如何测量魔杖中字符串的范围?

How do I measure the bounds of a string in wand?

我正在使用 Wand 生成其中包含自定义变量文本的 JPG。 我有一组宽度相同但高度不同的字符串。 有没有一种方法可以在边界内将长文本换行或计算文本所需的高度,以便在从数组中绘制文本时它们不会重叠。

with Drawing() as ctx:
        with Image(width=1080, height=1080, background=Color("WHITE")) as img:
            with Drawing() as draw: 
                for i,line in enumerate(lines):
                     metrics = draw.get_font_metrics(img, line, multiline=True)
                     draw.text(x=150, y=120+(i*35)+int(metrics.text_height), body=line)
                draw(img)
                img.sample(1080, 1080)
                img.save(filename="output.png")

这可能不是您要找的答案,但希望能让您走上正确的道路。

How do I measure the bounds of a string in wand?

你已经在做了。我建议使用更经典的偏移量和累加器方法来映射随每次迭代更新的位置,而不是 "smart-n-quick" one-liner 方法。

top_margin = 120
line_offset = 0
line_padding = 35
with Drawing() as ctx:
    with Image(width=1080, height=1080, background=Color("WHITE")) as img:
        with Drawing() as draw: 
            for i,line in enumerate(lines):
                metrics = draw.get_font_metrics(img, line, multiline=True)
                draw.text(x=150, y=y=top_margin + line_offset, body=line)
                line_offset += int(metrics.text_height) + line_padding

Is there a method to word wrap a long text inside a boundary or calculate the height needed for the text so when drawing the texts from the array they don't overlap.

简短的回答是。您将负责实施该算法。幸运的是,互联网上有很多可供参考的示例和研究文章。它可以像 find-the-last-space-before-overflow...

一样基本
lines = [
    'I\'m using Wand to generate a JPG with custom variable text inside it.',
    'I have an array of strings all with the same width but different heights',
    'Is there a method to word wrap a long text inside a boundary or calculate the height needed for the text so when drawing the texts from the array they don\'t overlap',
]
image_width = 540
image_height = 540
left_margin = 150
right_margin = image_width - left_margin * 2
top_margin = 120
line_padding = 35
line_offset = 0
with Drawing() as ctx:
    with Image(width=image_width, height=image_height, background=Color("LIGHTCYAN")) as img:
        with Drawing() as draw: 
            for i,line in enumerate(lines):
                metrics = draw.get_font_metrics(img, line, multiline=True)
                last_idx = 1
                # Do we need to do work?
                while metrics.text_width > right_margin:
                    last_breakpoint=0
                    # Scan text for possible breakpoints.
                    for idx in range(last_idx, len(line)):
                        if line[idx] == ' ':
                            last_breakpoint = idx
                        else:
                            # Determine if we need to insert a breakpoint.
                            metrics = draw.get_font_metrics(img, line[:idx], multiline=True)
                            if metrics.text_width >= right_margin:
                                line = line[:last_breakpoint].strip() + '\n' + line[last_breakpoint:].strip()
                                last_idx = last_breakpoint
                                break
                    # Double check any modifications to text was successful enough.
                    metrics = draw.get_font_metrics(img, line, multiline=True)
                draw.text(x=left_margin, y=top_margin + line_offset, body=line)
                line_offset += int(metrics.text_height) + line_padding
            draw(img)
            img.save(filename="output.png")

以上代码可以优化,Python 可能已经包含一些 better methods

进一步阅读...

source code ImageMagick's CAPTION: protocol is a good example. The algorithm repeatedly calls GetMultilineTypeMetrics as well as FormatMagickCaption 调整点数并插入 line-breaks。 wand 库并不真正支持字幕协议,但您可以 play-around 通过使用以下解决方法来使用它。

from wand.api import library
# ...
with Image(width=image_width, height=image_height, background=Color("LIGHTCYAN")) as img:
    for i,line in enumerate(lines):
        # Create a tempory image for each bounding box
        with Image() as throwaway:
            library.MagickSetSize(throwaway.wand, right_margin, line_padding)
            throwaway.read(filename='CAPTION:'+line)
            img.composite(throwaway, left_margin, top_margin + line_offset)
            line_offset += line_padding + throwaway.height
    img.save(filename="output.png")