Auto scale-X text of key popup preview

Bug: 9978106
Change-Id: I335fa3117ac2af2cb8220c4827dd54c1a1da4c5c

java/src/com/android/inputmethod/keyboard/MainKeyboardView.java

@@ -46,6 +46,7 @@ import com.android.inputmethod.keyboard.internal.GestureTrailsDrawingPreview;
 import com.android.inputmethod.keyboard.internal.KeyDrawParams;
 import com.android.inputmethod.keyboard.internal.KeyPreviewChoreographer;
 import com.android.inputmethod.keyboard.internal.KeyPreviewDrawParams;
+import com.android.inputmethod.keyboard.internal.KeyPreviewView;
 import com.android.inputmethod.keyboard.internal.LanguageOnSpacebarHelper;
 import com.android.inputmethod.keyboard.internal.MoreKeySpec;
 import com.android.inputmethod.keyboard.internal.NonDistinctMultitouchHelper;
@@ -764,6 +765,9 @@ public final class MainKeyboardView extends KeyboardView implements PointerTrack
     public void startDisplayLanguageOnSpacebar(final boolean subtypeChanged,
             final int languageOnSpacebarFormatType,
             final boolean hasMultipleEnabledIMEsOrSubtypes) {
+        if (subtypeChanged) {
+            KeyPreviewView.clearTextCache();
+        }
         mLanguageOnSpacebarFormatType = languageOnSpacebarFormatType;
         mHasMultipleEnabledIMEsOrSubtypes = hasMultipleEnabledIMEsOrSubtypes;
         final ObjectAnimator animator = mLanguageOnSpacebarFadeoutAnimator;

java/src/com/android/inputmethod/keyboard/internal/KeyPreviewView.java

@@ -17,7 +17,10 @@
 package com.android.inputmethod.keyboard.internal;
 
 import android.content.Context;
+import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
+import android.text.TextPaint;
+import android.text.TextUtils;
 import android.util.AttributeSet;
 import android.util.TypedValue;
 import android.view.Gravity;
@@ -26,6 +29,8 @@ import android.widget.TextView;
 import com.android.inputmethod.keyboard.Key;
 import com.android.inputmethod.latin.R;
 
+import java.util.HashSet;
+
 /**
  * The pop up key preview view.
  */
@@ -34,6 +39,9 @@ public class KeyPreviewView extends TextView {
     public static final int POSITION_LEFT = 1;
     public static final int POSITION_RIGHT = 2;
 
+    private final Rect mBackgroundPadding = new Rect();
+    private static final HashSet<String> sNoScaleXTextSet = new HashSet<>();
+
     public KeyPreviewView(final Context context, final AttributeSet attrs) {
         this(context, attrs, 0);
     }
@@ -58,7 +66,48 @@ public class KeyPreviewView extends TextView {
         setTextSize(TypedValue.COMPLEX_UNIT_PX, key.selectPreviewTextSize(drawParams));
         setTypeface(key.selectPreviewTypeface(drawParams));
         // TODO Should take care of temporaryShiftLabel here.
-        setText(key.getPreviewLabel());
+        setTextAndScaleX(key.getPreviewLabel());
+    }
+
+    private void setTextAndScaleX(final String text) {
+        setTextScaleX(1.0f);
+        setText(text);
+        if (sNoScaleXTextSet.contains(text)) {
+            return;
+        }
+        // TODO: Override {@link #setBackground(Drawable)} that is supported from API 16 and
+        // calculate maximum text width.
+        final Drawable background = getBackground();
+        if (background == null) {
+            return;
+        }
+        background.getPadding(mBackgroundPadding);
+        final int maxWidth = background.getIntrinsicWidth() - mBackgroundPadding.left
+                - mBackgroundPadding.right;
+        final float width = getTextWidth(text, getPaint());
+        if (width <= maxWidth) {
+            sNoScaleXTextSet.add(text);
+            return;
+        }
+        setTextScaleX(maxWidth / width);
+    }
+
+    public static void clearTextCache() {
+        sNoScaleXTextSet.clear();
+    }
+
+    private static float getTextWidth(final String text, final TextPaint paint) {
+        if (TextUtils.isEmpty(text)) {
+            return 0.0f;
+        }
+        final int len = text.length();
+        final float[] widths = new float[len];
+        final int count = paint.getTextWidths(text, 0, len, widths);
+        float width = 0;
+        for (int i = 0; i < count; i++) {
+            width += widths[i];
+        }
+        return width;
     }
 
     // Background state set