---
title: "Canvas"
description: ""
type: "interface"
---

<div class='type'>Interface</div>


<a id='references'></a>

<div class='sourceset sourceset-common'>Common</div>



```kotlin
@JvmDefaultWithCompatibility
interface Canvas
```

## Functions

```kotlin
fun save()
```


Saves a copy of the current transform and clip on the save stack.

Call `restore` to pop the save stack.

See also:
* `saveLayer`, which does the same thing but additionally also groups the commands done until the matching `restore`.


```kotlin
fun restore()
```


Pops the current save stack, if there is anything to pop. Otherwise, does nothing.

Use `save` and `saveLayer` to push state onto the stack.

If the state was pushed with with `saveLayer`, then this call will also cause the new layer
to be composited into the previous layer.


```kotlin
fun saveLayer(bounds: Rect, paint: Paint)
```


Saves a copy of the current transform and clip on the save stack, and then creates a new
group which subsequent calls will become a part of. When the save stack is later popped, the
group will be flattened into a layer and have the given `paint`'s `Paint.colorFilter` and
`Paint.blendMode` applied.

This lets you create composite effects, for example making a group of drawing commands
semi-transparent. Without using `saveLayer`, each part of the group would be painted
individually, so where they overlap would be darker than where they do not. By using
`saveLayer` to group them together, they can be drawn with an opaque color at first, and then
the entire group can be made transparent using the `saveLayer`'s paint.

Call `restore` to pop the save stack and apply the paint to the group.

## Using saveLayer with clips

When a rectangular clip operation (from `clipRect`) is not axis-aligned with the raster
buffer, or when the clip operation is not rectalinear (e.g. because it is a rounded rectangle
clip created by `clipPath`, the edge of the clip needs to be anti-aliased.

If two draw calls overlap at the edge of such a clipped region, without using `saveLayer`,
the first drawing will be anti-aliased with the background first, and then the second will be
anti-aliased with the result of blending the first drawing and the background. On the other
hand, if `saveLayer` is used immediately after establishing the clip, the second drawing will
cover the first in the layer, and thus the second alone will be anti-aliased with the
background when the layer is clipped and composited (when `restore` is called).

(Incidentally, rather than using `clipPath` with a rounded rectangle defined in a path to
draw rounded rectangles like this, prefer the `drawRoundRect` method.

## Performance considerations

Generally speaking, `saveLayer` is relatively expensive.

There are a several different hardware architectures for GPUs (graphics processing units, the
hardware that handles graphics), but most of them involve batching commands and reordering
them for performance. When layers are used, they cause the rendering pipeline to have to
switch render target (from one layer to another). Render target switches can flush the GPU's
command buffer, which typically means that optimizations that one could get with larger
batching are lost. Render target switches also generate a lot of memory churn because the GPU
needs to copy out the current frame buffer contents from the part of memory that's optimized
for writing, and then needs to copy it back in once the previous render target (layer) is
restored.

See also:
* `save`, which saves the current state, but does not create a new layer for subsequent commands.
* `BlendMode`, which discusses the use of `Paint.blendMode` with `saveLayer`.


```kotlin
fun translate(dx: Float, dy: Float)
```


Add a translation to the current transform, shifting the coordinate space horizontally by the
first argument and vertically by the second argument.


```kotlin
fun scale(sx: Float, sy: Float = sx)
```


Add an axis-aligned scale to the current transform, scaling by the first argument in the
horizontal direction and the second in the vertical direction.

If `sy` is unspecified, `sx` will be used for the scale in both directions.

#### Parameters

| | |
| --- | --- |
| sx | The amount to scale in X |
| sy | The amount to scale in Y |



```kotlin
fun rotate(degrees: Float)
```


Add a rotation (in degrees clockwise) to the current transform

#### Parameters

| | |
| --- | --- |
| degrees | to rotate clockwise |



```kotlin
fun skew(sx: Float, sy: Float)
```


Add an axis-aligned skew to the current transform, with the first argument being the
horizontal skew in degrees clockwise around the origin, and the second argument being the
vertical skew in degrees clockwise around the origin.


```kotlin
fun skewRad(sxRad: Float, syRad: Float)
```


Add an axis-aligned skew to the current transform, with the first argument being the
horizontal skew in radians clockwise around the origin, and the second argument being the
vertical skew in radians clockwise around the origin.


```kotlin
fun concat(matrix: Matrix)
```


Multiply the current transform by the specified 4⨉4 transformation matrix specified as a list
of values in column-major order.


```kotlin
fun clipRect(rect: Rect, clipOp: ClipOp = ClipOp.Intersect) =
        clipRect(rect.left, rect.top, rect.right, rect.bottom, clipOp)
```


Reduces the clip region to the intersection of the current clip and the given rectangle.

Use `ClipOp.Difference` to subtract the provided rectangle from the current clip.


```kotlin
fun clipRect(
        left: Float,
        top: Float,
        right: Float,
        bottom: Float,
        clipOp: ClipOp = ClipOp.Intersect,
    )
```


Reduces the clip region to the intersection of the current clip and the given bounds.

Use `ClipOp.Difference` to subtract the provided rectangle from the current clip.

#### Parameters

| | |
| --- | --- |
| left | Left bound of the clip region |
| top | Top bound of the clip region |
| right | Right bound of the clip region |
| bottom | Bottom bound of the clip region |
| clipOp | Clipping operation to conduct on the given bounds, defaults to `ClipOp.Intersect` |



```kotlin
fun clipPath(path: Path, clipOp: ClipOp = ClipOp.Intersect)
```


Reduces the clip region to the intersection of the current clip and the given `Path`.


```kotlin
fun drawLine(p1: Offset, p2: Offset, paint: Paint)
```


Draws a line between the given points using the given paint. The line is stroked, the value
of the `Paint.style` is ignored for this call.

The `p1` and `p2` arguments are interpreted as offsets from the origin.


```kotlin
fun drawRect(rect: Rect, paint: Paint) =
        drawRect(
            left = rect.left,
            top = rect.top,
            right = rect.right,
            bottom = rect.bottom,
            paint = paint,
        )
```


Draws a rectangle with the given `Paint`. Whether the rectangle is filled or stroked (or
both) is controlled by `Paint.style`.


```kotlin
fun drawRect(left: Float, top: Float, right: Float, bottom: Float, paint: Paint)
```


Draws a rectangle with the given `Paint`. Whether the rectangle is filled or stroked (or
both) is controlled by `Paint.style`.

#### Parameters

| | |
| --- | --- |
| left | The left bound of the rectangle |
| top | The top bound of the rectangle |
| right | The right bound of the rectangle |
| bottom | The bottom bound of the rectangle |
| paint | Paint used to color the rectangle with a fill or stroke |



```kotlin
fun drawRoundRect(
        left: Float,
        top: Float,
        right: Float,
        bottom: Float,
        radiusX: Float,
        radiusY: Float,
        paint: Paint,
    )
```


Draws a rounded rectangle with the given `Paint`. Whether the rectangle is filled or stroked
(or both) is controlled by `Paint.style`.


```kotlin
fun drawOval(rect: Rect, paint: Paint) =
        drawOval(
            left = rect.left,
            top = rect.top,
            right = rect.right,
            bottom = rect.bottom,
            paint = paint,
        )
```


Draws an axis-aligned oval that fills the given axis-aligned rectangle with the given
`Paint`. Whether the oval is filled or stroked (or both) is controlled by `Paint.style`.


```kotlin
fun drawOval(left: Float, top: Float, right: Float, bottom: Float, paint: Paint)
```


Draws an axis-aligned oval that fills the given bounds provided with the given `Paint`.
Whether the rectangle is filled or stroked (or both) is controlled by `Paint.style`.

#### Parameters

| | |
| --- | --- |
| left | The left bound of the rectangle |
| top | The top bound of the rectangle |
| right | The right bound of the rectangle |
| bottom | The bottom bound of the rectangle |
| paint | Paint used to color the rectangle with a fill or stroke |



```kotlin
fun drawCircle(center: Offset, radius: Float, paint: Paint)
```


Draws a circle centered at the point given by the first argument and that has the radius
given by the second argument, with the `Paint` given in the third argument. Whether the
circle is filled or stroked (or both) is controlled by `Paint.style`.


```kotlin
fun drawArc(
        rect: Rect,
        startAngle: Float,
        sweepAngle: Float,
        useCenter: Boolean,
        paint: Paint,
    ) =
        drawArc(
            left = rect.left,
            top = rect.top,
            right = rect.right,
            bottom = rect.bottom,
            startAngle = startAngle,
            sweepAngle = sweepAngle,
            useCenter = useCenter,
            paint = paint,
        )
```


Draw an arc scaled to fit inside the given rectangle. It starts from startAngle degrees
around the oval up to startAngle + sweepAngle degrees around the oval, with zero degrees
being the point on the right hand side of the oval that crosses the horizontal line that
intersects the center of the rectangle and with positive angles going clockwise around the
oval. If useCenter is true, the arc is closed back to the center, forming a circle sector.
Otherwise, the arc is not closed, forming a circle segment.

This method is optimized for drawing arcs and should be faster than `Path.arcTo`.


```kotlin
fun drawArc(
        left: Float,
        top: Float,
        right: Float,
        bottom: Float,
        startAngle: Float,
        sweepAngle: Float,
        useCenter: Boolean,
        paint: Paint,
    )
```


Draw an arc scaled to fit inside the given rectangle. It starts from startAngle degrees
around the oval up to startAngle + sweepAngle degrees around the oval, with zero degrees
being the point on the right hand side of the oval that crosses the horizontal line that
intersects the center of the rectangle and with positive angles going clockwise around the
oval. If useCenter is true, the arc is closed back to the center, forming a circle sector.
Otherwise, the arc is not closed, forming a circle segment.

This method is optimized for drawing arcs and should be faster than `Path.arcTo`.

#### Parameters

| | |
| --- | --- |
| left | Left bound of the arc |
| top | Top bound of the arc |
| right | Right bound of the arc |
| bottom | Bottom bound of the arc |
| startAngle | Starting angle of the arc relative to 3 o'clock |
| sweepAngle | Sweep angle in degrees clockwise |
| useCenter | Flag indicating whether or not to include the center of the oval in the |
| paint | Paint used to draw the arc. arc, and close it if it is being stroked. This will draw a wedge. |



```kotlin
fun drawArcRad(
        rect: Rect,
        startAngleRad: Float,
        sweepAngleRad: Float,
        useCenter: Boolean,
        paint: Paint,
    )
```


Draw an arc scaled to fit inside the given rectangle. It starts from startAngle radians
around the oval up to startAngle + sweepAngle radians around the oval, with zero radians
being the point on the right hand side of the oval that crosses the horizontal line that
intersects the center of the rectangle and with positive angles going clockwise around the
oval. If useCenter is true, the arc is closed back to the center, forming a circle sector.
Otherwise, the arc is not closed, forming a circle segment.

This method is optimized for drawing arcs and should be faster than `Path.arcTo`.


```kotlin
fun drawPath(path: Path, paint: Paint)
```


Draws the given `Path` with the given `Paint`. Whether this shape is filled or stroked (or
both) is controlled by `Paint.style`. If the path is filled, then subpaths within it are
implicitly closed (see `Path.close`).


```kotlin
fun drawImage(image: ImageBitmap, topLeftOffset: Offset, paint: Paint)
```


Draws the given `ImageBitmap` into the canvas with its top-left corner at the given `Offset`.
The image is composited into the canvas using the given `Paint`.


```kotlin
fun drawImageRect(
        image: ImageBitmap,
        srcOffset: IntOffset = IntOffset.Zero,
        srcSize: IntSize = IntSize(image.width, image.height),
        dstOffset: IntOffset = IntOffset.Zero,
        dstSize: IntSize = srcSize,
        paint: Paint,
    )
```


Draws the subset of the given image described by the `src` argument into the canvas in the
axis-aligned rectangle given by the `dst` argument.

This might sample from outside the `src` rect by up to half the width of an applied filter.

#### Parameters

| | |
| --- | --- |
| image | ImageBitmap to draw |
| srcOffset: | Optional offset representing the top left offset of the source image to draw, this defaults to the origin of `image` |
| srcSize: | Optional dimensions of the source image to draw relative to `srcOffset`, this defaults the width and height of `image` |
| dstOffset: | Offset representing the top left offset of the destination image to draw |
| dstSize: | Dimensions of the destination to draw |
| paint | Paint used to composite the `ImageBitmap` pixels into the canvas |



```kotlin
fun drawPoints(pointMode: PointMode, points: List<Offset>, paint: Paint)
```


Draws a sequence of points according to the given `PointMode`.

The `points` argument is interpreted as offsets from the origin.

See also:
* `drawRawPoints`, which takes `points` as a `FloatArray` rather than a `List<Offset>`.


```kotlin
fun drawRawPoints(pointMode: PointMode, points: FloatArray, paint: Paint)
```


Draws a sequence of points according to the given `PointMode`.

The `points` argument is interpreted as a list of pairs of floating point numbers, where each
pair represents an x and y offset from the origin.

See also:
* `drawPoints`, which takes `points` as a `List<Offset>` rather than a `List<Float32List>`.


```kotlin
fun drawVertices(vertices: Vertices, blendMode: BlendMode, paint: Paint)
```

```kotlin
fun enableZ()
```


Enables Z support which defaults to disabled. This allows layers drawn with different
elevations to be rearranged based on their elevation. It also enables rendering of shadows.


```kotlin
fun disableZ()
```


Disables Z support, preventing any layers drawn after this point from being visually
reordered or having shadows rendered. This is not impacted by any `save` or `restore` calls
as it is not considered part of the matrix or clip.