Kanvas

A lightweight 2D raster graphics and canvas library written in C.

Warning

Kanvas is under active development. The API is unstable and may change without notice.

Features

• Image-backed canvases
• Drawable primitives
• Alpha compositing
• PNG and PPM import/export
• Retained-mode rendering

Example

#include <kvs/kvs.h>

int main(void)
{
    kvs_canvas *canvas = kvs_canvas_create(KVS_SIZE(800, 600));

    kvs_drawable *rect = kvs_drawable_rect(KVS_SIZE(200, 100));

    kvs_drawable_set_color(rect, kvs_color_from_hex_rgba(0xFF000080));
    kvs_canvas_add(canvas, rect, KVS_POS(100, 100));

    kvs_drawable_set_color(rect, kvs_color_from_hex_rgba(0x00FF0080));
    kvs_canvas_add(canvas, rect, KVS_POS(200, 150));

    kvs_drawable_set_color(rect, kvs_color_from_hex_rgba(0x00FFFF80));
    kvs_canvas_add(canvas, rect, KVS_POS(225, 175));

    kvs_canvas_render(canvas);

    kvs_image *out = kvs_canvas_export_to_image(canvas);
    kvs_image_write_png(out, "output.png");
    kvs_image_destroy(out);

    kvs_canvas_destroy(canvas);

    kvs_drawable_destroy(rect);

    return 0;
}

This should result in the following image:

See examples/ for more.

Dependencies

• libpng (optional, disable with KVS_ENABLE_PNG=OFF)

Build

make

Or manually with CMake:

cmake -B build -S .
cmake --build build

Status

Early development. The API is unstable and tests are still being written.

Roadmap

• Image drawables

  • (optional) Use state.color as tint

• Basic color parsing

  • RGBA
  • RGB
  • Hexadecimal

• Drawable bounding boxes

• Rasterize per drawable instead of per pixel

• Moving from LinkedList to Array for Canvas Nodes

• Error handling

  • Error messages
  • Error types
  • Error handling helper macros and functions
  • (optional) errno integration

• Add tests

  • Basic tests
  • Mandatory tests
  • Stability tests
  • ABI tests
  • Additional tests

• Add color constants

  • Basic common color constants
  • (optional) Additional color constants

• Improve documentation and examples

• Blending mode support

  • Normal blending
  • Additive blending
  • Multiply blending
  • Configurable blending

• Clipping/scissor regions

• Image format support

  • PNG
    • Add more detailed PNG metadata
  • JPEG
  • (optional) BMP

• Introduce format-aware color representation

  • Generic pixel format abstraction
  • RGBA8888 support
  • RGB888 support

• Add pixel storage format support

  • BGRA8888
  • RGB565
  • GRAY8
  • Configurable pixel storage format

• Add color space support

  • sRGB
  • (optional) Linear RGB
  • Configurable color space

• Add color model support

  • RGB
  • HSL
  • HSV
  • (optional) Grayscale
  • (optional) CMYK
  • Configurable color model

• Drawable scaling

  • Nearest scaling
  • Bilinear scaling
  • (optional) Bicubic scaling
  • Configurable scaling

• Text drawables

  • FreeType integration
  • HarfBuzz shaping

• Stabilization

  • Stabilize the naming convention
  • Stabilize the standards
  • Stabilize the codebase
  • Stabilize the ABI
  • (optional) Stabilize the Build System

• Boolean drawable operations

  • Union operations
  • Subtract operations
  • Intersection operations
  • Masking operations

• Optimizations

  • Basic optimizations
  • Developer experience optimizations
  • Performance optimizations
  • (optional) Profiling

License

Licensed under the Apache License 2.0.
See LICENSE.