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Tweak internal resize logic #128

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Merged
merged 2 commits into from
Nov 4, 2025
Merged

Tweak internal resize logic #128

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3cdff15
Implement canvas zoom
almarklein Oct 30, 2025
7b3fb4d
remove public zoom methods
almarklein Nov 4, 2025
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49 changes: 33 additions & 16 deletions rendercanvas/base.py
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Original file line number Diff line number Diff line change
Expand Up @@ -151,8 +151,14 @@ def __init__(
if (self._rc_canvas_group and self._rc_canvas_group.get_loop())
else "no-loop",
}
self._set_size_info((0, 0), 1.0) # Init self.__size_info
self.__size_info["need_event"] = False
self.__size_info = {
"physical_size": (0, 0),
"native_pixel_ratio": 1.0,
"canvas_pixel_ratio": 1.0,
"total_pixel_ratio": 1.0,
"logical_size": (0.0, 0.0),
}
self.__need_size_event = False

# Events and scheduler
self._events = EventEmitter()
Expand Down Expand Up @@ -298,18 +304,29 @@ def _set_size_info(self, physical_size: Tuple[int, int], pixel_ratio: float):

The subclass must call this when the actual viewport has changed. So not in ``_rc_set_logical_size()``,
but e.g. when the underlying GUI layer fires a resize event, and maybe on init.

The given pixel-ratio represents the 'native' pixel ratio. The canvas'
zoom factor is multiplied with it to obtain the final pixel-ratio for
this canvas.
"""
w, h = physical_size
self.__size_info["physical_size"] = int(physical_size[0]), int(physical_size[1])
self.__size_info["native_pixel_ratio"] = float(pixel_ratio)
self.__resolve_total_pixel_ratio_and_logical_size()

def __resolve_total_pixel_ratio_and_logical_size(self):
physical_size = self.__size_info["physical_size"]
native_pixel_ratio = self.__size_info["native_pixel_ratio"]
canvas_pixel_ratio = self.__size_info["canvas_pixel_ratio"]

total_pixel_ratio = native_pixel_ratio * canvas_pixel_ratio
logical_size = (
physical_size[0] / total_pixel_ratio,
physical_size[1] / total_pixel_ratio,
)

psize = int(w), int(h)
pixel_ratio = float(pixel_ratio)
lsize = psize[0] / pixel_ratio, psize[1] / pixel_ratio
self.__size_info = {
"physical_size": psize,
"logical_size": lsize,
"pixel_ratio": pixel_ratio,
"need_event": True,
}
self.__size_info["total_pixel_ratio"] = total_pixel_ratio
self.__size_info["logical_size"] = logical_size
self.__need_size_event = True

def add_event_handler(
self, *args: EventTypeEnum | EventHandlerFunction, order: float = 0
Expand All @@ -332,15 +349,15 @@ def submit_event(self, event: dict) -> None:
# %% Scheduling and drawing

def __maybe_emit_resize_event(self):
if self.__size_info["need_event"]:
self.__size_info["need_event"] = False
if self.__need_size_event:
self.__need_size_event = False
lsize = self.__size_info["logical_size"]
self._events.emit(
{
"event_type": "resize",
"width": lsize[0],
"height": lsize[1],
"pixel_ratio": self.__size_info["pixel_ratio"],
"pixel_ratio": self.__size_info["total_pixel_ratio"],
# Would be nice to have more details. But as it is now, PyGfx errors if we add fields it does not know, so let's do later.
# "logical_size": self.__size_info["logical_size"],
# "physical_size": self.__size_info["physical_size"],
Expand Down Expand Up @@ -531,7 +548,7 @@ def get_pixel_ratio(self) -> float:
pixel ratio >= 2.0. On MacOS (with a Retina screen) the pixel ratio is
always 2.0.
"""
return self.__size_info["pixel_ratio"]
return self.__size_info["total_pixel_ratio"]

def close(self) -> None:
"""Close the canvas."""
Expand Down