Merge pull request matplotlib#27964 from AnsonTran/fix-logscale-axis

BUG: Fix NonUniformImage with nonlinear scale

Author: ksunden

lib/matplotlib/image.py

@@ -1085,12 +1085,16 @@ def make_image(self, renderer, magnification=1.0, unsampled=False):
                 B[:, :, 0:3] = A
                 B[:, :, 3] = 255
                 A = B
-        vl = self.axes.viewLim
         l, b, r, t = self.axes.bbox.extents
         width = int(((round(r) + 0.5) - (round(l) - 0.5)) * magnification)
         height = int(((round(t) + 0.5) - (round(b) - 0.5)) * magnification)
-        x_pix = np.linspace(vl.x0, vl.x1, width)
-        y_pix = np.linspace(vl.y0, vl.y1, height)
+
+        invertedTransform = self.axes.transData.inverted()
+        x_pix = invertedTransform.transform(
+            [(x, b) for x in np.linspace(l, r, width)])[:, 0]
+        y_pix = invertedTransform.transform(
+            [(l, y) for y in np.linspace(b, t, height)])[:, 1]
+
         if self._interpolation == "nearest":
             x_mid = (self._Ax[:-1] + self._Ax[1:]) / 2
             y_mid = (self._Ay[:-1] + self._Ay[1:]) / 2

lib/matplotlib/tests/baseline_images/test_image/nonuniform_and_pcolor.png

@@ -1414,6 +1414,27 @@ def test_nonuniform_and_pcolor():
         ax.set(xlim=(0, 10))
 
 
+@image_comparison(["nonuniform_logscale.png"], style="mpl20")
+def test_nonuniform_logscale():
+    _, axs = plt.subplots(ncols=3, nrows=1)
+
+    for i in range(3):
+        ax = axs[i]
+        im = NonUniformImage(ax)
+        im.set_data(np.arange(1, 4) ** 2, np.arange(1, 4) ** 2,
+                    np.arange(9).reshape((3, 3)))
+        ax.set_xlim(1, 16)
+        ax.set_ylim(1, 16)
+        ax.set_box_aspect(1)
+        if i == 1:
+            ax.set_xscale("log", base=2)
+            ax.set_yscale("log", base=2)
+        if i == 2:
+            ax.set_xscale("log", base=4)
+            ax.set_yscale("log", base=4)
+        ax.add_image(im)
+
+
 @image_comparison(
     ['rgba_antialias.png'], style='mpl20', remove_text=True,
     tol=0 if platform.machine() == 'x86_64' else 0.007)