android加载GIF动画

gif图动画在Android中还是比较常用的，比如像新浪微博中，有很多gif图片，而且展示非常好，所以我也想弄一个。经过我多方的搜索资料和整理，终于弄出来了，其实github上有很多开源的gif的展示代码，我下载过几个，但是都不是很理想，不是我完全想要的。所以有时候就得自己学会总结，把开源的东西整理成自己的，现在无聊，也正好有朋友需要，所以现在整理了一下，留着以后备用！

废话不多说，直接上图：





在这里主要用的是：android中的android.graphics.Movie 这个类，这是android提供给我们的一个非常方便的工具。

首先，重写控件View,自定义一个展示gif图的GifView，代码如下：

[java] view
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package net.loonggg.gif.view;

import net.loonggg.gif.R;

import android.annotation.SuppressLint;

import android.content.Context;

import android.content.res.TypedArray;

import android.graphics.Canvas;

import android.graphics.Movie;

import android.os.Build;

import android.util.AttributeSet;

import android.view.View;

public class GifView extends View {

/**

* 默认为1秒

*/

private static final int DEFAULT_MOVIE_DURATION = 1000;

private int mMovieResourceId;

private Movie mMovie;

private long mMovieStart;

private int mCurrentAnimationTime = 0;

private float mLeft;

private float mTop;

private float mScale;

private int mMeasuredMovieWidth;

private int mMeasuredMovieHeight;

private boolean mVisible = true;

private volatile boolean mPaused = false;

public GifView(Context context) {

this(context, null);

}

public GifView(Context context, AttributeSet attrs) {

this(context, attrs, R.styleable.CustomTheme_gifViewStyle);

}

public GifView(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

setViewAttributes(context, attrs, defStyle);

}

@SuppressLint("NewApi")

private void setViewAttributes(Context context, AttributeSet attrs,

int defStyle) {

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {

setLayerType(View.LAYER_TYPE_SOFTWARE, null);

}

// 从描述文件中读出gif的值，创建出Movie实例

final TypedArray array = context.obtainStyledAttributes(attrs,

R.styleable.GifView, defStyle, R.style.Widget_GifView);

mMovieResourceId = array.getResourceId(R.styleable.GifView_gif, -1);

mPaused = array.getBoolean(R.styleable.GifView_paused, false);

array.recycle();

if (mMovieResourceId != -1) {

mMovie = Movie.decodeStream(getResources().openRawResource(

mMovieResourceId));

}

}

/**

* 设置gif图资源

*

* @param movieResId

*/

public void setMovieResource(int movieResId) {

this.mMovieResourceId = movieResId;

mMovie = Movie.decodeStream(getResources().openRawResource(

mMovieResourceId));

requestLayout();

}

public void setMovie(Movie movie) {

this.mMovie = movie;

requestLayout();

}

public Movie getMovie() {

return mMovie;

}

public void setMovieTime(int time) {

mCurrentAnimationTime = time;

invalidate();

}

/**

* 设置暂停

*

* @param paused

*/

public void setPaused(boolean paused) {

this.mPaused = paused;

if (!paused) {

mMovieStart = android.os.SystemClock.uptimeMillis()

- mCurrentAnimationTime;

}

invalidate();

}

/**

* 判断gif图是否停止了

*

* @return

*/

public boolean isPaused() {

return this.mPaused;

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

if (mMovie != null) {

int movieWidth = mMovie.width();

int movieHeight = mMovie.height();

int maximumWidth = MeasureSpec.getSize(widthMeasureSpec);

float scaleW = (float) movieWidth / (float) maximumWidth;

mScale = 1f / scaleW;

mMeasuredMovieWidth = maximumWidth;

mMeasuredMovieHeight = (int) (movieHeight * mScale);

setMeasuredDimension(mMeasuredMovieWidth, mMeasuredMovieHeight);

} else {

setMeasuredDimension(getSuggestedMinimumWidth(),

getSuggestedMinimumHeight());

}

}

@Override

protected void onLayout(boolean changed, int l, int t, int r, int b) {

super.onLayout(changed, l, t, r, b);

mLeft = (getWidth() - mMeasuredMovieWidth) / 2f;

mTop = (getHeight() - mMeasuredMovieHeight) / 2f;

mVisible = getVisibility() == View.VISIBLE;

}

@Override

protected void onDraw(Canvas canvas) {

if (mMovie != null) {

if (!mPaused) {

updateAnimationTime();

drawMovieFrame(canvas);

invalidateView();

} else {

drawMovieFrame(canvas);

}

}

}

@SuppressLint("NewApi")

private void invalidateView() {

if (mVisible) {

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {

postInvalidateOnAnimation();

} else {

invalidate();

}

}

}

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_MOVIE_DURATION;

}

// 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);

canvas.scale(mScale, mScale);

mMovie.draw(canvas, mLeft / mScale, mTop / mScale);

canvas.restore();

}

@SuppressLint("NewApi")

@Override

public void onScreenStateChanged(int screenState) {

super.onScreenStateChanged(screenState);

mVisible = screenState == SCREEN_STATE_ON;

invalidateView();

}

@SuppressLint("NewApi")

@Override

protected void onVisibilityChanged(View changedView, int visibility) {

super.onVisibilityChanged(changedView, visibility);

mVisible = visibility == View.VISIBLE;

invalidateView();

}

@Override

protected void onWindowVisibilityChanged(int visibility) {

super.onWindowVisibilityChanged(visibility);

mVisible = visibility == View.VISIBLE;

invalidateView();

}

}

Movie其实管理着GIF动画中的多个帧，只需要通过 setTime() 一下就可以让它在draw()的时候绘出相应的那帧图像。通过当前时间与duration之间的换算关系，是很容易实现GIF动起来的效果。

其次，在xml布局文件中，把这个view定义进去，代码如下：

[html] view
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<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical" >

<net.loonggg.gif.view.GifView

android:id="@+id/gif1"

android:layout_width="100dp"

android:layout_height="100dp"

android:layout_gravity="center_horizontal"

android:enabled="false" />

<net.loonggg.gif.view.GifView

android:id="@+id/gif2"

android:layout_width="200dp"

android:layout_height="200dp"

android:layout_gravity="center_horizontal"

android:enabled="false" />

</LinearLayout>

最后，在MainActivity中的使用，代码如下：

[java] view
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package net.loonggg.gif;

import net.loonggg.gif.view.GifView;

import android.app.Activity;

import android.os.Bundle;

public class Gif extends Activity {

private GifView gif1, gif2;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

gif1 = (GifView) findViewById(R.id.gif1);

// 设置背景gif图片资源

gif1.setMovieResource(R.raw.kitty);

gif2 = (GifView) findViewById(R.id.gif2);

gif2.setMovieResource(R.raw.b);

// 设置暂停

// gif2.setPaused(true);

}

}

注意：与ImageView和其他View唯一的区别在于我加了一个gif属性。

[html] view
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<?xml version="1.0" encoding="utf-8"?>

<resources>

<declare-styleable name="GifView">

<attr name="gif" format="reference" />

<attr name="paused" format="boolean" />

</declare-styleable>

<declare-styleable name="CustomTheme">

<attr name="gifViewStyle" format="reference" />

</declare-styleable>

</resources>

这个代码已经非常好了，使用也非常方便，其实不懂代码是什么意思也可以很好的用，只需要懂得我写注释的那几行和Activity里面的那几行代码就可以了！

转载请注明出处：http://blog.csdn.net/loongggdroid/article/details/21166563

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