* added a test for B_DRAW_ON_CHILDREN view flag and documented the observed

behaviour in R5 and my conclusions.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@23153 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/tests/servers/app/Jamfile

@@ -165,6 +165,7 @@ SubInclude HAIKU_TOP src tests servers app code_to_name ;
 SubInclude HAIKU_TOP src tests servers app copy_bits ;
 SubInclude HAIKU_TOP src tests servers app cursor_test ;
 SubInclude HAIKU_TOP src tests servers app desktop_window ;
+SubInclude HAIKU_TOP src tests servers app draw_after_children ;
 SubInclude HAIKU_TOP src tests servers app event_mask ;
 SubInclude HAIKU_TOP src tests servers app following ;
 SubInclude HAIKU_TOP src tests servers app idle_test ;

src/tests/servers/app/draw_after_children/DrawAfterChildren.cpp

@@ -0,0 +1,174 @@
+
+#include <stdio.h>
+
+#include <Application.h>
+#include <View.h>
+#include <Window.h>
+
+/*-----------------------------------------------------------------------------
+
+OBSERVATION on R5 behaviour:
+
+* The hook function DrawAfterChildren is not called at all if the
+  view flags don't include B_DRAW_ON_CHILDREN.
+
+* If the view flags include B_DRAW_ON_CHILDREN, then any drawing commands
+  executed in Draw() AND DrawAfterChildren() will paint on top of children.
+
+* The background of a view with the B_DRAW_ON_CHILDREN flag set will not
+  be painted by the app_server when child views change position and areas
+  in the parent view are "exposed". If the expose events have other reasons,
+  the background is painted as usual.
+
+* The app_server side background painting of child views does not occur
+  after the Draw() hook of the parent view with B_DRAW_ON_CHILDREN has been
+  called. So while DrawAfterChildren() may be called after the Draw() hooks
+  of all children have been called, the background has been painted earlier.
+
+* It looks like the background painting inside app_server of a view with
+  B_DRAW_ON_CHILDREN paints over the background of any children, though
+  the background of the children is later painted too. Therefor, if a child
+  has B_TRANSPARENT_COLOR background, the background of the parent with
+  B_DRAW_ON_CHILDREN stays visible in the area of that child.
+
+* Both Draw() and DrawAfterChildren() appear to push their own graphics
+  states onto the state stack.
+
+
+CONCLUSION:
+
+It looks like the B_DRAW_ON_CHILDREN flag causes two effects:
+
+* The local view clipping region inside the app_server simply ignores
+  any children, this effects any drawing commands, those from Draw()
+  and those from DrawAfterChildren()
+
+* The DrawAfterChildren() hook is called after the children have drawn,
+  so that the user may move all drawing functions there which he does not
+  wish to have painted over by children.
+
+That areas exposed by moving child views are not repainted could
+be considered a bug of the R5 implementation.
+
+-----------------------------------------------------------------------------*/
+
+
+
+class TestView : public BView {
+public:
+	TestView(BRect frame);
+	~TestView();
+
+	virtual	void Draw(BRect updateRect);
+	virtual void DrawAfterChildren(BRect updateRect);
+};
+
+
+TestView::TestView(BRect frame)
+	: BView(frame, "TestView", B_FOLLOW_ALL,
+		B_WILL_DRAW | B_DRAW_ON_CHILDREN | B_FULL_UPDATE_ON_RESIZE)
+{
+	SetViewColor(200, 220, 255);
+}
+
+
+TestView::~TestView()
+{
+}
+
+
+void
+TestView::Draw(BRect updateRect)
+{
+	printf("Draw(BRect(%.1f, %.1f, %.1f, %.1f))\n",
+		updateRect.left, updateRect.top, updateRect.right, updateRect.bottom);
+
+	printf("pensize: %.2f\n", PenSize());
+
+	SetHighColor(0, 0, 255);
+	StrokeLine(Bounds().LeftBottom(), Bounds().RightTop());
+
+	SetPenSize(5);
+}
+
+void
+TestView::DrawAfterChildren(BRect updateRect)
+{
+	printf("DrawAfterChildren(BRect(%.1f, %.1f, %.1f, %.1f))\n",
+		updateRect.left, updateRect.top, updateRect.right, updateRect.bottom);
+
+	printf("pensize: %.2f\n", PenSize());
+
+	SetHighColor(255, 0, 0);
+	StrokeLine(Bounds().LeftTop(), Bounds().RightBottom());
+	Sync();
+
+	SetPenSize(7);
+}
+
+
+//	#pragma mark -
+
+class ChildView : public BView {
+public:
+	ChildView(BRect frame, const char* name, rgb_color viewColor);
+	~ChildView();
+
+	virtual	void Draw(BRect updateRect);
+};
+
+
+ChildView::ChildView(BRect frame, const char* name, rgb_color viewColor)
+	: BView(frame, name, B_FOLLOW_ALL, 0)
+{
+	SetLowColor(200, 200, 200);
+	SetViewColor(viewColor);
+	if (*(int32*)&viewColor == *(int32*)&B_TRANSPARENT_COLOR)
+		SetFlags(Flags() | B_WILL_DRAW);
+}
+
+
+ChildView::~ChildView()
+{
+}
+
+
+void
+ChildView::Draw(BRect updateRect)
+{
+	FillRect(updateRect, B_SOLID_LOW);
+}
+
+
+// #pragma mark -
+
+
+int
+main(int argc, char** argv)
+{
+	BApplication app("application/x-vnd.Haiku-DrawAfterChildren");
+
+	BRect frame(100, 100, 700, 400);
+	BWindow* window = new BWindow(frame, "Window",
+		B_TITLED_WINDOW, B_QUIT_ON_WINDOW_CLOSE);
+
+	frame.OffsetTo(B_ORIGIN);
+	TestView* view = new TestView(frame);
+	window->AddChild(view);
+
+	frame.InsetBy(20, 20);
+	frame.right = frame.left + frame.Width() / 2 - 10;
+	BView* child = new ChildView(frame, "child 1",
+		(rgb_color){ 200, 200, 200, 255 });
+	view->AddChild(child);
+
+	frame.OffsetBy(frame.Width() + 20, 0);
+	child = new ChildView(frame, "child 2", B_TRANSPARENT_COLOR);
+	view->AddChild(child);
+
+	window->Show();
+
+	app.Run();
+	return 0;
+}
+

src/tests/servers/app/draw_after_children/Jamfile

@@ -0,0 +1,18 @@
+SubDir HAIKU_TOP src tests servers app draw_after_children ;
+
+SetSubDirSupportedPlatformsBeOSCompatible ;
+AddSubDirSupportedPlatforms libbe_test ;
+
+UseHeaders [ FDirName os app ] ;
+UseHeaders [ FDirName os interface ] ;
+
+Application DrawAfterChildren :
+	DrawAfterChildren.cpp
+	: be $(TARGET_LIBSTDC++)
+;
+
+if $(TARGET_PLATFORM) = libbe_test {
+	HaikuInstall install-test-apps : $(HAIKU_APP_TEST_DIR) : DrawAfterChildren
+		: tests!apps ;
+}
+

src/tests/servers/app/draw_after_children/run

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+../../../../../generated/tests/libbe_test/x86/apps/run_haiku_registrar || exit
+
+if test -f ../../../../../generated/tests/libbe_test/x86/apps/haiku_app_server; then
+	../../../../../generated/tests/libbe_test/x86/apps//haiku_app_server &
+else
+	echo "You need to \"TARGET_PLATFORM=libbe_test jam install-test-apps\" first."
+fi
+
+sleep 1s
+
+if test -f ../../../../../generated/tests/libbe_test/x86/apps/DrawAfterChildren; then
+	../../../../../generated/tests/libbe_test/x86/apps/DrawAfterChildren
+else
+	echo "You need to \"TARGET_PLATFORM=libbe_test jam install-test-apps\" first."
+fi
+