仿微信页面切换图标颜色渐变效果

主要是提供一种思路，一般来书，类似效果无非就是在Canvas，Paint，Drawable等绘图类里搞来搞去。如果对绘图类比较熟悉的话，基本就没问题了，尤其游戏开发者。
我是记录一下，以后可以照抄了，具体见原帖：
http://blog.csdn.net/lmj623565791/article/details/41087219

import android.content.Context;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.graphics.Rect;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.os.Looper;import android.os.Parcelable;import android.util.AttributeSet;import android.util.Log;import android.util.TypedValue;import android.view.View;public class ChangeColorIconWithTextView extends View {private Bitmap mBitmap;private Canvas mCanvas;private Paint mPaint;/** * 选中的颜色 */private int mColor = 0xFFFF0000;/** * 透明度 0.0-1.0 */private float mAlpha = 0f;/** * 图标 */private Bitmap mIconBitmap;/** * 限制绘制icon的范围 */private Rect mIconRect;/** * icon底部文本 */private String mText = "微信";private int mTextSize = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 12,getResources().getDisplayMetrics());private Paint mTextPaint;private Rect mTextBound = new Rect();public ChangeColorIconWithTextView(Context context) {super(context);}/** * 初始化自定义属性值 *  * @param context * @param attrs */public ChangeColorIconWithTextView(Context context, AttributeSet attrs) {super(context, attrs);// 获取设置的图标TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ChangeColorIconView);int n = a.getIndexCount();for (int i = 0; i < n; i++) {int attr = a.getIndex(i);switch (attr) {case R.styleable.ChangeColorIconView_icon:BitmapDrawable drawable = (BitmapDrawable) a.getDrawable(attr);mIconBitmap = drawable.getBitmap();break;case R.styleable.ChangeColorIconView_color:mColor = a.getColor(attr, 0x45C01A);break;case R.styleable.ChangeColorIconView_text:mText = a.getString(attr);break;case R.styleable.ChangeColorIconView_text_size:mTextSize = (int) a.getDimension(attr,TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 10, getResources().getDisplayMetrics()));break;}}a.recycle();mTextPaint = new Paint();mTextPaint.setTextSize(mTextSize);mTextPaint.setColor(0xff555555);// 得到text绘制范围mTextPaint.getTextBounds(mText, 0, mText.length(), mTextBound);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);// 得到绘制icon的宽int bitmapWidth = Math.min(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),getMeasuredHeight() - getPaddingTop() - getPaddingBottom() - mTextBound.height());int left = getMeasuredWidth() / 2 - bitmapWidth / 2;int top = (getMeasuredHeight() - mTextBound.height()) / 2 - bitmapWidth / 2;// 设置icon的绘制范围mIconRect = new Rect(left, top, left + bitmapWidth, top + bitmapWidth);}@Overrideprotected void onDraw(Canvas canvas) {int alpha = (int) Math.ceil((255 * mAlpha));canvas.drawBitmap(mIconBitmap, null, mIconRect, null);setupTargetBitmap(alpha);drawSourceText(canvas, alpha);drawTargetText(canvas, alpha);canvas.drawBitmap(mBitmap, 0, 0, null);}private void setupTargetBitmap(int alpha) {mBitmap = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(), Config.ARGB_8888);mCanvas = new Canvas(mBitmap);mPaint = new Paint();mPaint.setColor(mColor);mPaint.setAntiAlias(true);mPaint.setDither(true);mPaint.setAlpha(alpha);mCanvas.drawRect(mIconRect, mPaint);mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));mPaint.setAlpha(255);mCanvas.drawBitmap(mIconBitmap, null, mIconRect, mPaint);}private void drawSourceText(Canvas canvas, int alpha) {mTextPaint.setTextSize(mTextSize);mTextPaint.setColor(0xff333333);mTextPaint.setAlpha(255 - alpha);canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2 - mTextBound.width() / 2,mIconRect.bottom + mTextBound.height(), mTextPaint);}private void drawTargetText(Canvas canvas, int alpha) {mTextPaint.setColor(mColor);mTextPaint.setAlpha(alpha);canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2 - mTextBound.width() / 2,mIconRect.bottom + mTextBound.height(), mTextPaint);}public void setIconAlpha(float alpha) {this.mAlpha = alpha;invalidateView();}private void invalidateView() {if (Looper.getMainLooper() == Looper.myLooper()) {invalidate();} else {postInvalidate();}}public void setIconColor(int color) {mColor = color;}public void setIcon(int resId) {this.mIconBitmap = BitmapFactory.decodeResource(getResources(), resId);if (mIconRect != null)invalidateView();}public void setIcon(Bitmap iconBitmap) {this.mIconBitmap = iconBitmap;if (mIconRect != null)invalidateView();}private static final String INSTANCE_STATE = "instance_state";private static final String STATE_ALPHA = "state_alpha";@Overrideprotected Parcelable onSaveInstanceState() {Bundle bundle = new Bundle();bundle.putParcelable(INSTANCE_STATE, super.onSaveInstanceState());bundle.putFloat(STATE_ALPHA, mAlpha);return bundle;}@Overrideprotected void onRestoreInstanceState(Parcelable state) {if (state instanceof Bundle) {Bundle bundle = (Bundle) state;mAlpha = bundle.getFloat(STATE_ALPHA);super.onRestoreInstanceState(bundle.getParcelable(INSTANCE_STATE));} else {super.onRestoreInstanceState(state);}}}

自定义属性：

<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="icon" format="reference" />    <attr name="color" format="color" />    <attr name="text" format="string" />    <attr name="text_size" format="dimension" />    <declare-styleable name="ChangeColorIconView">        <attr name="icon" />        <attr name="color" />        <attr name="text" />        <attr name="text_size" />    </declare-styleable></resources>

使用：

import java.lang.reflect.Field;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.List;import android.annotation.SuppressLint;import android.os.Bundle;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentActivity;import android.support.v4.app.FragmentPagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewConfiguration;import android.view.Window;@SuppressLint("NewApi")public class MainActivity extends FragmentActivity implementsOnPageChangeListener, OnClickListener{private ViewPager mViewPager;private List<Fragment> mTabs = new ArrayList<Fragment>();private FragmentPagerAdapter mAdapter;private String[] mTitles = new String[] { "First Fragment!","Second Fragment!", "Third Fragment!", "Fourth Fragment!" };private List<ChangeColorIconWithTextView> mTabIndicator = new ArrayList<ChangeColorIconWithTextView>();@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);setOverflowShowingAlways();getActionBar().setDisplayShowHomeEnabled(false);mViewPager = (ViewPager) findViewById(R.id.id_viewpager);initDatas();mViewPager.setAdapter(mAdapter);mViewPager.setOnPageChangeListener(this);}private void initDatas(){for (String title : mTitles){TabFragment tabFragment = new TabFragment();Bundle args = new Bundle();args.putString("title", title);tabFragment.setArguments(args);mTabs.add(tabFragment);}mAdapter = new FragmentPagerAdapter(getSupportFragmentManager()){@Overridepublic int getCount(){return mTabs.size();}@Overridepublic Fragment getItem(int arg0){return mTabs.get(arg0);}};initTabIndicator();}@Overridepublic boolean onCreateOptionsMenu(Menu menu){getMenuInflater().inflate(R.menu.main, menu);return true;}private void initTabIndicator(){ChangeColorIconWithTextView one = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_one);ChangeColorIconWithTextView two = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_two);ChangeColorIconWithTextView three = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_three);ChangeColorIconWithTextView four = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_four);mTabIndicator.add(one);mTabIndicator.add(two);mTabIndicator.add(three);mTabIndicator.add(four);one.setOnClickListener(this);two.setOnClickListener(this);three.setOnClickListener(this);four.setOnClickListener(this);one.setIconAlpha(1.0f);}@Overridepublic void onPageSelected(int arg0){}@Overridepublic void onPageScrolled(int position, float positionOffset,int positionOffsetPixels){// Log.e("TAG", "position = " + position + " , positionOffset = "// + positionOffset);if (positionOffset > 0){ChangeColorIconWithTextView left = mTabIndicator.get(position);ChangeColorIconWithTextView right = mTabIndicator.get(position + 1);left.setIconAlpha(1 - positionOffset);right.setIconAlpha(positionOffset);}}@Overridepublic void onPageScrollStateChanged(int state){}@Overridepublic void onClick(View v){resetOtherTabs();switch (v.getId()){case R.id.id_indicator_one:mTabIndicator.get(0).setIconAlpha(1.0f);mViewPager.setCurrentItem(0, false);break;case R.id.id_indicator_two:mTabIndicator.get(1).setIconAlpha(1.0f);mViewPager.setCurrentItem(1, false);break;case R.id.id_indicator_three:mTabIndicator.get(2).setIconAlpha(1.0f);mViewPager.setCurrentItem(2, false);break;case R.id.id_indicator_four:mTabIndicator.get(3).setIconAlpha(1.0f);mViewPager.setCurrentItem(3, false);break;}}/** * 重置其他的Tab */private void resetOtherTabs(){for (int i = 0; i < mTabIndicator.size(); i++){mTabIndicator.get(i).setIconAlpha(0);}}@Overridepublic boolean onMenuOpened(int featureId, Menu menu){if (featureId == Window.FEATURE_ACTION_BAR && menu != null){if (menu.getClass().getSimpleName().equals("MenuBuilder")){try{Method m = menu.getClass().getDeclaredMethod("setOptionalIconsVisible", Boolean.TYPE);m.setAccessible(true);m.invoke(menu, true);} catch (Exception e){}}}return super.onMenuOpened(featureId, menu);}private void setOverflowShowingAlways(){try{// true if a permanent menu key is present, false otherwise.ViewConfiguration config = ViewConfiguration.get(this);Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");menuKeyField.setAccessible(true);menuKeyField.setBoolean(config, false);} catch (Exception e){e.printStackTrace();}}}

布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:zhy="http://schemas.android.com/apk/res/com.zhy.weixin6.ui"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <android.support.v4.view.ViewPager        android:id="@+id/id_viewpager"        android:layout_width="fill_parent"        android:layout_height="0dp"        android:layout_weight="1" >    </android.support.v4.view.ViewPager>    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="60dp"        android:background="@drawable/tabbg"        android:orientation="horizontal" >        <com.zhy.weixin6.ui.ChangeColorIconWithTextView            android:id="@+id/id_indicator_one"            android:layout_width="0dp"            android:layout_height="fill_parent"            android:layout_weight="1"            android:padding="5dp"            zhy:icon="@drawable/ic_menu_start_conversation"            zhy:text="@string/tab_weixin"            zhy:text_size="12sp" />        <com.zhy.weixin6.ui.ChangeColorIconWithTextView            android:id="@+id/id_indicator_two"            android:layout_width="0dp"            android:layout_height="fill_parent"            android:layout_weight="1"            android:padding="5dp"            zhy:icon="@drawable/ic_menu_friendslist"            zhy:text="@string/tab_contact"            zhy:text_size="12sp" />        <com.zhy.weixin6.ui.ChangeColorIconWithTextView            android:id="@+id/id_indicator_three"            android:layout_width="0dp"            android:layout_height="fill_parent"            android:layout_weight="1"            android:padding="5dp"            zhy:icon="@drawable/ic_menu_emoticons"            zhy:text="@string/tab_find"            zhy:text_size="12sp" />        <com.zhy.weixin6.ui.ChangeColorIconWithTextView            android:id="@+id/id_indicator_four"            android:layout_width="0dp"            android:layout_height="fill_parent"            android:layout_weight="1"            android:padding="5dp"            zhy:icon="@drawable/ic_menu_allfriends"            zhy:text="@string/tab_me"            zhy:text_size="12sp" />    </LinearLayout></LinearLayout>

同样的效果：
http://www.open-open.com/lib/view/open1473666409185.html

一个优质的新闻客户端app
http://www.itlanbao.com/code/20151126/10000/100663.html