Create a NinePatch/NinePatchDrawable in runtime
I have a requirement on my Android application that parts on the graphics should be customizable, by retrieving new colors and images from the server side. Some of these images are nine-patch images.
I can't find a way to create and display these nine-patch images (that have been retrieved over the network).
The nine-patch images are retrieved and kept in the application as Bitmaps. In order to create a NinePatchDrawable, you either need the corresponding NinePatch or the chunk (byte[]) of the NinePatch. The NinePatch can NOT be loaded from the Resources, since the images doesn't exist in /res/drawable/. Furthermore, in order to create the NinePatch, you need the chunk of the NinePatch. So, it all drills down to the chunk.
I've searched through the Android source code and the Web and I can't seem to find any examples of this. To make things worse, all decoding of a NinePatch resources seem to be done natively.
Have anyone had any experiences with this kind of issue?
I'm targeting API level 4, if that is of importance.
getNinePatchChunk works just fine. It returned null because you were giving Bitmap a "source" ninepatch. It needs a "compiled" ninepatch image.
There are two types of ninepatch file formats in the Android world ("source" and "compiled"). The source version is where you add the 1px transparency border everywhere-- when you compile your app into a .apk later, aapt will convert your *.9.png files to the binary format that Android expects. This is where the png file gets its "chunk" metadata. (read more)
Okay, now down to business.
Client code, something like this:
InputStream stream = .. //whatever Bitmap bitmap = BitmapFactory.decodeStream(stream); byte[] chunk = bitmap.getNinePatchChunk(); boolean result = NinePatch.isNinePatchChunk(chunk); NinePatchDrawable patchy = new NinePatchDrawable(bitmap, chunk, new Rect(), null);Server-side, you need to prepare your images. You can use the Android Binary Resource Compiler. This automates some of the pain away from creating a new Android project just to compile some *.9.png files into the Android native format. If you were to do this manually, you would essentially make a project and throw in some *.9.png files ("source" files), compile everything into the .apk format, unzip the .apk file, then find the *.9.png file, and that's the one you send to your clients.
Also: I don't know if BitmapFactory.decodeStream knows about the npTc chunk in these png files, so it may or may not be treating the image stream correctly. The existence of Bitmap.getNinePatchChunk suggests that BitmapFactory might-- you could go look it up in the upstream codebase.
In the event that it does not know about the npTc chunk and your images are being screwed up significantly, then my answer changes a little.
Instead of sending the compiled ninepatch images to the client, you write a quick Android app to load compiled images and spit out the byte[] chunk. Then, you transmit this byte array to your clients along with a regular image-- no transparent borders, not the "source" ninepatch image, not the "compiled" ninepatch image. You can directly use the chunk to create your object.
Another alternative is to use object serialization to send ninepatch images (NinePatch) to your clients, such as with JSON or the built-in serializer.
Edit If you really, really need to construct your own chunk byte array, I would start by looking at do_9patch, isNinePatchChunk, Res_png_9patch and Res_png_9patch::serialize() in ResourceTypes.cpp. There's also a home-made npTc chunk reader from Dmitry Skiba. I can't post links, so if someone can edit my answer that would be cool.
do_9patch: https://android.googlesource.com/platform/frameworks/base/+/gingerbread/tools/aapt/Images.cpp
isNinePatchChunk: http://netmite.com/android/mydroid/1.6/frameworks/base/core/jni/android/graphics/NinePatch.cpp
struct Res_png_9patch: https://scm.sipfoundry.org/rep/sipX/main/sipXmediaLib/contrib/android/android_2_0_headers/frameworks/base/include/utils/ResourceTypes.h
Dmitry Skiba stuff: http://code.google.com/p/android4me/source/browse/src/android/graphics/Bitmap.java
If you need to create 9Patches on the fly check out this gist I made: https://gist.github.com/4391807
You pass it any bitmap and then give it cap insets similar to iOS.
I create a tool to create NinePatchDrawable from (uncompiled) NinePatch bitmap. See https://gist.github.com/knight9999/86bec38071a9e0a781ee .
The method
NinePatchDrawable createNinePatchDrawable(Resources res, Bitmap bitmap)
helps you.
For example,
ImageView imageView = (ImageView) findViewById(R.id.imageview);
Bitmap bitmap = loadBitmapAsset("my_nine_patch_image.9.png", this);
NinePatchDrawable drawable = NinePatchBitmapFactory.createNinePatchDrawable(getResources(), bitmap);
imageView.setBackground( drawable );
where
public static final Bitmap loadBitmapAsset(String fileName,Context context) {
final AssetManager assetManager = context.getAssets();
BufferedInputStream bis = null;
try {
bis = new BufferedInputStream(assetManager.open(fileName));
return BitmapFactory.decodeStream(bis);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
bis.close();
} catch (Exception e) {
}
}
return null;
}
In this sample case, the my_nine_patch_image.9.png is under the assets directory.
No need to use Android Binary Resource Compiler to prepare compiled 9patch pngs, just using aapt in android-sdk is ok, the command line is like this:
aapt.exe c -v -S /path/to/project -C /path/to/destination
So you basically want to create a NinePatchDrawable on demand, don't you? I tried the following code, maybe it works for you:
InputStream in = getResources().openRawResource(R.raw.test);
Drawable d = NinePatchDrawable.createFromStream(in, null);
System.out.println(d.getMinimumHeight() + ":" + d.getMinimumHeight());
I think this should work. You just have to change the first line to get the InputStream from the web. getNinePatchChunk() is not intended to be called from developers according to the documentation, and might break in the future.
WORKING AND TESTED - RUNTIME NINEPATCH CREATION
This is my implementation of android Ninepatch Builder, you can create NinePatches on Runtime through this class and code examples below by supplying any Bitmap
public class NinePatchBuilder {
int width,height;
Bitmap bitmap;
Resources resources;
private ArrayList<Integer> xRegions=new ArrayList<Integer>();
private ArrayList<Integer> yRegions=new ArrayList<Integer>();
public NinePatchBuilder(Resources resources,Bitmap bitmap){
width=bitmap.getWidth();
height=bitmap.getHeight();
this.bitmap=bitmap;
this.resources=resources;
}
public NinePatchBuilder(int width, int height){
this.width=width;
this.height=height;
}
public NinePatchBuilder addXRegion(int x, int width){
xRegions.add(x);
xRegions.add(x+width);
return this;
}
public NinePatchBuilder addXRegionPoints(int x1, int x2){
xRegions.add(x1);
xRegions.add(x2);
return this;
}
public NinePatchBuilder addXRegion(float xPercent, float widthPercent){
int xtmp=(int)(xPercent*this.width);
xRegions.add(xtmp);
xRegions.add(xtmp+(int)(widthPercent*this.width));
return this;
}
public NinePatchBuilder addXRegionPoints(float x1Percent, float x2Percent){
xRegions.add((int)(x1Percent*this.width));
xRegions.add((int)(x2Percent*this.width));
return this;
}
public NinePatchBuilder addXCenteredRegion(int width){
int x=(int)((this.width-width)/2);
xRegions.add(x);
xRegions.add(x+width);
return this;
}
public NinePatchBuilder addXCenteredRegion(float widthPercent){
int width=(int)(widthPercent*this.width);
int x=(int)((this.width-width)/2);
xRegions.add(x);
xRegions.add(x+width);
return this;
}
public NinePatchBuilder addYRegion(int y, int height){
yRegions.add(y);
yRegions.add(y+height);
return this;
}
public NinePatchBuilder addYRegionPoints(int y1, int y2){
yRegions.add(y1);
yRegions.add(y2);
return this;
}
public NinePatchBuilder addYRegion(float yPercent, float heightPercent){
int ytmp=(int)(yPercent*this.height);
yRegions.add(ytmp);
yRegions.add(ytmp+(int)(heightPercent*this.height));
return this;
}
public NinePatchBuilder addYRegionPoints(float y1Percent, float y2Percent){
yRegions.add((int)(y1Percent*this.height));
yRegions.add((int)(y2Percent*this.height));
return this;
}
public NinePatchBuilder addYCenteredRegion(int height){
int y=(int)((this.height-height)/2);
yRegions.add(y);
yRegions.add(y+height);
return this;
}
public NinePatchBuilder addYCenteredRegion(float heightPercent){
int height=(int)(heightPercent*this.height);
int y=(int)((this.height-height)/2);
yRegions.add(y);
yRegions.add(y+height);
return this;
}
public byte[] buildChunk(){
if(xRegions.size()==0){
xRegions.add(0);
xRegions.add(width);
}
if(yRegions.size()==0){
yRegions.add(0);
yRegions.add(height);
}
/* example code from a anwser above
// The 9 patch segment is not a solid color.
private static final int NO_COLOR = 0x00000001;
ByteBuffer buffer = ByteBuffer.allocate(56).order(ByteOrder.nativeOrder());
//was translated
buffer.put((byte)0x01);
//divx size
buffer.put((byte)0x02);
//divy size
buffer.put((byte)0x02);
//color size
buffer.put(( byte)0x02);
//skip
buffer.putInt(0);
buffer.putInt(0);
//padding
buffer.putInt(0);
buffer.putInt(0);
buffer.putInt(0);
buffer.putInt(0);
//skip 4 bytes
buffer.putInt(0);
buffer.putInt(left);
buffer.putInt(right);
buffer.putInt(top);
buffer.putInt(bottom);
buffer.putInt(NO_COLOR);
buffer.putInt(NO_COLOR);
return buffer;*/
int NO_COLOR = 1;//0x00000001;
int COLOR_SIZE=9;//could change, may be 2 or 6 or 15 - but has no effect on output
int arraySize=1+2+4+1+xRegions.size()+yRegions.size()+COLOR_SIZE;
ByteBuffer byteBuffer=ByteBuffer.allocate(arraySize * 4).order(ByteOrder.nativeOrder());
byteBuffer.put((byte) 1);//was translated
byteBuffer.put((byte) xRegions.size());//divisions x
byteBuffer.put((byte) yRegions.size());//divisions y
byteBuffer.put((byte) COLOR_SIZE);//color size
//skip
byteBuffer.putInt(0);
byteBuffer.putInt(0);
//padding -- always 0 -- left right top bottom
byteBuffer.putInt(0);
byteBuffer.putInt(0);
byteBuffer.putInt(0);
byteBuffer.putInt(0);
//skip
byteBuffer.putInt(0);
for(int rx:xRegions)
byteBuffer.putInt(rx); // regions left right left right ...
for(int ry:yRegions)
byteBuffer.putInt(ry);// regions top bottom top bottom ...
for(int i=0;i<COLOR_SIZE;i++)
byteBuffer.putInt(NO_COLOR);
return byteBuffer.array();
}
public NinePatch buildNinePatch(){
byte[] chunk=buildChunk();
if(bitmap!=null)
return new NinePatch(bitmap,chunk,null);
return null;
}
public NinePatchDrawable build(){
NinePatch ninePatch=buildNinePatch();
if(ninePatch!=null)
return new NinePatchDrawable(resources, ninePatch);
return null;
}
}
Now we can use ninepatch builder to create NinePatch or NinePatchDrawable or for creating NinePatch Chunk.
Example:
NinePatchBuilder builder=new NinePatchBuilder(getResources(), bitmap);
NinePatchDrawable drawable=builder.addXCenteredRegion(2).addYCenteredRegion(2).build();
//or add multiple patches
NinePatchBuilder builder=new NinePatchBuilder(getResources(), bitmap);
builder.addXRegion(30,2).addXRegion(50,1).addYRegion(20,4);
byte[] chunk=builder.buildChunk();
NinePatch ninepatch=builder.buildNinePatch();
NinePatchDrawable drawable=builder.build();
//Here if you don't want ninepatch and only want chunk use
NinePatchBuilder builder=new NinePatchBuilder(width, height);
byte[] chunk=builder.addXCenteredRegion(1).addYCenteredRegion(1).buildChunk();
Just copy paste the NinePatchBuilder class code in a java file and use the examples to create NinePatch on the fly during your app runtime, with any resolution.
The Bitmap class provides a method to do this yourbitmap.getNinePatchChunk(). I've never used it but it seems like thats what your looking for.
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