CanvasView/interpolationProxy are slow, is there anything faster?

Scripting
1

Hi,
I’m looking for a Python way to draw interpolated shapes live.
I have a working script doing that using the CanvasView and interpolationProxy but it’s too slow (especially when drawing more than one instance).

I’m guessing that there must be a more effective way since Glyphs manages to preview all instances live without any lag (same goes for VariableFontPreview).

Is there a way to get these performances? And if not what would be the way to get higher performances when to drawing a path interpolation using python (I don’t know Objective C)?

The way I’m doing it now:

def draw(self, view):    
    #New virtual instance
    thisInstance = GSInstance()
    #Associate to the font
    thisInstance.setFont_(Glyphs.fonts[0])
    #Calculate the incrementation between each step
    wght = value1
    wdth = value2

    #Set the position in the design space
    thisInstance.axes = [wght, wdth]
    #Get bezierpath of the interpolated glyph
    instanceFont = thisInstance.interpolatedFontProxy
    instanceGlyph = instanceFont.glyphs[Glyphs.font.selectedLayers[0].parent.name]
    instanceLayer = instanceGlyph.layers[instanceFont.fontMasterID()]   
    #Add inteprolated path to array
    layerCopy = instanceLayer.copyDecomposedLayer()

    #Scale to the Canvas Size
    layerCopy.applyTransform([
    scale, # x scale factor
    0.0, # x skew factor
    0.0, # y skew factor
    scale, # y scale factor
    valueX, # x position
    valueY  # y position
    ])
    layerCopy.bezierPath.fill()

I simplified/cleaned the code to make it more clear. In reality I’m drawing many glyph in the same canvas.
At first I tried using many canvas (with one interpolated path per canvas), but it didn’t make it better.

2

You need to keep the instance around. The instance and its font proxy can cache a lot and it is very expensive to recreate it for every frame. And have a look at the variable font preview plugin code.

1 Like
3

Of course!
That makes all the difference, thanks!

4

The variable font preview plugin doesn’t include any python, only a binary. But it’s fine now with the re-used instances.