WebP for Android [closed]

Use libwebp with NDK. libwebp-0.1.3 already comes with Android.mk file (outdated and with syntax errors, but still). It also got generated JNI bindings in /swig/ directory.

Here's how I got it working:

Download NDK, put it in system PATH.
download libwebp-0.1.3.tar.gz, place it in your_project_dir/jni
Replace Android.mk with the one below.
Create jni/src/libwebp_java_wrap.c with content from below.
create jni/Application.mk, with content from below.
run ndk-build from project directory. This generates .so files in /libs/. You can inspect them with nm -D libs/armeabi/libwebp.so. In the list you'll see both the native library functions (like WebPDecodeRGB) and their JNI counterparts (like Java_com_google_webp_libwebpJNI_WebPDecodeRGB)
Add /jni/swig/libwebp.jar to build path of your Android project
See below for example how to use it in Java code

Here's content for Android.mk. Changed from original: removed encoder bits as I don't need these, added libwebp_java_wrap.c, changed include $(BUILD_STATIC_LIBRARY) to include $(BUILD_SHARED_LIBRARY).

LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)
LOCAL_SRC_FILES := \
    src/dec/alpha.c \
    src/dec/frame.c \
    src/dec/idec.c \
    src/dec/layer.c \
    src/dec/quant.c \
    src/dec/tree.c \
    src/dec/vp8.c \
    src/dec/webp.c \
    src/dec/io.c \
    src/dec/buffer.c \
    src/dsp/yuv.c \
    src/dsp/upsampling.c \
    src/dsp/cpu.c \
    src/dsp/dec.c \
    src/dsp/dec_neon.c \
    src/dsp/enc.c \
    src/utils/bit_reader.c \
    src/utils/bit_writer.c \
    src/utils/thread.c \
    src/libwebp_java_wrap.c \

LOCAL_CFLAGS := -Wall -DANDROID -DHAVE_MALLOC_H -DHAVE_PTHREAD -DWEBP_USE_THREAD \
                -finline-functions -frename-registers -ffast-math \
                -s -fomit-frame-pointer -Isrc/webp

LOCAL_C_INCLUDES += $(LOCAL_PATH)/src

LOCAL_MODULE:= webp

include $(BUILD_SHARED_LIBRARY)

Content for libwebp_java_wrap.c is here, it's basically the same as bundled in libwebp tarball, except encoder bits removed.

Content for Application.mk:

# The ARMv7 is significanly faster due to the use of the hardware FPU
APP_ABI := armeabi armeabi-v7a
APP_PLATFORM := android-9

Here's how to use in Java code. Notice how it converts byte[] array to int[] color array--this will break if endianness changes, right? Also notice how it uses arrays instead of single integers for width and height so they are passed by reference.

static {
    System.loadLibrary("webp");
}

private Bitmap webpToBitmap(byte[] encoded) {

    int[] width = new int[] { 0 };
    int[] height = new int[] { 0 };
    byte[] decoded = libwebp.WebPDecodeARGB(encoded, encoded.length, width, height);

    int[] pixels = new int[decoded.length / 4];
    ByteBuffer.wrap(decoded).asIntBuffer().get(pixels);

    return Bitmap.createBitmap(pixels, width[0], height[0], Bitmap.Config.ARGB_8888);

}

WebP is supported for Android 4.0+, a.k.a. API level 14. You can check using android.os.Build.VERSION.SDK_INT >= 14.

We've written an Android library just for that.

https://github.com/EverythingMe/webp-android

webp-android is a library we use at EverythingMe since we love webp. We use it to save bandwidth as well as shrinking our APK sizes.

webp-android is an adaptation of chromium's webp decoder, and an addition of a JNI wrapper to easily use it it in your java code. It's also easy to load webp images from xml to an ImageView (with the included WebpImageView) like so:

<me.everything.webp.WebpImageView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  webp:webp_src="@drawable/your_webp_image" />

Google claims that WebP is supported starting from Android 4.0+ ( http://developer.android.com/guide/appendix/media-formats.html ), however in our own tests webp images show as blue questionmarks both in the standard browser and Chrome on Android 4.0 and 4.1. On Android 4.2 WebP images seem to be rendered ok in a webview and in google chrome.

WebP for Android [closed]

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