xUtils源码阅读（7）-GitDrawable

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通常情况下，ImageView是不支持Gif动画的，所以我们要向支持Gif的话，必须自己来处理。

在这里我们就不是对Drawable的包装了，我们是对Drawable的重新实现。同时由于Gif具有动画，所以又同时实现了Runnable,Animatable接口。

源码：

public class GifDrawable extends Drawable implements Runnable, Animatable {    private int byteCount;//数据大小    private int rate = 300;//播放的频率，多长时间刷新一次    private volatile boolean running;//是否正在运行    private final Movie movie;//gif的具体内容    private final int duration;//gif播放的时长    private final long begin = SystemClock.uptimeMillis();    public GifDrawable(Movie movie, int byteCount) {        this.movie = movie;        this.byteCount = byteCount;        this.duration = movie.duration();    }    public int getDuration() {        return duration;    }    public Movie getMovie() {        return movie;    }    public int getByteCount() {        if (byteCount == 0) {            byteCount = (movie.width() * movie.height() * 3) * (5/*fake frame count*/);        }        return byteCount;    }    public int getRate() {        return rate;    }    public void setRate(int rate) {        this.rate = rate;    }    @Override    public void draw(Canvas canvas) {        try {            int time = duration > 0 ? (int) (SystemClock.uptimeMillis() - begin) % duration : 0;            movie.setTime(time);            movie.draw(canvas, 0, 0);//git帧绘制            start();        } catch (Throwable ex) {            LogUtil.e(ex.getMessage(), ex);        }    }    @Override    public void start() {        if (!isRunning()) {            running = true;            run();        }    }    @Override    public void stop() {        if (isRunning()) {            this.unscheduleSelf(this);        }    }    @Override    public boolean isRunning() {        return running && duration > 0;    }    @Override    public void run() {        if (duration > 0) {            this.invalidateSelf();//页面失效            this.scheduleSelf(this, SystemClock.uptimeMillis() + rate);//过会儿再重绘        }    }    @Override    public void setAlpha(int alpha) {    }    @Override    public int getIntrinsicWidth() {        return movie.width();    }    @Override    public int getIntrinsicHeight() {        return movie.height();    }    @Override    public void setColorFilter(ColorFilter cf) {    }    @Override    public int getOpacity() {        return movie.isOpaque() ? PixelFormat.OPAQUE : PixelFormat.TRANSLUCENT;    }}

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