PGF backend: support affine image transformations

f0k · f0k · commit a43e3a01b4be · 2016-07-18T18:05:41.000+02:00
diff --git a/lib/matplotlib/backends/backend_pgf.py b/lib/matplotlib/backends/backend_pgf.py
@@ -609,7 +609,20 @@ def _pgf_path_draw(self, stroke=True, fill=False):
             actions.append("fill")
         writeln(self.fh, r"\pgfusepath{%s}" % ",".join(actions))
 
-    def draw_image(self, gc, x, y, im):
+    def option_scale_image(self):
+        """
+        pgf backend supports affine transform of image.
+        """
+        return True
+
+    def option_image_nocomposite(self):
+        """
+        return whether to generate a composite image from multiple images on
+        a set of axes
+        """
+        return not rcParams['image.composite_image']
+
+    def draw_image(self, gc, x, y, im, transform=None):
         # TODO: Almost no documentation for the behavior of this function.
         #       Something missing?
         h, w = im.shape[:2]
@@ -627,7 +640,17 @@ def draw_image(self, gc, x, y, im):
         writeln(self.fh, r"\begin{pgfscope}")
         self._print_pgf_clip(gc)
         f = 1. / self.dpi  # from display coords to inch
-        writeln(self.fh, r"\pgftext[at=\pgfqpoint{%fin}{%fin},left,bottom]{\pgfimage[interpolate=true,width=%fin,height=%fin]{%s}}" % (x * f, y * f, w * f, h * f, fname_img))
+        if transform is not None:
+            tr1, tr2, tr3, tr4, tr5, tr6 = transform.frozen().to_values()
+            # scale is already included in the above transform
+            w, h = 1, 1
+            # translation can be merged into this transform (makes it easier)
+            tr5 += x
+            tr6 += y
+            x, y = 0, 0
+            writeln(self.fh, r"\makeatletter\pgfsys@transformcm{%f}{%f}{%f}{%f}{%fin}{%fin}\makeatother" % (tr1, tr2, tr3, tr4, tr5 * f, tr6 * f))
+        interp = str(transform is None).lower()  # interpolation in PDF reader
+        writeln(self.fh, r"\pgftext[at=\pgfqpoint{%fin}{%fin},left,bottom]{\pgfimage[interpolate=%s,width=%fin,height=%fin]{%s}}" % (x * f, y * f, interp, w * f, h * f, fname_img))
         writeln(self.fh, r"\end{pgfscope}")
 
     def draw_tex(self, gc, x, y, s, prop, angle, ismath="TeX!", mtext=None):
