Better text positioning for JVM export

Author: IKupriyanov-HORIS

demo/demo-and-test-shared/src/commonMain/kotlin/demoAndTestShared/ImageComparer.kt

@@ -6,7 +6,6 @@
 
 package demoAndTestShared
 
-import org.jetbrains.letsPlot.commons.encoding.Png
 import org.jetbrains.letsPlot.commons.values.Bitmap
 import org.jetbrains.letsPlot.commons.values.Color
 import org.jetbrains.letsPlot.core.canvas.Canvas
@@ -51,14 +50,13 @@ class ImageComparer(
 
             bitmapIO.write(visualDiffBitmap, diffFilePath)
             bitmapIO.write(actualBitmap, actualFilePath)
-            val diffDataImage = Png.encodeDataImage(visualDiffBitmap)
 
             error(
                 """Image mismatch.
                 |    Diff: $diffFilePath
                 |    Actual: $actualFilePath
                 |    Expected: $expectedFilePath
-                |    Diff DataImage: $diffDataImage""".trimMargin()
+                |""".trimMargin()
             )
         } else {
             println("Image comparison passed: $expectedFilePath")

plot-image-export/src/jvmTest/kotlin/org/jetbrains/letsPlot/core/plot/export/PlotImageExportVisualTest.kt

@@ -71,6 +71,56 @@ class PlotImageExportVisualTest {
         assertPlot("plot_latex_formula_test.png", plotSpec)
     }
 
+    @Test
+    fun superscript() {
+        val spec = """
+            |{
+            |  "kind": "subplots",
+            |  "layout": { "ncol": 2.0, "nrow": 1.0, "name": "grid" },
+            |  "figures": [
+            |    {
+            |      "kind": "plot",
+            |      "ggtitle": { "text": "Default limits" },
+            |      "theme": { "name": "classic", "exponent_format": "pow", "text": { "family": "Noto Sans" }, "axis_title_y": { "blank": true } },
+            |      "scales": [ { "aesthetic": "y", "limits": [ 1e-08, 10000000.0 ], "trans": "log10" } ],
+            |      "layers": [
+            |        {
+            |          "geom": "text",
+            |          "mapping": {
+            |            "y": [ 1e-07, 1e-06, 1e-05, 0.0001, 0.001, 0.01, 0.1, 1.0, 10.0, 100.0, 1000.0, 10000.0, 100000.0, 1000000.0 ],
+            |            "label": [ 1e-07, 1e-06, 1e-05, 0.0001, 0.001, 0.01, 0.1, 1.0, 10.0, 100.0, 1000.0, 10000.0, 100000.0, 1000000.0 ]
+            |          },
+            |          "family": "Noto Sans",
+            |          "size": 10.0
+            |        }
+            |      ]
+            |    },
+            |    {
+            |      "kind": "plot",
+            |      "ggtitle": { "text": "Scientific notation for \\( x \\leq 10^{-3} \\) and \\( x \\geq 10^3 \\)" },
+            |      "theme": { "name": "classic", "exponent_format": [ "pow", -3.0, 3.0 ], "text": { "family": "Noto Sans" }, "axis_title_y": { "blank": true } },
+            |      "scales": [ { "aesthetic": "y", "limits": [ 1e-08, 10000000.0 ], "trans": "log10" } ],
+            |      "layers": [
+            |        {
+            |          "geom": "text",
+            |          "mapping": {
+            |            "y": [ 1e-07, 1e-06, 1e-05, 0.0001, 0.001, 0.01, 0.1, 1.0, 10.0, 100.0, 1000.0, 10000.0, 100000.0, 1000000.0 ],
+            |            "label": [ 1e-07, 1e-06, 1e-05, 0.0001, 0.001, 0.01, 0.1, 1.0, 10.0, 100.0, 1000.0, 10000.0, 100000.0, 1000000.0 ]
+            |          },
+            |          "family": "Noto Sans",
+            |          "size": 10.0
+            |        }
+            |      ]
+            |    }
+            |  ]
+            |}
+            |""".trimMargin()
+
+        val plotSpec = parsePlotSpec(spec)
+
+        assertPlot("plot_superscript_test.png", plotSpec)
+    }
+
     @Test
     fun `multi-level latex formula`() {
         val spec = """
@@ -255,6 +305,7 @@ class PlotImageExportVisualTest {
 
         assertPlot("plot_markdown2Xscale_test.png", plotSpec, scale = 2)
     }
+
     @Test
     fun markdown() {
         val spec = """