Make RendererCairo auto-infer surface size.

This avoids a redundant set_width_height on the caller side, and
prevents the width/height from getting out of sync from the actual
surface size.

Author: anntzer

doc/api/next_api_changes/deprecations/21981-AL.rst

@@ -1,4 +1,8 @@
 ``RendererGTK3Cairo`` and ``RendererGTK4Cairo``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-... have been deprecated.  Use ``RendererCairo`` instead, which has gained the
-``set_context`` method.
+... have been deprecated.  Use ``RendererCairo`` instead, which has gained
+the ``set_context`` method, which also auto-infers the size of the underlying
+surface.
+
+``RendererCairo.set_ctx_from_surface`` and ``RendererCairo.set_width_height``
+have likewise been deprecated, in favor of ``set_context``.

lib/matplotlib/backends/backend_cairo.py

@@ -134,15 +134,28 @@ def __init__(self, dpi):
         super().__init__()
 
     def set_context(self, ctx):
-        self.gc.ctx = _to_context(ctx)
+        surface = ctx.get_target()
+        if hasattr(surface, "get_width") and hasattr(surface, "get_height"):
+            size = surface.get_width(), surface.get_height()
+        elif hasattr(surface, "get_extents"):  # GTK4 RecordingSurface.
+            ext = surface.get_extents()
+            size = ext.width, ext.height
+        else:  # vector surfaces.
+            ctx.save()
+            ctx.reset_clip()
+            rect, *rest = ctx.copy_clip_rectangle_list()
+            if rest:
+                raise TypeError("Cannot infer surface size")
+            size = rect.width, rect.height
+            ctx.restore()
+        self.gc.ctx = ctx
+        self.width, self.height = size
 
+    @_api.deprecated("3.6", alternative="set_context")
     def set_ctx_from_surface(self, surface):
         self.gc.ctx = cairo.Context(surface)
-        # Although it may appear natural to automatically call
-        # `self.set_width_height(surface.get_width(), surface.get_height())`
-        # here (instead of having the caller do so separately), this would fail
-        # for PDF/PS/SVG surfaces, which have no way to report their extents.
 
+    @_api.deprecated("3.6")
     def set_width_height(self, width, height):
         self.width = width
         self.height = height
@@ -474,9 +487,8 @@ def print_rgba(self, fobj):
     def _get_printed_image_surface(self):
         self._renderer.dpi = self.figure.dpi
         width, height = self.get_width_height()
-        self._renderer.set_width_height(width, height)
         surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
-        self._renderer.set_ctx_from_surface(surface)
+        self._renderer.set_context(cairo.Context(surface))
         self.figure.draw(self._renderer)
         return surface
 
@@ -516,8 +528,7 @@ def _save(self, fmt, fobj, *, orientation='portrait'):
             raise ValueError("Unknown format: {!r}".format(fmt))
 
         self._renderer.dpi = self.figure.dpi
-        self._renderer.set_width_height(width_in_points, height_in_points)
-        self._renderer.set_ctx_from_surface(surface)
+        self._renderer.set_context(cairo.Context(surface))
         ctx = self._renderer.gc.ctx
 
         if orientation == 'landscape':

lib/matplotlib/backends/backend_gtk3cairo.py

@@ -26,8 +26,6 @@ def on_draw_event(self, widget, ctx):
                 self.get_style_context(), ctx,
                 allocation.x, allocation.y,
                 allocation.width, allocation.height)
-            self._renderer.set_width_height(
-                allocation.width * scale, allocation.height * scale)
             self._renderer.dpi = self.figure.dpi
             self.figure.draw(self._renderer)
 

lib/matplotlib/backends/backend_gtk4cairo.py

@@ -27,8 +27,6 @@ def on_draw_event(self, widget, ctx):
                 self.get_style_context(), ctx,
                 allocation.x, allocation.y,
                 allocation.width, allocation.height)
-            self._renderer.set_width_height(
-                allocation.width * scale, allocation.height * scale)
             self._renderer.dpi = self.figure.dpi
             self.figure.draw(self._renderer)
 

lib/matplotlib/backends/backend_qtcairo.py

@@ -21,8 +21,7 @@ def paintEvent(self, event):
         height = int(self.device_pixel_ratio * self.height())
         if (width, height) != self._renderer.get_canvas_width_height():
             surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
-            self._renderer.set_ctx_from_surface(surface)
-            self._renderer.set_width_height(width, height)
+            self._renderer.set_context(cairo.Context(surface))
             self._renderer.dpi = self.figure.dpi
             self.figure.draw(self._renderer)
         buf = self._renderer.gc.ctx.get_target().get_data()

lib/matplotlib/backends/backend_tkcairo.py

@@ -12,8 +12,7 @@ def draw(self):
         width = int(self.figure.bbox.width)
         height = int(self.figure.bbox.height)
         surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
-        self._renderer.set_ctx_from_surface(surface)
-        self._renderer.set_width_height(width, height)
+        self._renderer.set_context(cairo.Context(surface))
         self._renderer.dpi = self.figure.dpi
         self.figure.draw(self._renderer)
         buf = np.reshape(surface.get_data(), (height, width, 4))

lib/matplotlib/backends/backend_wxcairo.py

@@ -24,8 +24,7 @@ class FigureCanvasWxCairo(_FigureCanvasWxBase, FigureCanvasCairo):
     def draw(self, drawDC=None):
         size = self.figure.bbox.size.astype(int)
         surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, *size)
-        self._renderer.set_ctx_from_surface(surface)
-        self._renderer.set_width_height(*size)
+        self._renderer.set_context(cairo.Context(surface))
         self._renderer.dpi = self.figure.dpi
         self.figure.draw(self._renderer)
         self.bitmap = wxcairo.BitmapFromImageSurface(surface)