fix(ImagePreviewer): 修复连续旋转时角度倒转与来回摆动

docs/controls/desktop/data-display/image-previewer/changelog.md

@@ -2,6 +2,10 @@
 
 本文档记录 ImagePreviewer 控件级设计、API、主题契约、Token 和实现结构的变化。它不替代仓库根目录 `CHANGELOG.md`，也不作为正式版本发布说明。
 
+## 2026-10-21
+
+- 修复快速连续点击旋转时图片角度倒转、来回摆动的问题：`Scale=1` 时不再向 `RenderTransform` 写入无意义的 Scale 操作，避免 Avalonia 的 TransformOperations 插值在动画重定向后退化为矩阵分解并归一化旋转角。
+
 ## 2026-10-17
 
 - 新增 `IsWheelZoomEnabled=true`，只控制滚轮；统一滚轮刻度、指针锚点、拖拽平移、双击与捏合缩放，运行时缩放范围变化立即钳制比例和刷新按钮。

src/AtomUI.Desktop.Controls/ImagePreviewer/ImageViewer.cs

@@ -882,8 +882,17 @@ internal class ImageViewer : TemplatedControl, IMotionAwareControl
 
     private void GenerateImageRenderTransform()
     {
-        var builder = TransformOperations.CreateBuilder(2);
-        builder.AppendScale(ImageScaleX, ImageScaleY);
+        // Avalonia's TransformOperations interpolator rewrites a no-op scale operation
+        // to Identity during the animation. A retargeted transition then sees mismatched
+        // operation types, falls back to matrix decomposition and normalizes the
+        // rotation angle, which makes repeated rotate clicks spin backwards.
+        var hasScale = !MathUtils.AreClose(ImageScaleX, 1.0) ||
+                       !MathUtils.AreClose(ImageScaleY, 1.0);
+        var builder = TransformOperations.CreateBuilder(hasScale ? 2 : 1);
+        if (hasScale)
+        {
+            builder.AppendScale(ImageScaleX, ImageScaleY);
+        }
         builder.AppendRotate(ImageRotate);
         ImageRenderTransform = builder.Build();
     }