控制 ezdxf 输出到 PDF 时的线宽

Question

我正在尝试在ezdxf中绘制一些基本的圆形和正方形，然后写入pdf。 当我只绘制几个单位时，情况看起来很好。 但当我画很多的时候，线条就会变得更粗。 dfxattribs={'lineweight':0} 没有任何乱七八糟的效果。 我认为 ezdxf 或 pdf 转换器在某种程度上可以缩放东西。 它似乎固定了 PDF 的大小，然后将其缩小以适合，但线宽被固定为其他缩放比例，最终结果是粗线。

这里有一些例子。

def test():
    from numpy import arange
    doc = ezdxf.new(dxfversion="R2010")
    doc.units = units.MM
    doc.header['$LWDISPLAY'] = 1
    msp = doc.modelspace()
    blk = doc.blocks.new(name='MYBLOCK')
    blk.add_circle((0,0), 1, dxfattribs={'lineweight':0})
    blk.add_polyline2d(((-1,-1),(1,-1),(1,1),(-1,1)))

    pos_step = 2.0
    blockscale = 1.0
    for x in arange(0, pos_step*5, pos_step):
        for y in arange(0, pos_step*3, pos_step):
            msp.add_blockref('MYBLOCK', 
                            (x, y),
                            dxfattribs={'xscale': blockscale,
                                        'yscale': blockscale})

    msp.add_linear_dim(
        base = (0,-pos_step/2),
        p1   = (0,0),
        p2   = (pos_step,0),
        override = {'dimblk': ezdxf.ARROWS.closed_filled}
        ).render()
    matplotlib.qsave(msp, 'test.pdf')

这里的输出看起来不错。 pdf 为 6.5x4.8 [英寸]：

如果我跨过 50 个单位：

for x in arange(0, pos_step*50, pos_step):

我觉得线条变粗了，但看起来还不错。 pdf 为 16x2 [英寸]：

如果我跨过 500 个单位：

for x in arange(0, pos_step*500, pos_step):

线条明显变粗。 pdf 为 16x2 [英寸]：

如果我们疯狂地拥有 5000 个单位：

    for x in arange(0, pos_step*5000, pos_step):

线条太粗了，只是一块白色。 pdf 为 16x2 [英寸]：

所以我认为这与 pdf 表大小保持不变有关，即使放置了越来越多的块。 如何获得此测试所有版本的一些粗细线？ 是否可以手动缩放PDF输出的大小，或者设置一些更好的自动参数？

Answer 1

新的测试代码，源自：

https://ezdxf.mozman.at/docs/howto/drawing-addon.html#how-to-set-the-page-size-in-inches https://github.com/mozman/ezdxf/discussions/797

def export_to_scale(doc, msp, filename, paper_size, minxy, maxxy, dpi = 300):
    """Render the modelspace content with to a specific paper size and scale.
    Args:
        doc -- the ezpdf doc
        msp -- the modelspace
        filename -- the filename
        paper_size: paper size in inches
        minxy: lower left corner tuple of the modelspace area to render
        maxxy: upper right corner tuple of the modelspace area to render
        dpi: pixel density on paper as dots per inch
    """
    ctx = RenderContext(doc)
    fig: plt.Figure = plt.figure(dpi=dpi)
    ax: plt.Axes = fig.add_axes([0, 0, 1, 1])

    # disable all margins
    ax.margins(0)

    # Set the final render limits in drawing units:
    ax.set_xlim(minxy[0], maxxy[0])
    ax.set_ylim(minxy[1], maxxy[1])

    mspp = LayoutProperties.from_layout(msp)
    mspp.set_colors("#eaeaea")
    config = Configuration.defaults()
    config = config.with_changes(min_lineweight = 0.1)


    out = MatplotlibBackend(ax)
    # finalizing invokes auto-scaling by default!
    Frontend(ctx, out, config=config).draw_layout(msp, finalize=False, layout_properties=mspp)
    fig.set_size_inches(paper_size[0], paper_size[1], forward=True)
    fig.savefig(filename, dpi=dpi)
    plt.close(fig)

def test():
    from numpy import arange
    doc = ezdxf.new(dxfversion="R2010")
    doc.units = units.MM
    doc.header['$LWDISPLAY'] = 0
    msp = doc.modelspace()

    blk = doc.blocks.new(name='MYBLOCK')
    blk.add_circle((0,0), 1, dxfattribs={'lineweight': -2})
    blk.add_polyline2d(((-1,-1),(1,-1),(1,1),(-1,1)), close=True, dxfattribs={'lineweight': -2})

    pos_step = 2.0
    blockscale = 1.0
    for x in arange(0, pos_step*500, pos_step):
        for y in arange(0, pos_step*3, pos_step):
            msp.add_blockref('MYBLOCK', 
                            (x, y),
                            dxfattribs={'xscale': blockscale,
                                        'yscale': blockscale,
                                        'lineweight': 100})

    msp.add_linear_dim(
        base = (0,-pos_step),
        p1   = (0, 0),
        p2   = (pos_step,0),
        override = {'dimblk': ezdxf.ARROWS.closed_filled}
        ).render()

    export_to_scale(doc, msp, 'test.pdf', (17,11), (-10,-10), (pos_step*501,pos_step*4), 300)