Add example using openrndr from Java

[jbellis]

Motivation

Edwin asked for this

Proposed Solution

package jbe.openrndr.run;

import java.nio.ByteBuffer;
import java.security.SecureRandom;

import org.openrndr.ApplicationKt;
import org.openrndr.Configuration;
import org.openrndr.Program;
import org.openrndr.color.ColorRGBa;
import org.openrndr.extra.noise.SimplexNoise1DKt;

import static java.lang.Math.abs;

public class OpenrndrJavaDemo extends Program {
    private int seed;

    @Override
    public void setup() {
        super.setup();
        seed = ByteBuffer.wrap(SecureRandom.getSeed(4)).getInt();
    }

    @Override
    public void draw() {
        drawer.clear(ColorRGBa.Companion.getPINK());
        drawer.setFill(ColorRGBa.Companion.getWHITE());
        drawer.circle(drawer.getBounds().getCenter(),
                      abs(SimplexNoise1DKt.simplex(seed, getSeconds())) * getHeight() * 0.5);
    }

    public static void main(String[] args) {
        var c = new Configuration();
        c.setWidth(1200);
        c.setHeight(1200);
        ApplicationKt.application(new OpenrndrJavaDemo(), c);
    }
}

Detailed Design

This is a short example similar to the first one from the Guide that illustrates a few principles:

• openrndr tends to prefer closures to inheritance, but this is not as idiomatic in Java as in Kotlin. Structuring around Program setup and draw methods lets us offer a structure familiar to Java users (even more familiar if they come from Processing).
• Kotlin companion objects are exposed to Java via a .Companion static field
• Top-level functions are exposed to Java as static methods in a class with Kt appended, so Application's functions are found in ApplicationKt; SimplexNoise1D's functions are found in SimplexNoise1DKt.

Open Questions

No response

Help make it happen!

• [X] I am willing to submit a PR to implement this change.
• [ ] I am willing to submit a PR to implement this change, but would need some guidance.
• [ ] I am not willing to submit a PR to implement this change.

[jbellis]

Here is a direct translation of the Kotlin template that does not require https://github.com/openrndr/openrndr/pull/270:

import kotlin.Unit;
import org.openrndr.ApplicationBuilderKt;
import org.openrndr.ExtensionStage;
import org.openrndr.color.ColorRGBa;
import org.openrndr.draw.ColorTransformsKt;
import org.openrndr.draw.FontMapKt;

import static java.lang.Math.cos;
import static java.lang.Math.sin;
import static org.openrndr.draw.ColorBufferJVM.loadImage;
import static org.openrndr.draw.LoadFontKt.loadFont;

public class TemplateProgram {
    public static void main(String[] args) {
        ApplicationBuilderKt.application(build -> {
            build.configure(c -> {
                c.setWidth(768);
                c.setHeight(576);
                return Unit.INSTANCE;
            });

            build.program((p, continuation) -> {
                var image = loadImage("data/images/pm5544.png", null, null);
                var font = loadFont(p,
                                    "data/fonts/default.otf",
                                    64.0,
                                    FontMapKt.getDefaultFontmapCharacterSet(),
                                    p.drawer.getContext().getContentScale());

                p.extend(ExtensionStage.BEFORE_DRAW, userDraw -> {
                    p.drawer.getDrawStyle().setColorMatrix(ColorTransformsKt.tint(ColorRGBa.Companion.getWHITE().shade(0.2)));
                    p.drawer.image(image);

                    p.drawer.setFill(ColorRGBa.Companion.getPINK());
                    p.drawer.circle(cos(p.getSeconds()) * p.getWidth() / 2.0 + p.getWidth() / 2.0,
                                       sin(0.5 * p.getSeconds()) * p.getHeight() / 2.0 + p.getHeight() / 2.0, 140.0);

                    p.drawer.setFontMap(font);
                    p.drawer.setFill(ColorRGBa.Companion.getWHITE());
                    p.drawer.text("OPENRNDR", p.getWidth() / 2.0, p.getHeight() / 2.0);

                    return Unit.INSTANCE;
                });
                return Unit.INSTANCE;
            });
            return Unit.INSTANCE;
        });
    }
}

[edwinRNDR]

Closing this issue. OPENRNDR has become more dependent on Kotlin language features and support for Java is not in enough in demand to justify the effort.