mirror of
https://github.com/Orama-Interactive/Pixelorama.git
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4658b1cfb6
* APNG loader: Import addon to take over APNG handling * APNG loader: Transition code to using the AImgIO addon * APNG loader: Can now open APNGs. * AImgIO: Update to fix bugs * APNG loader: HTML5 * APNG loader: gdformat/gdlint addon * APNG loader: OpenSave formatting fix * APNG Loader: Add ignore line to OpenSave because it's too big * Fix GIFAnimationExporter bug caused by the switch to the addon
131 lines
3.8 KiB
GDScript
131 lines
3.8 KiB
GDScript
class_name AImgIOAPNGExporter
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extends AImgIOBaseExporter
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# APNG exporter. To be clear, this is effectively magic.
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func _init():
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mime_type = "image/apng"
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func export_animation(
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frames: Array,
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fps_hint: float,
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progress_report_obj: Object,
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progress_report_method,
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progress_report_args
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) -> PoolByteArray:
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var frame_count := len(frames)
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var result := AImgIOAPNGStream.new()
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# Magic number
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result.write_magic()
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# From here on out, all data is written in "chunks".
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# IHDR
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var image: Image = frames[0].content
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var chunk := result.start_chunk()
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chunk.put_32(image.get_width())
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chunk.put_32(image.get_height())
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chunk.put_32(0x08060000)
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chunk.put_8(0)
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result.write_chunk("IHDR", chunk.data_array)
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# acTL
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chunk = result.start_chunk()
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chunk.put_32(frame_count)
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chunk.put_32(0)
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result.write_chunk("acTL", chunk.data_array)
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# For each frame... (note: first frame uses IDAT)
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var sequence := 0
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for i in range(frame_count):
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image = frames[i].content
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# fcTL
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chunk = result.start_chunk()
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chunk.put_32(sequence)
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sequence += 1
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# image w/h
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chunk.put_32(image.get_width())
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chunk.put_32(image.get_height())
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# offset x/y
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chunk.put_32(0)
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chunk.put_32(0)
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write_delay(chunk, frames[i].duration, fps_hint)
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# dispose / blend
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chunk.put_8(0)
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chunk.put_8(0)
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# So depending on who you ask, there might be supposed to be a second
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# checksum here. The problem is, if there is, it's not well-explained.
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# Plus, actual readers don't seem to require it.
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# And the W3C specification just copy/pastes the (bad) Mozilla spec.
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# Dear Mozilla spec writers: If you wanted a second checksum,
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# please indicate it's existence in the fcTL chunk structure.
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result.write_chunk("fcTL", chunk.data_array)
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# IDAT/fdAT
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chunk = result.start_chunk()
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if i != 0:
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chunk.put_32(sequence)
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sequence += 1
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# setup chunk interior...
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var ichk := result.start_chunk()
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write_padded_lines(ichk, image)
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chunk.put_data(ichk.data_array.compress(File.COMPRESSION_DEFLATE))
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# done with chunk interior
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if i == 0:
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result.write_chunk("IDAT", chunk.data_array)
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else:
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result.write_chunk("fdAT", chunk.data_array)
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# Done with this frame!
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progress_report_obj.callv(progress_report_method, progress_report_args)
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# Final chunk.
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result.write_chunk("IEND", PoolByteArray())
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return result.finish()
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func write_delay(sp: StreamPeer, duration: float, fps_hint: float):
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# Obvious bounds checking
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duration = max(duration, 0)
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fps_hint = min(32767, max(fps_hint, 1))
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# The assumption behind this is that in most cases durations match the FPS hint.
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# And in most cases the FPS hint is integer.
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# So it follows that num = 1 and den = fps.
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# Precision is increased so we catch more complex cases.
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# But you should always get perfection for integers.
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var den := min(32767, max(fps_hint, 1))
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var num := max(duration, 0) * den
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# If the FPS hint brings us out of range before we start, try some obvious integers
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var fallback := 10000
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while num > 32767:
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num = max(duration, 0) * den
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den = fallback
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if fallback == 1:
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break
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fallback /= 10
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# If the fallback plan failed, give up and set the duration to 1 second.
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if num > 32767:
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sp.put_16(1)
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sp.put_16(1)
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return
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# Raise to highest safe precision
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# This is what handles the more complicated cases (usually).
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while num < 16384 and den < 16384:
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num *= 2
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den *= 2
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# Write out
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sp.put_16(int(round(num)))
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sp.put_16(int(round(den)))
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func write_padded_lines(sp: StreamPeer, img: Image):
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if img.get_format() != Image.FORMAT_RGBA8:
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push_warning("Image format in AImgIOAPNGExporter should only ever be RGBA8.")
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return
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var data := img.get_data()
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var y := 0
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var w := img.get_width()
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var h := img.get_height()
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var base := 0
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while y < h:
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var nl := base + (w * 4)
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var line := data.subarray(base, nl - 1)
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sp.put_8(0)
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sp.put_data(line)
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y += 1
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base = nl
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