GDI+ Classes

Source: source/classes/tgdiplus.prg

Standalone classes: Graphics, Pen, Brush, GDIBmp, Path, Region

FiveWin provides a comprehensive set of GDI+ wrapper classes for high-quality 2D rendering with anti-aliasing, alpha transparency, gradient brushes, path-based drawing, and image processing. These classes wrap the Windows GDI+ flat API and require no external ActiveX components. GDI+ is initialized automatically when the first class is instantiated.

Graphics Class

The main drawing surface. All drawing operations begin with a Graphics object.

Method	Description
`New( hDC [, lNoHighQuality] )`	Create from a device context handle
`NewWnd( hWnd [, lNoHighQuality] )`	Create for window drawing
`NewFromWnd( oWnd [, lNoHighQuality] )`	Create from a TWindow object
`NewImg( hImg [, lNoHighQuality] )`	Create for off-screen image rendering
`SetHighQuality()`	Enable anti-aliased rendering
`SetNormalQuality()`	Disable anti-aliasing for speed
`DrawLine( oPen, nLeft, nTop, nRight, nBottom )`	Draw a line
`DrawRect( oPen, oBrush, nLeft, nTop, nWidth, nHeight )`	Draw a rectangle
`DrawEllipse( oPen, oBrush, nLeft, nTop, nWidth, nHeight )`	Draw an ellipse
`DrawArc( oPen, nLeft, nTop, nW, nH, nStartAngle, nSweepAngle )`	Draw an arc
`DrawRoundRect( oPen, oBrush, nLeft, nTop, nW, nH, nRadius )`	Draw a rounded rectangle
`DrawPath( oPen, oPath )`	Draw a graphics path outline
`FillPath( oBrush, oPath )`	Fill a graphics path
`DrawImage( oImage, nTop, nLeft [, nW, nH] )`	Draw an image
`Clear( nTrans, nRed, nGreen, nBlue )`	Clear the surface with an ARGB color
`Translate( nRow, nCol )`	Translate the coordinate system
`Rotate( nAngle )`	Rotate the coordinate system
`Scale( nX, nY )`	Scale the coordinate system
`Destroy()`	Release the GDI+ graphics object

GDI+ Pen Class

GDI+ pen for drawing lines with color, width, and style.

Method	Description
`New( nAlpha, nR, nG, nB, nSize )`	Create a pen with ARGB color and size. Alpha 0..255.
`SetColor( nAlpha, nR, nG, nB )`	Change pen color
`SetSize( nSize )`	Change pen width
`SetStyle( nStyle )`	Set pen style (e.g., GDI_PEN_ROUND for rounded ends)
`SetLineJoin( nJoin )`	Set line join style
`Destroy()`	Release the GDI+ pen

GDI+ Brush Class

GDI+ brush for filling shapes with solid colors or gradients.

Method	Description
`NewSolidBrush( nAlpha, nR, nG, nB )`	Create a solid ARGB brush
`NewGradientBrush( nTop, nLeft, nW, nH, nType, nA1, nR1, nG1, nB1, nA2, nR2, nG2, nB2 )`	Create a linear gradient brush. nType: 0=horizontal, 1=vertical, 2=diagonal-right, 3=diagonal-left.
`AngleGradientBrush( ... nAngle, lScala )`	Create a gradient at an arbitrary angle
`Destroy()`	Release the GDI+ brush

GDIBmp Class

GDI+ bitmap for loading, manipulating, and saving images.

Method	Description
`New( cFile )`	Load an image from file (BMP, JPG, GIF, TIF, PNG, EMF, WMF, ICO)
`Resize( nWidth, nHeight )`	Resize the image (maintains aspect ratio if one dimension is omitted)
`Rotate( nRotate )`	Rotate/flip the image
`ImageRotate( nDegrees )`	Rotate by arbitrary angle
`Save( cFile [, nQuality] )`	Save to file. nQuality applies to JPEG (0-100).
`GetWidth() / GetHeight()`	Return image dimensions
`CreateThumbnail( nW, nH )`	Create a thumbnail GDIBmp
`Conver24to32Alpha()`	Convert 24-bit to 32-bit with alpha transparency
`GetGDIHbitmap()`	Extract a GDI bitmap handle for use with GDI functions
`End() / Destroy()`	Release the GDI+ image

Path Class

GDI+ graphics path for complex shape construction.

Method	Description
`New()`	Create an empty path
`AddLine( nLeft, nTop, nRight, nBottom )`	Add a line segment
`AddArc( nLeft, nTop, nW, nH, nStartAngle, nSweepAngle )`	Add an arc
`AddRectangle( nLeft, nTop, nRight, nBottom )`	Add a rectangle
`AddRoundRect( x, y, nW, nH, nRadius )`	Add a rounded rectangle
`AddElipse( nTop, nLeft, nW, nH )`	Add an ellipse
`AddString( cText, cFont, nStyle, eMSize, ... )`	Add text as a path outline
`StarFigure() / CloseFigure()`	Begin/close a figure within the path
`Translate() / Rotate() / Scale()`	Transform the path
`Destroy()`	Release the path

Region Class

Method	Description
`NewFromPath( oPath )`	Create a GDI+ region from a Path object
`IsRegionVisible( nX, nY, oGraphics )`	Test if a point is visible in the region
`Destroy()`	Release the region

Example

#include "FiveWin.ch"

function Main()

   local oWnd, oGraphics, oPen, oBrush

   DEFINE WINDOW oWnd TITLE "GDI+ Demo" SIZE 500, 400

   oWnd:bPainted = {| hDC |
      local oGraphics := Graphics():New( hDC )
      local oPen      := Pen():New( 255, 255, 0, 0, 3 )   // Red pen, 3px
      local oBrush    := Brush():NewSolidBrush( 128, 0, 0, 255 ) // Semi-transparent blue

      // Draw a red ellipse outline
      oGraphics:DrawEllipse( oPen, oBrush, 50, 50, 200, 150 )

      // Semi-transparent blue fill is applied automatically by DrawEllipse

      oPen:Destroy()
      oBrush:Destroy()
      oGraphics:Destroy()
      }

   ACTIVATE WINDOW oWnd CENTERED

return nil

Notes

GDI+ is initialized automatically via an init procedure GdiPlusStart() and shut down via exit procedure GdiPlusEnd(). No manual startup/shutdown is needed.
All GDI+ classes are standalone in the sense that they do not derive from TControl or any other FiveWin base class.
GDIBmp supports loading from file, from resource (PNG or bitmap), and from memory string. Supported input formats: BMP, JPG, GIF, TIF, PNG, EMF, WMF, ICO. Output formats: BMP, JPG, GIF, TIF, PNG.
The Graphics class sets page unit to pixels by default and enables high quality (anti-aliased) rendering unless lNoHighQuality is .T.