distance to point measurer

app/src/main/java/com/mirenkov/ktheightmap/MapCanvas.kt

@@ -18,6 +18,7 @@ import androidx.compose.ui.graphics.asImageBitmap
 import androidx.compose.ui.graphics.drawscope.Stroke
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.ParagraphStyle
 import androidx.compose.ui.text.SpanStyle
 import androidx.compose.ui.text.buildAnnotatedString
@@ -25,11 +26,27 @@ import androidx.compose.ui.text.drawText
 import androidx.compose.ui.text.rememberTextMeasurer
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.withStyle
+import kotlin.math.abs
 import kotlin.math.absoluteValue
 import kotlin.math.floor
+import kotlin.math.max
+import kotlin.math.min
 import kotlin.math.pow
 import kotlin.math.sqrt
 
+fun distanceString(targetMeters: Int): AnnotatedString {
+    return buildAnnotatedString {
+        withStyle(ParagraphStyle(textAlign = TextAlign.Center)) {
+            withStyle(SpanStyle(color = Color.White)) {
+                val text = if (targetMeters >= 100000)
+                    "${targetMeters / 1000}km"
+                else
+                    "${targetMeters}m"
+                append(text)
+            }
+        }
+    }
+}
 @OptIn(ExperimentalUnsignedTypes::class)
 @Composable
 fun MapCanvas(
@@ -189,6 +206,7 @@ fun MapCanvas(
                 }
             }
         }
+
         // Placed point and line to center
         if (pointLat != 0F) {
             val pointOffsetX = SphereMercator.mercateLon(pointLon.toDouble(), level, -TILE_SIZE.toDouble()).toFloat() - offsetX
@@ -203,6 +221,8 @@ fun MapCanvas(
                 start = Offset(pointOffsetX, pointOffsetY),
                 end = Offset(halvedX, halvedY)
             )
+
+
             val startHeight = KhmParser.getHeight(pointLon, pointLat, ctx)
             if (pointOffsetX >= 0 && pointOffsetY >= 0 && pointOffsetX < size.width && pointOffsetY < size.height)
                 drawText(
@@ -241,6 +261,17 @@ fun MapCanvas(
                         )
                 }
             }
+            val lineLength = sqrt((pointOffsetX - halvedX).pow(2) + (pointOffsetY - halvedY).pow(2))
+            val lineMeters = (lineLength * SphereMercator.scaledMetersPerPixel(level + 1)).toInt()
+            drawText(
+                textMeasurer = textMeasurer,
+                text = distanceString(lineMeters),
+                size = Size(160F, 48F),
+                topLeft = Offset(
+                    halvedX,
+                    halvedY - 80F
+                )
+            )
         }
 
         // Cursor path
@@ -316,17 +347,7 @@ fun MapCanvas(
         // Distance measurer text
         drawText(
             textMeasurer = textMeasurer,
-            text = buildAnnotatedString {
+            text = distanceString(targetMeters),
-                withStyle(ParagraphStyle(textAlign = TextAlign.Center)) {
-                    withStyle(SpanStyle(color = Color.White)) {
-                        val text = if (targetMeters >= 100000)
-                            "${targetMeters / 1000}km"
-                        else
-                            "${targetMeters}m"
-                        append(text)
-                    }
-                }
-            },
             topLeft = Offset(targetPixels.toFloat() * 2F, measurerHeight),
             size = Size(targetPixels.toFloat() * 2F, 48F)
         )