giflib加载GIF文件

 giflib是一款用C语言写的加载GIF库，在性能方面比Glide要好很多，首先来看一下性能对比。

glide加载gif

giflib加载gif

 从上图中我们可以看出在CPU使用率上，giflib比glide好很多了，内存占用上giflib比glide也要好一些。那么如何使用giflib尼？

 首先需要下载 framesequence及giflib（以上网站需要翻墙，请自备梯子）

 giflib文件目录如下：

 framesequence文件目录如下：

 下载完毕后，我们就将 framesequence下的jni目录复制到as的main下， giflib复制到 jni/giflib目录下。目录结构如下（删除了与webp相关的文件）：

 这样就可以开始编译so文件了，但是由于giflib使用的是 Android.bp进行编译的（不会呀o(╥﹏╥)o）。所有我就根据 Android.bp来重新写了份Android.mk文件，然后 ndk-build该文件即可。

#
# Copyright (C) 2014 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := gif
LOCAL_SRC_FILES := \
 giflib/dgif_lib.c \
 giflib/egif_lib.c \
 giflib/gifalloc.c \
 giflib/gif_err.c \
 giflib/gif_hash.c \
 giflib/openbsd-reallocarray.c \
 giflib/quantize.c

LOCAL_CFLAGS += \
    -Werror \
    -Wno-format \
    -Wno-sign-compare \
    -Wno-unused-parameter \
    -DHAVE_CONFIG_H \

LOCAL_SDK_VERSION := 8

include $(BUILD_STATIC_LIBRARY)

include $(CLEAR_VARS)
## Main library

LOCAL_STATIC_LIBRARIES := gif

LOCAL_LDFLAGS := -llog -ljnigraphics

LOCAL_C_INCLUDES := \
 giflib

LOCAL_MODULE := framesequence
LOCAL_SRC_FILES := \
 BitmapDecoderJNI.cpp \
 FrameSequence.cpp \
 FrameSequenceJNI.cpp \
 FrameSequence_gif.cpp \
 JNIHelpers.cpp \
 Registry.cpp \
 Stream.cpp

ifeq ($(FRAMESEQUENCE_INCLUDE_WEBP),true)
 LOCAL_C_INCLUDES += external/webp/include
 LOCAL_SRC_FILES += FrameSequence_webp.cpp
 LOCAL_STATIC_LIBRARIES += libwebp-decode
endif

LOCAL_CFLAGS += \
    -Wall \
    -Werror \
    -Wno-unused-parameter \
    -Wno-unused-variable \
    -Wno-overloaded-virtual \
    -fvisibility=hidden \

LOCAL_SDK_VERSION := 8

include $(BUILD_SHARED_LIBRARY)
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 由于没有使用CMake，所以应该在build.gradle下进行如下配置

externalNativeBuild{ ndkBuild{ path "src/main/jni/Android.mk" } }

 最后我们点击rebuild即可生成so文件。那么如何使用尼？

 在使用之前需要将framesequence目录下的src里面的所有文件拷贝到as的Java目录下。然后就可以使用了。使用代码如下（也可以去阅读framesequence下的示例代码）：

    FrameSequenceDrawable mDrawable;
    int mResourceId;

    // This provider is entirely unnecessary, just here to validate the acquire/release process
    private class CheckingProvider implements FrameSequenceDrawable.BitmapProvider {
        HashSet<Bitmap> mBitmaps = new HashSet<Bitmap>();

        @Override
        public Bitmap acquireBitmap(int minWidth, int minHeight) {
            Bitmap bitmap =
                    Bitmap.createBitmap(minWidth + 1, minHeight + 4, Bitmap.Config.ARGB_8888);
            mBitmaps.add(bitmap);
            return bitmap;
        }

        @Override
        public void releaseBitmap(Bitmap bitmap) {
            if (!mBitmaps.contains(bitmap)) throw new IllegalStateException();
            mBitmaps.remove(bitmap);
            bitmap.recycle();
        }

        public boolean isEmpty() {
            return mBitmaps.isEmpty();
        }
    }

    final CheckingProvider mProvider = new CheckingProvider();


//传入资源，设置相关参数
        InputStream is = getResources().openRawResource(mResourceId);
        FrameSequence fs = FrameSequence.decodeStream(is);//传入的是InputStream
        mDrawable = new FrameSequenceDrawable(fs, mProvider);
//        mDrawable.setLoopBehavior(LOOP_FINITE);//只播放一次
        mDrawable.setOnFinishedListener(new FrameSequenceDrawable.OnFinishedListener() {
            @Override
            public void onFinished(FrameSequenceDrawable drawable) {
                Toast.makeText(getApplicationContext(),
                        "The animation has finished", Toast.LENGTH_SHORT).show();
            }
        });
        drawableView.setBackgroundDrawable(mDrawable);
//开始播放
 mDrawable.start();
 //暂停播放
 mDrawable.stop();
 //裁剪成圆形
 mDrawable.setCircleMaskEnabled(!mDrawable.getCircleMaskEnabled());
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 目前giflib加载的都是本地的，那么如何加载线上GIF尼？其实可以把giflib与glide结合起来，由glide负责下载、缓存等的实现，giflib来负责GIF的加载。具体实现可以参考我写的一个demo