GdipSetInterpolationMode

Targets Windows
1

I’m upgrading from Xojo 2019 to 2022.

In 2019, I had this code to get higher quality drawing:

Public Sub SetGDIInterpolationMode(g as Graphics)
  #if TargetWin32
    // sets high quality interpolation mode for resizing info
    // useful when using @2x retina graphics on Win32 
    //
    // Note: you set this on the destination graphics, not on the source
    // see https://forum.xojo.com/9403-scale-quality-of-canvas-control/0
    if g = nil then
      return
    end if
    dim ghnd as integer = g.Handle(Graphics.HandleTypeGDIPlusGraphics)
    // see https://msdn.microsoft.com/en-us/library/windows/desktop/ms534141(v=vs.85).aspx
    Soft Declare Function GdipSetInterpolationMode Lib "gdiplus" (graphicsHandle as int32, Mode as int32) As int32
    
    const InterpolationModeDefault = 0
    const InterpolationModeLowQuality = 1
    const InterpolationModeHighQuality = 2
    const InterpolationModeBilinear = 3
    const InterpolationModeBicubic = 4
    const InterpolationModeNearestNeighbor = 5
    const InterpolationModeHighQualityBilinear = 6
    const InterpolationModeHighQualityBicubic = 7
    
    dim mode as integer = InterpolationModeHighQualityBicubic    
       
    call GdipSetInterpolationMode(ghnd,mode)
  #endif

End Sub

This no longer compiles in 2022.

Is it still needed? If so, what’s the new method?

2

I would think this is gone since GDI plus is no longer used at all ?

1 Like
3

I think you are right. Is there an explanation of the new graphics framework xojo is using these days?

4

Its called Direct2D.

There is some info on Microsoft web. Though its sort of sparse, its not used all that much.

5

There is now an AntiAliasMode property built into the graphics class. I’ve never used it but it might be a suitable replacement.

6

Thanks! - but it appears to have a documentation bug - it’s not a Boolean…

https://documentation.xojo.com/api/graphics/graphics.html#graphics-antialiasmode

AntiAliasMode As Boolean

Controls the level of interpolation/quality when drawing scaled Pictures. Valid modes are from the Graphics.AntiAliasModes enumeration: LowQuality, DefaultQuality, and HighQuality. The default is DefaultQuality.

Use High Quality (set in Paint event of a Canvas):