From 92aee35222d92f76b1dfe719bac10ca8bdc37ac1 Mon Sep 17 00:00:00 2001
From: "Tadashi G. Takaoka" <takaoka@google.com>
Date: Fri, 14 Dec 2012 15:13:19 +0900
Subject: [PATCH] Fix gesture trail width calculation
Change-Id: I41e0a95437aa9b8ec9a8eefb3bc5eb0452284b60
---
.../internal/GesturePreviewTrail.java | 36 ++++++++++++++-----
1 file changed, 27 insertions(+), 9 deletions(-)
diff --git a/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java b/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
index 3a57f673a6..f8949b2ad9 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/GesturePreviewTrail.java
@@ -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);
--
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