[WIP] Add support to save apng

drawBot/context/__init__.py

@@ -1,6 +1,7 @@
 from .gifContext import GIFContext
+from .pngContext import PNGContext
 from .icnsContext import ICNSContext
-from .imageContext import BMPContext, JPEGContext, PNGContext, TIFFContext
+from .imageContext import BMPContext, JPEGContext, TIFFContext
 from .imageObjectContext import NSImageContext, PILContext
 from .mp4Context import MP4Context
 from .pdfContext import PDFContext

drawBot/context/imageContext.py

@@ -246,18 +246,6 @@ class BMPContext(ImageContext):
     fileExtensions = ["bmp"]
 
 
-class PNGContext(ImageContext):
-    fileExtensions = ["png"]
-
-    saveImageOptions = getSaveImageOptions(
-        [
-            "imagePNGGamma",
-            "imagePNGInterlaced",
-            "imageColorSyncProfileData",
-        ]
-    )
-
-
 class TIFFContext(ImageContext):
     fileExtensions = ["tif", "tiff"]
 

drawBot/context/mp4Context.py

@@ -4,7 +4,7 @@
 
 from drawBot.misc import warnings
 
-from .imageContext import PNGContext
+from .pngContext import PNGContext
 from .tools.mp4Tools import generateMP4
 
 

drawBot/context/pdfContext.py

@@ -4,9 +4,9 @@
 from packaging.version import Version
 
 from ..macOSVersion import macOSVersion
-from ..misc import DrawBotError, isGIF, isPDF
+from ..misc import DrawBotError, isGIF, isPDF, isPNG
 from .baseContext import BaseContext, FormattedString, newFramesetterWithAttributedString
-from .tools import gifTools
+from .tools import gifTools, apng
 
 
 def sendPDFtoPrinter(pdfDocument):
@@ -266,6 +266,7 @@ def _getImageSource(self, key, pageNumber):
                     url = AppKit.NSURL.fileURLWithPath_(path)
                 _isPDF, _ = isPDF(url)
                 _isGIF, _ = isGIF(url)
+                _isPNG, _ = isPNG(url)
                 if _isPDF:
                     pdf = Quartz.CGPDFDocumentCreateWithURL(url)
                     if pdf is not None:
@@ -284,6 +285,15 @@ def _getImageSource(self, key, pageNumber):
                         self._cachedImages[key] = False, Quartz.CGImageSourceCreateImageAtIndex(source, 0, None)
                     else:
                         raise DrawBotError("No image found at frame %s in %s" % (pageNumber, key))
+                elif _isPNG:
+                    if pageNumber is not None:
+                        image = AppKit.NSImage.alloc().initByReferencingURL_(url)
+                    else:
+                        animatedPNG = apng.APNG.open(path)
+                        if pageNumber >= len(animatedPNG.frames):
+                            raise DrawBotError("No image found at frame %s in %s" % (pageNumber, key))
+                        pngData, pngFrameOptions = animatedPNG.frames[pageNumber - 1]
+                        image = AppKit.NSImage.alloc().initWithData_(pngData.to_bytes())
                 else:
                     image = AppKit.NSImage.alloc().initByReferencingURL_(url)
             if image and not _isPDF:

drawBot/context/pngContext.py

@@ -0,0 +1,57 @@
+import tempfile
+
+import Quartz  # type: ignore
+
+from .imageContext import ImageContext, getSaveImageOptions
+from .tools.apng import APNG
+
+
+class PNGContext(ImageContext):
+    fileExtensions = ["png"]
+
+    saveImageOptions = getSaveImageOptions(
+        [
+            "imagePNGGamma",
+            "imagePNGInterlaced",
+            "imageColorSyncProfileData",
+        ]
+    )
+
+    _delay_den = 100
+    _delay = 1 / _delay_den
+
+    def __init__(self):
+        super().__init__()
+        self._delayData = []
+
+    def _frameDuration(self, seconds):
+        # `delay_num` specifies 1/100ths of a second; see https://wiki.mozilla.org/APNG_Specification#.60fcTL.60:_The_Frame_Control_Chunk%3E
+        self._delayData[-1] = int(seconds * self._delay_den)
+
+    def _newPage(self, width, height):
+        super()._newPage(width, height)
+        self._delayData.append(self._delay)
+
+    def _writeDataToFile(self, data, path, options):
+        pdfDocument = Quartz.PDFDocument.alloc().initWithData_(data)
+        pageCount = pdfDocument.pageCount()
+        shouldBeAnimated = pageCount > 1
+
+        tempPath = path
+        if shouldBeAnimated:
+            options["multipage"] = True
+            tempPath = tempfile.mkstemp(suffix=".png")[1]
+
+        self._inputPaths = []
+        super()._writeDataToFile(data, tempPath, options)
+
+        if shouldBeAnimated:
+            animatedPNG = APNG()
+            for inputPath, delay in zip(self._inputPaths, self._delayData):
+                animatedPNG.append_file(inputPath, delay=delay, delay_den=self._delay_den)
+            animatedPNG.save(path)
+        del self._inputPaths
+
+    def _storeImageData(self, imageData, imagePath):
+        super()._storeImageData(imageData, imagePath)
+        self._inputPaths.append(imagePath)