shared/java/PaintFilterCanvas.java

package org.jetbrains.skija;

import java.lang.ref.*;
import org.jetbrains.annotations.*;
import org.jetbrains.skija.impl.*;

/**
 * A utility proxy base class for implementing draw/paint filters.
 */
public abstract class PaintFilterCanvas extends Canvas {
    static { Library.staticLoad(); }
    
    /**
     * @param unrollDrawable if needed to filter nested drawable content using this canvas (for drawables there is no paint to filter)
     */
    public PaintFilterCanvas(@NotNull Canvas canvas, boolean unrollDrawable) {
        super(_nMake(Native.getPtr(canvas), unrollDrawable), true, canvas);
        Stats.onNativeCall();
        _nAttachToJava(_ptr);
        Stats.onNativeCall();
        Reference.reachabilityFence(canvas);
    }

    /**
     *  Called with the paint that will be used to draw the specified type.
     *  The implementation may modify the paint as they wish.
     *
     *  The result boolean is used to determine whether the draw op is to be
     *  executed (true) or skipped (false).
     *
     *  Note: The base implementation calls onFilter() for top-level/explicit paints only.
     */
    public abstract boolean onFilter(@NotNull Paint paint);

    public final boolean onFilter(long paintPtr) {
        Paint paint = new Paint(paintPtr, false);
        return onFilter(paint);
    }

    public        native void _nAttachToJava(long canvasPtr);
    public static native long _nMake(long canvasPtr, boolean unrollDrawable);
}