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...)

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;
	@Override
	protected 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() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				if(flag){
					rotateImg1.setBitmap(b);
					flag = false;
				}
				else{
					rotateImg1.setBitmap(a);
					flag = true;
				}
			}
		});

	}

	@Override
	public 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;
	}

	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		mOrientationListener.enable();
	}

	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.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
		}

		@Override
		public void onOrientationChanged(int orientation) {
			// TODO Auto-generated method stub
			if(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);
		}

	}
	@Override
	public void onConfigurationChanged(Configuration newConfig) {
		// TODO Auto-generated method stub
		super.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