshold - xDeltaToGrid + halfCellWidth; + final int xStart = Math.max(halfCellWidth, + xMiddleOfLeftCell + (xDeltaToGrid <= halfCellWidth ? 0 : mCellWidth)); + final int xEnd = Math.min(fullGridWidth, key.mX + key.mWidth + threshold); + + int baseIndexOfCurrentRow = (yStart / mCellHeight) * mGridWidth + (xStart / mCellWidth); + for (int centerY = yStart; centerY <= yEnd; centerY += mCellHeight) { + int index = baseIndexOfCurrentRow; + for (int centerX = xStart; centerX <= xEnd; centerX += mCellWidth) { + if (key.squaredDistanceToEdge(centerX, centerY) < thresholdSquared) { + neighborsFlatBuffer[index * keyCount + neighborCountPerCell[index]] = key; + ++neighborCountPerCell[index]; } + ++index; } - mGridNeighbors[(y / mCellHeight) * mGridWidth + (x / mCellWidth)] = - Arrays.copyOfRange(neighborKeys, 0, count); + baseIndexOfCurrentRow += mGridWidth; } } + + for (int i = 0; i < gridSize; ++i) { + final int base = i * keyCount; + mGridNeighbors[i] = + Arrays.copyOfRange(neighborsFlatBuffer, base, base + neighborCountPerCell[i]); + } } public void fillArrayWithNearestKeyCodes(final int x, final int y, final int primaryKeyCode,