Crate epaint

A simple 2D graphics library for turning simple 2D shapes and text into textured triangles.

Made for egui.

Create some Shape:s and pass them to tessellate_shapes to generate Mesh:es that you can then paint using some graphics API of your choice (e.g. OpenGL).

Coordinate system

The left-top corner of the screen is (0.0, 0.0), with X increasing to the right and Y increasing downwards.

epaint uses logical points as its coordinate system. Those related to physical pixels by the pixels_per_point scale factor. For example, a high-dpi screeen can have pixels_per_point = 2.0, meaning there are two physical screen pixels for each logical point.

Angles are in radians, and are measured clockwise from the X-axis, which has angle=0.

Feature flags

• bytemuck — bytemuck enables you to cast Vertex to &[u8].

• cint — cint enables interoperability with other color libraries.

• color-hex — Enable the hex_color macro.

• deadlock_detection — This will automatically detect deadlocks due to double-locking on the same thread. If your app freezes, you may want to enable this! Only affects mutex::RwLock (which epaint and egui uses a lot).

• default_fonts (enabled by default) — If set, epaint will use include_bytes! to bundle some fonts. If you plan on specifying your own fonts you may disable this feature.

• extra_debug_asserts — Enable additional checks if debug assertions are enabled (debug builds).

• extra_asserts — Always enable additional checks.

• log — Turn on the log feature, that makes egui log some errors using the log crate.

• mint — mint enables interoperability with other math libraries such as glam and nalgebra.

• puffin — Enable profiling with the puffin crate.

  Only enabled on native, because of the low resolution (1ms) of clocks in browsers.

• rayon — Enable parallel tessellation using rayon.

  This can help performance for graphics-intense applications.

• serde — Allow serialization using serde.

• unity — Change Vertex layout to be compatible with unity

Optional dependencies

• document-features — Enable this when generating docs.
• serde — Allow serialization using serde .

Re-exports

• pub use self::image::ColorImage;
• pub use self::image::FontImage;
• pub use self::image::ImageData;
• pub use self::image::ImageDelta;
• pub use self::stats::PaintStats;
• pub use self::tessellator::TessellationOptions;
• pub use self::tessellator::Tessellator;
• pub use self::text::FontFamily;
• pub use self::text::FontId;
• pub use self::text::Fonts;
• pub use self::text::Galley;
• pub use self::textures::TextureManager;
• pub use tessellator::tessellate_shapes;
  Deprecated
• pub use ahash;
• pub use ecolor;
• pub use emath;

Modules

• image
• mutex
  Helper module that adds extra checks when the deadlock_detection feature is turned on.
• shape_transform
• stats
  Collect statistics about what is being painted.
• tessellator
  Converts graphics primitives into textured triangles.
• text
  Everything related to text, fonts, text layout, cursors etc.
• textures
• util

Macros

• epaint_assert
  An assert that is only active when epaint is compiled with the extra_asserts feature or with the extra_debug_asserts feature in debug builds.
• hex_color
  Construct a crate::Color32 from a hex RGB or RGBA string.

Structs

• CircleShape
  How to paint a circle.
• ClippedPrimitive
  A Mesh or PaintCallback within a clip rectangle.
• ClippedShape
  A Shape within a clip rectangle.
• Color32
  This format is used for space-efficient color representation (32 bits).
• CubicBezierShape
  A cubic Bézier Curve.
• EllipseShape
  How to paint an ellipse.
• Hsva
  Hue, saturation, value, alpha. All in the range [0, 1]. No premultiplied alpha.
• HsvaGamma
  Like Hsva but with the v value (brightness) being gamma corrected so that it is somewhat perceptually even.
• Margin
  A value for all four sides of a rectangle, often used to express padding or spacing.
• Mesh
  Textured triangles in two dimensions.
• Mesh16
  A version of Mesh that uses 16-bit indices.
• PaintCallback
  If you want to paint some 3D shapes inside an egui region, you can use this.
• PaintCallbackInfo
  Information passed along with PaintCallback (Shape::Callback).
• PathShape
  A path which can be stroked and/or filled (if closed).
• Pos2
  A position on screen.
• QuadraticBezierShape
  A quadratic Bézier Curve.
• Rect
  A rectangular region of space.
• RectShape
  How to paint a rectangle.
• Rgba
  0-1 linear space RGBA color with premultiplied alpha.
• Rounding
  How rounded the corners of things should be
• Shadow
  The color and fuzziness of a fuzzy shape.
• Stroke
  Describes the width and color of a line.
• TextShape
  How to paint some text on screen.
• TextureAtlas
  Contains font data in an atlas, where each character occupied a small rectangle.
• TextureHandle
  Used to paint images.
• Vec2
  A vector has a direction and length. A Vec2 is often used to represent a size.
• Vertex

Enums

• Primitive
  A rendering primitive - either a Mesh or a PaintCallback.
• Shape
  A paint primitive such as a circle or a piece of text. Coordinates are all screen space points (not physical pixels).
• TextureId
  What texture to use in a Mesh mesh.

Constants

• HAS_RAYON
  Was epaint compiled with the rayon feature?
• WHITE_UV
  The UV coordinate of a white region of the texture mesh. The default egui texture has the top-left corner pixel fully white. You need need use a clamping texture sampler for this to work (so it doesn’t do bilinear blending with bottom right corner).

Functions

• pos2
  pos2(x, y) == Pos2::new(x, y)
• vec2
  vec2(x, y) == Vec2::new(x, y)