Merge "Avoid drawing too long gesture preview trails"

main
Tadashi G. Takaoka 2013-05-07 11:58:09 +00:00 committed by Android (Google) Code Review
commit 104bb70c65
1 changed files with 17 additions and 6 deletions

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@ -34,14 +34,18 @@ public final class GestureStrokeWithPreviewPoints extends GestureStroke {
private int mLastY; private int mLastY;
private double mMinPreviewSamplingDistance; private double mMinPreviewSamplingDistance;
private double mDistanceFromLastSample; private double mDistanceFromLastSample;
private double mInterpolationDistanceThreshold;
// TODO: Move these constants to resource. // TODO: Move these constants to resource.
// TODO: Use "dp" instead of ratio to the keyWidth because table has rather large keys.
// The minimum trail distance between sample points for preview in keyWidth unit when using // The minimum trail distance between sample points for preview in keyWidth unit when using
// interpolation. // interpolation.
private static final float MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH = 0.2f; private static final float MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH = 0.2f;
// The angular threshold to use interpolation in radian. PI/12 is 15 degree. // The angular threshold to use interpolation in radian. PI/12 is 15 degree.
private static final double INTERPOLATION_ANGULAR_THRESHOLD = Math.PI / 12.0d; private static final double INTERPOLATION_ANGULAR_THRESHOLD = Math.PI / 12.0d;
private static final int MAX_INTERPOLATION_PARTITION = 4; // The distance threshold to use interpolation in keyWidth unit.
private static final float INTERPOLATION_DISTANCE_THRESHOLD_TO_KEY_WIDTH = 0.5f;
private static final int MAX_INTERPOLATION_PARTITIONS = 6;
public GestureStrokeWithPreviewPoints(final int pointerId, final GestureStrokeParams params) { public GestureStrokeWithPreviewPoints(final int pointerId, final GestureStrokeParams params) {
super(pointerId, params); super(pointerId, params);
@ -66,6 +70,7 @@ public final class GestureStrokeWithPreviewPoints extends GestureStroke {
public void setKeyboardGeometry(final int keyWidth, final int keyboardHeight) { public void setKeyboardGeometry(final int keyWidth, final int keyboardHeight) {
super.setKeyboardGeometry(keyWidth, keyboardHeight); super.setKeyboardGeometry(keyWidth, keyboardHeight);
mMinPreviewSamplingDistance = keyWidth * MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH; mMinPreviewSamplingDistance = keyWidth * MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH;
mInterpolationDistanceThreshold = keyWidth * INTERPOLATION_DISTANCE_THRESHOLD_TO_KEY_WIDTH;
} }
private boolean needsSampling(final int x, final int y) { private boolean needsSampling(final int x, final int y) {
@ -138,14 +143,20 @@ public final class GestureStrokeWithPreviewPoints extends GestureStroke {
mInterpolator.setInterval(p0, p1, p2, p3); mInterpolator.setInterval(p0, p1, p2, p3);
final double m1 = Math.atan2(mInterpolator.mSlope1Y, mInterpolator.mSlope1X); final double m1 = Math.atan2(mInterpolator.mSlope1Y, mInterpolator.mSlope1X);
final double m2 = Math.atan2(mInterpolator.mSlope2Y, mInterpolator.mSlope2X); final double m2 = Math.atan2(mInterpolator.mSlope2Y, mInterpolator.mSlope2X);
final double dm = Math.abs(angularDiff(m2, m1)); final double deltaAngle = Math.abs(angularDiff(m2, m1));
final int partition = Math.min((int)Math.ceil(dm / INTERPOLATION_ANGULAR_THRESHOLD), final int partitionsByAngle = (int)Math.ceil(
MAX_INTERPOLATION_PARTITION); deltaAngle / INTERPOLATION_ANGULAR_THRESHOLD);
final double deltaDistance = Math.hypot(mInterpolator.mP1X - mInterpolator.mP2X,
mInterpolator.mP1Y - mInterpolator.mP2Y);
final int partitionsByDistance = (int)Math.ceil(deltaDistance
/ mInterpolationDistanceThreshold);
final int partitions = Math.min(MAX_INTERPOLATION_PARTITIONS,
Math.max(partitionsByAngle, partitionsByDistance));
final int t1 = eventTimes.get(d1); final int t1 = eventTimes.get(d1);
final int dt = pt[p2] - pt[p1]; final int dt = pt[p2] - pt[p1];
d1++; d1++;
for (int i = 1; i < partition; i++) { for (int i = 1; i < partitions; i++) {
final float t = i / (float)partition; final float t = i / (float)partitions;
mInterpolator.interpolate(t); mInterpolator.interpolate(t);
eventTimes.add(d1, (int)(dt * t) + t1); eventTimes.add(d1, (int)(dt * t) + t1);
xCoords.add(d1, (int)mInterpolator.mInterpolatedX); xCoords.add(d1, (int)mInterpolator.mInterpolatedX);