NinePatchBitmapFactory.java

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.graphics.Rect;
import android.graphics.drawable.NinePatchDrawable;
import android.util.DisplayMetrics;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.List;

/**
 * User: bgriffey
 * Date: 12/27/12
 * Time: 2:37 PM
 */
public class NinePatchBitmapFactory {

	private static final int NO_COLOR = 0x00000001;
	
	private static final int TRANSPARENT_COLOR = 0x00000000;
	
	public static NinePatchDrawable createNinePatchDrawable(Resources res, Bitmap bitmap) {
		RangeLists rangeLists = checkBitmap(bitmap);
		Bitmap trimedBitmap = trimBitmap(bitmap);
		NinePatchDrawable drawable = createNinePatchWithCapInsets( res , trimedBitmap , rangeLists.rangeListX , rangeLists.rangeListY , null );
		return drawable;
	}
	
	
	public static NinePatchDrawable createNinePatchWithCapInsets(Resources res, Bitmap bitmap,
			List<Range> rangeListX, List<Range> rangeListY , String srcName) {
		ByteBuffer buffer = getByteBuffer(rangeListX,rangeListY);
		NinePatchDrawable drawable = new NinePatchDrawable(res,bitmap, buffer.array(), new Rect(), srcName);
		return drawable;
	}
	
	private static ByteBuffer getByteBuffer(List<Range> rangeListX, List<Range> rangeListY) {
		ByteBuffer buffer = ByteBuffer.allocate(4 + 4*7 + 4*2*rangeListX.size() + 4*2*rangeListY.size() + 4*9).order(ByteOrder.nativeOrder());
		buffer.put((byte)0x01); // was serialised
		buffer.put((byte) (rangeListX.size() * 2) ); // x div
		buffer.put((byte) (rangeListY.size() * 2) ); // y div
		buffer.put((byte)0x09); // color
		
		// 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);

		for (Range range : rangeListX) {
			buffer.putInt( range.start );
			buffer.putInt( range.end );
		}
		for (Range range : rangeListY) {
			buffer.putInt( range.start);
			buffer.putInt( range.end );
		}
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		buffer.putInt(NO_COLOR);
		
		return buffer;
		
		
	}
	
	public static class RangeLists {
		public List<Range> rangeListX;
		public List<Range> rangeListY;
	}
	
	public static class Range {
		public int start;
		public int end;
	}
	
	public static RangeLists checkBitmap(Bitmap bitmap) {
		int width = bitmap.getWidth();
		int height = bitmap.getHeight();
		
		List<Range> rangeListX = new ArrayList<Range>();
		
		int pos = -1;
		for (int i=1;i<width-1;i++) {
			int color = bitmap.getPixel(i, 0);
			int alpha = Color.alpha( color );
			int red = Color.red( color );
			int green = Color.green( color );
			int blue = Color.blue( color );
//			System.out.println( String.valueOf(alpha) + "," + String.valueOf(red) + "," + String.valueOf(green) + "," + String.valueOf(blue) );
			if (alpha == 255 && red == 0 && green == 0 && blue == 0) {
				if (pos == -1) {
					pos = i-1;
				}
			} else {
				if (pos != -1) {
					Range range = new Range();
					range.start = pos;
					range.end = i-1;
					rangeListX.add( range );
					pos = -1;
				}
			}
		}
		if (pos != -1) {
			Range range = new Range();
			range.start = pos;
			range.end = width-2;
			rangeListX.add( range );
		}
		for (Range range : rangeListX) {
			System.out.println( "(" + range.start + "," + range.end + ")" );
		}
		
		List<Range> rangeListY = new ArrayList<Range>();
		
		pos = -1;
		for (int i=1;i<height-1;i++) {
			int color = bitmap.getPixel(0, i);
			int alpha = Color.alpha( color );
			int red = Color.red( color );
			int green = Color.green( color );
			int blue = Color.blue( color );
			if (alpha == 255 && red == 0 && green == 0 && blue == 0) {
				if (pos == -1) {
					pos = i-1;
				}
			} else {
				if (pos != -1) {
					Range range = new Range();
					range.start = pos;
					range.end = i-1;
					rangeListY.add( range );
					pos = -1;
				}
			}
			
		}
		if (pos != -1) {
			Range range = new Range();
			range.start = pos;
			range.end = height-2;
			rangeListY.add( range );
		}
		for (Range range : rangeListY) {
			System.out.println( "(" + range.start + "," + range.end + ")" );
		}
		
		RangeLists rangeLists = new RangeLists();
		rangeLists.rangeListX = rangeListX;
		rangeLists.rangeListY = rangeListY;
		
		return rangeLists;
	}
	
	public static Bitmap trimBitmap(Bitmap bitmap) {
		int width = bitmap.getWidth();
		int height = bitmap.getHeight();
		
		Bitmap result = Bitmap.createBitmap(bitmap , 1 , 1 , width -2 , height -2 );
		
		return result;
		
	}
	
	public static Bitmap loadBitmap(File file) {
	    BufferedInputStream bis = null;
	    try {
	        bis = new BufferedInputStream( new FileInputStream(file) );
	        return BitmapFactory.decodeStream(bis);
	    } catch (IOException e) {
	        e.printStackTrace();
	    } finally {
	        try {
	            bis.close();
	        } catch (Exception e) {
	            
	        }
	    }
	    return null;
	}
	
	public static String getDensityPostfix(Resources res) {
	    String result = null;
	    switch (res.getDisplayMetrics().densityDpi) {
	    case DisplayMetrics.DENSITY_LOW:
	        result = "ldpi";
	        break;
	    case DisplayMetrics.DENSITY_MEDIUM:
	        result = "mdpi";
	        break;
	    case DisplayMetrics.DENSITY_HIGH:
	        result = "hdpi";
	        break;
	    case DisplayMetrics.DENSITY_XHIGH:
	        result = "xhdpi";
	        break;
	    case DisplayMetrics.DENSITY_XXHIGH:
	        result = "xxhdpi";
	        break;
	    case DisplayMetrics.DENSITY_XXXHIGH:
	        result = "xxxhdpi";
	        break;
	    }
	    return result;
	}
}