Bug 463127 - [Win32] Transparent background not honored on Composite

with Scrollbars on Windows

Change-Id: I3e0df1bf9468583f933fe94e21b3decf7ec53d84
Signed-off-by: Niraj Modi <niraj.modi@in.ibm.com>

5 files changed, 54 insertions, 5 deletions

diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java
index 8c92131e4d..b74f39318c 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java
@@ -305,7 +305,7 @@ public Point computeSize (int wHint, int hHint, boolean changed) {
 void createHandle () {
 	super.createHandle ();
 	state |= CANVAS;
-	if ((style & (SWT.H_SCROLL | SWT.V_SCROLL)) == 0 || findThemeControl () == parent) {
+	if (applyThemeBackground ()) {
 		state |= THEME_BACKGROUND;
 	}
 	if ((style & SWT.TRANSPARENT) != 0) {
@@ -315,6 +315,23 @@ void createHandle () {
 	}
 }
 
+@Override
+boolean applyThemeBackground () {
+	/*
+	 * Composite with scrollbars would not inherit the theme because it was
+	 * probably being used to implement a control similar to a Text, List,
+	 * Table, or Tree, and those controls do not inherit the background theme.
+	 * We assume that a Composite that did not have scrollbars was probably just
+	 * being used to group some other controls, therefore it should inherit.
+	 * 
+	 * But when Composite background is set to COLOR_TRANSPARENT (i.e.
+	 * backgroundAlpha as '0') which means parent theme should be inherited, so
+	 * enable the THEME_BACKGROUND in 'state' to support background transparent.
+	 * Refer bug 463127 & related bug 234649.
+	 */
+	return (super.applyThemeBackground() || (style & (SWT.H_SCROLL | SWT.V_SCROLL)) == 0 || findThemeControl () == parent);
+}
+
 /** 
  * Fills the interior of the rectangle specified by the arguments,
  * with the receiver's background. 
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Scrollable.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Scrollable.java
index 8adb7f7792..57edfda1f5 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Scrollable.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Scrollable.java
@@ -142,6 +142,23 @@ void createWidget () {
 	if ((style & SWT.V_SCROLL) != 0) verticalBar = createScrollBar (SWT.V_SCROLL);
 }
 
+@Override
+void updateBackgroundColor () {
+	if (applyThemeBackground ()) {
+		state |= THEME_BACKGROUND;
+	} else {
+		state &= ~THEME_BACKGROUND;
+	}
+	super.updateBackgroundColor ();
+}
+
+/**
+* @return true if THEME_BACKGROUND needs to be applied.
+*/
+boolean applyThemeBackground () {
+	return backgroundAlpha == 0;
+}
+
 void destroyScrollBar (int type) {
 	long /*int*/ hwnd = scrolledHandle ();
 	int bits = OS.GetWindowLong (hwnd, OS.GWL_STYLE);
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Table.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Table.java
index b0a87fa38e..f30a6dcb86 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Table.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Table.java
@@ -1628,6 +1628,15 @@ void createHandle () {
 	}
 }
 
+@Override
+boolean applyThemeBackground () {
+	/*
+	 * Just inheriting the THEME_BACKGROUND doesn't turn complete Table
+	 * background transparent, TableItem background remains as-is.
+	 */
+	return false;
+}
+
 void createHeaderToolTips () {
 	if (OS.IsWinCE) return;
 	if (headerToolTipHandle != 0) return;
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java
index f0e5feaf3f..aa13243d0b 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java
@@ -275,12 +275,17 @@ void createHandle () {
 	super.createHandle ();
 	OS.SendMessage (handle, OS.EM_LIMITTEXT, 0, 0);
 	if ((style & SWT.READ_ONLY) != 0) {
-		if ((style & (SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL)) == 0) {
+		if (applyThemeBackground ()) {
 			state |= THEME_BACKGROUND;
 		}
 	}
 }
 
+@Override
+boolean applyThemeBackground () {
+	return (super.applyThemeBackground() || (style & (SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL)) == 0);
+}
+
 /**
  * Adds the listener to the collection of listeners who will
  * be notified when the receiver's text is modified, by sending
diff --git a/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet365.java b/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet365.java
index 34e03f364c..1b96765b01 100644
--- a/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet365.java
+++ b/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet365.java
@@ -169,7 +169,7 @@ public class Snippet365 {
 					group.setBackground(display.getSystemColor(SWT.COLOR_WIDGET_BACKGROUND));

 					sash.setBackground(display.getSystemColor(SWT.COLOR_DARK_CYAN));

 					slider.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

-					list.setBackground(null);

+					list.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

 					text.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

 					

 					// ContainerGroup

@@ -197,8 +197,8 @@ public class Snippet365 {
 					// Default

 					defaultBackgroundGroup.setBackground(display.getSystemColor(SWT.COLOR_WIDGET_BACKGROUND));

 					push.setBackground(display.getSystemColor(SWT.COLOR_WIDGET_BACKGROUND));

-					combo.setBackground(null);

-					ccombo.setBackground(null);

+					combo.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

+					ccombo.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

 					dateTime.setBackground(null);

 					progressBar.setBackground(null);

 					expandBar.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

@@ -292,6 +292,7 @@ public class Snippet365 {
 

 		// List

 		list = new List(nativeGroup, SWT.BORDER);

+		list.setBackground(display.getSystemColor(SWT.COLOR_CYAN));

 		list.add("one");

 		list.add("two");

 		list.add("three");