> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/opencv/opencv/llms.txt
> Use this file to discover all available pages before exploring further.

# Drawing Functions

> Functions for drawing geometric shapes and text on images

Drawing functions work with matrices/images of arbitrary depth. The boundaries of shapes can be rendered with antialiasing (implemented only for 8-bit images for now).

## Color Convention

For color images, the channel ordering is normally Blue, Green, Red (BGR). This is what imshow, imread, and imwrite expect. If you form a color using the Scalar constructor, it should look like:

```cpp theme={null}
Scalar(blue_component, green_component, red_component[, alpha_component])
```

## Line Drawing

### line

Draws a line segment connecting two points.

```cpp theme={null}
void line(InputOutputArray img, Point pt1, Point pt2, const Scalar& color,
          int thickness = 1, int lineType = LINE_8, int shift = 0);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="pt1" type="Point">
  First point of the line segment.
</ParamField>

<ParamField path="pt2" type="Point">
  Second point of the line segment.
</ParamField>

<ParamField path="color" type="Scalar">
  Line color.
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Line thickness.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the line. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the point coordinates.
</ParamField>

The function line draws the line segment between pt1 and pt2 points in the image. The line is clipped by the image boundaries.

<Tabs>
  <Tab title="C++">
    ```cpp theme={null}
    Mat img = Mat::zeros(400, 400, CV_8UC3);
    line(img, Point(50, 50), Point(350, 350), Scalar(0, 255, 0), 2);
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null}
    img = np.zeros((400, 400, 3), dtype=np.uint8)
    cv2.line(img, (50, 50), (350, 350), (0, 255, 0), 2)
    ```
  </Tab>
</Tabs>

***

### arrowedLine

Draws an arrow segment pointing from the first point to the second one.

```cpp theme={null}
void arrowedLine(InputOutputArray img, Point pt1, Point pt2, const Scalar& color,
                 int thickness=1, int line_type=8, int shift=0, double tipLength=0.1);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="pt1" type="Point">
  The point the arrow starts from.
</ParamField>

<ParamField path="pt2" type="Point">
  The point the arrow points to.
</ParamField>

<ParamField path="color" type="Scalar">
  Line color.
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Line thickness.
</ParamField>

<ParamField path="line_type" type="int" default="8">
  Type of the line. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the point coordinates.
</ParamField>

<ParamField path="tipLength" type="double" default="0.1">
  The length of the arrow tip in relation to the arrow length.
</ParamField>

***

## Shape Drawing

### rectangle

Draws a simple, thick, or filled up-right rectangle.

```cpp theme={null}
void rectangle(InputOutputArray img, Point pt1, Point pt2,
               const Scalar& color, int thickness = 1,
               int lineType = LINE_8, int shift = 0);

void rectangle(InputOutputArray img, Rect rec,
               const Scalar& color, int thickness = 1,
               int lineType = LINE_8, int shift = 0);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="pt1" type="Point">
  Vertex of the rectangle.
</ParamField>

<ParamField path="pt2" type="Point">
  Vertex of the rectangle opposite to pt1.
</ParamField>

<ParamField path="rec" type="Rect">
  Alternative rectangle specification.
</ParamField>

<ParamField path="color" type="Scalar">
  Rectangle color or brightness (grayscale image).
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Thickness of lines that make up the rectangle. Negative values, like FILLED, mean that the function has to draw a filled rectangle.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the line. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the point coordinates.
</ParamField>

<Tabs>
  <Tab title="C++">
    ```cpp theme={null}
    // Draw rectangle outline
    rectangle(img, Point(100, 100), Point(300, 200), Scalar(255, 0, 0), 2);

    // Draw filled rectangle
    rectangle(img, Rect(50, 250, 200, 100), Scalar(0, 0, 255), FILLED);
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null}
    # Draw rectangle outline
    cv2.rectangle(img, (100, 100), (300, 200), (255, 0, 0), 2)

    # Draw filled rectangle
    cv2.rectangle(img, (50, 250, 200, 100), (0, 0, 255), cv2.FILLED)
    ```
  </Tab>
</Tabs>

***

### circle

Draws a circle.

```cpp theme={null}
void circle(InputOutputArray img, Point center, int radius,
            const Scalar& color, int thickness = 1,
            int lineType = LINE_8, int shift = 0);
```

<ParamField path="img" type="InputOutputArray">
  Image where the circle is drawn.
</ParamField>

<ParamField path="center" type="Point">
  Center of the circle.
</ParamField>

<ParamField path="radius" type="int">
  Radius of the circle.
</ParamField>

<ParamField path="color" type="Scalar">
  Circle color.
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Thickness of the circle outline, if positive. Negative values, like FILLED, mean that a filled circle is to be drawn.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the circle boundary. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the coordinates of the center and in the radius value.
</ParamField>

<Tabs>
  <Tab title="C++">
    ```cpp theme={null}
    circle(img, Point(200, 200), 50, Scalar(0, 255, 255), 3);
    circle(img, Point(300, 300), 75, Scalar(255, 255, 0), FILLED);
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null}
    cv2.circle(img, (200, 200), 50, (0, 255, 255), 3)
    cv2.circle(img, (300, 300), 75, (255, 255, 0), cv2.FILLED)
    ```
  </Tab>
</Tabs>

***

### ellipse

Draws a simple or thick elliptic arc or fills an ellipse sector.

```cpp theme={null}
void ellipse(InputOutputArray img, Point center, Size axes,
             double angle, double startAngle, double endAngle,
             const Scalar& color, int thickness = 1,
             int lineType = LINE_8, int shift = 0);

void ellipse(InputOutputArray img, const RotatedRect& box, const Scalar& color,
             int thickness = 1, int lineType = LINE_8);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="center" type="Point">
  Center of the ellipse.
</ParamField>

<ParamField path="axes" type="Size">
  Half of the size of the ellipse main axes.
</ParamField>

<ParamField path="angle" type="double">
  Ellipse rotation angle in degrees.
</ParamField>

<ParamField path="startAngle" type="double">
  Starting angle of the elliptic arc in degrees.
</ParamField>

<ParamField path="endAngle" type="double">
  Ending angle of the elliptic arc in degrees.
</ParamField>

<ParamField path="box" type="RotatedRect">
  Alternative ellipse representation via RotatedRect. This means that the function draws an ellipse inscribed in the rotated rectangle.
</ParamField>

<ParamField path="color" type="Scalar">
  Ellipse color.
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Thickness of the ellipse arc outline, if positive. Otherwise, this indicates that a filled ellipse sector is to be drawn.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the ellipse boundary. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the coordinates of the center and values of axes.
</ParamField>

To draw the whole ellipse, not an arc, pass startAngle=0 and endAngle=360. If startAngle is greater than endAngle, they are swapped.

***

## Polygon Drawing

### polylines

Draws several polygonal curves.

```cpp theme={null}
void polylines(InputOutputArray img, InputArrayOfArrays pts,
               bool isClosed, const Scalar& color,
               int thickness = 1, int lineType = LINE_8, int shift = 0);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="pts" type="InputArrayOfArrays">
  Array of polygonal curves.
</ParamField>

<ParamField path="isClosed" type="bool">
  Flag indicating whether the drawn polylines are closed or not. If they are closed, the function draws a line from the last vertex of each curve to its first vertex.
</ParamField>

<ParamField path="color" type="Scalar">
  Polyline color.
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Thickness of the polyline edges.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the line segments. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the vertex coordinates.
</ParamField>

***

### fillPoly

Fills the area bounded by one or more polygons.

```cpp theme={null}
void fillPoly(InputOutputArray img, InputArrayOfArrays pts,
              const Scalar& color, int lineType = LINE_8, int shift = 0,
              Point offset = Point());
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="pts" type="InputArrayOfArrays">
  Array of polygons where each polygon is represented as an array of points.
</ParamField>

<ParamField path="color" type="Scalar">
  Polygon color.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the polygon boundaries. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the vertex coordinates.
</ParamField>

<ParamField path="offset" type="Point" default="Point()">
  Optional offset of all points of the contours.
</ParamField>

The function fillPoly fills an area bounded by several polygonal contours. The function can fill complex areas, for example, areas with holes, contours with self-intersections, and so forth.

***

### fillConvexPoly

Fills a convex polygon.

```cpp theme={null}
void fillConvexPoly(InputOutputArray img, InputArray points,
                    const Scalar& color, int lineType = LINE_8,
                    int shift = 0);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="points" type="InputArray">
  Polygon vertices.
</ParamField>

<ParamField path="color" type="Scalar">
  Polygon color.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Type of the polygon boundaries. See LineTypes.
</ParamField>

<ParamField path="shift" type="int" default="0">
  Number of fractional bits in the vertex coordinates.
</ParamField>

This function is much faster than fillPoly. It can fill not only convex polygons but any monotonic polygon without self-intersections.

***

## Text Rendering

### putText

Draws a text string.

```cpp theme={null}
void putText(InputOutputArray img, const String& text, Point org,
             int fontFace, double fontScale, Scalar color,
             int thickness = 1, int lineType = LINE_8,
             bool bottomLeftOrigin = false);
```

<ParamField path="img" type="InputOutputArray">
  Image.
</ParamField>

<ParamField path="text" type="String">
  Text string to be drawn.
</ParamField>

<ParamField path="org" type="Point">
  Bottom-left corner of the text string in the image.
</ParamField>

<ParamField path="fontFace" type="int">
  Font type. See HersheyFonts.
</ParamField>

<ParamField path="fontScale" type="double">
  Font scale factor that is multiplied by the font-specific base size.
</ParamField>

<ParamField path="color" type="Scalar">
  Text color.
</ParamField>

<ParamField path="thickness" type="int" default="1">
  Thickness of the lines used to draw a text.
</ParamField>

<ParamField path="lineType" type="int" default="LINE_8">
  Line type. See LineTypes.
</ParamField>

<ParamField path="bottomLeftOrigin" type="bool" default="false">
  When true, the image data origin is at the bottom-left corner. Otherwise, it is at the top-left corner.
</ParamField>

The function putText renders the specified text string in the image. Symbols that cannot be rendered using the specified font are replaced by question marks.

<Tabs>
  <Tab title="C++">
    ```cpp theme={null}
    putText(img, "OpenCV", Point(50, 100), 
            FONT_HERSHEY_SIMPLEX, 1.5, Scalar(255, 255, 255), 2);
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null}
    cv2.putText(img, 'OpenCV', (50, 100), 
                cv2.FONT_HERSHEY_SIMPLEX, 1.5, (255, 255, 255), 2)
    ```
  </Tab>
</Tabs>

***

### getTextSize

Calculates the width and height of a text string.

```cpp theme={null}
Size getTextSize(const String& text, int fontFace,
                 double fontScale, int thickness,
                 int* baseLine);
```

<ParamField path="text" type="String">
  Input text string.
</ParamField>

<ParamField path="fontFace" type="int">
  Font to use. See HersheyFonts.
</ParamField>

<ParamField path="fontScale" type="double">
  Font scale factor that is multiplied by the font-specific base size.
</ParamField>

<ParamField path="thickness" type="int">
  Thickness of lines used to render the text.
</ParamField>

<ParamField path="baseLine" type="int*">
  y-coordinate of the baseline relative to the bottom-most text point.
</ParamField>

The function calculates and returns the size of a box that contains the specified text.

***

## Enumerations

### LineTypes

Types of line:

* `FILLED` (-1) - Filled shape
* `LINE_4` (4) - 4-connected line
* `LINE_8` (8) - 8-connected line
* `LINE_AA` (16) - Antialiased line

### HersheyFonts

Hershey font types:

* `FONT_HERSHEY_SIMPLEX` (0) - Normal size sans-serif font
* `FONT_HERSHEY_PLAIN` (1) - Small size sans-serif font
* `FONT_HERSHEY_DUPLEX` (2) - Normal size sans-serif font (more complex than SIMPLEX)
* `FONT_HERSHEY_COMPLEX` (3) - Normal size serif font
* `FONT_HERSHEY_TRIPLEX` (4) - Normal size serif font (more complex than COMPLEX)
* `FONT_HERSHEY_COMPLEX_SMALL` (5) - Smaller version of COMPLEX
* `FONT_HERSHEY_SCRIPT_SIMPLEX` (6) - Hand-writing style font
* `FONT_HERSHEY_SCRIPT_COMPLEX` (7) - More complex variant of SCRIPT\_SIMPLEX
* `FONT_ITALIC` (16) - Flag for italic font

### MarkerTypes

Marker types used for the drawMarker function:

* `MARKER_CROSS` (0) - A crosshair marker shape
* `MARKER_TILTED_CROSS` (1) - A 45 degree tilted crosshair marker shape
* `MARKER_STAR` (2) - A star marker shape
* `MARKER_DIAMOND` (3) - A diamond marker shape
* `MARKER_SQUARE` (4) - A square marker shape
* `MARKER_TRIANGLE_UP` (5) - An upwards pointing triangle marker shape
* `MARKER_TRIANGLE_DOWN` (6) - A downwards pointing triangle marker shape