Package net.codecrete.qrbill.canvas

Class PNGCanvas

java.lang.Object

net.codecrete.qrbill.canvas.AbstractCanvas

net.codecrete.qrbill.canvas.PNGCanvas

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, ByteArrayResult, Canvas

public class PNGCanvas
extends AbstractCanvas
implements ByteArrayResult

Canvas for generating PNG files.

PNGs are not an optimal file format for QR bills. Vector formats such a SVG or PDF are of better quality and use far less processing power to generate.

Nested Class Summary

Nested classes/interfaces inherited from interface net.codecrete.qrbill.canvas.Canvas

Canvas.LineStyle

Field Summary

Fields inherited from class net.codecrete.qrbill.canvas.AbstractCanvas

MM_TO_PT

Constructor Summary

Constructors

Constructor	Description
PNGCanvas(double width, double height, int resolution, java.lang.String fontFamilyList)	Creates a new instance with the specified image size, resolution and font family.

Method Summary

Modifier and Type	Method	Description
void	addRectangle(double x, double y, double width, double height)	Adds a rectangle to the path
void	close()
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)	Fills the current path and ends it
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(java.lang.String text, double x, double y, int fontSize, boolean isBold)	Adds text to the graphics.
void	saveAs(java.nio.file.Path path)	Saves the resulting PNG image to the specified path.
void	setTransformation(double translateX, double translateY, double rotate, double scaleX, double scaleY)	Sets a translation, rotation and scaling for the subsequent operations
void	startPath()	Starts a path that can be filled or stroked
void	strokePath(double strokeWidth, int color)	Strokes the current path and ends it
void	strokePath(double strokeWidth, int color, Canvas.LineStyle lineStyle)	Strokes the current path and ends it
byte[]	toByteArray()	Gets the resulting graphics as a byte array.
void	writeTo(java.io.OutputStream os)	Writes the resulting PNG image to the specified output stream.

Methods inherited from class net.codecrete.qrbill.canvas.AbstractCanvas

getAscender, getDescender, getLineHeight, getTextWidth, putTextLines, setupFontMetrics, splitLines

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PNGCanvas

public PNGCanvas(double width,
                 double height,
                 int resolution,
                 java.lang.String fontFamilyList)

Creates a new instance with the specified image size, resolution and font family.

It is recommended to use at least 144 dpi for a readable result.

The first font family in the list is used.

Parameters:

width - image width, in mm

height - image height, in mm

resolution - resolution of the result (in dpi)

fontFamilyList - list of font families (comma separated, CSS syntax)

Method Detail

setTransformation

public void setTransformation(double translateX,
                              double translateY,
                              double rotate,
                              double scaleX,
                              double scaleY)

Description copied from interface: Canvas

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.

Specified by:

setTransformation in interface Canvas

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)

putText

public void putText(java.lang.String text,
                    double x,
                    double y,
                    int fontSize,
                    boolean isBold)

Description copied from interface: Canvas

Adds text to the graphics.

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

Specified by:

putText in interface Canvas

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

startPath

public void startPath()

Description copied from interface: Canvas

Starts a path that can be filled or stroked

Specified by:

startPath in interface Canvas

moveTo

public void moveTo(double x,
                   double y)

Description copied from interface: Canvas

Moves the current point of the open path to the specified position.

Specified by:

moveTo in interface Canvas

Parameters:

x - x-coordinate of position

y - y-coordinate of position

lineTo

public void lineTo(double x,
                   double y)

Description copied from interface: Canvas

Adds a line segment to the open path from the previous point to the specified position.

Specified by:

lineTo in interface Canvas

Parameters:

x - x-coordinate of position

y - y-coordinate of position

cubicCurveTo

public void cubicCurveTo(double x1,
                         double y1,
                         double x2,
                         double y2,
                         double x,
                         double y)

Description copied from interface: Canvas

Adds a cubic Beziér curve to the open path going from the previous point to the specified position. Two control points control the curve

Specified by:

cubicCurveTo in interface Canvas

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

addRectangle

public void addRectangle(double x,
                         double y,
                         double width,
                         double height)

Description copied from interface: Canvas

Adds a rectangle to the path

Specified by:

addRectangle in interface Canvas

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)

closeSubpath

public void closeSubpath()

Description copied from interface: Canvas

Closes the current subpath

Specified by:

closeSubpath in interface Canvas

fillPath

public void fillPath(int color)

Description copied from interface: Canvas

Fills the current path and ends it

Specified by:

fillPath in interface Canvas

Parameters:

color - the fill color (expressed similar to HTML, e.g. 0xffffff for white)

strokePath

public void strokePath(double strokeWidth,
                       int color)
                throws java.io.IOException

Description copied from interface: Canvas

Strokes the current path and ends it

The path is stroked with a solid line.

Specified by:

strokePath in interface Canvas

Parameters:

strokeWidth - the stroke width (in pt)

color - the stroke color (expressed similar to HTML, e.g. 0xffffff for white)

Throws:

java.io.IOException - thrown if the graphics cannot be generated

strokePath

public void strokePath(double strokeWidth,
                       int color,
                       Canvas.LineStyle lineStyle)

Description copied from interface: Canvas

Strokes the current path and ends it

Specified by:

strokePath in interface Canvas

Parameters:

strokeWidth - the stroke width (in pt)

color - the stroke color (expressed similar to HTML, e.g. 0xffffff for white)

lineStyle - the line style

toByteArray

public byte[] toByteArray()
                   throws java.io.IOException

Description copied from interface: ByteArrayResult

Gets the resulting graphics as a byte array.

Specified by:

toByteArray in interface ByteArrayResult

Returns:

the byte array

Throws:

java.io.IOException - thrown if the construction of the byte array fails

writeTo

public void writeTo(java.io.OutputStream os)
             throws java.io.IOException

Writes the resulting PNG image to the specified output stream.

Parameters:

os - the output stream

Throws:

java.io.IOException - thrown if the image cannot be written

saveAs

public void saveAs(java.nio.file.Path path)
            throws java.io.IOException

Saves the resulting PNG image to the specified path.

Parameters:

path - the path to write to

Throws:

java.io.IOException - thrown if the image cannot be written

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable