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  • 在Android中显示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:

    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:

    <?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:

    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。

    <?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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  • 原文地址:https://www.cnblogs.com/loonggg/p/4981807.html
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