How do I create a simple rounded rectangle button in libgdx? - libgdx

Question

How do I create a simple rounded rectangle button in libgdx without using images? The button should have a drop shadow and should handle pressed state. I want it to be programmatic to make it easy to change the color, style later, etc.

Answer 1

My understanding of your question was how to create a rounded rectangle within the program without having to pre-generate any images outside of code.
I was in a similar situation a while back and I ended writing the function below which generates a Pixmap rounded rectangle based on the parameters (all units are in pixels). It also works with differing alpha values to allow for opacity (which is why there are two Pixmap objects used).
The resulting Pixmap can then easily be passed to a constructor of a Texture if you find that easier to render with.
public static Pixmap createRoundedRectangle(int width, int height, int cornerRadius, Color color) {
Pixmap pixmap = new Pixmap(width, height, Pixmap.Format.RGBA8888);
Pixmap ret = new Pixmap(width, height, Pixmap.Format.RGBA8888);
pixmap.setColor(color);
pixmap.fillCircle(cornerRadius, cornerRadius, cornerRadius);
pixmap.fillCircle(width - cornerRadius - 1, cornerRadius, cornerRadius);
pixmap.fillCircle(cornerRadius, height - cornerRadius - 1, cornerRadius);
pixmap.fillCircle(width - cornerRadius - 1, height - cornerRadius - 1, cornerRadius);
pixmap.fillRectangle(cornerRadius, 0, width - cornerRadius * 2, height);
pixmap.fillRectangle(0, cornerRadius, width, height - cornerRadius * 2);
ret.setColor(color);
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
if (pixmap.getPixel(x, y) != 0) ret.drawPixel(x, y);
}
}
pixmap.dispose();
return ret;
}
Using this function it shouldn't be too difficult to make your own wrapper object (e.g. RoundedRectangle) which would re-draw the image every time one of the parameters was changed and needed to be rendered.