how to change a color in an image programmatically?

I have a .PNG image with a transparent background and a drawing in it with a black color, how could I change the "black drawing color" in this image to any color i want programmatically; using rim 4.5 API ? THANKS IN ADVA开发者_StackOverflowNCE ....

I found the solution, here it is for those who are interested.

Bitmap colorImage(Bitmap image, int color) {
    int[] rgbData= new int[image.getWidth() * image.getHeight()];
    image.getARGB(rgbData, 
                  0, 
                  image.getWidth(), 
                  0, 
                  0, 
                  image.getWidth(), 
                  image.getHeight());
    for (int i = 0; i < rgbData.length; i++) {
        int alpha = 0xFF000000 & rgbData[i];
        if((rgbData[i] & 0x00FFFFFF) == 0x00000000)
            rgbData[i]= alpha | color;
    }
    image.setARGB(rgbData,
                  0, 
                  image.getWidth(),
                  0,
                  0,
                  image.getWidth(),
                  image.getHeight());
    return image;
}

You can parse the image RGBs searching for the black color and replace it with whatever color you desire.

You can read your PNG image to byte array and edit palette chunk. This method is suitable only for PNG-8 images. Here is my code:

public static Image createImage(String filename) throws Throwable
    {
        DataInputStream dis = null;
        InputStream is = null;

        try {
            is = new Object().getClass().getResourceAsStream(filename);
            dis = new DataInputStream(is);

            int pngLength = dis.available();
            byte[] png = new byte[pngLength];
            int offset = 0;
            dis.read(png, offset, 4);   offset += 4;    //‰PNG  
            dis.read(png, offset, 4);   offset += 4;    //....
            while (true) {
                //length
                dis.read(png, offset, 4);   offset += 4;
                int length = (png[offset-1]&0xFF) | ((png[offset-2]&0xFF)<<8) | ((png[offset-3]&0xFF)<<16) | ((png[offset-4]&0xFF)<<24);
                //chunk type
                dis.read(png, offset, 4);   offset += 4;
                int type = (png[offset-1]&0xFF) | ((png[offset-2]&0xFF)<<8) | ((png[offset-3]&0xFF)<<16) | ((png[offset-4]&0xFF)<<24);

                //chunk data
                for (int i=0; i<length; i++) {
                    dis.read(png, offset, 1);   offset += 1;
                }
                //CRC
                dis.read(png, offset, 4);   offset += 4;
                int crc = (png[offset-1]&0xFF) | ((png[offset-2]&0xFF)<<8) | ((png[offset-3]&0xFF)<<16) | ((png[offset-4]&0xFF)<<24);

                if (type == 0x504C5445) {   //'PLTE'
                    int CRCStart = offset-4;
                    int PLTEStart = offset-4-length;

                    //modify PLTE chunk
                    for (int i=PLTEStart; i<PLTEStart+length; i+=3) {
                        png[i+0] = ...
                        png[i+1] = ...
                        png[i+2] = ...
                    }

                    int newCRC = crc(png, PLTEStart-4, length+4);
                    png[CRCStart+0] = (byte)(newCRC>>24);
                    png[CRCStart+1] = (byte)(newCRC>>16);
                    png[CRCStart+2] = (byte)(newCRC>>8);
                    png[CRCStart+3] = (byte)(newCRC);

                }
                if (offset >= pngLength)
                    break;
            }

            return Image.createImage(png, 0, pngLength);
        } catch (Throwable e) {
            throw e;
        } finally {
            MainCanvas.closeInputStream(dis);
            MainCanvas.closeInputStream(is);
        }
    }