Class PNGCanvas

Canvas for generating PNG files.

Inheritance
object
AbstractCanvas
PNGCanvas
Implements
Inherited Members
Namespace: Codecrete.SwissQRBill.PixelCanvas
Assembly: Codecrete.SwissQRBill.Generator.dll
Syntax
public class PNGCanvas : AbstractCanvas, ICanvas, IDisposable
Remarks

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

Constructors

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PNGCanvas(double, double, int, string)

Initializes a new instance of a PNG canvas with the given size, resolution and font family.

The QR bill will be drawn in the bottom left corner of the image.

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

Declaration
public PNGCanvas(double width, double height, int resolution, string fontFamilyList)
Parameters
Type Name Description
double width

The image width, in mm.
double height

The image height, in mm.
int resolution

The resolution of the image to generate (in pixels per inch).
string fontFamilyList

A list font family names, separated by comma (same syntax as for CSS). The first font family will be used.

Methods

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AddRectangle(double, double, double, double)

Adds a rectangle to the open path.

Declaration
public override void AddRectangle(double x, double y, double width, double height)
Parameters
Type Name Description
double x

The rectangle's left position (in mm).
double y

The rectangle's top position (in mm).
double width

The rectangle's width (in mm).
double height

The rectangle's height (in mm).
Overrides
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Close()

Closes this instance and frees resources.

After a call to this method, the canvas can no longer be used for drawing.

Declaration
protected void Close()
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CloseSubpath()

Closes the current subpath. The next path operation will implicitly open a new subpath.

Declaration
public override void CloseSubpath()
Overrides
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CubicCurveTo(double, double, double, double, double, double)

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

Declaration
public override void CubicCurveTo(double x1, double y1, double x2, double y2, double x, double y)
Parameters
Type Name Description
double x1

The x-coordinate of first control point.
double y1

The y-coordinate of first control point.
double x2

The x-coordinate of second control point.
double y2

The y-coordinate of second control point.
double x

The x-coordinate of position.
double y

The y-coordinate of position.
Overrides
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Dispose(bool)

Frees and releases resources.

Declaration
protected override void Dispose(bool disposing)
Parameters
Type Name Description
bool disposing

indicates whether the method is called from a Dispose method (true) or from a finalizer (false).
Overrides
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FillPath(int, bool)

Fills the current path and discards it.

Declaration
public override void FillPath(int color, bool smoothing = true)
Parameters
Type Name Description
int color

The fill color (expressed similar to HTML, e.g. 0xffffff for white).
bool smoothing

true for using smoothing techniques such as antialiasing, false otherwise
Overrides
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LineTo(double, double)

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

Declaration
public override void LineTo(double x, double y)
Parameters
Type Name Description
double x

The x-coordinate of position.
double y

The y-coordinate of position.
Overrides
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MoveTo(double, double)

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

Declaration
public override void MoveTo(double x, double y)
Parameters
Type Name Description
double x

The x-coordinate of position.
double y

The y-coordinate of position.
Overrides
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PutText(string, double, double, int, bool)

Draws text to the canvas.

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

Declaration
public override void PutText(string text, double x, double y, int fontSize, bool isBold)
Parameters
Type Name Description
string text

The text to draw.
double x

The x position of the text's start (in mm).
double y

The y position of the text's top (in mm).
int fontSize

The font size (in pt).
bool isBold

Flag indicating if the text is in bold or regular weight.
Overrides
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SaveAs(string)

Writes the resulting graphics as a PNG image to the specified file path.

The canvas can no longer be used for drawing after calling this method.

Declaration
public void SaveAs(string path)
Parameters
Type Name Description
string path

The path (file name) to write to.
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SetTransformation(double, double, double, double, double)

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.

Declaration
public override void SetTransformation(double translateX, double translateY, double rotate, double scaleX, double scaleY)
Parameters
Type Name Description
double translateX

The translation in x direction (in mm).
double translateY

The translation in y direction (in mm).
double rotate

The rotation angle, in radians.
double scaleX

The scale factor in x direction (1.0 = no scaling).
double scaleY

The scale factor in y direction (1.0 = no scaling).
Overrides
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StartPath()

Starts a path that can be filled or stroked.

Declaration
public override void StartPath()
Overrides
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StrokePath(double, int, LineStyle, bool)

Strokes the current path and discards it.

Declaration
public override void StrokePath(double strokeWidth, int color, LineStyle lineStyle = LineStyle.Solid, bool smoothing = true)
Parameters
Type Name Description
double strokeWidth

The stroke width (in pt).
int color

The stroke color (expressed similar to HTML, e.g. 0xffffff for white).
LineStyle lineStyle

The line style
bool smoothing

true for using smoothing techniques such as antialiasing, false otherwise
Overrides
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ToByteArray()

Gets the resulting graphics encoded as a PNG image in a byte array.

The canvas can no longer be used for drawing after calling this method.

Declaration
public override byte[] ToByteArray()
Returns
Type Description
byte[]

The byte array containing the PNG image
Overrides
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WriteTo(Stream)

Writes the resulting graphics as a PNG image to the specified stream.

The canvas can no longer be used for drawing after calling this method.

Declaration
public void WriteTo(Stream stream)
Parameters
Type Name Description
Stream stream

The stream to write to.

Implements