Android-GIF图片显示

摘自博客：

在Android中显示GIF动画

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。

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。

1、自定义view：

package com.example.lenovo.myapplication.activity;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;import com.example.lenovo.myapplication.R;/** * Created by lenovo on 2017/7/4. */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();    }}

2、res/value/attrs:

<?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>    <style name="Widget_GifView"></style></resources>

3、布局：

    <com.example.lenovo.myapplication.activity.GifView        android:id="@+id/gif1"        android:layout_width="match_parent"        android:layout_height="222dp"        android:layout_gravity="center_horizontal"        android:enabled="false" />    <com.example.lenovo.myapplication.activity.GifView        android:id="@+id/gif2"        android:layout_width="200dp"        android:layout_height="200dp"        android:layout_gravity="center_horizontal"        android:enabled="false" />

4、使用：

/** * Created by lenovo on 2017/7/4. */public class MainActivityII extends AppCompatActivity {    private GifView gif1, gif2;    @Override    protected void onCreate(@Nullable 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.boliang);        gif2 = (GifView) findViewById(R.id.gif2);        gif2.setMovieResource(R.raw.boliang);        // 设置暂停        gif2.setPaused(true);    }}

遇到问题：

1、未设置抗锯齿：

    private void drawMovieFrame(Canvas canvas) {        // 设置要显示的帧，绘制即可        mMovie.setTime(mCurrentAnimationTime);        canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG| Paint.FILTER_BITMAP_FLAG));//在此方法中为canvas添加抗锯齿        canvas.save(Canvas.MATRIX_SAVE_FLAG);        canvas.scale(mScale, mScale);        mMovie.draw(canvas, mLeft / mScale, mTop / mScale);        canvas.restore();    }

参考：Android画图之抗锯齿paint和Canvas两种方式实例

设置抗锯齿方法:

方法一：给Paint加上抗锯齿标志。然后将Paint对象作为参数传给canvas的绘制方法。

 paint.setAntiAlias(true); 

方法二：给Canvas加上抗锯齿标志。
有些地方不能用paint的，就直接给canvas加抗锯齿，更方便。

canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG));