Generates LibGDX BitmapFont and TextureAtlas at build time with Gradle

build-dependency-1.gradle

buildscript {
    repositories {
        mavenCentral()
        maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
        jcenter()
        mavenLocal()
    }
    dependencies {
        classpath 'de.richsource.gradle.plugins:gwt-gradle-plugin:0.6'
        classpath 'com.android.tools.build:gradle:1.5.0'

        classpath('fr.avianey.androidsvgdrawable:gradle-plugin:3.0.0') {
            // should be excluded to avoid conflict
            exclude group: 'xerces'
        }
    }
}

build-dependency-2.gradle

buildscript {
    repositories {
        mavenCentral()
        maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
        jcenter()
        mavenLocal()
    }
    dependencies {
        classpath 'de.richsource.gradle.plugins:gwt-gradle-plugin:0.6'
        classpath 'com.android.tools.build:gradle:1.5.0'

        classpath "com.badlogicgames.gdx:gdx-tools:1.7.3-SNAPSHOT"
        classpath "com.badlogicgames.gdx:gdx-tools:1.7.3-SNAPSHOT:distribution"
        classpath "com.badlogicgames.gdx:gdx:1.7.3-SNAPSHOT"
        classpath "com.badlogicgames.gdx:gdx-platform:1.7.3-SNAPSHOT:natives-desktop"
        classpath "com.badlogicgames.gdx:gdx-freetype:1.7.3-SNAPSHOT"
        classpath "com.badlogicgames.gdx:gdx-freetype-platform:1.7.3-SNAPSHOT:natives-desktop"

        classpath('fr.avianey.androidsvgdrawable:gradle-plugin:3.0.0') {
            // should be excluded to avoid conflict
            exclude group: 'xerces'
        }
    }
}

build.gradle

compileJava.dependsOn generateATLAS

card1-w64mdpi.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg
   xmlns:dc="http://purl.org/dc/elements/1.1/"
   xmlns:cc="http://creativecommons.org/ns#"
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:svg="http://www.w3.org/2000/svg"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   width="90px" height="140px" viewBox="0 0 90 140"
   version="1.1">
    <rect
       style="fill:#f2f2f2;fill-opacity:1;stroke:none;stroke-opacity:1"
       width="90" height="140" x="0" y="0" rx="8" ry="8" />
    <image x="26" y="82" width="38" height="38" xlink:href="#{suit_.*}" />
    <image x="22" y="16" width="46" height="46" xlink:href="#{rank_.*}" />
    <path
       style="fill:#000000;fill-opacity:0.1254902;stroke:none;stroke-opacity:1"
       d="M 45 0 L 45 140 L 82 140 C 86.432 140 90 136.432 90 132 L 90 8 C 90 3.568 86.432 4.9515947e-17 82 0 L 45 0 z " />
</svg>

card2-w64mdpi.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg
   xmlns:dc="http://purl.org/dc/elements/1.1/"
   xmlns:cc="http://creativecommons.org/ns#"
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:svg="http://www.w3.org/2000/svg"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   width="90px" height="140px" viewBox="0 0 90 140"
   version="1.1">
   <defs>
    <image id="suit" x="25" y="50" width="40" height="40" xlink:href="#{suit_.*}" />
    <image id="rank" x="7" y="7" width="30" height="30" xlink:href="#{rank_.*}" />
   </defs>
    <rect 
       style="fill:#f2f2f2;fill-opacity:1;stroke:none;stroke-opacity:1"
       width="90" height="140" rx="8" ry="8" x="0" y="0" />
    <use xlink:href="#suit" />
    <use xlink:href="#rank" />
    <use xlink:href="#rank" transform="translate(60, 110) rotate(180, 15, 15)"/>
    <path
       style="fill:#000000;fill-opacity:0.1254902;stroke:none;stroke-opacity:1"
       d="M 45 0 L 45 140 L 82 140 C 86.432 140 90 136.432 90 132 L 90 8 C 90 3.568 86.432 4.9515947e-17 82 0 L 45 0 z " />
</svg>

generateATLAS.gradle

import com.badlogic.gdx.tools.texturepacker.TexturePacker
task generateATLAS(dependsOn: [generatePNG, generateFONT]) {
    ext.inputDir = file("${rootProject.projectDir}/android/build/generated/assets")
    ext.outputDir = file("${rootProject.projectDir}/android/assets/")
    inputs.file inputDir
    outputs.dir outputDir
    doLast {
        TexturePacker.process(inputDir.getAbsolutePath(), outputDir.getAbsolutePath(), "skin")
    }
}

generateFONT.gradle

import com.badlogic.gdx.Gdx
import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration
import com.badlogic.gdx.backends.lwjgl.LwjglFiles
import com.badlogic.gdx.backends.lwjgl.LwjglGraphics
import com.badlogic.gdx.backends.lwjgl.LwjglInput
import com.badlogic.gdx.backends.lwjgl.LwjglNativesLoader
import com.badlogic.gdx.backends.lwjgl.LwjglNet
import com.badlogic.gdx.files.FileHandle
import com.badlogic.gdx.graphics.Color
import com.badlogic.gdx.graphics.Pixmap
import com.badlogic.gdx.graphics.g2d.PixmapPacker
import com.badlogic.gdx.graphics.g2d.freetype.FreeTypeFontGenerator
import com.badlogic.gdx.tools.bmfont.BitmapFontWriter
task generateFONT(dependsOn: [initHeadlessLibGDX]) {
    ext.inputFont = file("${rootProject.projectDir}/resources/font/Cantarell-Regular.ttf")
    ext.outputPNGDir = file("${rootProject.projectDir}/android/build/generated/assets/")
    ext.outputPNGName = "cantarell.png"
    ext.outputFNT = file("${rootProject.projectDir}/android/assets/cantarell.fnt")
    ext.padding = 3
    inputs.file inputFont
    outputs.files files(new File(outputPNGDir, outputPNGName), outputFNT)
    doLast {
        outputPNGDir.mkdirs();
        // from https://github.com/libgdx/libgdx/wiki/Hiero#bitmapfontwriter
        FreeTypeFontGenerator.FreeTypeFontParameter param = new FreeTypeFontGenerator.FreeTypeFontParameter();
        param.characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890." /* Hiero.EXTENDED_CHARS */;
        param.size = 32;
        param.color = new Color(1, 1, 1, 1f);
        param.borderWidth = (padding - 1);
        param.borderColor = new Color(0, 0, 0, 1f);
        param.renderCount = 3;
        param.packer = new PixmapPacker(512, 512, Pixmap.Format.RGBA8888, padding, false, new PixmapPacker.SkylineStrategy());

        FreeTypeFontGenerator generator = new FreeTypeFontGenerator(new FileHandle(inputFont.getAbsolutePath()));
        FreeTypeFontGenerator.FreeTypeBitmapFontData data = generator.generateData(param);

        BitmapFontWriter.FontInfo info = new BitmapFontWriter.FontInfo();
        info.padding = new BitmapFontWriter.Padding(padding, padding, padding, padding);
        BitmapFontWriter.writeFont(data, (String[]) [outputPNGName], new FileHandle(outputFNT.getAbsolutePath()), info, 512, 512);
        BitmapFontWriter.writePixmaps(param.packer.getPages(), new FileHandle(outputPNGDir.getAbsolutePath()), "cantarell");
    }
}

generatePNG.gradle

task generatePNG(type: fr.avianey.androidsvgdrawable.gradle.SvgDrawableTask) {
    from = files("${rootProject.projectDir}/resources/svg/svg")
    to = file("${rootProject.projectDir}/android/build/generated/assets")
    createMissingDirectories = true
    overwriteMode = "ifModified"
    outputFormat = "PNG"
    outputType = "raw"
    svgMaskFiles = files("${rootProject.projectDir}/resources/svg/mask")
    svgMaskResourceFiles = files("${rootProject.projectDir}/resources/svg/masked")
    svgMaskedSvgOutputDirectory = file("${rootProject.projectDir}/android/build/generated/svg")
}

initHeadlessLibGDX.gradle

task initHeadlessLibGDX {
    LwjglNativesLoader.load();
    Gdx.graphics = new LwjglGraphics(new LwjglApplicationConfiguration());
    Gdx.files = new LwjglFiles();
    Gdx.input = new LwjglInput();
    Gdx.net = new LwjglNet();
}

LibGDXCardDeck.java

import com.badlogic.gdx.ApplicationListener;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.assets.AssetManager;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.g2d.TextureAtlas;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.Image;
import com.badlogic.gdx.scenes.scene2d.ui.Label;
import com.badlogic.gdx.scenes.scene2d.ui.Skin;
import com.badlogic.gdx.scenes.scene2d.ui.Table;
import com.badlogic.gdx.scenes.scene2d.utils.SpriteDrawable;
import com.badlogic.gdx.utils.Scaling;
import com.badlogic.gdx.utils.viewport.ScreenViewport;

public class CardDeckApplication implements ApplicationListener {

    private static final String[] RANKS = new String [] {"ace", "king", "queen", "jack", "ten", "nine", "eight", "seven", "six", "five", "four", "three", "two"};
    private static final String[] SUITS = new String [] {"spade", "heart", "diamond", "club"};

    private static final int BACKGROUND = 0x0A6B0DFF;
    private static final float r = ((BACKGROUND >> 24) & 0xFF) / ((float) 0xFF);
    private static final float g = ((BACKGROUND >> 16) & 0xFF) / ((float) 0xFF);
    private static final float b = ((BACKGROUND >>  8) & 0xFF) / ((float) 0xFF);

    private Skin skin;
    private Stage stage;
    private TextureAtlas atlas;
    private AssetManager manager;
    private boolean initialized = false;

    @Override
    public void create () {
        manager = new AssetManager();
        manager.load("skin.json", Skin.class);
        manager.load("skin.atlas", TextureAtlas.class);
        stage = new Stage(new ScreenViewport());
        Gdx.input.setInputProcessor(stage);
    }

    @Override
    public void resize(int width, int height) {
        stage.getViewport().update(width, height, true);
    }

    @Override
    public void render() {
        Gdx.gl.glClearColor(r, g, b, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        if (!manager.update()) {
            // still loading
            return;
        } else if (!initialized) {
            // loading done
            initializeAssets();
            initialized = true;
        }

        stage.act(Gdx.graphics.getRawDeltaTime());
        stage.draw();
    }

    @Override
    public void pause() {}

    @Override
    public void resume() {}

    @Override
    public void dispose() {
        initialized = false;
        stage.dispose();
        manager.dispose();
    }

    private void initializeAssets() {
        skin = manager.get("skin.json", Skin.class);
        atlas = manager.get("skin.atlas", TextureAtlas.class);

        // layout
        Table table = new Table();
        table.pad(10);
        table.defaults().space(10);
        table.setFillParent(true);

        // header
        table.row();
        table.add(new Label("LibGDX Card Deck", skin, "cantarell")).colspan(RANKS.length);

        // deck
        for (String suit : SUITS) {
            table.row();
            for (String rank : RANKS) {
                table.add(
                        new Image(
                                new SpriteDrawable(atlas.createSprite(String.format("card_suit_%s_rank_%s", suit, rank))),
                                Scaling.fit));
            }
        }

        stage.addActor(table);
    }
}