android自定义GifView显示gif动画

  gif动画在web开发中使用的非常的多,利用gif,许多动画不必再用程序编写,现在有非常多的App已经使用到了gif动画,可是android sdk并没有为我们提供gif这种View,所以我们只能自定义一个View,去实现gif效果.

   android虽然没有为我们提供现成的GifView,但是为我们提供了Movie类,这个类就是用来实现GifView的关键类.它主要有两个最重要的方法,一个是根据动画播放时间设置当前要现显示的帧,二是将当前要显示的帧绘制到画布中.下面看一下效果图:

点击暂停按钮还可以暂停gif动画.

   下面就看是如何实现的:

    1.首先将需要用到的属性先自定义好:如下代码所示:

 

<?xml version="1.0" encoding="utf-8"?><resources>    <declare-styleable name="gifCommon">        <attr name="gif_src" format="reference" />        <attr name="decode_stream" format="boolean" />        <attr name="default_animation_time" format="integer" />    </declare-styleable></resources>

   三个属性分别代表:gif资源,是否采用流编码,默认动画间隔时间.

   2.自定义GifView代码.

package view;import java.io.ByteArrayOutputStream;import java.io.InputStream;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Movie;import android.util.AttributeSet;import android.view.View;import com.example.drawbaledemo.R;/** * @author rzq * */public class GifView extends View {private Movie mMovie;        /**         * 动画开始时间         /        private long mMovieStart;private boolean mPaused = false;        /**         * 当前帧动画时间         /        private int mCurrentAnimationTime ;/**         * 自定义的三个属性         /        private boolean decode_STREAM;private int src_ID;private int default_time;public GifView(Context context) {super(context);init(context, null);}public GifView(Context context, AttributeSet set) {super(context, set);init(context, set);}private void init(Context context, AttributeSet set) {TypedArray a = context.obtainStyledAttributes(set,R.styleable.gifCommon);src_ID = a.getResourceId(R.styleable.gifCommon_gif_src, -1);decode_STREAM = a.getBoolean(R.styleable.gifCommon_decode_stream, true);default_time = a.getInteger(R.styleable.gifCommon_default_animation_time, 1000);a.recycle();setFocusable(true);java.io.InputStream is;is = context.getResources().openRawResource(src_ID);if (decode_STREAM) {mMovie = Movie.decodeStream(is);    // 根据文件流创建Movier绘制对象} else {byte[] array = streamToBytes(is);mMovie = Movie.decodeByteArray(array, 0, array.length);}}@Overrideprotected void onDraw(Canvas canvas) {if (mMovie != null) {if (!mPaused) {// 更新帧时间updateAnimationTime();drawMovieFrame(canvas);invalidate();} else {// 暂停时，不更新帧时间，则只画当前帧drawMovieFrame(canvas);}}}private void updateAnimationTime() {long now = android.os.SystemClock.uptimeMillis();// 如果第一帧，记录起始时间if (mMovieStart == 0) {mMovieStart = now;}// 取出动画的时长int dur = mMovie.duration();if (dur == 0) {dur = default_time;}// 算出需要显示第几帧mCurrentAnimationTime = (int) ((now - mMovieStart) % dur);}private void drawMovieFrame(Canvas canvas) {// 设置要显示的帧，绘制即可mMovie.setTime(mCurrentAnimationTime);canvas.save(Canvas.MATRIX_SAVE_FLAG);mMovie.draw(canvas, 0, 0);canvas.restore();}/** * 设置暂停 *  * @param paused */public void setPaused(boolean paused) {this.mPaused = paused;if (!paused) {/** * 更新动画起点时间 */mMovieStart = android.os.SystemClock.uptimeMillis()- mCurrentAnimationTime;}invalidate();}/** * 判断gif图是否停止了 *  * @return */public boolean isPaused() {return this.mPaused;}/** * 重写此方法，使自定义View支持wrap_content */@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {int widthMode = MeasureSpec.getMode(widthMeasureSpec);int widthSize = MeasureSpec.getSize(widthMeasureSpec);int heightMode = MeasureSpec.getMode(heightMeasureSpec);int heightSize = MeasureSpec.getSize(heightMeasureSpec);int width;int height;if (widthMode == MeasureSpec.EXACTLY) {width = widthSize;} else {int desired = (int) (getPaddingLeft() + mMovie.width() + getPaddingRight());width = Math.min(desired,widthSize);}if (heightMode == MeasureSpec.EXACTLY) {height = heightSize;} else {int desired = (int) (getPaddingTop() + mMovie.height() + getPaddingBottom());height = Math.min(desired,heightSize);}setMeasuredDimension(width, height);}/** * 将流转化为字节数组 *  * @param is * @return */private static byte[] streamToBytes(InputStream is) {ByteArrayOutputStream os = new ByteArrayOutputStream(1024);byte[] buffer = new byte[1024];int len;try {while ((len = is.read(buffer)) >= 0) {os.write(buffer, 0, len);}} catch (java.io.IOException e) {}return os.toByteArray();}}

  3.布局文件中使用GifView.

  

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:gif="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="#fed952"    android:gravity="center" >    <view.GifView        android:id="@+id/gif_view"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:background="#ffffff"        gif:decode_stream="true"        gif:default_animation_time="1000"        gif:gif_src="@drawable/animated_gif" />    <TextView        android:id="@+id/btn"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@+id/gif_view"        android:text="暂停" /></RelativeLayout>

与使用普通的View一样,将需要的资源传入即可.