Package net.codecrete.qrbill.canvas

Interface Canvas

All Superinterfaces:
AutoCloseable, Closeable
All Known Implementing Classes:
AbstractCanvas, Graphics2DCanvas, PDFCanvas, PNGCanvas, SVGCanvas
public interface Canvas extends Closeable
Common interface for all output formats to draw the QR bill.

The coordinate system has its origin in the bottom left corner. The y-axis extends from the bottom to the top.

The graphics model is similar to the one used by PDF, in particular with regards to the orientation of the y axis, the concept of a current path, and using the baseline for positioning text.

Instance of this class are expected to use a single font family for the QR bill (regular and bold font weight).

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static enum 
    Canvas.LineStyle
    Line style

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addRectangle(double x, double y, double width, double height)
    Adds a rectangle to the path
    void
    closeSubpath()
    Closes the current subpath
    void
    cubicCurveTo(double x1, double y1, double x2, double y2, double x, double y)
    Adds a cubic Beziér curve to the open path going from the previous point to the specified position.
    void
    fillPath(int color, boolean smoothing)
    Fills the current path and ends it
    double
    getAscender(int fontSize)
    Distance between baseline and top of the highest letter.
    double
    getDescender(int fontSize)
    Distance between baseline and bottom of letter extending the farthest below the baseline.
    double
    getLineHeight(int fontSize)
    Distance between the baselines of two consecutive text lines.
    double
    getTextWidth(CharSequence text, int fontSize, boolean isBold)
    Returns the width of the specified text for the specified font size
    void
    lineTo(double x, double y)
    Adds a line segment to the open path from the previous point to the specified position.
    void
    moveTo(double x, double y)
    Moves the current point of the open path to the specified position.
    void
    putText(String text, double x, double y, int fontSize, boolean isBold)
    Adds text to the graphics.
    void
    putTextLines(String[] lines, double x, double y, int fontSize, double leading)
    Adds several lines of text to the graphics.
    void
    setTransformation(double translateX, double translateY, double rotate, double scaleX, double scaleY)
    Sets a translation, rotation and scaling for the subsequent operations
    String[]
    splitLines(String text, double maxLength, int fontSize)
    Splits the text into lines.
    void
    startPath()
    Starts a path that can be filled or stroked
    void
    strokePath(double strokeWidth, int color, Canvas.LineStyle lineStyle, boolean smoothing)
    Strokes the current path and ends it

    Methods inherited from interface java.io.Closeable

    close

  • Method Details

    • setTransformation

      void setTransformation(double translateX, double translateY, double rotate, double scaleX, double scaleY) throws IOException
      Sets a translation, rotation and scaling for the subsequent operations

      Before a new translation is applied, the coordinate system is reset to it's original state.

      The transformations are applied in the order translation, rotation, scaling.

      Parameters:
      translateX - translation in x direction (in mm)
      translateY - translation in y direction (in mm)
      rotate - rotation angle, in radians
      scaleX - scale factor in x direction (1.0 = no scaling)
      scaleY - scale factor in y direction (1.0 = no scaling)
      Throws:
      IOException - thrown if the graphics cannot be generated

    • putText

      void putText(String text, double x, double y, int fontSize, boolean isBold) throws IOException
      Adds text to the graphics.

      The text position refers to the left most point on the text's baseline.

      Parameters:
      text - the text
      x - x position of the text's start (in mm)
      y - y position of the text's top (in mm)
      fontSize - the font size (in pt)
      isBold - indicates if the text is in bold or regular weight
      Throws:
      IOException - thrown if the graphics cannot be generated

    • putTextLines

      void putTextLines(String[] lines, double x, double y, int fontSize, double leading) throws IOException
      Adds several lines of text to the graphics.

      The text position refers to the left most point on the baseline of the first text line. Additional lines then follow below.

      Parameters:
      lines - the text lines
      x - x position of the text's start (in mm)
      y - y position of the text's top (in mm)
      fontSize - the font size (in pt)
      leading - additional vertical space between text lines (in mm)
      Throws:
      IOException - thrown if the graphics cannot be generated

    • startPath

      void startPath() throws IOException
      Starts a path that can be filled or stroked
      Throws:
      IOException - thrown if the graphics cannot be generated

    • moveTo

      void moveTo(double x, double y) throws IOException
      Moves the current point of the open path to the specified position.
      Parameters:
      x - x-coordinate of position
      y - y-coordinate of position
      Throws:
      IOException - thrown if the graphics cannot be generated

    • lineTo

      void lineTo(double x, double y) throws IOException
      Adds a line segment to the open path from the previous point to the specified position.
      Parameters:
      x - x-coordinate of position
      y - y-coordinate of position
      Throws:
      IOException - thrown if the graphics cannot be generated

    • cubicCurveTo

      void cubicCurveTo(double x1, double y1, double x2, double y2, double x, double y) throws IOException
      Adds a cubic Beziér curve to the open path going from the previous point to the specified position. Two control points control the curve
      Parameters:
      x1 - x-coordinate of first control point
      y1 - y-coordinate of first control point
      x2 - x-coordinate of second control point
      y2 - y-coordinate of second control point
      x - x-coordinate of position
      y - y-coordinate of position
      Throws:
      IOException - thrown if the graphics cannot be generated

    • addRectangle

      void addRectangle(double x, double y, double width, double height) throws IOException
      Adds a rectangle to the path
      Parameters:
      x - the rectangle's left position (in mm)
      y - the rectangle's top position (in mm)
      width - the rectangle's width (in mm)
      height - rectangle's height (in mm)
      Throws:
      IOException - thrown if the graphics cannot be generated

    • closeSubpath

      void closeSubpath() throws IOException
      Closes the current subpath
      Throws:
      IOException - thrown if the graphics cannot be generated

    • fillPath

      void fillPath(int color, boolean smoothing) throws IOException
      Fills the current path and ends it
      Parameters:
      color - the fill color (expressed similar to HTML, e.g. 0xffffff for white)
      smoothing - true for using smoothing techniques such as antialiasing, false otherwise
      Throws:
      IOException - thrown if the graphics cannot be generated

    • strokePath

      void strokePath(double strokeWidth, int color, Canvas.LineStyle lineStyle, boolean smoothing) throws IOException
      Strokes the current path and ends it
      Parameters:
      strokeWidth - the stroke width (in pt)
      color - the stroke color (expressed similar to HTML, e.g. 0xffffff for white)
      lineStyle - the line style
      smoothing - true for using smoothing techniques such as antialiasing, false otherwise
      Throws:
      IOException - thrown if the graphics cannot be generated

    • getAscender

      double getAscender(int fontSize)
      Distance between baseline and top of the highest letter.
      Parameters:
      fontSize - the font size (in pt)
      Returns:
      the distance (in mm)

    • getDescender

      double getDescender(int fontSize)
      Distance between baseline and bottom of letter extending the farthest below the baseline.
      Parameters:
      fontSize - the font size (in pt)
      Returns:
      the distance (in mm)

    • getLineHeight

      double getLineHeight(int fontSize)
      Distance between the baselines of two consecutive text lines.
      Parameters:
      fontSize - the font size (in pt)
      Returns:
      the distance (in mm)

    • getTextWidth

      double getTextWidth(CharSequence text, int fontSize, boolean isBold)
      Returns the width of the specified text for the specified font size
      Parameters:
      text - text
      fontSize - font size (in pt)
      isBold - indicates if the text is in bold or regular weight
      Returns:
      width (in mm)

    • splitLines

      String[] splitLines(String text, double maxLength, int fontSize)
      Splits the text into lines.

      If a line would exceed the specified maximum length, line breaks are inserted. Newlines are treated as fixed line breaks.

      Parameters:
      text - the text
      maxLength - the maximum line length (in pt)
      fontSize - the font size (in pt)
      Returns:
      an array of text lines