Font to Texture Support

[ToxicBakery]

Once Texture Atlas is implement we should move to implement font support. As font support is not exactly an task this I have gone ahead and jump started the development. Attached is a debug image showing my poorly aligned and placed texture printing. Once the texture atlas code is in place I can re-use it greatly improve the letter placements and thus generate a nice clean atlas.

My implementation currently is below. This will change heavily once the atlas implementation pushes to master at which time I will remove this placeholder.

public class FontAtlas {

    public enum CharacterType {
        //@formatter:off
        ALPHA_LOWER(97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
                109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120,
                121, 122), 
        ALPHA_UPPER(65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78,
                79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90), 
        NUMERIC(48, 49, 50, 51, 52, 53, 54, 55, 56, 57), 
        SYMBOLS(32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
                47, 58, 59, 60, 61, 62, 63, 64, 91, 92, 93, 94, 95, 96);
        //@formatter:on

        int[] chars;

        CharacterType(final int... chars) {
            this.chars = chars;
        }
    }

    protected final SparseArray<Character> charList;

    protected Paint mPaint;
    protected Bitmap mTexture;

    protected FontAtlas(Builder builder) {
        // Validate data
        if (builder.types.size() == 0
                && builder.mCustomCharacters.length() == 0)
            throw new FontAtlasException("No characters or types specified!");
        if (builder.mTypeface == null)
            throw new FontAtlasException("Typeface never set!");

        // Construct paint for determining character sizes
        mPaint = new Paint();
        mPaint.setColor(builder.mColor);
        mPaint.setTextSize(builder.mTextSize);
        mPaint.setTypeface(builder.mTypeface);

        // Determine the number of characters that need to be displayed
        int typeCount = builder.mCustomCharacters.length();
        for (int i = 0, j = builder.types.size(); i < j; i++)
            typeCount += builder.types.get(i).chars.length;

        // Calculate the size of each character
        charList = new SparseArray<Character>(typeCount);
        Character tempChar;
        int maxCharHeight = 0;
        int maxCharWidth = 0;
        for (int i = 0, j = builder.types.size(); i < j; i++) {
            int[] chars = builder.types.get(i).chars;
            for (int k = 0; k < chars.length; k++) {
                tempChar = new Character(chars[k], mPaint);
                maxCharWidth = maxCharWidth < tempChar.w ? tempChar.w
                        : maxCharWidth;
                maxCharHeight = maxCharHeight < tempChar.h ? tempChar.h
                        : maxCharHeight;
                charList.append(chars[k], tempChar);
            }
        }
        for (int i = 0, j = builder.mCustomCharacters.length(); i < j; i++) {
            tempChar = new Character(builder.mCustomCharacters.substring(i, i+1), mPaint);
            maxCharWidth = maxCharWidth < tempChar.w ? tempChar.w
                    : maxCharWidth;
            maxCharHeight = maxCharHeight < tempChar.h ? tempChar.h
                    : maxCharHeight;
            charList.append(9000 + i, tempChar);
        }

        // Determine the estimated minimum size, this is a little wasteful but safe
        int nextPOT = maxCharHeight * maxCharWidth * charList.size();
        nextPOT--;
        nextPOT = (nextPOT >> 1) | nextPOT;
        nextPOT = (nextPOT >> 2) | nextPOT;
        nextPOT = (nextPOT >> 4) | nextPOT;
        nextPOT = (nextPOT >> 8) | nextPOT;
        nextPOT = (nextPOT >> 16) | nextPOT;
        nextPOT++;
        nextPOT = (int) Math.sqrt(nextPOT);

        // Create the bitmap using the next power of two
        mTexture = Bitmap.createBitmap(nextPOT, nextPOT, Config.ARGB_8888);

        final Canvas c = new Canvas(mTexture);

        Character ch;
        int key;
        int lineWidth = 0;
        for (int i = 0, j = charList.size(); i < j; i++) {
            if (lineWidth > nextPOT) {
                lineWidth = 0;
                c.translate(0, (float) Math.ceil(mPaint.getTextSize()));
            }

            key = charList.keyAt(i);
            ch = charList.get(key);
            c.drawText(String.valueOf((char) key), lineWidth, ch.h, mPaint);
            lineWidth += ch.w;
        }
    }

    public Bitmap getTexture() {
        return mTexture;
    }

    /*
     * private static Rect rectSrc = new Rect(); private static Rect rectDst = new Rect();
     * 
     * public static void drawLetter(final FontAtlas atlas, final Canvas canvas, final String c) {
     * canvas.drawBitmap(atlas.mTexture, rectSrc, rectDst, atlas.mPaint); }
     */

    /**
     * Stores data about a character such as width and height. This class is not thread safe.
     */
    private final static class Character {
        private static final Rect rect = new Rect();

        public int w;
        public int h;
        public int x;
        public int y;

        public Character(int charID, Paint paint) {
            determineSize(String.valueOf((char) charID), paint);
        }

        public Character(String c, Paint paint) {
            determineSize(c, paint);
        }

        private final void determineSize(final String c, final Paint paint) {
            paint.getTextBounds(c, 0, 1, rect);

            w = rect.right - rect.left;
            h = rect.bottom - rect.top;
        }
    }

    public static class Builder {

        protected final List<CharacterType> types = new ArrayList<CharacterType>();

        protected int mColor = 0xFFFFFFFF;
        protected String mCustomCharacters = "";
        protected float mTextSize = 12;
        protected Typeface mTypeface;

        public FontAtlas build() {
            return new FontAtlas(this);
        }

        public Builder addCharacterType(final CharacterType type) {
            if (types.contains(type))
                throw new RuntimeException(
                        "You can only add a CharacterType once!");

            types.add(type);
            return this;
        }

        public Builder setColor(final int color) {
            mColor = color;
            return this;
        }

        public Builder setCustomCharacters(final String customCharacters) {
            mCustomCharacters = customCharacters;
            return this;
        }

        public Builder setTextSize(float textSize) {
            if (textSize <= 0)
                throw new FontAtlasException(
                        "Text size must be greater than 0!");

            mTextSize = textSize;
            return this;
        }

        public Builder setTypeface(final Typeface typeface) {
            if (typeface == null)
                throw new FontAtlasException("Typeface can not be null.");

            mTypeface = typeface;
            return this;
        }

    }

    public static class FontAtlasException extends RuntimeException {
        private static final long serialVersionUID = 5553942987103836543L;

        public FontAtlasException(final String ex) {
            super(ex);
        }
    }

}

[Davhed]

Oh very nice! I was hoping I wouldn't have to tackle this... so much appreciation here. :+1:

[ToxicBakery]

Yep, it seemed like it might be fun to do.

[MasDennis]

This is great. I'm glad you are picking this up!

[Davhed]

So the packing and retrieval code is working now if you want to play with it a bit.

620

[Davhed]

@ToxicBakery I will try and pick this up tonight/tomorrow. After this week I'm going to be really busy with the new job, so if I can't get it done before then I will be sure to communicate that.