在上一篇，是使用代码通过构造方法传入要播放的gif动画的id进行获取的。本文进一步改造，让GifView和ImageView一样可以在布局文件中设置src属性，并在GifView中我们使用反射动态获取src的图片资源ID，然后对它进行播放。这样使用起来就灵活多了。代码如下：

GifView：

package com.home.gifview;import java.io.InputStream;
import java.lang.reflect.Field;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Movie;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.ImageView;public class GifView extends ImageView {private Movie movie;private long movieStart;private int imageWidth;private int imageHeight;public GifView(Context context) {super(context);}public GifView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public GifView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.GifView);int resourceId = getResourceId(a, context, attrs);if (resourceId != 0) {InputStream is = getResources().openRawResource(resourceId);movie = Movie.decodeStream(is);if (movie != null) {Bitmap bitmap = BitmapFactory.decodeStream(is);imageWidth = bitmap.getWidth();imageHeight = bitmap.getHeight();bitmap.recycle();}}}@Overrideprotected void onDraw(Canvas canvas) {if (movie == null) {// 普通图片则直接调用父类的onDraw()方法super.onDraw(canvas);} else {playGif(canvas);invalidate();}}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);if (movie != null) {// 如果是gif图片则定制GifView的大小setMeasuredDimension(imageWidth, imageHeight);}}/*** 播放gif动画* * @param canvas* @return*/private boolean playGif(Canvas canvas) {long now = SystemClock.uptimeMillis();if (movieStart == 0) {movieStart = now;}int duration = movie.duration();if (duration == 0) {duration = 1000;}int relTime = (int) ((now - movieStart) % duration);movie.setTime(relTime);movie.draw(canvas, 0, 0);if ((now - movieStart) >= duration) {movieStart = 0;return true;}return false;}/*** 使用反射，获取到src指定图片资源所对应的id。* * @param a* @param context* @param attrs* @return*/private int getResourceId(TypedArray a, Context context, AttributeSet attrs) {try {Field field = TypedArray.class.getDeclaredField("mValue");field.setAccessible(true);TypedValue typedValueObject = (TypedValue) field.get(a);return typedValueObject.resourceId;} catch (Exception e) {e.printStackTrace();} finally {if (a != null) {a.recycle();}}return 0;}
}

attrs.xml：

<?xml version="1.0" encoding="utf-8"?>
<resources><declare-styleable name="GifView"></declare-styleable></resources>

main.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent" ><com.home.gifview.GifViewandroid:id="@+id/main_gifView"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerInParent="true"android:src="@drawable/loading" /></RelativeLayout>

禁用硬件加速：

android:hardwareAccelerated="false"