REPORT-65049 【主题边框】悬浮元素的跟随主题单元格样式显示，出现两种样式重叠的效果

【问题原因】
1. 单独使用CellStylePreviewPane单元格样式预览面板时，需要CellStylePreviewPane在样式切换
时清理画布并重绘
2. 在CellRectangleStylePreviewPane使用CellStylePreviewPane时，也需要清理画布并重绘，
但此时的清理是CellRectangleStylePreviewPane完成。CellStylePreviewPane不清理画布，否则会
导致表示透明的马赛克图片不显示.

【改动思路】
CellStylePreviewPane增加一个是否自动清理画布的控制变量

designer-base/src/main/java/com/fr/design/cell/CellRectangleStylePreviewPane.java

@@ -46,7 +46,7 @@ public class CellRectangleStylePreviewPane extends JPanel {
 
         for (int r = 0; r < ROW_COUNT; r++) {
             for (int c = 0; c < COLUMN_COUNT; c++) {
-                CellStylePreviewPane pane = new CellStylePreviewPane();
+                CellStylePreviewPane pane = new CellStylePreviewPane(false);
                 TemplateCellElement cellElement = DefaultThemedTemplateCellElementCase.createInstance(c, r);
                 int flags = CellBorderSourceFlag.INVALID_BORDER_SOURCE;
                 if (supportInnerBorder) {

designer-base/src/main/java/com/fr/design/cell/CellStylePreviewPane.java

@@ -33,7 +33,10 @@ public class CellStylePreviewPane extends JPanel {
     private String paintText = "Report";
     private Style style = Style.DEFAULT_STYLE;
 
-    public CellStylePreviewPane() {
+    private final boolean autoClearCanvas;
+
+    public CellStylePreviewPane(boolean autoClearCanvas) {
+        this.autoClearCanvas  = autoClearCanvas;
         setPreferredSize(new Dimension(0, 0));
     }
 
@@ -55,6 +58,9 @@ public class CellStylePreviewPane extends JPanel {
     @Override
     public void paint(Graphics g) {
         Graphics2D g2d = (Graphics2D) g;
+        if (autoClearCanvas) {
+            g2d.clearRect(0, 0, getWidth(), getHeight());
+        }
         g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
         g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
 

designer-realize/src/main/java/com/fr/design/report/ReportStylePane.java

@@ -53,6 +53,7 @@ import java.awt.CardLayout;
 import java.awt.Color;
 import java.awt.Component;
 import java.awt.Dimension;
+import java.awt.Graphics;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
@@ -78,7 +79,7 @@ public class ReportStylePane extends BasicPane {
 		setLayout(FRGUIPaneFactory.createBorderLayout());
 		setBorder(BorderFactory.createEmptyBorder(10, 10, 0, 10));
 
-		previewArea = new CellStylePreviewPane();
+		previewArea = new CellStylePreviewPane(true);
 		followingThemeButtonGroup = new UIButtonGroup<>(FOLLOWING_THEME_STRING_ARRAYS);
 		followingThemeButtonGroup.setAutoFireStateChanged(false);
 		customStylePane = new CustomFloatStyleSettingPane();