From 89d80d080fbb2c53d1a09102a2e4ffb71d7bb0fc Mon Sep 17 00:00:00 2001
From: conradchen <conradchen@google.com>
Date: Thu, 18 Nov 2021 22:33:58 +0000
Subject: [PATCH] [TopAppBar] Fix expanded title margin not applied

In the original logic we compares interpolated text size to decide if the available width should be the collapsed one or the expanded one. This logic wouldn't work if the collapsed text size and the expanded text size are the same. Refactors the logic to make the decision by interpolating fraction directly.

Resolves https://github.com/material-components/material-components-android/issues/2459

PiperOrigin-RevId: 410901171
---
 .../internal/CollapsingTextHelper.java        | 37 +++++++++----------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/lib/java/com/google/android/material/internal/CollapsingTextHelper.java b/lib/java/com/google/android/material/internal/CollapsingTextHelper.java
index 6f988aae3..da029511a 100644
--- a/lib/java/com/google/android/material/internal/CollapsingTextHelper.java
+++ b/lib/java/com/google/android/material/internal/CollapsingTextHelper.java
@@ -599,21 +599,20 @@ public final class CollapsingTextHelper {
         currentDrawX = expandedDrawX;
         currentDrawY = expandedDrawY;
 
-        setInterpolatedTextSize(expandedTextSize);
+        setInterpolatedTextSize(/* fraction= */ 0);
       } else {
         textBlendFraction = 1F;
         currentDrawX = collapsedDrawX;
         currentDrawY = collapsedDrawY - max(0, currentOffsetY);
 
-        setInterpolatedTextSize(collapsedTextSize);
+        setInterpolatedTextSize(/* fraction= */ 1);
       }
     } else {
       textBlendFraction = fraction;
       currentDrawX = lerp(expandedDrawX, collapsedDrawX, fraction, positionInterpolator);
       currentDrawY = lerp(expandedDrawY, collapsedDrawY, fraction, positionInterpolator);
 
-      setInterpolatedTextSize(
-          lerp(expandedTextSize, collapsedTextSize, fraction, textSizeInterpolator));
+      setInterpolatedTextSize(fraction);
     }
 
     setCollapsedTextBlend(
@@ -703,10 +702,8 @@ public final class CollapsingTextHelper {
   }
 
   private void calculateBaseOffsets(boolean forceRecalculate) {
-    final float currentTextSize = this.currentTextSize;
-
     // We then calculate the collapsed text size, using the same logic
-    calculateUsingTextSize(collapsedTextSize, forceRecalculate);
+    calculateUsingTextSize(/* fraction= */ 1, forceRecalculate);
     if (textToDraw != null && textLayout != null) {
       textToDrawCollapsed =
           TextUtils.ellipsize(textToDraw, textPaint, textLayout.getWidth(), TruncateAt.END);
@@ -748,7 +745,7 @@ public final class CollapsingTextHelper {
         break;
     }
 
-    calculateUsingTextSize(expandedTextSize, forceRecalculate);
+    calculateUsingTextSize(/* fraction= */ 0, forceRecalculate);
     float expandedTextHeight = textLayout != null ? textLayout.getHeight() : 0;
     float expandedTextWidth = 0;
     if (textLayout != null && maxLines > 1) {
@@ -792,7 +789,7 @@ public final class CollapsingTextHelper {
     // The bounds have changed so we need to clear the texture
     clearTexture();
     // Now reset the text size back to the original
-    setInterpolatedTextSize(currentTextSize);
+    setInterpolatedTextSize(expandedFraction);
   }
 
   private float measureTextWidth(TextPaint textPaint, CharSequence textToDraw) {
@@ -923,8 +920,8 @@ public final class CollapsingTextHelper {
         .isRtl(text, 0, text.length());
   }
 
-  private void setInterpolatedTextSize(float textSize) {
-    calculateUsingTextSize(textSize);
+  private void setInterpolatedTextSize(float fraction) {
+    calculateUsingTextSize(fraction);
 
     // Use our texture if the scale isn't 1.0
     useTexture = USE_SCALING_TEXTURE && scale != 1f;
@@ -937,12 +934,12 @@ public final class CollapsingTextHelper {
     ViewCompat.postInvalidateOnAnimation(view);
   }
 
-  private void calculateUsingTextSize(final float textSize) {
-    calculateUsingTextSize(textSize, /* forceRecalculate= */ false);
+  private void calculateUsingTextSize(final float fraction) {
+    calculateUsingTextSize(fraction, /* forceRecalculate= */ false);
   }
 
   @SuppressWarnings("ReferenceEquality") // Matches the Typeface comparison in TextView
-  private void calculateUsingTextSize(final float textSize, boolean forceRecalculate) {
+  private void calculateUsingTextSize(final float fraction, boolean forceRecalculate) {
     if (text == null) {
       return;
     }
@@ -955,7 +952,7 @@ public final class CollapsingTextHelper {
     float newLetterSpacing;
     boolean updateDrawText = false;
 
-    if (isClose(textSize, collapsedTextSize)) {
+    if (isClose(fraction, /* targetValue= */ 1)) {
       newTextSize = collapsedTextSize;
       newLetterSpacing = collapsedLetterSpacing;
       scale = 1f;
@@ -971,12 +968,14 @@ public final class CollapsingTextHelper {
         currentTypeface = expandedTypeface;
         updateDrawText = true;
       }
-      if (isClose(textSize, expandedTextSize)) {
+      if (isClose(fraction, /* targetValue= */ 0)) {
         // If we're close to the expanded text size, snap to it and use a scale of 1
         scale = 1f;
       } else {
         // Else, we'll scale down from the expanded text size
-        scale = textSize / expandedTextSize;
+        scale =
+            lerp(expandedTextSize, collapsedTextSize, fraction, textSizeInterpolator)
+                / expandedTextSize;
       }
 
       float textSizeRatio = collapsedTextSize / expandedTextSize;
@@ -1185,10 +1184,10 @@ public final class CollapsingTextHelper {
 
   /**
    * Returns true if {@code value} is 'close' to it's closest decimal value. Close is currently
-   * defined as it's difference being < 0.001.
+   * defined as it's difference being < 0.00001.
    */
   private static boolean isClose(float value, float targetValue) {
-    return Math.abs(value - targetValue) < 0.001f;
+    return Math.abs(value - targetValue) < 0.00001f;
   }
 
   public ColorStateList getExpandedTextColor() {