Use floating labels for preference forms

chrome/android/java/src/org/chromium/chrome/browser/widget/FloatLabelLayout.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/FloatLabelLayout.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/FloatLabelLayout.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/FloatLabelLayout.java
new file mode 100644
index 0000000000000000000000000000000000000000..522f0afb5b4afde5c6a90a240da98dc6f05c70eb
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/FloatLabelLayout.java
@@ -0,0 +1,275 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+
+package org.chromium.chrome.browser.widget;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.os.Build;
+import android.support.v4.view.ViewCompat;
+import android.support.v4.view.ViewPropertyAnimatorListenerAdapter;
+import android.text.Editable;
+import android.text.TextUtils;
+import android.text.TextWatcher;
+import android.util.AttributeSet;
+import android.util.TypedValue;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.animation.AnimationUtils;
+import android.view.animation.Interpolator;
+import android.widget.EditText;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+import org.chromium.chrome.R;
+
+/**
+ * Layout which uses a {@link android.widget.TextView} to show a floating label above an
+ * {@link android.widget.EditText} when the hint is hidden due to the user inputting text.
+ *
+ * @see <a href="https://dribbble.com/shots/1254439--GIF-Mobile-Form-Interaction">Matt D. Smith on Dribble</a>
+ * @see <a href="http://bradfrostweb.com/blog/post/float-label-pattern/">Brad Frost's blog post</a>
+ *
+ * This class was originally written by Chris Banes; it should be replaced if/when floating labels
+ * are available in the support library.
+ * @see https://gist.github.com/chrisbanes/11247418
+ *
+ * Example XML layout:
+ * <?xml version="1.0" encoding="utf-8"?>
+ *
+ * <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

[newt (away), 2015/01/28 20:20:19]

I'd remove the XML declaration and LinearLayout from this example. They don't
add anything and makes it harder to see the interesting bit.

[Theresa, 2015/01/29 05:22:13]

Done.

+ *     xmlns:app="http://schemas.android.com/apk/res-auto"
+ *     android:orientation="vertical"
+ *     android:layout_width="match_parent"
+ *     android:layout_height="match_parent">
+ *     <org.chromium.chrome.browser.widget.FloatLabelLayout
+ *          android:layout_width="match_parent"
+ *          android:layout_height="wrap_content"
+ *          app:floatLabelTextAppearance="@style/TextAppearance.YourApp.FloatLabel">
+ *          <EditText
+ *              android:id="@+id/edit_username"
+ *              android:layout_width="match_parent"
+ *              android:layout_height="wrap_content"
+ *              android:hint="@string/account_username_hint" />
+ *     </org.chromium.chrome.browser.widget.FloatLabelLayout>
+ * </LinearLayout>
+ */
+public class FloatLabelLayout extends LinearLayout {
+
+    private static final long ANIMATION_DURATION = 150;
+
+    private static final float DEFAULT_LABEL_PADDING_LEFT = 3f;
+    private static final float DEFAULT_LABEL_PADDING_TOP = 4f;
+    private static final float DEFAULT_LABEL_PADDING_RIGHT = 3f;
+    private static final float DEFAULT_LABEL_PADDING_BOTTOM = 4f;
+
+    private EditText mEditText;
+    private TextView mLabel;
+
+    private CharSequence mHint;
+    private Interpolator mInterpolator;
+
+    public FloatLabelLayout(Context context) {
+        this(context, null);
+    }
+
+    public FloatLabelLayout(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public FloatLabelLayout(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+
+        setOrientation(VERTICAL);
+
+        final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FloatLabelLayout);
+
+        int leftPadding = a.getDimensionPixelSize(
+                R.styleable.FloatLabelLayout_floatLabelPaddingLeft,
+                dipsToPix(DEFAULT_LABEL_PADDING_LEFT));
+        int topPadding = a.getDimensionPixelSize(
+                R.styleable.FloatLabelLayout_floatLabelPaddingTop,
+                dipsToPix(DEFAULT_LABEL_PADDING_TOP));
+        int rightPadding = a.getDimensionPixelSize(
+                R.styleable.FloatLabelLayout_floatLabelPaddingRight,
+                dipsToPix(DEFAULT_LABEL_PADDING_RIGHT));
+        int bottomPadding = a.getDimensionPixelSize(
+                R.styleable.FloatLabelLayout_floatLabelPaddingBottom,
+                dipsToPix(DEFAULT_LABEL_PADDING_BOTTOM));
+        mHint = a.getText(R.styleable.FloatLabelLayout_floatLabelHint);
+
+        mLabel = new TextView(context);
+        mLabel.setPadding(leftPadding, topPadding, rightPadding, bottomPadding);
+        mLabel.setVisibility(INVISIBLE);
+        mLabel.setText(mHint);
+        ViewCompat.setPivotX(mLabel, 0f);
+        ViewCompat.setPivotY(mLabel, 0f);
+
+        mLabel.setTextAppearance(context,
+                a.getResourceId(R.styleable.FloatLabelLayout_floatLabelTextAppearance,
+                        android.R.style.TextAppearance_Small));
+        a.recycle();
+
+        addView(mLabel, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
+
+        mInterpolator = AnimationUtils.loadInterpolator(context,
+                Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP
+                    ? android.R.interpolator.fast_out_slow_in
+                    : android.R.anim.decelerate_interpolator);
+    }
+
+    @Override
+    public final void addView(View child, int index, ViewGroup.LayoutParams params) {
+        if (child instanceof EditText) {
+            setEditText((EditText) child);
+        }
+
+        // Carry on adding the View...
+        super.addView(child, index, params);
+    }
+
+    private void setEditText(EditText editText) {
+        // If we already have an EditText, throw an exception
+        if (mEditText != null) {
+            throw new IllegalArgumentException("We already have an EditText, can only have one");
+        }
+        mEditText = editText;
+
+        // Update the label visibility with no animation
+        updateLabelVisibility(false);
+
+        // Add a TextWatcher so that we know when the text input has changed
+        mEditText.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void afterTextChanged(Editable s) {
+                updateLabelVisibility(true);
+            }
+
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {}
+        });
+
+        // Add focus listener to the EditText so that we can notify the label that it is activated.
+        // Allows the use of a ColorStateList for the text color on the label
+        mEditText.setOnFocusChangeListener(new OnFocusChangeListener() {
+            @Override
+            public void onFocusChange(View view, boolean focused) {
+                updateLabelVisibility(true);
+            }
+        });
+
+        // If we do not have a valid hint, try and retrieve it from the EditText
+        if (TextUtils.isEmpty(mHint)) {
+            setHint(mEditText.getHint());
+        }
+    }
+
+    private void updateLabelVisibility(boolean animate) {
+        boolean hasText = !TextUtils.isEmpty(mEditText.getText());
+        boolean isFocused = mEditText.isFocused();
+
+        mLabel.setActivated(isFocused);
+
+        if (hasText || isFocused) {
+            // We should be showing the label so do so if it isn't already
+            if (mLabel.getVisibility() != VISIBLE) {
+                showLabel(animate);
+            }
+        } else {
+            // We should not be showing the label so hide it
+            if (mLabel.getVisibility() == VISIBLE) {
+                hideLabel(animate);
+            }
+        }
+    }
+
+    /**
+     * @return the {@link android.widget.EditText} text input
+     */
+    public EditText getEditText() {
+        return mEditText;
+    }
+
+    /**
+     * @return the {@link android.widget.TextView} label
+     */
+    public TextView getLabel() {
+        return mLabel;
+    }
+
+    /**
+     * Set the hint to be displayed in the floating label
+     */
+    public void setHint(CharSequence hint) {
+        mHint = hint;
+        mLabel.setText(hint);
+    }
+
+    /**
+     * Show the label
+     */
+    private void showLabel(boolean animate) {
+        if (animate) {
+            mLabel.setVisibility(View.VISIBLE);
+            ViewCompat.setTranslationY(mLabel, mLabel.getHeight());
+
+            float scale = mEditText.getTextSize() / mLabel.getTextSize();
+            ViewCompat.setScaleX(mLabel, scale);
+            ViewCompat.setScaleY(mLabel, scale);
+
+            ViewCompat.animate(mLabel)
+                    .translationY(0f)
+                    .scaleY(1f)
+                    .scaleX(1f)
+                    .setDuration(ANIMATION_DURATION)
+                    .setListener(null)
+                    .setInterpolator(mInterpolator).start();
+        } else {
+            mLabel.setVisibility(VISIBLE);
+        }
+
+        mEditText.setHint(null);
+    }
+
+    /**
+     * Hide the label
+     */
+    private void hideLabel(boolean animate) {
+        if (animate) {
+            float scale = mEditText.getTextSize() / mLabel.getTextSize();
+            ViewCompat.setScaleX(mLabel, 1f);
+            ViewCompat.setScaleY(mLabel, 1f);
+            ViewCompat.setTranslationY(mLabel, 0f);
+
+            ViewCompat.animate(mLabel)
+                    .translationY(mLabel.getHeight())
+                    .setDuration(ANIMATION_DURATION)
+                    .scaleX(scale)
+                    .scaleY(scale)
+                    .setListener(new ViewPropertyAnimatorListenerAdapter() {
+                        @Override
+                        public void onAnimationEnd(View view) {
+                            mLabel.setVisibility(INVISIBLE);
+                            mEditText.setHint(mHint);
+                        }
+                    })
+                    .setInterpolator(mInterpolator).start();
+        } else {
+            mLabel.setVisibility(INVISIBLE);
+            mEditText.setHint(mHint);
+        }
+    }
+
+    /**
+     * Helper method to convert dips to pixels.
+     */
+    private int dipsToPix(float dps) {
+        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dps,
+                getResources().getDisplayMetrics());
+    }
+}