feat: enable auto-png configuration (#1652)

docs/configuration.rst

@@ -348,7 +348,7 @@ AUTO_*
 
 These configurations indicates that thumbor will try to automatically convert
 the image format to a lighter image format, according to this compression order:
-`WEBP, AVIF, JPG, HEIF` — from highest (`WEBP`) to lowest (`HEIF`) priority.
+`WEBP, AVIF, JPG, HEIF, PNG` — from highest (`WEBP`) to lowest (`PNG`) priority.
 
 AUTO\_WEBP
 ^^^^^^^^^^
@@ -401,6 +401,17 @@ specifies that the browser supports "*/*", "image/jpg" or "image/jpeg".
 
    AUTO_JPG = True
 
+AUTO\_PNG
+^^^^^^^^^
+
+This option indicates whether thumbor should send PNG images
+automatically if the request comes with an "Accept" header that
+specifies that the browser supports "image/png".
+
+.. code:: python
+
+   AUTO_PNG = True
+
 AUTO\_HEIF
 ^^^^^^^^^^
 

tests/handlers/test_base_handler_with_auto_png.py

@@ -0,0 +1,127 @@
+# -*- coding: utf-8 -*-
+
+# thumbor imaging service
+# https://github.com/thumbor/thumbor/wiki
+
+# Licensed under the MIT license:
+# http://www.opensource.org/licenses/mit-license
+# Copyright (c) 2024 globo.com thumbor@g.globo
+
+from shutil import which
+
+from preggy import expect
+from tornado.testing import gen_test
+
+from tests.handlers.test_base_handler import BaseImagingTestCase
+from thumbor.config import Config
+from thumbor.context import Context, ServerParameters
+from thumbor.importer import Importer
+
+# pylint: disable=broad-except,abstract-method,attribute-defined-outside-init,line-too-long,too-many-public-methods
+# pylint: disable=too-many-lines
+
+MIMETYPE = "image/png"
+
+
+class ImageOperationsWithAutoPngTestCase(BaseImagingTestCase):
+    def get_context(self):
+        cfg = Config(SECURITY_KEY="ACME-SEC")
+        cfg.LOADER = "thumbor.loaders.file_loader"
+        cfg.FILE_LOADER_ROOT_PATH = self.loader_path
+        cfg.STORAGE = "thumbor.storages.no_storage"
+        cfg.AUTO_PNG = True
+
+        importer = Importer(cfg)
+        importer.import_modules()
+        server = ServerParameters(
+            8889, "localhost", "thumbor.conf", None, "info", None
+        )
+        server.security_key = "ACME-SEC"
+        ctx = Context(server, cfg, importer)
+        ctx.server.gifsicle_path = which("gifsicle")
+        return ctx
+
+    async def get_as_png(self, url):
+        return await self.async_fetch(
+            url, headers={"Accept": f"{MIMETYPE},*/*;q=0.8"}
+        )
+
+    @gen_test
+    async def test_can_auto_convert_jpeg_to_png(self):
+        response = await self.get_as_png("/unsafe/image.jpg")
+
+        expect(response.code).to_equal(200)
+        expect(response.headers["Content-type"]).to_equal(MIMETYPE)
+        expect(response.body).to_be_png()
+
+    @gen_test
+    async def test_can_auto_convert_heic_to_png(self):
+        response = await self.get_as_png("/unsafe/image.heic")
+
+        expect(response.code).to_equal(200)
+        expect(response.headers["Content-type"]).to_equal(MIMETYPE)
+        expect(response.body).to_be_png()
+
+    @gen_test
+    async def test_should_not_convert_animated_gifs_to_png(self):
+        response = await self.get_as_png("/unsafe/animated.gif")
+
+        expect(response.code).to_equal(200)
+        expect(response.body).to_be_gif()
+
+    @gen_test
+    async def test_should_convert_image_with_small_width_and_no_height_to_png(
+        self,
+    ):
+        response = await self.get_as_png("/unsafe/0x0:1681x596/1x/image.jpg")
+
+        expect(response.code).to_equal(200)
+        expect(response.headers["Content-type"]).to_equal(MIMETYPE)
+        expect(response.body).to_be_png()
+
+    @gen_test
+    async def test_should_convert_monochromatic_jpeg_to_png(self):
+        response = await self.get_as_png("/unsafe/grayscale.jpg")
+        expect(response.code).to_equal(200)
+        expect(response.headers["Content-type"]).to_equal(MIMETYPE)
+        expect(response.body).to_be_png()
+
+    @gen_test
+    async def test_should_convert_cmyk_jpeg_to_png(self):
+        response = await self.get_as_png("/unsafe/cmyk.jpg")
+        expect(response.code).to_equal(200)
+        expect(response.headers["Content-type"]).to_equal(MIMETYPE)
+        expect(response.body).to_be_png()
+
+    @gen_test
+    async def test_shouldnt_convert_to_cmyk_to_png_if_format_specified(self):
+        response = await self.get_as_png(
+            "/unsafe/filters:format(png)/cmyk.jpg"
+        )
+        expect(response.code).to_equal(200)
+        expect(response.body).to_be_png()
+
+    @gen_test
+    async def test_shouldnt_convert_cmyk_to_png_if_gif(self):
+        response = await self.get_as_png(
+            "/unsafe/filters:format(gif)/cmyk.jpg"
+        )
+        expect(response.code).to_equal(200)
+        expect(response.body).to_be_gif()
+
+    @gen_test
+    async def test_shouldnt_convert_gif_to_png_if_format_specified(self):
+        response = await self.get_as_png(
+            "/unsafe/filters:format(gif)/image.jpg"
+        )
+        expect(response.code).to_equal(200)
+        expect(response.body).to_be_gif()
+
+    @gen_test
+    async def test_should_convert_to_png_if_format_invalid(self):
+        response = await self.get_as_png(
+            "/unsafe/filters:format(asdf)/image.jpg"
+        )
+        expect(response.code).to_equal(200)
+        expect(response.headers["Content-type"]).to_equal(MIMETYPE)
+        expect(response.body).to_be_png()

thumbor/config.py

@@ -207,6 +207,13 @@
     "(via Accept header) and pillow-heif is enabled",
     "Imaging",
 )
+Config.define(
+    "AUTO_PNG",
+    False,
+    "Specifies whether PNG format should be used automatically if the request accepts it "
+    "(via Accept header)",
+    "Imaging",
+)
 Config.define(
     "AUTO_PNG_TO_JPG",
     False,

thumbor/handlers/__init__.py

@@ -465,6 +465,19 @@ def can_auto_convert_to_jpg(self):
 
         return False
 
+    def can_auto_convert_to_png(self):
+        auto_png = self.context.config.AUTO_PNG
+        accepts_png = self.accepts_mime_type("image/png")
+
+        if (
+            auto_png
+            and accepts_png
+            and not self.context.request.engine.is_multiple()
+        ):
+            return True
+
+        return False
+
     def define_image_type(self, context, result):
         if result is not None:
             if isinstance(result, ResultStorageResult):
@@ -509,6 +522,11 @@ def define_image_type(self, context, result):
             logger.debug(
                 "Image format set by AUTO_HEIF as %s.", image_extension
             )
+        elif self.can_auto_convert_to_png():
+            image_extension = ".png"
+            logger.debug(
+                "Image format set by AUTO_PNG as %s.", image_extension
+            )
         else:
             image_extension = context.request.engine.extension
             logger.debug(

thumbor/thumbor.conf

@@ -38,6 +38,9 @@ home = expanduser("~")
 ## Automatically converts images to JPG if Accepts header present
 # AUTO_JPG = False
 
+## Automatically converts images to PNG if Accepts header present
+# AUTO_PNG = False
+#
 ## Automatically converts images to Avif if Accepts header present and
 ## pillow-avif-plugin is enabled
 # AUTO_AVIF = False