在Android中顯示GIF動畫

時間 2019-11-24

原文原文鏈接

gif圖動畫在android中仍是比較經常使用的，好比像新浪微博中，有不少gif圖片，並且展現很是好，因此我也想弄一個。通過我多方的搜索資料和整理，終於弄出來了，其實github上有不少開源的gif的展現代碼，我下載過幾個，可是都不是很理想，不是我徹底想要的。因此有時候就得本身學會總結，把開源的東西整理成本身的，如今無聊，也正好有朋友須要，因此如今整理了一下，留着之後備用！html

廢話很少說，直接上圖：java

在這裏主要用的是：android中的android.graphics.Movie 這個類，這是android提供給咱們的一個很是方便的工具。android

首先，重寫控件View,自定義一個展現gif圖的GifView，代碼以下：git

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 {

	/**
	 * 默認爲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);
		}
		// 從描述文件中讀出gif的值，建立出Movie實例
		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));
		}
	}

	/**
	 * 設置gif圖資源
	 * 
	 * @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();
	}

	/**
	 * 設置暫停
	 * 
	 * @param paused
	 */
	public void setPaused(boolean paused) {
		this.mPaused = paused;
		if (!paused) {
			mMovieStart = android.os.SystemClock.uptimeMillis()
					- mCurrentAnimationTime;
		}
		invalidate();
	}

	/**
	 * 判斷gif圖是否中止了
	 * 
	 * @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();
		// 若是第一幀，記錄起始時間
		if (mMovieStart == 0) {
			mMovieStart = now;
		}
		// 取出動畫的時長
		int dur = mMovie.duration();
		if (dur == 0) {
			dur = DEFAULT_MOVIE_DURATION;
		}
		// 算出須要顯示第幾幀
		mCurrentAnimationTime = (int) ((now - mMovieStart) % dur);
	}

	private void drawMovieFrame(Canvas canvas) {
		// 設置要顯示的幀，繪製便可
		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其實管理着GIF動畫中的多個幀，只須要經過 setTime() 一下就可讓它在draw()的時候繪出相應的那幀圖像。經過當前時間與duration之間的換算關係，是很容易實現GIF動起來的效果。

其次，在xml佈局文件中，把這個view定義進去，代碼以下：程序員

<?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>

最後，在MainActivity中的使用，代碼以下：

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);
		// 設置背景gif圖片資源
		gif1.setMovieResource(R.raw.kitty);
		gif2 = (GifView) findViewById(R.id.gif2);
		gif2.setMovieResource(R.raw.b);
		// 設置暫停
		// gif2.setPaused(true);

	}

}

注意：與ImageView和其餘View惟一的區別在於我加了一個gif屬性。

<?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>

這個代碼已經很是好了，使用也很是方便，其實不懂代碼是什麼意思也能夠很好的用，只須要懂得我寫註釋的那幾行和Activity裏面的那幾行代碼就能夠了！

轉載請註明出處：http://blog.csdn.net/loongggdroid/article/details/21166563github

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