Android UI:看看Google官方自定义带旋转动画的ImageView-----RotateImageView怎么写(附 图片淡入淡出效果)

众所周知，想要让ImageView旋转的话，可以用setRotation()让其围绕中心点旋转，但这个旋转是不带动画的，也就是旋转屏幕时图片噌的一下就转过去了，看不到旋转的过程，此UI体验不大好，为此需要自定义带旋转动画的ImageView.虽然Google SDK里基本控件里没有，但在Camera的原生APP代码里却给出了带旋转动画的ImageView，即今天的主角：RotateImageView。

尽管民间已有链接1 链接2  链接3 提供思路实现带旋转动画的ImageView，都不如Google官方标配的啊。先上源码吧，为实现此目的，需要四个文件：

1、Rotatable.java

/* * Copyright (C) 2011 The Android Open Source Project * * 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. */package com.android.ui;public interface Rotatable {    // Set parameter 'animation' to true to have animation when rotation.    public void setOrientation(int orientation, boolean animation);}

他就是个接口，里面有setOrientation这个方法。Google这么写是因为有大量自定义UI都要继承这个接口。

2、TwoStateImageView.java

/* * Copyright (C) 2011 The Android Open Source Project * * 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. */package com.android.ui;import android.content.Context;import android.util.AttributeSet;import android.widget.ImageView;/** * A @{code ImageView} which change the opacity of the icon if disabled. */public class TwoStateImageView extends ImageView {    private static final int ENABLED_ALPHA = 255;    private static final int DISABLED_ALPHA = (int) (255 * 0.4);    private boolean mFilterEnabled = true;    public TwoStateImageView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public TwoStateImageView(Context context) {        this(context, null);    }    @SuppressWarnings("deprecation")    @Override    public void setEnabled(boolean enabled) {        super.setEnabled(enabled);        if (mFilterEnabled) {            if (enabled) {                setAlpha(ENABLED_ALPHA);            } else {                setAlpha(DISABLED_ALPHA);            }        }    }    public void enableFilter(boolean enabled) {        mFilterEnabled = enabled;    }}

在ImageView的基础上增加了mFilterEnabled这个属性，开关打开后，通过改变图片的Alpha实现两种状态，默认这个开关是开的，图片透明度为255，即不透明。

3、RotateImageView.java

/* * Copyright (C) 2009 The Android Open Source Project * * 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. */package com.android.ui;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Rect;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.graphics.drawable.TransitionDrawable;import android.media.ThumbnailUtils;import android.util.AttributeSet;import android.util.Log;import android.view.ViewGroup.LayoutParams;import android.view.animation.AnimationUtils;import android.widget.ImageView;/** * A @{code ImageView} which can rotate it's content. */public class RotateImageView extends TwoStateImageView implements Rotatable {    @SuppressWarnings("unused")    private static final String TAG = "RotateImageView";    private static final int ANIMATION_SPEED = 270; // 270 deg/sec    private int mCurrentDegree = 0; // [0, 359]    private int mStartDegree = 0;    private int mTargetDegree = 0;    private boolean mClockwise = false, mEnableAnimation = true;    private long mAnimationStartTime = 0;    private long mAnimationEndTime = 0;    public RotateImageView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public RotateImageView(Context context) {        super(context);    }    protected int getDegree() {        return mTargetDegree;    }    // Rotate the view counter-clockwise    @Override    public void setOrientation(int degree, boolean animation) {        mEnableAnimation = animation;        // make sure in the range of [0, 359]        degree = degree >= 0 ? degree % 360 : degree % 360 + 360;        if (degree == mTargetDegree) return;        mTargetDegree = degree;        if (mEnableAnimation) {            mStartDegree = mCurrentDegree;            mAnimationStartTime = AnimationUtils.currentAnimationTimeMillis();            int diff = mTargetDegree - mCurrentDegree;            diff = diff >= 0 ? diff : 360 + diff; // make it in range [0, 359]            // Make it in range [-179, 180]. That's the shorted distance between the            // two angles            diff = diff > 180 ? diff - 360 : diff;            mClockwise = diff >= 0;            mAnimationEndTime = mAnimationStartTime                    + Math.abs(diff) * 1000 / ANIMATION_SPEED;        } else {            mCurrentDegree = mTargetDegree;        }        invalidate();    }    @Override    protected void onDraw(Canvas canvas) {        Drawable drawable = getDrawable();        if (drawable == null) return;        Rect bounds = drawable.getBounds();        int w = bounds.right - bounds.left;        int h = bounds.bottom - bounds.top;        if (w == 0 || h == 0) return; // nothing to draw        if (mCurrentDegree != mTargetDegree) {            long time = AnimationUtils.currentAnimationTimeMillis();            if (time < mAnimationEndTime) {                int deltaTime = (int)(time - mAnimationStartTime);                int degree = mStartDegree + ANIMATION_SPEED                        * (mClockwise ? deltaTime : -deltaTime) / 1000;                degree = degree >= 0 ? degree % 360 : degree % 360 + 360;                mCurrentDegree = degree;                invalidate();            } else {                mCurrentDegree = mTargetDegree;            }        }        int left = getPaddingLeft();        int top = getPaddingTop();        int right = getPaddingRight();        int bottom = getPaddingBottom();        int width = getWidth() - left - right;        int height = getHeight() - top - bottom;        int saveCount = canvas.getSaveCount();        // Scale down the image first if required.        if ((getScaleType() == ImageView.ScaleType.FIT_CENTER) &&                ((width < w) || (height < h))) {            float ratio = Math.min((float) width / w, (float) height / h);            canvas.scale(ratio, ratio, width / 2.0f, height / 2.0f);        }        canvas.translate(left + width / 2, top + height / 2);        canvas.rotate(-mCurrentDegree);        canvas.translate(-w / 2, -h / 2);        drawable.draw(canvas);        canvas.restoreToCount(saveCount);    }    private Bitmap mThumb;    private Drawable[] mThumbs;    private TransitionDrawable mThumbTransition;    public void setBitmap(Bitmap bitmap) {        // Make sure uri and original are consistently both null or both        // non-null.        if (bitmap == null) {            mThumb = null;            mThumbs = null;            setImageDrawable(null);            setVisibility(GONE);            return;        }        LayoutParams param = getLayoutParams();        //下面四行代码被我注释掉了，换成了固定值400*400 by yanguoqi 2014-3-28//        final int miniThumbWidth = param.width//                - getPaddingLeft() - getPaddingRight();//        final int miniThumbHeight = param.height//                - getPaddingTop() - getPaddingBottom();        final int miniThumbWidth = 400;        final int miniThumbHeight = 400;                Log.i("yan", "param.width = " + param.width + " getPaddingLeft() = "        + getPaddingLeft() + " getPaddingRight()" + getPaddingRight());        Log.i("yan", "miniThumbWidth = " + miniThumbWidth);        mThumb = ThumbnailUtils.extractThumbnail(                bitmap, miniThumbWidth, miniThumbHeight);        Drawable drawable;        if (mThumbs == null || !mEnableAnimation) {            mThumbs = new Drawable[2];            mThumbs[1] = new BitmapDrawable(getContext().getResources(), mThumb);            setImageDrawable(mThumbs[1]);        } else {            mThumbs[0] = mThumbs[1];            mThumbs[1] = new BitmapDrawable(getContext().getResources(), mThumb);            mThumbTransition = new TransitionDrawable(mThumbs);            setImageDrawable(mThumbTransition);            mThumbTransition.startTransition(500);        }        setVisibility(VISIBLE);    }}

整体没啥可说的，在setBitmap处有四句代码运行不正确我给换成了固定值。这个setBitmap干啥呢?是为了实现在同一个ImageView切换图片时的淡入淡出效果，如果单纯是旋转则不需要这个函数。不过本文的测试代码还是对这一功能做了测试。其思想也很简单，用Drawable[] mThumbs来存两个缩略图，第一次set的时候缩略图存一张，第二次再set的时候再放数组里一张，然后将Drawable[]数组实例化到TransitionDrawable变量里，通过这个变量的startTransition()显示淡入淡出效果，里面的参数表示时间。如果设成1000毫秒即1秒则会非常明显。关于TransitionDrawable的更多用法和解释可以参见 这里

4、有了以上三个文件其实已经可以完成旋转ImageView了，在布局里定义成RotateImageView即可。但仍需要角度。下面这个函数是将连续的旋转角度0---360度变换成0°、90°、180°、270°四个值。我们旋转屏幕时，当成一定角度时才旋转图片，而不是稍微动一下就旋转，除非需求如此。

Util.java

package com.android.util;import android.app.Activity;import android.view.OrientationEventListener;import android.view.Surface;public class Util {public static final int ORIENTATION_HYSTERESIS = 5;public static int roundOrientation(int orientation, int orientationHistory) {boolean changeOrientation = false;if (orientationHistory == OrientationEventListener.ORIENTATION_UNKNOWN) {changeOrientation = true;} else {int dist = Math.abs(orientation - orientationHistory);dist = Math.min( dist, 360 - dist );changeOrientation = ( dist >= 45 + ORIENTATION_HYSTERESIS );}if (changeOrientation) {return ((orientation + 45) / 90 * 90) % 360;}return orientationHistory;}    public static int getDisplayRotation(Activity activity) {        int rotation = activity.getWindowManager().getDefaultDisplay()                .getRotation();        switch (rotation) {            case Surface.ROTATION_0: return 0;            case Surface.ROTATION_90: return 90;            case Surface.ROTATION_180: return 180;            case Surface.ROTATION_270: return 270;        }        return 0;    }}

下面就要解决如何获得屏幕旋转角度的问题。最初我也想着用onConfigurationChanged()但发现这就是扯淡，这个只能检测此时处在横屏还是竖屏。后面再交代其用法。最终是用OrientationEventListener监测的。

MainActivity.java代码如下：

package org.yanzi.testrotateimageview;import android.app.Activity;import android.content.Context;import android.content.res.Configuration;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.OrientationEventListener;import android.view.View;import android.widget.Button;import android.widget.ImageView;import com.android.ui.RotateImageView;import com.android.util.Util;public class MainActivity extends Activity {private static final String tag = "yan";RotateImageView rotateImg1;RotateImageView rotateImg2;ImageView commonImg;Button fadeBtn;MyOrientationEventListener mOrientationListener;Bitmap a;Bitmap b;boolean flag = true;int mOrientation = OrientationEventListener.ORIENTATION_UNKNOWN;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initUI();mOrientationListener = new MyOrientationEventListener(this);b = BitmapFactory.decodeResource(getResources(), R.drawable.kunqing2);a = BitmapFactory.decodeResource(getResources(), R.drawable.kunlong);fadeBtn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubif(flag){rotateImg1.setBitmap(b);flag = false;}else{rotateImg1.setBitmap(a);flag = true;}}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();mOrientationListener.enable();}@Overrideprotected void onPause() {// TODO Auto-generated method stubsuper.onPause();mOrientationListener.disable();}private void initUI(){rotateImg1 = (RotateImageView)findViewById(R.id.rotate_img_1);rotateImg1.setImageResource(R.drawable.nan_1);rotateImg2 = (RotateImageView)findViewById(R.id.rotate_img_2);rotateImg2.setImageResource(R.drawable.nan_2);commonImg = (ImageView)findViewById(R.id.common_img);fadeBtn = (Button)findViewById(R.id.btn_fade);}private class MyOrientationEventListener extends OrientationEventListener{public MyOrientationEventListener(Context context) {super(context);// TODO Auto-generated constructor stub}@Overridepublic void onOrientationChanged(int orientation) {// TODO Auto-generated method stubif(orientation == OrientationEventListener.ORIENTATION_UNKNOWN){return;}mOrientation = Util.roundOrientation(orientation, mOrientation);Log.i(tag, "MyOrientationEventListener mOrientation = " + mOrientation);rotateImg1.setOrientation(mOrientation, true);rotateImg2.setOrientation(mOrientation, true);commonImg.setRotation(-mOrientation);}}@Overridepublic void onConfigurationChanged(Configuration newConfig) {// TODO Auto-generated method stubsuper.onConfigurationChanged(newConfig);int degree = newConfig.orientation;Log.i("yan", "onConfigurationChanged = " + degree);}}

布局如下：activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <Button        android:id="@+id/btn_fade"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="淡入淡出\n效果测试" />    <com.android.ui.RotateImageView         android:id="@+id/rotate_img_1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentTop="true"        android:layout_centerHorizontal="true"/>    <com.android.ui.RotateImageView         android:id="@+id/rotate_img_2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginTop="20dip"        android:layout_below="@id/rotate_img_1"        android:layout_centerHorizontal="true"/>    <ImageView         android:id="@+id/common_img"         android:layout_width="wrap_content"        android:layout_height="wrap_content"          android:layout_below="@id/rotate_img_2"          android:layout_marginTop="20dip"        android:layout_centerHorizontal="true"        android:src="@drawable/nan_1"/></RelativeLayout>

运行效果: 下图是初始界面，三幅图，前两个是RotateImageView，第三个是一般的ImageView.可以看出当RoteteImageView设置不使用动画时，其旋转效果和ImageView的setRotation是一样的。第一幅图和第二图的差别，第一图南怀瑾先生的，四周不带透明区域，第二幅图我用ps做了四周的透明处理。

如果不使用文中的Util.roundOrientation()函数，即有个角度就让它转，如果它的四周没有透明区域的话将会看到下图:

（抱歉，截图不是一次截的，但效果是真实的，此图周四晚截得）

下面这幅图是用大中兴的geek牛逼的连续拍照拍下来的，记录了四周不带透明区域旋转时图片变形的场景:

第一副图片里的淡入淡出测试按钮大家自己按看效果，太晚了不传图了。

代码下载:http://download.csdn.net/detail/yanzi1225627/7115009

------------------本文系原创，转载注明作者:yanzi1225627