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在上一篇,是使用代碼通過構造方法傳入要播放的gif動畫的id進行擷取的。本文進一步改造,讓GifView和ImageView一樣可以在布局檔案中設定src屬性,并在GifView中我們使用反射動态擷取src的圖檔資源ID,然後對它進行播放。這樣使用起來就靈活多了。代碼如下:
GifView:
package com.home.gifview;
import java.io.InputStream;
import java.lang.reflect.Field;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Movie;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.ImageView;
public class GifView extends ImageView {
private Movie movie;
private long movieStart;
private int imageWidth;
private int imageHeight;
public GifView(Context context) {
super(context);
}
public GifView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public GifView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.GifView);
int resourceId = getResourceId(a, context, attrs);
if (resourceId != 0) {
InputStream is = getResources().openRawResource(resourceId);
movie = Movie.decodeStream(is);
if (movie != null) {
Bitmap bitmap = BitmapFactory.decodeStream(is);
imageWidth = bitmap.getWidth();
imageHeight = bitmap.getHeight();
bitmap.recycle();
}
}
}
@Override
protected void onDraw(Canvas canvas) {
if (movie == null) {
// 普通圖檔則直接調用父類的onDraw()方法
super.onDraw(canvas);
} else {
playGif(canvas);
invalidate();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (movie != null) {
// 如果是gif圖檔則定制GifView的大小
setMeasuredDimension(imageWidth, imageHeight);
}
}
/**
* 播放gif動畫
*
* @param canvas
* @return
*/
private boolean playGif(Canvas canvas) {
long now = SystemClock.uptimeMillis();
if (movieStart == 0) {
movieStart = now;
}
int duration = movie.duration();
if (duration == 0) {
duration = 1000;
}
int relTime = (int) ((now - movieStart) % duration);
movie.setTime(relTime);
movie.draw(canvas, 0, 0);
if ((now - movieStart) >= duration) {
movieStart = 0;
return true;
}
return false;
}
/**
* 使用反射,擷取到src指定圖檔資源所對應的id。
*
* @param a
* @param context
* @param attrs
* @return
*/
private int getResourceId(TypedArray a, Context context, AttributeSet attrs) {
try {
Field field = TypedArray.class.getDeclaredField("mValue");
field.setAccessible(true);
TypedValue typedValueObject = (TypedValue) field.get(a);
return typedValueObject.resourceId;
} catch (Exception e) {
e.printStackTrace();
} finally {
if (a != null) {
a.recycle();
}
}
return 0;
}
}
attrs.xml:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="GifView"></declare-styleable>
</resources>
main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.home.gifview.GifView
android:id="@+id/main_gifView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:src="@drawable/loading" />
</RelativeLayout>
禁用硬體加速:
android:hardwareAccelerated="false"