Merge pull request matplotlib#2665 from piannucci/retina

MacOSX backend supports 2x DPI images and MathTeX.

Author: pelson

lib/matplotlib/backends/backend_macosx.py

@@ -107,6 +107,9 @@ def draw_gouraud_triangle(self, gc, points, colors, transform):
         points = transform.transform(points)
         gc.draw_gouraud_triangle(points, colors)
 
+    def get_image_magnification(self):
+        return self.gc.get_image_magnification()
+
     def draw_image(self, gc, x, y, im):
         im.flipud_out()
         nrows, ncols, data = im.as_rgba_str()
@@ -115,19 +118,21 @@ def draw_image(self, gc, x, y, im):
 
     def draw_tex(self, gc, x, y, s, prop, angle, ismath='TeX!', mtext=None):
         # todo, handle props, angle, origins
+        scale = self.gc.get_image_magnification()
         size = prop.get_size_in_points()
         texmanager = self.get_texmanager()
         key = s, size, self.dpi, angle, texmanager.get_font_config()
         im = self.texd.get(key) # Not sure what this does; just copied from backend_agg.py
         if im is None:
-            Z = texmanager.get_grey(s, size, self.dpi)
+            Z = texmanager.get_grey(s, size, self.dpi*scale)
             Z = numpy.array(255.0 - Z * 255.0, numpy.uint8)
 
         gc.draw_mathtext(x, y, angle, Z)
 
     def _draw_mathtext(self, gc, x, y, s, prop, angle):
+        scale = self.gc.get_image_magnification()
         ox, oy, width, height, descent, image, used_characters = \
-            self.mathtext_parser.parse(s, self.dpi, prop)
+            self.mathtext_parser.parse(s, self.dpi*scale, prop)
         gc.draw_mathtext(x, y, angle, 255 - image.as_array())
 
     def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):

src/_macosx.m

@@ -2996,6 +2996,18 @@ static void _data_provider_release(void* info, const void* data, size_t size)
     Py_DECREF(image);
 }
 
+/* Consider the drawing origin to be in user coordinates
+ * but the image size to be in device coordinates */
+static void draw_image_user_coords_device_size(CGContextRef cr, CGImageRef im,
+        float x, float y, npy_intp ncols, npy_intp nrows)
+{
+    CGRect dst;
+    dst.origin = CGPointMake(x,y);
+    dst.size = CGContextConvertSizeToUserSpace(cr, CGSizeMake(ncols,nrows));
+    dst.size.height = fabs(dst.size.height); /* believe it or not... */
+    CGContextDrawImage(cr, dst, im);
+}
+
 static PyObject*
 GraphicsContext_draw_mathtext(GraphicsContext* self, PyObject* args)
 {
@@ -3078,14 +3090,14 @@ static void _data_provider_release(void* info, const void* data, size_t size)
 
     if (angle==0.0)
     {
-        CGContextDrawImage(cr, CGRectMake(x,y,ncols,nrows), bitmap);
+        draw_image_user_coords_device_size(cr, bitmap, x, y, ncols, nrows);
     }
     else
     {
         CGContextSaveGState(cr);
         CGContextTranslateCTM(cr, x, y);
         CGContextRotateCTM(cr, angle*M_PI/180);
-        CGContextDrawImage(cr, CGRectMake(0,0,ncols,nrows), bitmap);
+        draw_image_user_coords_device_size(cr, bitmap, 0, 0, ncols, nrows);
         CGContextRestoreGState(cr);
     }
     CGImageRelease(bitmap);
@@ -3175,13 +3187,27 @@ static void _data_provider_release(void* info, const void* data, size_t size)
         return NULL;
     }
 
-    CGContextDrawImage(cr, CGRectMake(x,y,ncols,nrows), bitmap);
+    draw_image_user_coords_device_size(cr, bitmap, x, y, ncols, nrows);
     CGImageRelease(bitmap);
 
     Py_INCREF(Py_None);
     return Py_None;
 }
 
+static PyObject*
+GraphicsContext_get_image_magnification(GraphicsContext* self)
+{
+    CGContextRef cr = self->cr;
+    if (!cr)
+    {
+        PyErr_SetString(PyExc_RuntimeError, "CGContextRef is NULL");
+        return NULL;
+    }
+
+    CGSize pixelSize = CGContextConvertSizeToDeviceSpace(cr, CGSizeMake(1,1));
+    return PyFloat_FromDouble(pixelSize.width);
+}
+
 
 static PyMethodDef GraphicsContext_methods[] = {
     {"save",
@@ -3294,6 +3320,11 @@ static void _data_provider_release(void* info, const void* data, size_t size)
      METH_VARARGS,
      "Draw an image at (x,y) in the graphics context."
     },
+    {"get_image_magnification",
+     (PyCFunction)GraphicsContext_get_image_magnification,
+     METH_NOARGS,
+     "Returns the scale factor between user and device coordinates."
+    },
     {NULL}  /* Sentinel */
 };