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Merge pull request #42 from bigbluebutton/cairo-scaling
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Limit the max size of image surface to render PDF
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@kepstin
kepstin authored Apr 11, 2023
2 parents 56edc82 + 5a89896 commit b80b130
Showing 1 changed file with 80 additions and 49 deletions.
129 changes: 80 additions & 49 deletions bbb_presentation_video/renderer/presentation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,9 @@ class ImageType(Enum):
TLDRAW_DRAWING_SIZE_2_6_0 = Size(2048, 1536)
TLDRAW_DRAWING_SIZE_2_6_1 = Size(1440, 1080)

PDF_MAX_ZOOM = 10.0
PDF_MAX_SIZE = 32767 # Max image dimension supported by cairo


@attr.s(order=False, slots=True, auto_attribs=True)
class Transform(object):
Expand Down Expand Up @@ -105,6 +108,7 @@ class PresentationRenderer(Generic[CairoSomeSurface]):
pan_zoom_changed: bool
tldraw_whiteboard: bool
tldraw_drawing_size: Size
pdf_max_size: Size

filename: Optional[Union[str, bytes, PathLike[Any]]]
filetype: ImageType
Expand Down Expand Up @@ -132,6 +136,12 @@ def __init__(
self.tldraw_drawing_size = TLDRAW_DRAWING_SIZE_2_6_1
else:
self.tldraw_drawing_size = TLDRAW_DRAWING_SIZE_2_6_0
# Render PDF slides with a maximum zoom, but ensure not to exceed an absolute
# maximum size
self.pdf_max_size = Size(
min(self.size.width * PDF_MAX_ZOOM, PDF_MAX_SIZE),
min(self.size.height * PDF_MAX_ZOOM, PDF_MAX_SIZE),
)

self.presentation = None
self.presentation_slide = {}
Expand Down Expand Up @@ -214,6 +224,75 @@ def update_pan_zoom(self, event: events.PanZoomEvent) -> None:
self.pan_zoom_changed = True
print(f"\tPresentation: pan: {self.pan} zoom: {self.zoom}")

def render_pdf(self) -> None:
assert isinstance(self.page, Poppler.Page)
assert self.page_size is not None

ctx = self.ctx

# This bit of nastiness is to work around Poppler bugs,
# which would otherwise contaminate the main cairo ctx
# with an error status, making it unusable.
try:
# Limit the max size that we render the page at. If the zoom would need it
# to be rendered at higher size, we'll render it blurry, but that's ok.
scaled_width = self.page_size.width * self.trans.scale
scaled_height = self.page_size.height * self.trans.scale
pdf_scale = max(
# Absolute max width/height based on max zoom and cairo limits
scaled_width / self.pdf_max_size.width,
scaled_height / self.pdf_max_size.height,
# Render anything smaller at 1:1 scale
1.0,
)
width = max(ceil(scaled_width / pdf_scale), 1)
height = max(ceil(scaled_height / pdf_scale), 1)

print(
f"\tPresentation: PDF surface size {width}x{height}, scale {pdf_scale:.3f}"
)

# Render the entire pdf page to a new image surface without clipping, to
# work around poppler bugs
pdfSurface = cairo.ImageSurface(cairo.FORMAT_RGB24, width, height)
pdfCtx = cairo.Context(pdfSurface)
# on an opaque white background
pdfCtx.set_source_rgb(1, 1, 1)
pdfCtx.paint()
pdfCtx.scale(self.trans.scale / pdf_scale, self.trans.scale / pdf_scale)
self.page.render(pdfCtx)

pdfPattern = cairo.SurfacePattern(pdfSurface)

# Now render that image surface as a pattern onto the main context. It is
# usually rendered at 1:1 pixel ratio, so only translation and clipping
# should be used. Since it's an img src, it should be pixel aligned.
# padding
ctx.translate(
floor(self.trans.padding.width),
floor(self.trans.padding.height),
)
# clipping
ctx.rectangle(
0,
0,
ceil(self.trans.size.width * self.trans.scale),
ceil(self.trans.size.height * self.trans.scale),
)
ctx.clip()
# panning
ctx.translate(
ceil(-self.trans.pos.x * self.trans.scale),
ceil(-self.trans.pos.y * self.trans.scale),
)
# scaling, if slide exceeded max resolution
if pdf_scale > 1.0:
ctx.scale(pdf_scale, pdf_scale)
ctx.set_source(pdfPattern)
ctx.paint()
except (SystemError, MemoryError) as e:
print(f"Poppler rendering failed: {e}")

def finalize_frame(self) -> bool:
needs_render = False

Expand Down Expand Up @@ -343,55 +422,7 @@ def finalize_frame(self) -> bool:
Gdk.cairo_set_source_pixbuf(ctx, self.page, 0, 0)
ctx.paint()
elif self.filetype is ImageType.PDF:
assert isinstance(self.page, Poppler.Page)
assert self.page_size is not None
# This bit of nastiness is to work around Poppler bugs,
# which would otherwise contaminate the main cairo ctx
# with an error status, making it unusable.
try:
# Render the entire pdf page to a new image surface
# without clipping, to work around poppler bugs
pdfSurface = cairo.ImageSurface(
cairo.FORMAT_RGB24,
int(ceil(self.page_size.width * self.trans.scale)),
int(ceil(self.page_size.height * self.trans.scale)),
)
pdfCtx = cairo.Context(pdfSurface)
# on an opaque white background
pdfCtx.set_source_rgb(1, 1, 1)
pdfCtx.paint()
pdfCtx.scale(self.trans.scale, self.trans.scale)
self.page.render(pdfCtx)

pdfPattern = cairo.SurfacePattern(pdfSurface)

# Now render that image surface as a pattern onto
# the main context
# It is already rendered at 1:1 pixel ratio, so
# only translation and clipping should be used.
# Since it's an img src, it should be pixel aligned.
# padding
ctx.translate(
floor(self.trans.padding.width),
floor(self.trans.padding.height),
)
# clipping
ctx.rectangle(
0,
0,
ceil(self.trans.size.width * self.trans.scale),
ceil(self.trans.size.height * self.trans.scale),
)
ctx.clip()
# panning
ctx.translate(
ceil(-self.trans.pos.x * self.trans.scale),
ceil(-self.trans.pos.y * self.trans.scale),
)
ctx.set_source(pdfPattern)
ctx.paint()
except (SystemError, MemoryError) as e:
print(f"Poppler rendering failed: {e}")
self.render_pdf()

self.pattern = ctx.pop_group()

Expand Down

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