Canvas

class Canvas

User-facing drawing API.

Canvas provides high-level drawing commands that are recorded through a Device. Use save()/restore() for state management and clipRect() for clipping.

Paint-based drawing (advanced)

void draw(Rect r, const Paint &paint): Draw a rectangle with a Paint (supports blend modes, opacity).

void draw(Point p1, Point p2, const Paint &paint): Draw a line with a Paint (supports blend modes, opacity).

Public Functions

explicit Canvas(Device *device)

Construct a Canvas that records into a device.

Parameters:: device – The device to record drawing commands into.

void clipRect(Rect r)

Intersect the current clip with a rectangle.

Parameters:: r – The clipping rectangle.

void concat(const Matrix &m): Post-concatenate a matrix onto the current transform.

void drawImage(std::shared_ptr<Image> image, f32 x, f32 y)

Draw an image at the given position (alpha-blended).

Parameters:

image – Shared pointer to the image.
x – X position.
y – Y position.

void drawLine(Point p1, Point p2, Color c, f32 width = 1.0f)

Draw a line between two points.

Parameters:

p1 – Start point.
p2 – End point.
c – Line color.
width – Line width (default 1.0).

void drawPolyline(const Point *pts, i32 count, Color c, f32 width = 1.0f)

Draw a connected series of line segments.

Parameters:

pts – Array of vertices.
count – Number of points.
c – Line color.
width – Line width (default 1.0).

void drawText(Point p, std::string_view text, Color c)

Draw text at the given position.

Parameters:

p – Position of the text baseline.
text – UTF-8 text to draw.
c – Text color.

void fillCircle(f32 cx, f32 cy, f32 radius, Color c)

Fill a circle with a solid color.

Parameters:

cx – Center X.
cy – Center Y.
radius – Circle radius.
c – Fill color.

void fillRect(Rect r, Color c)

Fill a rectangle with a solid color.

Parameters:

r – The rectangle to fill.
c – Fill color.

void fillRoundRect(Rect r, f32 rx, f32 ry, Color c)

Fill a rounded rectangle with a solid color.

Parameters:

r – The rectangle.
rx – Corner radius in X.
ry – Corner radius in Y.
c – Fill color.

Matrix getMatrix() const: Return the current transform matrix.

void restore(): Restore the most recently saved clip state.

void rotate(f32 radians): Rotate the current transform.

void save(): Save the current clip state onto the stack.

void scale(f32 sx, f32 sy): Scale the current transform.

void setMatrix(const Matrix &m): Replace the current transform with the given matrix.

void strokeCircle(f32 cx, f32 cy, f32 radius, Color c, f32 width = 1.0f)

Stroke a circle outline.

Parameters:

cx – Center X.
cy – Center Y.
radius – Circle radius.
c – Stroke color.
width – Stroke line width (default 1.0).

void strokeRect(Rect r, Color c, f32 width = 1.0f)

Stroke a rectangle outline.

Parameters:

r – The rectangle to stroke.
c – Stroke color.
width – Stroke line width (default 1.0).

void strokeRoundRect(Rect r, f32 rx, f32 ry, Color c, f32 width = 1.0f)

Stroke a rounded rectangle outline.

Parameters:

r – The rectangle.
rx – Corner radius in X.
ry – Corner radius in Y.
c – Stroke color.
width – Stroke line width (default 1.0).

void translate(f32 dx, f32 dy): Translate the current transform.