PGF backend: support affine image transformations

f0k · f0k · commit 4bcb38f358e1 · 2016-08-16T16:12:13.000+02:00
diff --git a/lib/matplotlib/backends/backend_pgf.py b/lib/matplotlib/backends/backend_pgf.py
@@ -609,9 +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):
-        # TODO: Almost no documentation for the behavior of this function.
-        #       Something missing?
+    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):
         h, w = im.shape[:2]
         if w == 0 or h == 0:
             return
@@ -627,7 +638,22 @@ 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 None:
+            writeln(self.fh,
+                    r"\pgfsys@transformshift{%fin}{%fin}" % (x * f, y * f))
+            w, h = w * f, h * f
+        else:
+            tr1, tr2, tr3, tr4, tr5, tr6 = transform.frozen().to_values()
+            writeln(self.fh,
+                    r"\pgfsys@transformcm{%f}{%f}{%f}{%f}{%fin}{%fin}" %
+                    (tr1 * f, tr2 * f, tr3 * f, tr4 * f,
+                     (tr5 + x) * f, (tr6 + y) * f))
+            w = h = 1  # scale is already included in the transform
+        interp = str(transform is None).lower()  # interpolation in PDF reader
+        writeln(self.fh,
+                r"\pgftext[left,bottom]"
+                r"{\pgfimage[interpolate=%s,width=%fin,height=%fin]{%s}}" %
+                (interp, w, h, fname_img))
         writeln(self.fh, r"\end{pgfscope}")
 
     def draw_tex(self, gc, x, y, s, prop, angle, ismath="TeX!", mtext=None):
