Gradient Backgrounds in your forms with GDI+

After reading this post, read also: Gradient backgrounds in your forms with gdi+ part 2

 

Gdi+ brings us the possibility to create many cool effects such as gradient colors. This feature was not included in _gdiplus.vcx, but can also be accessed easily with a simple call to the flat API. A great part of the codes below that are related to the creation of the gradient brush is from Bo Durban.

To apply this to forms is really easy. add the codes below to the load, resize and destroy events of any form:

 

load event

LOCAL lcGradFile
m.lcGradFile = ADDBS(SYS(2023)) + SYS(2015) + ".bmp"
THIS.ADDPROPERTY("cTempGradFile", m.lcGradFile)

IF FILE(m.lcGradFile)
    CLEAR RESOURCES (m.lcGradFile)
ENDIF

LOCAL lnRgbColor1
m.lnRgbColor1 = RGB(60,30,180) && blue

* create gradient image 
SET CLASSLIB TO HOME() + "ffc/_gdiplus.vcx" ADDITIVE

* declare API 
DECLARE LONG gdipCreateLinebrushI IN GDIPLUS.DLL ;
    STRING point1, STRING point2, ;
    LONG color1, LONG color2, ;
    LONG wrapmode, LONG @linegradient

* create a colorobject and store argb color values to variables 
LOCAL loClr AS gpColor OF HOME() + "ffc/_gdiplus.vcx"
LOCAL lnColor1, lnColor2
m.loClr = CREATEOBJECT("gpcolor")
m.loClr.FoxRgb = m.lnRgbColor1
m.lnColor1 = m.loClr.ARGB
m.loClr.FoxRgb = RGB(255,255,255) && white
m.lnColor2 = m.loClr.ARGB

* create a bitmap 
LOCAL loBmp AS gpBitmap OF HOME() + "ffc/_gdiplus.vcx"
m.loBmp = CREATEOBJECT("gpbitmap")
m.loBmp.CREATE(1,THISFORM.HEIGHT)

* get a bitmap graphics object 
LOCAL loGfx AS gpGraphics OF HOME() + "ffc/_gdiplus.vcx"
m.loGfx = CREATEOBJECT("gpgraphics")
m.loGfx.CreateFromImage(m.loBmp)

* get a gradient brush 
LOCAL loBrush AS gpBrush OF HOME() + "ffc/_gdiplus.vcx"
LOCAL hBrush && brush handle
m.hBrush = 0
gdipCreateLinebrushI(BINTOC(0,"4rs") + BINTOC(0,"4rs"), ;
      BINTOC(0,"4rs") + BINTOC(THISFORM.HEIGHT,"4rs"), ;
      m.lnColor1, m.lnColor2, 0, @m.hBrush)
m.loBrush = CREATEOBJECT("gpbrush")
m.loBrush.sethandle(m.hBrush, .T.)

* fill the bitmap with our gradient 
m.loGfx.FillRectangle(m.loBrush,0,0,1,THISFORM.HEIGHT)
m.loBmp.SaveToFile(m.lcGradFile,"image/bmp")

THISFORM.ADDOBJECT("imgbackground","image")
WITH THISFORM.imgbackground
    .STRETCH = 2
    .WIDTH = THISFORM.WIDTH
    .HEIGHT = THISFORM.HEIGHT
    .PICTURE = m.lcGradFile
    .VISIBLE = .T.
ENDWITH
RETURN

resize event

Thisform.imgbackground.Width = Thisform.Width 
Thisform.imgbackground.Height = Thisform.Height

destroy event

WITH THISFORM
    IF FILE(.cTempGradFile)
        CLEAR RESOURCES (.cTempGradFile)
        ERASE (.cTempGradFile)
    ENDIF
ENDWITH

New GDI+ classes

The code I presented in the Load event works pretty fine, but sounds really ugly, when comparing to what we are able to do with GdiPlusX

The code below will replace all codes related to the creation of the gradient color in the load event.

* create a GDI+ linear gradient image using GdiPlusX
DO LOCFILE("system.app")

LOCAL loBmp AS xfcBitmap
LOCAL loGfx AS xfcGraphics
LOCAL loBrush AS xfcBrush
WITH _SCREEN.SYSTEM.Drawing
    m.loBmp = .BITMAP.New(1, THISFORM.HEIGHT)
    m.loGfx = .Graphics.FromImage(m.loBmp)
    m.loBrush = .Drawing2d.LinearGradientBrush.New( ;
          .Rectangle.New(0, 0, 1, THISFORM.HEIGHT), ;
          .COLOR.FromRgb(lnRgbColor1), .COLOR.White, 1)
    m.loGfx.FillRectangle(m.loBrush, m.loBrush.Rectangle)
    m.loBmp.SAVE(lcGradFile, .Imaging.ImageFormat.bmp)
ENDWITH

 

Related post: Gradient backgrounds in your VFP forms with GDI+ Part 2