GUI: Remove the ThemeItem draw queues

Drawing nows happens directly when the Dialog or Widget draw methods are
called. This makes it easy to debug why a particular low level draw
method was called, by inspecting the call stack.

This replaces the notion of "buffering" by two independant ways to
control what is drawn and where:
- The active layer is used to select whether the foreground or
  background part of the dialogs are rendered by the draw calls.
- The active surface is used to select if the draw calls affect the back
  buffer or the screen.

The foreground layer of the active dialog is drawn directly to the
screen. Its background layer is drawn to the back buffer. This way
widgets can restore the back buffer in order to update without having to
redraw the dialog's background.

Dialogs lower in the dialog stack are drawn entirely to the back buffer.

1 files changed, 5 insertions, 4 deletions

diff --git a/gui/widgets/popup.cpp b/gui/widgets/popup.cpp
index f59a89e543..40af769a34 100644
--- a/gui/widgets/popup.cpp
+++ b/gui/widgets/popup.cpp
@@ -37,7 +37,6 @@ class PopUpDialog : public Dialog {
 protected:
 	PopUpWidget	*_popUpBoss;
 	int			_clickX, _clickY;
-	byte		*_buffer;
 	int			_selection;
 	uint32		_openTime;
 	bool		_twoColumns;
@@ -49,7 +48,7 @@ protected:
 public:
 	PopUpDialog(PopUpWidget *boss, int clickX, int clickY);
 
-	void drawDialog();
+	void drawDialog(DrawLayer layerToDraw) override;
 
 	void handleMouseUp(int x, int y, int button, int clickCount);
 	void handleMouseWheel(int x, int y, int direction);	// Scroll through entries with scroll wheel
@@ -70,9 +69,9 @@ protected:
 PopUpDialog::PopUpDialog(PopUpWidget *boss, int clickX, int clickY)
 	: Dialog(0, 0, 16, 16),
 	_popUpBoss(boss) {
+	_backgroundType = ThemeEngine::kDialogBackgroundNone;
 
 	_openTime = 0;
-	_buffer = nullptr;
 	_entriesPerColumn = 1;
 
 	// Copy the selection index
@@ -148,7 +147,9 @@ PopUpDialog::PopUpDialog(PopUpWidget *boss, int clickX, int clickY)
 	_clickY = clickY - _y;
 }
 
-void PopUpDialog::drawDialog() {
+void PopUpDialog::drawDialog(DrawLayer layerToDraw) {
+	Dialog::drawDialog(layerToDraw);
+
 	// Draw the menu border
 	g_gui.theme()->drawWidgetBackground(Common::Rect(_x, _y, _x+_w, _y+_h), 0);