fix: align text annotations in captures

app.go

@@ -3,10 +3,12 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
 	"image"
+	"image/png"
 	"log/slog"
 	"os"
 	"path/filepath"
@@ -519,7 +521,8 @@ func (a *App) captureSelectedPNG(result CaptureResult, pc *pendingCapture) ([]by
 		return nil, err
 	}
 	if len(result.Annotations) > 0 {
-		cropped, err = application.ApplyAnnotations(cropped, result.Annotations, pc.Display.Scale)
+		scaleX, scaleY := annotationScalesForCapture(cropped, rect, pc.Display.Scale)
+		cropped, err = application.ApplyAnnotationsWithScale(cropped, result.Annotations, scaleX, scaleY)
 		if err != nil {
 			return nil, err
 		}
@@ -527,6 +530,33 @@ func (a *App) captureSelectedPNG(result CaptureResult, pc *pendingCapture) ([]by
 	return cropped, nil
 }
 
+func annotationScalesForCapture(pngBytes []byte, rect RegionRect, fallback float64) (float64, float64) {
+	if fallback <= 0 {
+		fallback = 1
+	}
+	scaleX := fallback
+	scaleY := fallback
+
+	cfg, err := png.DecodeConfig(bytes.NewReader(pngBytes))
+	if err != nil {
+		return scaleX, scaleY
+	}
+	if rect.W > 0 && cfg.Width > 0 {
+		scaleX = saneAnnotationScale(float64(cfg.Width)/float64(rect.W), fallback)
+	}
+	if rect.H > 0 && cfg.Height > 0 {
+		scaleY = saneAnnotationScale(float64(cfg.Height)/float64(rect.H), fallback)
+	}
+	return scaleX, scaleY
+}
+
+func saneAnnotationScale(scale, fallback float64) float64 {
+	if scale >= 0.25 && scale <= 8 {
+		return scale
+	}
+	return fallback
+}
+
 func (a *App) chooseSaveDirectory() (string, error) {
 	return wruntime.OpenDirectoryDialog(a.ctx, wruntime.OpenDialogOptions{
 		Title:                "Save screenshot to folder",