class mrpt::img::CCanvas

Overview

This virtual class defines the interface of any object accepting drawing primitives on it.

A number of text fonts can be selected with CCanvas::selectTextFont(). These are the implemented font names:

• “6x13”

• “6x13B” (bold)

• “6x13O” (italic)

• “9x15”

• “9x15B” (bold)

• “10x20”

• “18x18ja” (Japanese, UNICODE character values)

For an example of each font check the corresponding wiki page.

See also:

CImage

#include <mrpt/img/CCanvas.h>

class CCanvas
{
public:
    // enums

    enum TPenStyle;

    // construction

    CCanvas();
    CCanvas(const CCanvas& other);
    CCanvas(CCanvas&& other);

    // methods

    CCanvas& operator = (const CCanvas& other);
    CCanvas& operator = (CCanvas&& other);
    virtual void setPixel(const TPixelCoord& pt, const mrpt::img::TColor& color) = 0;
    virtual int32_t getWidth() const = 0;
    virtual int32_t getHeight() const = 0;

    virtual void line(
        const TPixelCoord& pt0,
        const TPixelCoord& pt1,
        const mrpt::img::TColor& color,
        int32_t width = 1,
        TPenStyle penStyle = psSolid
        );

    void rectangle(const TPixelCoord& pt0, const TPixelCoord& pt1, const mrpt::img::TColor& color, int32_t width = 1);
    void triangle(const TPixelCoord& pt, int32_t size, mrpt::img::TColor color, bool inferior = true, int32_t width = 1);
    virtual void filledRectangle(const TPixelCoord& pt0, const TPixelCoord& pt1, mrpt::img::TColor color);
    virtual void textOut(const TPixelCoord& pt, const std::string& str, mrpt::img::TColor color);
    virtual void selectTextFont(const std::string& fontName);
    virtual void drawImage(const TPixelCoord& pt, const mrpt::img::CImage& img);
    void drawMark(const TPixelCoord& pt, const mrpt::img::TColor& color, char type, int32_t size = 5, int32_t width = 1);

    virtual void drawCircle(
        const TPixelCoord& center,
        int32_t radius,
        const mrpt::img::TColor& color = mrpt::img::TColor(255, 255, 255),
        int32_t width = 1
        );

    void ellipseGaussian(
        const mrpt::math::CMatrixFixed<double, 2, 2>& cov2D,
        double mean_x,
        double mean_y,
        double confIntervalStds = 2,
        const mrpt::img::TColor& color = mrpt::img::TColor(255, 255, 255),
        int32_t width = 1,
        int nEllipsePoints = 20
        );
};

// direct descendants

class CImage;

Methods

virtual void setPixel(const TPixelCoord& pt, const mrpt::img::TColor& color) = 0

Changes the value of the pixel (x,y).

Pixel coordinates starts at the left-top corner of the image, and start in (0,0). The meaning of the parameter “color” depends on the implementation: it will usually be a 24bit RGB value (0x00RRGGBB), but it can also be just a 8bit gray level.

You can also use a TColor() type as input and it will be automatically converted to size_t.

This method must support (x,y) values OUT of the actual image size without neither raising exceptions, nor leading to memory access errors.

virtual int32_t getWidth() const = 0

Returns the width of the image in pixels.

virtual int32_t getHeight() const = 0

Returns the height of the image in pixels.

virtual void line(
    const TPixelCoord& pt0,
    const TPixelCoord& pt1,
    const mrpt::img::TColor& color,
    int32_t width = 1,
    TPenStyle penStyle = psSolid
    )

Draws a line.

Parameters:

pt0	The starting point
pt1	The end point
color	The color of the line
width	The desired width of the line (this is IGNORED in this virtual class) This method may be redefined in some classes implementing this interface in a more appropriate manner.

void rectangle(const TPixelCoord& pt0, const TPixelCoord& pt1, const mrpt::img::TColor& color, int32_t width = 1)

Draws a rectangle (an empty rectangle, without filling)

Parameters:

pt0	The top-left point
pt1	The right-bottom coordinate
color	The color of the line
width	The desired width of the line.

See also:

filledRectangle

void triangle(
    const TPixelCoord& pt,
    int32_t size,
    mrpt::img::TColor color,
    bool inferior = true,
    int32_t width = 1
    )

Draws a triangle.

Parameters:

pt	The triangle center
size	The size of the triangle
color	The color of the line
inferior	The position of the triangle
width	The desired width of the line.

See also:

triangle

virtual void filledRectangle(const TPixelCoord& pt0, const TPixelCoord& pt1, mrpt::img::TColor color)

Draws a filled rectangle.

Parameters:

pt0	The top-left point
pt1	The right-bottom point
color	The color of the rectangle fill This method may be redefined in some classes implementing this interface in a more appropriate manner.

See also:

rectangle

virtual void textOut(const TPixelCoord& pt, const std::string& str, mrpt::img::TColor color)

Renders 2D text using bitmap fonts.

Parameters:

pt	The point where the text is to be drawn
str	The string to put. If using UNICODE characters, use UTF-8 encoding.
color	The text color

See also:

selectTextFont

virtual void selectTextFont(const std::string& fontName)

Select the current font used when drawing text.

Valid font names:

• 5x7

• 6x13

• 6x13B

• 6x13O

• 9x15 (Default at start-up)

• 9x15B

• 10x20

• 18x18ja (Asian characters for UTF-8 strings - Only available if MRPT is built with MRPT_HAS_ASIAN_FONTS = true)

  

Parameters:

fontName

The name of the font

See also:

textOut, The example in this page.

virtual void drawImage(const TPixelCoord& pt, const mrpt::img::CImage& img)

Draws an image as a bitmap at a given position.

Parameters:

pt	The top-left corner on this canvas where the image is to be drawn
img	The image to be drawn in this canvas This method may be redefined in some classes implementing this interface in a more appropriate manner.

void drawMark(
    const TPixelCoord& pt,
    const mrpt::img::TColor& color,
    char type,
    int32_t size = 5,
    int32_t width = 1
    )

Draw a mark.

Parameters:

pt	The point where the mark is to be drawn
color	The color of the cross
size	The size of the cross
type	The cross type. It could be: ‘x’, ‘+’, ‘:’(like ‘+’ but clear at the center dot), or ‘s’ (square)
width	The desired width of the cross (this is IGNORED yet)

virtual void drawCircle(
    const TPixelCoord& center,
    int32_t radius,
    const mrpt::img::TColor& color = mrpt::img::TColor(255, 255, 255),
    int32_t width = 1
    )

Draws a circle of a given radius.

Parameters:

pt	The center coordinate
radius	The radius - in pixels.
color	The color of the circle.
width	The desired width of the line (this is IGNORED in this virtual class)

void ellipseGaussian(
    const mrpt::math::CMatrixFixed<double, 2, 2>& cov2D,
    double mean_x,
    double mean_y,
    double confIntervalStds = 2,
    const mrpt::img::TColor& color = mrpt::img::TColor(255, 255, 255),
    int32_t width = 1,
    int nEllipsePoints = 20
    )

Draws an ellipse representing a given confidence interval of a 2D Gaussian distribution.

Parameters:

mean_x	The x coordinate of the center point of the ellipse.
mean_y	The y coordinate of the center point of the ellipse.
cov2D	A 2x2 covariance matrix.
confIntervalStds	How many “sigmas” for the confidence level (i.e. 2->95%, 3=99.97%,…)
color	The color of the ellipse
width	The desired width of the line (this is IGNORED in this virtual class)
nEllipsePoints	The number of points to generate to approximate the ellipse shape.
std::exception	On an invalid matrix.