Android(安卓)播放 Gif 图片控件

接到个需求要播放一个带 Gif 图片的动画，ios 本身就对 Gif 是支持的，android 需要自己实现，因此需要自己自定义一个控件，废话不多，现在贴上代码如下：
/** * 播放 Gif View * Created by William on 2017/7/4. */public class UMGifImageView extends View {    private static final int DEFAULT_VIEW_DURATION = 1000;    private int mMovieResourceId;    private Movie mMovie;    private long mMovieStart;    private int mCurrentAnimationTime = 0;    /**     * Position for drawing animation frames in the center of the view.     */    private float mLeft;    private float mTop;    /**     * Scaling factor to fit the animation within view bounds.     */    private float mScale;    /**     * Scaled movie frames width and height.     */    private int mMeasuredMovieWidth;    private int mMeasuredMovieHeight;    private volatile boolean mPaused = false;    private boolean mVisible = true;    public UMGifImageView(Context context) {        this(context, null);    }    public UMGifImageView(Context context, AttributeSet attrs) {        this(context, attrs, R.styleable.CustomTheme_GifViewStyle);    }    public UMGifImageView(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) {        /**         * Starting from HONEYCOMB have to turn off HW acceleration to draw         * Movie on Canvas.         */        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {            setLayerType(View.LAYER_TYPE_SOFTWARE, null);        }        final TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.GifImageView, defStyle,                R.style.Widget_GifMoviewView);        mMovieResourceId = array.getResourceId(R.styleable.GifImageView_gif, -1);        mPaused = array.getBoolean(R.styleable.GifImageView_paused, false);        array.recycle();        if (mMovieResourceId != -1) {            mMovie = Movie.decodeStream(getResources().openRawResource(mMovieResourceId));        }    }    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();    }    public void setPaused(boolean paused) {        this.mPaused = paused;        /**         * Calculate new movie start time, so that it resumes from the same         * frame.         */        if (!paused) {            mMovieStart = android.os.SystemClock.uptimeMillis() - mCurrentAnimationTime;        }        invalidate();    }    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();            /*             * Calculate horizontal scaling             */            float scaleH = 1f;            int measureModeWidth = MeasureSpec.getMode(widthMeasureSpec);            if (measureModeWidth != MeasureSpec.UNSPECIFIED) {                int maximumWidth = MeasureSpec.getSize(widthMeasureSpec);                if (movieWidth > maximumWidth) {                    scaleH = (float) movieWidth / (float) maximumWidth;                }            }            /*             * calculate vertical scaling             */            float scaleW = 1f;            int measureModeHeight = MeasureSpec.getMode(heightMeasureSpec);            if (measureModeHeight != MeasureSpec.UNSPECIFIED) {                int maximumHeight = MeasureSpec.getSize(heightMeasureSpec);                if (movieHeight > maximumHeight) {                    scaleW = (float) movieHeight / (float) maximumHeight;                }            }            /*             * calculate overall scale             */            mScale = 1f / Math.max(scaleH, scaleW);            mMeasuredMovieWidth = (int) (movieWidth * mScale);            mMeasuredMovieHeight = (int) (movieHeight * mScale);            setMeasuredDimension(mMeasuredMovieWidth, mMeasuredMovieHeight);        } else {            /*             * No movie set, just set minimum available size.             */            setMeasuredDimension(getSuggestedMinimumWidth(), getSuggestedMinimumHeight());        }    }    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        super.onLayout(changed, l, t, r, b);        /*         * Calculate left / top for drawing in center         */        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);            }        }    }    /**     * Invalidates view only if it is visible.     * 
     * {@link #postInvalidateOnAnimation()} is used for Jelly Bean and higher.     */    @SuppressLint("NewApi")    private void invalidateView() {        if (mVisible) {            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {                postInvalidateOnAnimation();            } else {                invalidate();            }        }    }    /**     * Calculate current animation time     */    private void updateAnimationTime() {        long now = android.os.SystemClock.uptimeMillis();        if (mMovieStart == 0) {            mMovieStart = now;        }        int dur = mMovie.duration();        if (dur == 0) {            dur = DEFAULT_VIEW_DURATION;        }        mCurrentAnimationTime = (int) ((now - mMovieStart) % dur);    }    /**     * Draw current GIF frame     */    private void drawMovieFrame(Canvas canvas) {        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();    }}
然后还要在 attrs.xml 文件中自定义属性：
最后，就可以在自己的布局文件中直接使用了：
其中 custom:gif 是直接引用 gif 图片，把 gif 图片放在 drawable 文件夹中即可。
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