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, Canvas

public class PNGCanvas
extends AbstractCanvas

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.

Field Summary

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

MM_TO_PT

Constructor Summary

Constructors

Constructor	Description
PNGCanvas(int resolution)	Creates a new instance

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 speicifed position.
void	fillPath(int color)	Fills the current path and ends it
byte[]	getResult()	Returns the generated graphics as a byte array
void	lineTo(double x, double y)	Adds a line segment to the open path from the previous point to the speicifed 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	setTransformation(double translateX, double translateY, double rotate, double scaleX, double scaleY)	Sets a translation, rotation and scaling for the subsequent operations
void	setupPage(double width, double height, java.lang.String fontFamilyList)	Sets up the page
void	startPath()	Starts a path that can be filled or stroked
void	strokePath(double strokeWidth, int color)	Strokes the current path and ends it

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(int resolution)

Creates a new instance

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

Parameters:

resolution - resolution of the result (in dpi)

Method Detail

setupPage

public void setupPage(double width,
                      double height,
                      java.lang.String fontFamilyList)

Description copied from interface: Canvas

Sets up the page

The page (and graphics context) is not valid until this method has been called.

The font family can be specified as a comma separated list, e.g. "Helvetica,Arial,sans". The first family will be used to calculate text widths. For formats that support it (e.g. SVG), the entire list will be used in the generated graphics file. Other format will just use the first one.

Parameters:

width - width of page (in mm)

height - height of page (in mm)

fontFamilyList - font family to use

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 after page setup (see setupPage).

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)

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.

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

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.

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 speicifed position.

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 speicifed 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

addRectangle

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

Description copied from interface: Canvas

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)

closeSubpath

public void closeSubpath()

Description copied from interface: Canvas

Closes the current subpath

fillPath

public void fillPath(int color)

Description copied from interface: Canvas

Fills the current path and ends it

Parameters:

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

strokePath

public void strokePath(double strokeWidth,
                       int color)

Description copied from interface: Canvas

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)

getResult

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

Description copied from interface: Canvas

Returns the generated graphics as a byte array

After this method was called, the page is no longer valid.

Returns:

the byte array

Throws:

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

close

public void close()