improved the alpha blending code, now works properly for nesting/redraw (changed meaning of WIDGET_CLEARBG a little bit for this)

svn-id: r4509

3 files changed, 53 insertions, 8 deletions

diff --git a/gui/dialog.cpp b/gui/dialog.cpp
index 9031e0e210..9942bcfa39 100644
--- a/gui/dialog.cpp
+++ b/gui/dialog.cpp
@@ -25,12 +25,52 @@
 #include "widget.h"
 #include "newgui.h"
 
+Dialog::~Dialog()
+{
+	teardownScreenBuf();
+}
+
+void Dialog::setupScreenBuf()
+{
+	// Create _screenBuf if it doesn't already exist
+	if (!_screenBuf)
+		_screenBuf = new byte[320*200];
+	
+	// Draw the fixed parts of the dialog: background and border.
+	_gui->blendArea(_x, _y, _w, _h, _gui->_bgcolor);
+	_gui->box(_x, _y, _w, _h);
+
+	// Draw a bgcolor rectangle for all widgets which have WIDGET_CLEARBG set. 
+	Widget *w = _firstWidget;
+	while (w) {
+		if (w->_flags & WIDGET_CLEARBG)
+			_gui->fillArea(_x + w->_x, _y + w->_y, w->_w, w->_h, _gui->_bgcolor);
+		// FIXME - should we also draw borders here if WIDGET_BORDER is set?
+		w = w->_next;
+	}
+	
+	// Finally blit this to _screenBuf
+	_gui->blitTo(_screenBuf, _x, _y, _w, _h); 
+}
+
+void Dialog::teardownScreenBuf()
+{
+	if (_screenBuf) {
+		delete [] _screenBuf;
+		_screenBuf = 0;
+	}
+}
+
 void Dialog::draw()
 {
 	Widget *w = _firstWidget;
 
-	_gui->fillArea(_x, _y, _w, _h, _gui->_bgcolor);
-	_gui->box(_x, _y, _w, _h);
+	if (_screenBuf) {
+		_gui->blitFrom(_screenBuf, _x, _y, _w, _h); 
+	} else {
+		_gui->fillArea(_x, _y, _w, _h, _gui->_bgcolor);
+		_gui->box(_x, _y, _w, _h);
+	}
 	_gui->setAreaDirty(_x, _y, _w, _h);
 
 	while (w) {
diff --git a/gui/dialog.h b/gui/dialog.h
index f91bc681a6..77eaf57738 100644
--- a/gui/dialog.h
+++ b/gui/dialog.h
@@ -43,11 +43,13 @@ protected:
 	int16	_x, _y;
 	uint16	_w, _h;
 	Widget	*_mouseWidget;
+	byte	*_screenBuf;
 
 public:
 	Dialog(NewGui *gui, int x, int y, int w, int h)
-		: _gui(gui), _firstWidget(0), _x(x), _y(y), _w(w), _h(h), _mouseWidget(0)
+		: _gui(gui), _firstWidget(0), _x(x), _y(y), _w(w), _h(h), _mouseWidget(0), _screenBuf(0)
 		{}
+	virtual ~Dialog();
 
 	virtual void draw();
 
@@ -58,6 +60,9 @@ public:
 	virtual void handleCommand(uint32 cmd);
 	
 	NewGui	*getGui()	{ return _gui; }
+	
+	void	setupScreenBuf();
+	void	teardownScreenBuf();
 
 protected:
 	Widget* findWidget(int x, int y); // Find the widget at pos x,y if any
diff --git a/gui/widget.cpp b/gui/widget.cpp
index 510eb8428b..bf45fb522f 100644
--- a/gui/widget.cpp
+++ b/gui/widget.cpp
@@ -43,8 +43,8 @@ void Widget::draw()
 	_x += _boss->_x;
 	_y += _boss->_y;
 
-	// Clear background
-	if (_flags & WIDGET_CLEARBG)
+	// Clear background (unless alpha blending is enabled)
+	if (_flags & WIDGET_CLEARBG && !_boss->_screenBuf)
 		gui->fillArea(_x, _y, _w, _h, gui->_bgcolor);
 
 	// Draw border
@@ -94,7 +94,7 @@ void StaticTextWidget::drawWidget(bool hilite)
 ButtonWidget::ButtonWidget(Dialog *boss, int x, int y, int w, int h, const char *label, uint32 cmd, uint8 hotkey)
 	: StaticTextWidget(boss, x, y, w, h, label), _cmd(cmd), _hotkey(hotkey)
 {
-	_flags = WIDGET_ENABLED | WIDGET_BORDER /* | WIDGET_CLEARBG */ ;
+	_flags = WIDGET_ENABLED | WIDGET_BORDER | WIDGET_CLEARBG ;
 	_type = kButtonWidget;
 }
 
@@ -148,7 +148,7 @@ void CheckboxWidget::drawWidget(bool hilite)
 	if (_state)
 		gui->drawBitmap(checked_img, _x + 3, _y + 3, gui->_textcolor);
 	else
-		gui->fillArea(_x + 3, _y + 3, 8, 8, gui->_bgcolor);
+		gui->fillArea(_x + 2, _y + 2, 10, 10, gui->_bgcolor);
 	
 	// Finally draw the label
 	gui->drawString(_text, _x + 20, _y + 3, _w, gui->_textcolor);
@@ -159,7 +159,7 @@ void CheckboxWidget::drawWidget(bool hilite)
 SliderWidget::SliderWidget(Dialog *boss, int x, int y, int w, int h, const char *label, uint32 cmd, uint8 hotkey)
 	: ButtonWidget(boss, x, y, w, h, label, cmd, hotkey), _value(0), _old_value(1)
 {
-	_flags = WIDGET_ENABLED | WIDGET_TRACK_MOUSE;
+	_flags = WIDGET_ENABLED | WIDGET_TRACK_MOUSE | WIDGET_CLEARBG;
 	_type = kSliderWidget;
 }