From 0d69cb6ef7cfa1cf1c99575d61ba336782a45f66 Mon Sep 17 00:00:00 2001
From: Sunny Goyal <sunnygoyal@google.com>
Date: Mon, 4 Oct 2021 15:31:38 -0700
Subject: [PATCH] Adding support for dynamic letter spacing for icon labels

Bug: 201697936
Test: Manual
Change-Id: I0ab81291c40afcac30c5caf7b5638889908775f8
---
 src/com/android/launcher3/BubbleTextView.java | 74 +++++++++++++++++++
 .../launcher3/config/FeatureFlags.java        |  4 +
 2 files changed, 78 insertions(+)

diff --git a/src/com/android/launcher3/BubbleTextView.java b/src/com/android/launcher3/BubbleTextView.java
index 9da2b798b8..eec6e0ad2e 100644
--- a/src/com/android/launcher3/BubbleTextView.java
+++ b/src/com/android/launcher3/BubbleTextView.java
@@ -16,6 +16,7 @@
 
 package com.android.launcher3;
 
+import static com.android.launcher3.config.FeatureFlags.ENABLE_ICON_LABEL_AUTO_SCALING;
 import static com.android.launcher3.graphics.PreloadIconDrawable.newPendingIcon;
 import static com.android.launcher3.icons.GraphicsUtils.setColorAlphaBound;
 
@@ -33,6 +34,7 @@ import android.graphics.Rect;
 import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
 import android.icu.text.MessageFormat;
+import android.text.TextPaint;
 import android.text.TextUtils.TruncateAt;
 import android.util.AttributeSet;
 import android.util.Property;
@@ -88,6 +90,9 @@ public class BubbleTextView extends TextView implements ItemInfoUpdateReceiver,
     private static final int DISPLAY_SEARCH_RESULT = 6;
     private static final int DISPLAY_SEARCH_RESULT_SMALL = 7;
 
+    private static final float MIN_LETTER_SPACING = -0.5f;
+    private static final int MAX_SEARCH_LOOP_COUNT = 20;
+
     private static final int[] STATE_PRESSED = new int[]{android.R.attr.state_pressed};
     private static final float HIGHLIGHT_SCALE = 1.16f;
 
@@ -454,6 +459,75 @@ public class BubbleTextView extends TextView implements ItemInfoUpdateReceiver,
         return result;
     }
 
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        super.onSizeChanged(w, h, oldw, oldh);
+        checkForEllipsis();
+    }
+
+    @Override
+    protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
+        super.onTextChanged(text, start, lengthBefore, lengthAfter);
+        checkForEllipsis();
+    }
+
+    private void checkForEllipsis() {
+        if (!ENABLE_ICON_LABEL_AUTO_SCALING.get()) {
+            return;
+        }
+        float width = getWidth() - getCompoundPaddingLeft() - getCompoundPaddingRight();
+        if (width <= 0) {
+            return;
+        }
+        setLetterSpacing(0);
+
+        String text = getText().toString();
+        TextPaint paint = getPaint();
+        if (paint.measureText(text) < width) {
+            return;
+        }
+
+        float spacing = findBestSpacingValue(paint, text, width, MIN_LETTER_SPACING);
+        // Reset the paint value so that the call to TextView does appropriate diff.
+        paint.setLetterSpacing(0);
+        setLetterSpacing(spacing);
+    }
+
+    /**
+     * Find the appropriate text spacing to display the provided text
+     * @param paint the paint used by the text view
+     * @param text the text to display
+     * @param allowedWidthPx available space to render the text
+     * @param minSpacingEm minimum spacing allowed between characters
+     * @return the final textSpacing value
+     *
+     * @see #setLetterSpacing(float)
+     */
+    private float findBestSpacingValue(TextPaint paint, String text, float allowedWidthPx,
+            float minSpacingEm) {
+        paint.setLetterSpacing(minSpacingEm);
+        if (paint.measureText(text) > allowedWidthPx) {
+            // If there is no result at high limit, we can do anything more
+            return minSpacingEm;
+        }
+
+        float lowLimit = 0;
+        float highLimit = minSpacingEm;
+
+        for (int i = 0; i < MAX_SEARCH_LOOP_COUNT; i++) {
+            float value = (lowLimit + highLimit) / 2;
+            paint.setLetterSpacing(value);
+            if (paint.measureText(text) < allowedWidthPx) {
+                highLimit = value;
+            } else {
+                lowLimit = value;
+            }
+        }
+
+        // At the end error on the higher side
+        return highLimit;
+    }
+
     @SuppressWarnings("wrongcall")
     protected void drawWithoutDot(Canvas canvas) {
         super.onDraw(canvas);
diff --git a/src/com/android/launcher3/config/FeatureFlags.java b/src/com/android/launcher3/config/FeatureFlags.java
index 0acafc0b96..f41c19b8e7 100644
--- a/src/com/android/launcher3/config/FeatureFlags.java
+++ b/src/com/android/launcher3/config/FeatureFlags.java
@@ -269,6 +269,10 @@ public final class FeatureFlags {
             "ENABLE_BACK_SWIPE_HOME_ANIMATION", true,
             "Enables home animation to icon when user swipes back.");
 
+    public static final BooleanFlag ENABLE_ICON_LABEL_AUTO_SCALING = getDebugFlag(
+            "ENABLE_ICON_LABEL_AUTO_SCALING", true,
+            "Enables scaling/spacing for icon labels to make more characters visible");
+
     public static void initialize(Context context) {
         synchronized (sDebugFlags) {
             for (DebugFlag flag : sDebugFlags) {