assembly_handbook/ahb_parts_cache.py

import FreeCAD as App
import FreeCADGui as Gui

class PartCachedView:
    def __init__(self, direction, x_direction, obj):
        self.direction = direction
        self.x_direction = x_direction
        self.doc_name = obj.Document.Name
        self.obj_name = obj.Name
        self.cached_lines = None
        
    def render(self):
        import numpy as np
        import os
        
        doc = App.getDocument(self.doc_name) #: :type doc: App.Document
        obj = doc.getObject(self.obj_name) #: :type obj: App.DocumentObject
        
        # create temporary view
        page = doc.addObject('TechDraw::DrawPage', 'TmpPage')
        if not page.KeepUpdated: page.KeepUpdated = True
        template = doc.addObject('TechDraw::DrawSVGTemplate', 'Template')
        import ahb_locator
        template.Template = os.path.join(os.path.dirname(ahb_locator.__file__), "resources/A4_Landscape_blank.svg")
        page.Template = template
            
        tmpView = doc.addObject('TechDraw::DrawViewPart', 'TmpView')
        tmpView.Direction = self.direction
        tmpView.XDirection = self.x_direction
        tmpView.Perspective = False
        tmpView.ScaleType = 'Custom'
        tmpView.Scale = 1.0
        tmpView.XSource = [obj]
        page.addView(tmpView)
        tmpView.recompute()
        
        # copy edges relative to center
        tmpCenter = self.computePartCenter(tmpView, obj)
        
        # count lines
        tmpEdges = tmpView.getVisibleEdges()
        numLines = 0
        for edge in tmpEdges:
            if not hasattr(edge.Curve, 'Degree') or edge.Curve.Degree == 1: numLines += 1
        
        # store all lines in a packed array of floats (for each line: X1, Y1, X2, Y2)
        self.cached_lines = np.empty([numLines, 4])
        lineIdx = 0
        for edge in tmpEdges:
            if not hasattr(edge.Curve, 'Degree') or edge.Curve.Degree == 1:
                sx = 1.0
                sy = -1.0
                self.cached_lines[lineIdx] = [
                    edge.Vertexes[0].Point.x*sx - tmpCenter.x,
                    edge.Vertexes[0].Point.y*sy - tmpCenter.y,
                    edge.Vertexes[1].Point.x*sx - tmpCenter.x,
                    edge.Vertexes[1].Point.y*sy - tmpCenter.y
                ]
                lineIdx = lineIdx + 1
        
        # delete temporary view
        doc.removeObject(page.Name)
    
    def computePartCenter(self, view, obj):
        if obj.TypeId == 'App::Link':
            partLink = obj
            objectCenterWorld = partLink.LinkPlacement.Matrix.multiply(partLink.LinkedObject.Shape.CenterOfGravity)
        else:
            objectCenterWorld = obj.Shape.CenterOfGravity
        
        vertId = view.makeCosmeticVertex3d(objectCenterWorld)
        vert = view.getCosmeticVertex(vertId)
        objectCenterView = vert.Point
        view.removeCosmeticVertex(vertId)
        return objectCenterView

class PartsCache:
    part_views = {}
    
    def getPart2DView(self, view, obj):
        key = (view.Direction.x, view.Direction.y, view.Direction.z, view.XDirection.x, view.XDirection.y, view.XDirection.z, obj.Document.Name, obj.Name)
        part_view = self.part_views.get(key, None)
        if part_view is None:
            part_view = PartCachedView(view.Direction, view.XDirection, obj)
            part_view.render()
            self.part_views[key] = part_view
        return part_view