Class Gradient

CodenameOne/src/com/codename1/ui/Gradient.java:47–245

/// `Graphics` or `Style`. `copy()` produces a defensive deep clone for
/// places that must outlive caller mutation (e.g. async paint queues).
public abstract class Gradient implements Paint {
    /// Sentinel returned by `getKind()` for `LinearGradient` instances.
    public static final byte KIND_LINEAR = 0;
    /// Sentinel returned by `getKind()` for `RadialGradient` instances.
    public static final byte KIND_RADIAL = 1;
    /// Sentinel returned by `getKind()` for `ConicGradient` instances.
    public static final byte KIND_CONIC = 2;

    /// Cycle modes mirroring `MultipleGradientPaint.CycleMethod`. Repeated as
    /// byte constants here so that this class (and the .res serializer) does
    /// not pull the enum across the resource format boundary.
    public static final byte CYCLE_NONE = 0;
    public static final byte CYCLE_REPEAT = 1;
    public static final byte CYCLE_REFLECT = 2;

    private int[] colors;
    private float[] positions;
    private byte cycleMethod = CYCLE_NONE;

    // Weak-ref token (Display.createSoftWeakRef) holding a previously rasterized
    // ARGB image for fillGradient's default software path. Sized to the last
    // rectangle the gradient was drawn into; if a different size comes in we
    // re-rasterize. The cache is intentionally weak so it does not pin large
    // bitmaps in memory when the gradient is not actively painting.
    private Object cachedRasterRef;
    private int cachedRasterWidth;
    private int cachedRasterHeight;

    Gradient(int[] colors, float[] positions) {
        if (colors == null || positions == null || colors.length != positions.length || colors.length < 2) {
            throw new IllegalArgumentException("colors and positions must be same length, at least 2");
        }
        this.colors = colors;
        this.positions = positions;
    }

    /// Parses a CSS gradient function string and returns the corresponding
    /// `Gradient` subclass. Supports `linear-gradient`, `radial-gradient`,
    /// `conic-gradient`, and the `repeating-*` variants. Mirrors the syntax
    /// accepted by the build-time CSS compiler so a string copied verbatim
    /// from a `.css` file produces the same gradient at runtime.
    ///
    /// Returns null if `css` is null/empty or does not look like a gradient
    /// function call. Throws `IllegalArgumentException` on hard parse errors
    /// (unknown direction, missing stops, malformed colors).
    public static Gradient parseCss(String css) {
        return CSSGradientParser.parse(css);
    }

    /// Returns one of `KIND_LINEAR`, `KIND_RADIAL`, `KIND_CONIC`.
    public abstract byte getKind();

    /// ARGB stop colors (length >= 2).
    public final int[] getColors() {
        return colors;
    }

    /// Stop positions in [0,1] aligned with `getColors()`.