GIMP Python插件：如何在导出后撤销图像缩放操作

我写了一个GIMP插件，用来把图像导出成不同尺寸，作为React Native Android项目的图标，代码如下：

from gimpfu import *
import os


def execScale(image, drawable, toSave, isRound):
    addround = ""

    if(isRound):
        addround = "_round"

    scale_and_export(image, drawable, 192, toSave + "\\mipmap-xxxhdpi\\ic_launcher" + addround + ".png")
    scale_and_export(image, drawable, 144, toSave + "\\mipmap-xxhdpi\\ic_launcher" + addround + ".png")
    scale_and_export(image, drawable, 96, toSave + "\\mipmap-xhdpi\\ic_launcher" + addround + ".png")
    scale_and_export(image, drawable, 72, toSave + "\\mipmap-hdpi\\ic_launcher" + addround + ".png")
    scale_and_export(image, drawable, 48, toSave + "\\mipmap-mdpi\\ic_launcher" + addround + ".png")

    pdb.gimp_image_scale(image, 1024, 1024)

    return


def scale_and_export(image, drawable, size, filename):
    try:
        os.makedirs(os.path.dirname(filename))
    except OSError:
        print("Path exists")

    pdb.gimp_image_scale(image, size, size)
    pdb.gimp_file_save(image, drawable, filename, "?")

register(
    "scale",
    "Scale image to be usable in a react-native android project as an icon",
    "Scale image to be usable in a react-native android project as an icon",
    "JaRoMaster",
    "JaRoMaster",
    "2022",
    "<Image>/CustomPlugins/Scale",
    "RGB*, GRAY*",
    [
        (PF_DIRNAME, "toSave", "export", 0),
        (PF_BOOL, "isRound", "Round: ", False)
    ],
    [],
    execScale)

main()

现在的问题是：每次缩放后图像都会越来越模糊，最后导出的48×48图像，比直接从初始尺寸缩放过来的模糊很多。想问有没有办法在导出后撤销缩放操作？

问题出在你每次都是直接修改原图像，后续缩放是基于已经缩小过的图像进行的，自然会累积模糊。正确的做法是每次都基于原始图像的副本进行缩放导出，这样所有尺寸都从原图生成，清晰度一致，而且原图像完全不受影响，根本不需要撤销缩放。

修改后的代码如下：

from gimpfu import *
import os


def execScale(image, drawable, toSave, isRound):
    addround = "_round" if isRound else ""
    
    # 定义所有需要导出的尺寸和对应目录
    sizes = [
        (192, "mipmap-xxxhdpi"),
        (144, "mipmap-xxhdpi"),
        (96, "mipmap-xhdpi"),
        (72, "mipmap-hdpi"),
        (48, "mipmap-mdpi")
    ]

    for size, dir_name in sizes:
        # 创建原图的副本，基于副本操作，不改动原图
        temp_image = pdb.gimp_image_duplicate(image)
        temp_drawable = pdb.gimp_image_get_active_drawable(temp_image)
        
        # 拼接导出路径
        export_path = os.path.join(toSave, dir_name, f"ic_launcher{addround}.png")
        scale_and_export(temp_image, temp_drawable, size, export_path)
        
        # 关闭副本，释放资源
        pdb.gimp_image_delete(temp_image)

    return


def scale_and_export(image, drawable, size, filename):
    try:
        # 自动处理目录已存在的情况，简化逻辑
        os.makedirs(os.path.dirname(filename), exist_ok=True)
    except OSError as e:
        print(f"创建目录出错: {e}")

    pdb.gimp_image_scale(image, size, size)
    # 用文件名作为第四个参数，符合GIMP API规范
    pdb.gimp_file_save(image, drawable, filename, filename)


register(
    "scale",
    "Scale image to be usable in a react-native android project as an icon",
    "Scale image to be usable in a react-native android project as an icon",
    "JaRoMaster",
    "JaRoMaster",
    "2022",
    "<Image>/CustomPlugins/Scale",
    "RGB*, GRAY*",
    [
        (PF_DIRNAME, "toSave", "导出目录", 0),
        (PF_BOOL, "isRound", "是否为圆形图标", False)
    ],
    [],
    execScale)

main()

修改核心点 #

• 用pdb.gimp_image_duplicate(image)生成原图副本，所有缩放导出操作都在副本上进行，原图像保持初始状态，无需后续还原。
• 所有尺寸均基于原始图像生成，彻底解决多次缩放累积的模糊问题。
• 用os.path.join拼接路径，比硬编码反斜杠更适配不同系统。
• 优化目录创建逻辑，exist_ok=True避免重复创建目录时的报错。
• 调整gimp_file_save的参数，符合GIMP官方API的规范用法。

内容的提问来源于stack exchange，提问作者JaRoMaster