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Avoid drawing too long gesture preview trails

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Bug: 7167303
Change-Id: I63c2e8fb60f76e80346b67fd44399fa91930f2f0
This commit is contained in:
Tadashi G. Takaoka 2013-05-07 18:41:16 +09:00
parent 9d71a6c968
commit 80e396d83c
1 changed files with 17 additions and 6 deletions
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23
java/src/com/android/inputmethod/keyboard/internal/GestureStrokeWithPreviewPoints.java
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@ -34,14 +34,18 @@ public final class GestureStrokeWithPreviewPoints extends GestureStroke {
private int mLastY;
private double mMinPreviewSamplingDistance;
private double mDistanceFromLastSample;
private double mInterpolationDistanceThreshold;
// 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
// interpolation.
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.
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) {
super(pointerId, params);
@ -66,6 +70,7 @@ public final class GestureStrokeWithPreviewPoints extends GestureStroke {
public void setKeyboardGeometry(final int keyWidth, final int keyboardHeight) {
super.setKeyboardGeometry(keyWidth, keyboardHeight);
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) {
@ -138,14 +143,20 @@ public final class GestureStrokeWithPreviewPoints extends GestureStroke {
mInterpolator.setInterval(p0, p1, p2, p3);
final double m1 = Math.atan2(mInterpolator.mSlope1Y, mInterpolator.mSlope1X);
final double m2 = Math.atan2(mInterpolator.mSlope2Y, mInterpolator.mSlope2X);
final double dm = Math.abs(angularDiff(m2, m1));
final int partition = Math.min((int)Math.ceil(dm / INTERPOLATION_ANGULAR_THRESHOLD),
MAX_INTERPOLATION_PARTITION);
final double deltaAngle = Math.abs(angularDiff(m2, m1));
final int partitionsByAngle = (int)Math.ceil(
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 dt = pt[p2] - pt[p1];
d1++;
for (int i = 1; i < partition; i++) {
final float t = i / (float)partition;
for (int i = 1; i < partitions; i++) {
final float t = i / (float)partitions;
mInterpolator.interpolate(t);
eventTimes.add(d1, (int)(dt * t) + t1);
xCoords.add(d1, (int)mInterpolator.mInterpolatedX);