JavaCPP Presets for Skia

Introduction

This directory contains the JavaCPP Presets module for:

• Mono/Skia 2.80.1 https://github.com/mono/skia

Please refer to the parent README.md file for more detailed information about the JavaCPP Presets.

Documentation

Java API documentation is available here:

• http://bytedeco.org/javacpp-presets/skia/apidocs/

∗ Bindings are currently available only for the C API of Mono/Skia.

Sample Usage

Here is a simple example of Mono/Skia ported to Java from this C source file:

• https://github.com/mono/skia/blob/xamarin-mobile-bindings/experimental/c-api-example/skia-c-example.c

We can use Maven 3 to download and install automatically all the class files as well as the native binaries. To run this sample code, after creating the pom.xml and SkiaCExample.java source files below, simply execute on the command line:

 $ mvn compile exec:java

The pom.xml build file

<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.bytedeco.skia</groupId>
    <artifactId>skiacexample</artifactId>
    <version>1.5.4</version>
    <properties>
        <exec.mainClass>SkiaCExample</exec.mainClass>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>skia-platform</artifactId>
            <version>2.80.1-1.5.4</version>
        </dependency>
    </dependencies>
    <build>
        <sourceDirectory>.</sourceDirectory>
    </build>
</project>

The SkiaCExample.java source file

import java.io.FileOutputStream;
import java.io.IOException;

import org.bytedeco.javacpp.*;

import org.bytedeco.skia.*;
import static org.bytedeco.skia.global.Skia.*;

public class SkiaCExample {
    private static sk_surface_t makeSurface(int w, int h) {
        sk_imageinfo_t info = new sk_imageinfo_t();
        info.width(w);
        info.height(h);
        info.colorType(BGRA_8888_SK_COLORTYPE);
        info.alphaType(PREMUL_SK_ALPHATYPE);
        return sk_surface_new_raster(info, 0, null);
    }

    private static void emitPng(String path, sk_surface_t surface) throws IOException {
        sk_image_t image = sk_surface_new_image_snapshot(surface);
        sk_data_t data = sk_image_encode(image);
        sk_image_unref(image);
        Pointer pointer = sk_data_get_data(data).limit(sk_data_get_size(data));
        FileOutputStream out = new FileOutputStream(path);
        out.getChannel().write(pointer.asByteBuffer());
        out.close();
    }

    private static void draw(sk_canvas_t canvas) {
        sk_paint_t fill = sk_paint_new();
        sk_paint_set_color(fill, 0xFF0000FF);
        sk_canvas_draw_paint(canvas, fill);

        sk_paint_set_color(fill, 0xFF00FFFF);
        sk_rect_t rect = new sk_rect_t();
        rect.left(100.0f);
        rect.top(100.0f);
        rect.right(540.0f);
        rect.bottom(380.0f);
        sk_canvas_draw_rect(canvas, rect, fill);

        sk_paint_t stroke = sk_paint_new();
        sk_paint_set_color(stroke, 0xFFFF0000);
        sk_paint_set_antialias(stroke, true);
        sk_paint_set_style(stroke, STROKE_SK_PAINT_STYLE);
        sk_paint_set_stroke_width(stroke, 5.0f);
        sk_path_t path = sk_path_new();

        sk_path_move_to(path, 50.0f, 50.0f);
        sk_path_line_to(path, 590.0f, 50.0f);
        sk_path_cubic_to(path, -490.0f, 50.0f, 1130.0f, 430.0f, 50.0f, 430.0f);
        sk_path_line_to(path, 590.0f, 430.0f);
        sk_canvas_draw_path(canvas, path, stroke);

        sk_paint_set_color(fill, 0x8000FF00);
        sk_rect_t rect2 = new sk_rect_t();
        rect2.left(120.0f);
        rect2.top(120.0f);
        rect2.right(520.0f);
        rect2.bottom(360.0f);
        sk_canvas_draw_oval(canvas, rect2, fill);

        sk_path_delete(path);
        sk_paint_delete(stroke);
        sk_paint_delete(fill);
    }

    public static void main (String[] args) throws IOException {
        sk_surface_t surface = makeSurface(640, 480);
        sk_canvas_t canvas = sk_surface_get_canvas(surface);
        draw(canvas);
        emitPng("skia-c-example.png", surface);
        sk_surface_unref(surface);
    }
}