REPORT-55491 【交互验收】【组件背景分离】在组件属性下的「主体背景」设置，在配置界面不生效，看不到效果

【问题原因】
1. 绘制报表块缩略图时，填充了白色背景，导致组件样式背景被覆盖
2. 优化报表块缩略图时，即在ElementCaseImage中截取部分缩略图时，丢弃了Alpha通道
3. 表单布局预览绘制表格缩略图时使用了默认的白色纸张背景(表单报表块的表格没有纸张背景的概念）
【改动思路】
1. 绘制报表块缩略图时，不要使用白色背景填充，保持透明
2. 优化报表块缩略图时，使用subImage完成截取功能，保留Alpha通道
3. 表单布局预览绘制表格缩略图时，忽略纸张背景
4. 替换默认的报表块预览图（此图用于将报表块拖拽到面板中时显示作为
报表块的缩略图使用）,因此也要支持半透明

designer-form/src/main/java/com/fr/design/designer/creator/XElementCase.java

@@ -41,7 +41,7 @@ public class XElementCase extends XBorderStyleWidgetCreator implements FormEleme
 
     static {
         try {
-            DEFAULT_BACKGROUND = BaseUtils.readImageWithCache("com/fr/base/images/report/elementcase.png");
+            DEFAULT_BACKGROUND = BaseUtils.readImageWithCache("com/fr/base/images/report/elementcase_translucent.png");
         } catch (Throwable e) {
             //IBM jdk 1.5.0_22 并发下读取图片有时会异常(EOFException), 这个图片反正只有设计器用到, 捕获住
             DEFAULT_BACKGROUND = CoreGraphHelper.createBufferedImage(0, 0);
@@ -183,7 +183,8 @@ public class XElementCase extends XBorderStyleWidgetCreator implements FormEleme
         if (editor == null) {
             setBorder(DEFALUTBORDER);
             editor = new JPanel();
-            editor.setBackground(null);
+            editor.setOpaque(false);
+            editor.setBackground(new Color(0, 0, 0, 0));
             editor.setLayout(null);
             imageLable = initImageBackground();
 
@@ -218,7 +219,8 @@ public class XElementCase extends XBorderStyleWidgetCreator implements FormEleme
     private void setLabelBackground(Image image, UILabel imageLable) {
         ImageIcon icon = new ImageIcon(image);
         imageLable.setIcon(icon);
-        imageLable.setOpaque(true);
+        imageLable.setOpaque(false);
+        imageLable.setBackground(new Color(0, 0, 0, 0));
         imageLable.setLayout(null);
         imageLable.setBounds(0, 0, icon.getIconWidth(), icon.getIconHeight());
     }

designer-realize/src/main/java/com/fr/design/mainframe/form/FormElementCaseDesigner.java

@@ -43,9 +43,9 @@ import javax.swing.JComponent;
 import javax.swing.JPanel;
 import javax.swing.JScrollBar;
 import java.awt.BorderLayout;
-import java.awt.Color;
 import java.awt.Dimension;
-import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Transparency;
 import java.awt.image.BufferedImage;
 
 /**
@@ -129,19 +129,23 @@ public class FormElementCaseDesigner
     public BufferedImage getElementCaseImage(Dimension size) {
         BufferedImage image = null;
         try {
-            image = new java.awt.image.BufferedImage(size.width, size.height,
-                    java.awt.image.BufferedImage.TYPE_INT_RGB);
-            Graphics g = image.getGraphics();
+            int width = size.width;
+            int height = size.height;
 
-            //填充白色背景, 不然有黑框
-            Color oldColor = g.getColor();
-            g.setColor(Color.WHITE);
-            g.fillRect(0, 0, size.width, size.height);
-            g.setColor(oldColor);
+            image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
+            Graphics2D g2d = image.createGraphics();
+            // 创建一个支持透明背景的buffer image
+            image = g2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
+            g2d.dispose();
+            g2d = image.createGraphics();
 
             Grid grid = this.elementCasePane != null ? this.elementCasePane.getGrid() : null;
             if (grid != null) {
-                grid.paintAll(g);
+                boolean oldTranslucent = grid.isTranslucent();
+                // 截缩图图时grid需支持半透明，不能用默认白色填充画布，否则会遮挡组件样式背景
+                grid.setTranslucent(true);
+                grid.paint(g2d);
+                grid.setTranslucent(oldTranslucent);
             }
 
         } catch (Exception e) {

designer-realize/src/main/java/com/fr/grid/Grid.java

@@ -134,6 +134,9 @@ public class Grid extends BaseGridComponent {
 
     private boolean needRequestFocus = true;
 
+    // 截取缩略图时需透明（不能用默认白色填充），否则会遮挡组件样式的背景，其余情况的绘制可以用白色等默认颜色填充
+    private boolean isTranslucent = false;
+
     public Grid(int resolution) {
         this.resolution = resolution;
         // 能触发processEvent，不管是否给component增加listener
@@ -1458,4 +1461,12 @@ public class Grid extends BaseGridComponent {
         this.paginateLineShowType = paginateLineShowType;
         this.getElementCasePane().repaint();
     }
+
+    public boolean isTranslucent() {
+        return isTranslucent;
+    }
+
+    public void setTranslucent(boolean translucent) {
+        isTranslucent = translucent;
+    }
 }

designer-realize/src/main/java/com/fr/grid/GridUI.java

@@ -1128,8 +1128,10 @@ public class GridUI extends ComponentUI {
         double realWidth = gridSize.getWidth();// 宽度
         double realHeight = gridSize.getHeight();// 高度
 
-        // 画背景
-        this.paintBackground(g2d, grid, elementCase, resolution);
+        if (!grid.isTranslucent()) {
+            // 画背景
+            this.paintBackground(g2d, grid, elementCase, resolution);
+        }
 
         // 画Grid Line
         this.paintGridLine(g2d, grid, elementCase, realWidth, realHeight, resolution);