Java bitmap font: blitting 1-bit image with different colors

Question

I\'d like to implement a simple bitmap font drawing in Java AWT-based application. Application draws on a Graphics object, where I\'d like to implement a simple

Answer 1

Okay, looks like I've found the best solution. The key to success was accessing raw pixel arrays in underlying AWT structures. Initialization goes something like that:

public class ConsoleCanvas extends Canvas {
    protected BufferedImage buffer;
    protected int w;
    protected int h;
    protected int[] data;

    public ConsoleCanvas(int w, int h) {
        super();
        this.w = w;
        this.h = h;
    }

    public void initialize() {
        data = new int[h * w];

        // Fill data array with pure solid black
        Arrays.fill(data, 0xff000000);

        // Java's endless black magic to get it working
        DataBufferInt db = new DataBufferInt(data, h * w);
        ColorModel cm = ColorModel.getRGBdefault();
        SampleModel sm = cm.createCompatibleSampleModel(w, h);
        WritableRaster wr = Raster.createWritableRaster(sm, db, null);
        buffer = new BufferedImage(cm, wr, false, null);
    }

    @Override
    public void paint(Graphics g) {
        update(g);
    }

    @Override
    public void update(Graphics g) {
        g.drawImage(buffer, 0, 0, null);
    }
}

After this one, you've got both a buffer that you can blit on canvas updates and underlying array of ARGB 4-byte ints - data.

Single character can be drawn like that:

private void putChar(int dx, int dy, char ch, int fore, int back) {
    int charIdx = 0;
    int canvasIdx = dy * canvas.w + dx;
    for (int i = 0; i < CHAR_HEIGHT; i++) {
        for (int j = 0; j < CHAR_WIDTH; j++) {
            canvas.data[canvasIdx] = font[ch][charIdx] ? fore : back;
            charIdx++;
            canvasIdx++;
        }
        canvasIdx += canvas.w - CHAR_WIDTH;
    }
}

This one uses a simple boolean[][] array, where first index chooses character and second index iterates over raw 1-bit character pixel data (true => foreground, false => background).

I'll try to publish a complete solution as a part of my Java terminal emulation class set soon.

This solution benchmarks for impressive 26007 strings / sec or 1846553 chars / sec - that's 2.3x times faster than previous best non-colorized drawImage().