ClayJ is a high performance, zero dependency, UI layout library for Java.
It is a pure Java port of Clay, designed to be framework and backend agnostic.
This project would not exist without the work of the following developers:
- Nic Barker (nicbarker) - The creator of the original Clay C library. ClayJ directly implements the layout mathematics and architectural philosophy designed by Nic.
- Patricio Whittingslow (soypat) - The author of Glay, a Go port of Clay.
ClayJ is available on Maven Central.
<dependency>
<groupId>io.github.christechs</groupId>
<artifactId>ClayJ</artifactId>
<version>1.0.0</version>
</dependency>implementation 'io.github.christechs:ClayJ:1.0.0'implementation("io.github.christechs:ClayJ:1.0.0")Since ClayJ is backend agnostic, you need to tell it how to measure text and how to handle errors. Everything else relies on a simple beginLayout() and endLayout() loop.
Call ClayJ.initialize() once at the start of your application. You must also provide a MeasureTextFunction so the engine knows how wide your strings are before rendering them.
import io.github.christechs.clayj.math.Dimensions;
import static io.github.christechs.clayj.ClayJ.*;
// Initialize with max elements, max text cache, and window dimensions
initialize(8192, 8192, new Dimensions(1920, 1080));
// Set the Error Handler
setErrorHandler(errorType -> {
System.err.println("ClayJ Error [" + errorType + "]: " + errorType.getDefaultMessage());
});
// Set the Text Measurement
setMeasureTextFunction((text, start, len, config, outDimensions) -> {
float width = MyRenderer.measureText(text.subSequence(start, start + len), config.fontSize);
float height = config.lineHeight > 0 ? config.lineHeight : config.fontSize;
outDimensions.set(width, height);
});In your application's render loop, you update the pointer/scroll state, declare your UI tree using the builder methods, and then iterate over the resulting render commands.
import io.github.christechs.clayj.enums.*;
import io.github.christechs.clayj.LayoutResults;
import static io.github.christechs.clayj.ClayJ.*;
public void render(float deltaTime) {
setLayoutDimensions(windowWidth, windowHeight);
setPointerState(new Vector2(mouseX, mouseY), isMouseDown);
updateScrollContainers(true, new Vector2(scrollDeltaX, scrollDeltaY), deltaTime);
beginLayout();
el(decl().id("Root").bg(15, 15, 18)
.layout(layout().sizing(SizingType.GROW, 0, SizingType.GROW, 0)
.dir(LayoutDirection.TOP_TO_BOTTOM)
.padding(16).gap(8)), () -> {
el(decl().id("Header").bg(38, 38, 45)
.layout(layout().sizing(SizingType.GROW, 0, SizingType.FIXED, 50)
.align(LayoutAlignmentX.CENTER, LayoutAlignmentY.CENTER)), () -> {
text("Welcome to ClayJ", txt().size(24).color(245, 245, 250));
});
boolean isHovered = pointerOver("MyButton");
el(decl().id("MyButton").bg(isHovered ? 130 : 100, 140, 255)
.layout(layout().sizing(SizingType.FIT, 0, SizingType.FIXED, 40)
.padding(16, 8)), () -> {
text("Click Me!", txt().size(16).color(255, 255, 255));
});
});
LayoutResults results = endLayout();
renderUI(results);
}ClayJ outputs a flat array of RenderCommand objects. You loop through these and draw them whatever backend you prefer.
private void renderUI(LayoutResults results) {
for (int i = 0; i < results.length(); i++) {
RenderCommand cmd = results.get(i);
switch (cmd.commandType) {
case RECTANGLE:
MyRenderer.drawRect(cmd.boundingBox, cmd.renderData.backgroundColor, cmd.renderData.cornerRadius);
break;
case TEXT:
MyRenderer.drawText(cmd.renderData.text, cmd.boundingBox.x, cmd.boundingBox.y, cmd.renderData.textColor);
break;
case SCISSOR_START:
MyRenderer.pushClip(cmd.boundingBox);
break;
case SCISSOR_END:
MyRenderer.popClip();
break;
// Handle IMAGE, BORDER, and CUSTOM
}
}
}ClayJ is licensed under the zlib/libpng license.
Copyright (c) 2026 Christian Steenkamp
This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the
use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software in a
product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not
be misrepresented as being the original software.
3. This notice may not be removed or altered from any source
distribution.
Clay (Original C Library)
- Copyright (c) 2024 Nic Barker
- Licensed under the zlib/libpng license.
Glay (Go Port)
BSD 3-Clause License
Copyright (c) 2023, Patricio Whittingslow
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
-
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
-
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
-
Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.