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Merge "Fix gesture trail width calculation"

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Tadashi G. Takaoka 2012-12-26 19:01:31 -08:00 committed by Android (Google) Code Review
parent 5112b59db2 92aee35222
commit 1dbec26f8f
1 changed files with 27 additions and 9 deletions
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36
java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
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@ -101,6 +101,16 @@ final class GesturePreviewTrail {
}
}
/**
* Calculate the alpha of a gesture trail.
* A gesture trail starts from fully opaque. After mFadeStartDelay has been passed, the alpha
* of a trail reduces in proportion to the elapsed time. Then after mFadeDuration has been
* passed, a trail becomes fully transparent.
*
* @param elapsedTime the elapsed time since a trail has been made.
* @param params gesture trail display parameters
* @return the width of a gesture trail
*/
private static int getAlpha(final int elapsedTime, final Params params) {
if (elapsedTime < params.mFadeoutStartDelay) {
return Constants.Color.ALPHA_OPAQUE;
@ -111,10 +121,19 @@ final class GesturePreviewTrail {
return Constants.Color.ALPHA_OPAQUE - decreasingAlpha;
}
/**
* Calculate the width of a gesture trail.
* A gesture trail starts from the width of mTrailStartWidth and reduces its width in proportion
* to the elapsed time. After mTrailEndWidth has been passed, the width becomes mTraiLEndWidth.
*
* @param elapsedTime the elapsed time since a trail has been made.
* @param params gesture trail display parameters
* @return the width of a gesture trail
*/
private static float getWidth(final int elapsedTime, final Params params) {
return Math.max((params.mTrailLingerDuration - elapsedTime)
* (params.mTrailStartWidth - params.mTrailEndWidth)
/ params.mTrailLingerDuration, 0.0f);
final int deltaTime = params.mTrailLingerDuration - elapsedTime;
final float deltaWidth = params.mTrailStartWidth - params.mTrailEndWidth;
return (deltaTime * deltaWidth) / params.mTrailLingerDuration + params.mTrailEndWidth;
}
private final RoundedLine mRoundedLine = new RoundedLine();
@ -154,7 +173,7 @@ final class GesturePreviewTrail {
final RoundedLine line = mRoundedLine;
int p1x = getXCoordValue(xCoords[startIndex]);
int p1y = yCoords[startIndex];
int lastTime = sinceDown - eventTimes[startIndex];
final int lastTime = sinceDown - eventTimes[startIndex];
float maxWidth = getWidth(lastTime, params);
float r1 = maxWidth / 2.0f;
// Initialize bounds rectangle.
@ -167,20 +186,19 @@ final class GesturePreviewTrail {
final float r2 = width / 2.0f;
// Draw trail line only when the current point isn't a down point.
if (!isDownEventXCoord(xCoords[i])) {
final int alpha = getAlpha(elapsedTime, params);
paint.setAlpha(alpha);
final Path path = line.makePath(p1x, p1y, r1, p2x, p2y, r2);
if (path != null) {
final int alpha = getAlpha(elapsedTime, params);
paint.setAlpha(alpha);
canvas.drawPath(path, paint);
// Take union for the bounds.
outBoundsRect.union(p2x, p2y);
maxWidth = Math.max(maxWidth, width);
}
// Take union for the bounds.
maxWidth = Math.max(maxWidth, width);
}
p1x = p2x;
p1y = p2y;
r1 = r2;
lastTime = elapsedTime;
}
// Take care of trail line width.
final int inset = -((int)maxWidth + 1);