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FloatLabel介绍——Android EditText的一种交互实现

2014-05-26 15:10 本站整理 浏览(55)
这里介绍一种EditText的交互实现,这里是最初的设计->https://dribbble.com/shots/1254439--GIF-Mobile-Form-Interaction,这里是之后在Android上的实现->https://gist.github.com/chrisbanes/11247418#file-attrs-xml,看了下作者的其他项目,就是Andorid—PullDownToRefresh的作者。
原理很简单,对EditText包裹了一个容器FrameLayout,并在layout里自动添加一个对应的TextView,当EditText有输入的时候对TextView做动画显示出来。下面是具体的使用过程:
1、布局文件
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:app="http://schemas.android.com/apk/res-auto"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
 
    <com.example.floatlabeldemo.FloatLabelLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            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"
            android:singleLine="true"
            android:inputType="textNoSuggestions"
            android:imeOptions="actionNext"
            android:nextFocusDown="@+id/edit_password" />
 
    </com.example.floatlabeldemo.FloatLabelLayout>
 
    <com.example.floatlabeldemo.FloatLabelLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            app:floatLabelTextAppearance="@style/TextAppearance.YourApp.FloatLabel">
 
        <EditText
            android:id="@+id/edit_password"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="@string/account_password_hint"
            android:singleLine="true"
            android:inputType="textNoSuggestions"
            android:imeOptions="actionDone" />
 
    </com.example.floatlabeldemo.FloatLabelLayout>
 
</LinearLayout>

tips:每个FloatLabelLayout里只能添加一个EditText
下面是FloatLabelLayout里的自定义参数 attrs.xml
<resources>
 
    <declare-styleable name="FloatLabelLayout">
        <attr name="floatLabelTextAppearance" format="reference" />
        <attr name="floatLabelSidePadding" format="reference|dimension" />
    </declare-styleable>
 
</resources>

其中的floatLabelTextAppearance是对TextView显示的一些设置,如下styles.xml
<style name="TextAppearance.YourApp.FloatLabel" parent="android:TextAppearance.Small">
        <item name="android:textColor">@color/float_label</item>
        <item name="android:textSize">11sp</item>
        <item name="android:textStyle">bold</item>
    </style>

有上面这些就可以demo显示了,效果如下

下面是FloatLabelLayout的具体实现
/*
 * Copyright (C) 2014 Chris Banes
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0  *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.content.Context;
import android.content.res.TypedArray;
import android.text.Editable;
import android.text.TextUtils;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.TextView;
 
/**
 * Layout which an {@link android.widget.EditText} to show a floating label 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>
 */
public final class FloatLabelLayout extends FrameLayout {
 
    private static final long ANIMATION_DURATION = 150;
 
    private static final float DEFAULT_PADDING_LEFT_RIGHT_DP = 12f;
 
    private EditText mEditText;
    private TextView mLabel;
 
    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);
 
        final TypedArray a = context
                .obtainStyledAttributes(attrs, R.styleable.FloatLabelLayout);
 
        final int sidePadding = a.getDimensionPixelSize(
                R.styleable.FloatLabelLayout_floatLabelSidePadding,
                dipsToPix(DEFAULT_PADDING_LEFT_RIGHT_DP));
        mLabel = new TextView(context);
        mLabel.setPadding(sidePadding, 0, sidePadding, 0);
        mLabel.setVisibility(INVISIBLE);
 
        mLabel.setTextAppearance(context,
                a.getResourceId(R.styleable.FloatLabelLayout_floatLabelTextAppearance,
                        android.R.style.TextAppearance_Small));
 
        addView(mLabel, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
 
        a.recycle();
    }
 
    @Override
    public final void addView(View child, int index, ViewGroup.LayoutParams params) {
        if (child instanceof 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");
            }
 
            // Update the layout params so that the EditText is at the bottom, with enough top
            // margin to show the label
            final LayoutParams lp = new LayoutParams(params);
            lp.gravity = Gravity.BOTTOM;
            lp.topMargin = (int) mLabel.getTextSize();
            params = lp;
 
            setEditText((EditText) child);
        }
 
        // Carry on adding the View...
        super.addView(child, index, params);
    }
 
    private void setEditText(EditText editText) {
        mEditText = editText;
 
        // Add a TextWatcher so that we know when the text input has changed
        mEditText.addTextChangedListener(new TextWatcher() {
 
            @Override
            public void afterTextChanged(Editable s) {
                if (TextUtils.isEmpty(s)) {
                    // The text is empty, so hide the label if it is visible
                    if (mLabel.getVisibility() == View.VISIBLE) {
                        hideLabel();
                    }
                } else {
                    // The text is not empty, so show the label if it is not visible
                    if (mLabel.getVisibility() != View.VISIBLE) {
                        showLabel();
                    }
                }
            }
 
            @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) {
                mLabel.setActivated(focused);
            }
        });
 
        mLabel.setText(mEditText.getHint());
    }
 
    /**
     * @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;
    }
 
    /**
     * Show the label using an animation
     */
    private void showLabel() {
        mLabel.setVisibility(View.VISIBLE);
        mLabel.setAlpha(0f);
        mLabel.setTranslationY(mLabel.getHeight());
        mLabel.animate()
                .alpha(1f)
                .translationY(0f)
                .setDuration(ANIMATION_DURATION)
                .setListener(null).start();
    }
 
    /**
     * Hide the label using an animation
     */
    private void hideLabel() {
        mLabel.setAlpha(1f);
        mLabel.setTranslationY(0f);
        mLabel.animate()
                .alpha(0f)
                .translationY(mLabel.getHeight())
                .setDuration(ANIMATION_DURATION)
                .setListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        mLabel.setVisibility(View.GONE);
                    }
                }).start();
    }
 
    /**
     * Helper method to convert dips to pixels.
     */
    private int dipsToPix(float dps) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dps,
                getResources().getDisplayMetrics());
    }
}

在初始化的时候就会添加一个TextView,然后对EditText的输入进行监听,做相应的动画交互。因为使用了版本的api,所以在level11以前使用需要将动画效果用View Animation来实现。