Gradients

The ca.corbett.extras.gradient package contains some neat utilities and components related to color gradients. Let's start with a visual demonstration of the capabilities, and then take a look at the code.

We can also render text with a color gradient:

Integration with swing-forms

The ColorField in swing-forms understands both solid colors or color gradients, and allows you to present a form field for user selection of both or of either. You can also use the GradientColorChooser to allow your users to configure a color gradient interactively if you are not working with swing-forms.

Integration with properties

The ColorProperty property in ca.corbett.extras.properties understands both solid colors or color gradients, and allows you to create a property that allows the user to choose either one, or restricts them to one or the other.

Other integrations

If your application uses a JDesktopPane, you may want to consider upgrading to the swing-extras class CustomizableDesktopPane, which allows you to use a gradient as a background.

Of course, the gradient images generated by the GradientUtil are compatible with ImageUtil, so you can easily generate gradient images and save them.

How do I generate gradients?

Everything is driven from the Gradient record, which is very easy to set up:

public record Gradient(GradientType type, Color color1, Color color2) {

    public static Gradient createDefault() {
        return new Gradient(GradientType.VERTICAL_STRIPE, Color.WHITE, Color.BLACK);
    }
}}

This record contains a static factory method for creating a "default" gradient quickly and easily, or you can create a new one by specifying the start and end colors for the gradient, and then selecting a GradientType:

public enum GradientType {

    /**
     * Describes a single gradient that progresses linearly from left to right, color 1 to color 2.
     */
    HORIZONTAL_LINEAR("Horizontal linear"),

    /**
     * Describes a single gradient that progresses linearly from top to bottom, color 1 to color 2.
     */
    VERTICAL_LINEAR("Vertical linear"),

    /**
     * Describes a two-part gradient that progresses linearly from top to center, color 1 to
     * color 2, and then center to bottom, color 2 to color 1. The end result is a gradient that
     * looks like a horizontal stripe running along the center of the image.
     */
    HORIZONTAL_STRIPE("Horizontal stripe"),

    /**
     * Describes a two-part gradient that progresses linearly from left to center, color 1 to
     * color 2, and then center to right, color 2 to color 1. The end result is a gradient that
     * looks like a vertical stripe running up the center of the image.
     */
    VERTICAL_STRIPE("Vertical stripe"),

    /**
     * Represents a single gradient that progresses linearly from top left to bottom right,
     * color 1 to color 2.
     */
    DIAGONAL1("Diagonal 1"),

    /**
     * Represents a single gradient that progresses linearly from bottom left to top right,
     * color 1 to color 2.
     */
    DIAGONAL2("Diagonal 2"),

    /**
     * Describes a four-part gradient that progresses linearly from each corner of the image
     * towards the center, color 1 to color 2.
     */
    STAR("Star");
    
    // ...
}

From there, we can talk to the GradientUtil class, which has methods for actually rendering the gradient:

public static BufferedImage createGradientImage(Gradient conf, int width, int height) {...}
public static void fill(Gradient conf, Graphics2D graphics, int x1, int y1, int width, int height) {...}
public static void drawRect(Gradient conf, Graphics2D graphics, int x1, int y1, int width, int height) {...}
public static void drawString(Gradient conf, Graphics2D graphics, int textX, int textY, String string) {...}
public static void drawString(Gradient conf, Graphics2D graphics, int gradientX1, int gradientY1, 
                              int gradientX2, int gradientY2, int textX, int textY, String string) {...}

We see that every method requires a Gradient record which describes the gradient to be rendered, and then there are options to control the size and shape of the gradient. Very easy to use, and can produce quite nice results!