haiku/headers/os/interface/View.h
DarkWyrm dcb1e9166d Replaced _view_attr with comparable ViewAttr class and removed a crash
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5619 a95241bf-73f2-0310-859d-f6bbb57e9c96
2003-12-07 22:09:58 +00:00

684 lines
22 KiB
C++

//------------------------------------------------------------------------------
// Copyright (c) 2001-2002, OpenBeOS
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// File Name: View.h
// Author: Erik Jaesler (erik@cgsoftware.com)
// Description: BView is the base class for all views (clipped regions
// within a window).
//------------------------------------------------------------------------------
#ifndef _VIEW_H
#define _VIEW_H
// Standard Includes -----------------------------------------------------------
// System Includes -------------------------------------------------------------
#include <BeBuild.h>
#include <Font.h>
#include <Handler.h>
#include <InterfaceDefs.h>
#include <Rect.h>
// Project Includes ------------------------------------------------------------
// Local Includes --------------------------------------------------------------
// Local Defines ---------------------------------------------------------------
// Globals ---------------------------------------------------------------------
// view definitions ------------------------------------------------------------
enum {
B_PRIMARY_MOUSE_BUTTON = 0x01,
B_SECONDARY_MOUSE_BUTTON = 0x02,
B_TERTIARY_MOUSE_BUTTON = 0x04
};
enum {
B_ENTERED_VIEW = 0,
B_INSIDE_VIEW,
B_EXITED_VIEW,
B_OUTSIDE_VIEW
};
enum {
B_POINTER_EVENTS = 0x00000001,
B_KEYBOARD_EVENTS = 0x00000002
};
enum {
B_LOCK_WINDOW_FOCUS = 0x00000001,
B_SUSPEND_VIEW_FOCUS = 0x00000002,
B_NO_POINTER_HISTORY = 0x00000004
};
enum {
B_TRACK_WHOLE_RECT,
B_TRACK_RECT_CORNER
};
enum {
B_FONT_FAMILY_AND_STYLE = 0x00000001,
B_FONT_SIZE = 0x00000002,
B_FONT_SHEAR = 0x00000004,
B_FONT_ROTATION = 0x00000008,
B_FONT_SPACING = 0x00000010,
B_FONT_ENCODING = 0x00000020,
B_FONT_FACE = 0x00000040,
B_FONT_FLAGS = 0x00000080,
B_FONT_ALL = 0x000000FF
};
const uint32 B_FULL_UPDATE_ON_RESIZE = 0x80000000UL; /* 31 */
const uint32 _B_RESERVED1_ = 0x40000000UL; /* 30 */
const uint32 B_WILL_DRAW = 0x20000000UL; /* 29 */
const uint32 B_PULSE_NEEDED = 0x10000000UL; /* 28 */
const uint32 B_NAVIGABLE_JUMP = 0x08000000UL; /* 27 */
const uint32 B_FRAME_EVENTS = 0x04000000UL; /* 26 */
const uint32 B_NAVIGABLE = 0x02000000UL; /* 25 */
const uint32 B_SUBPIXEL_PRECISE = 0x01000000UL; /* 24 */
const uint32 B_DRAW_ON_CHILDREN = 0x00800000UL; /* 23 */
const uint32 B_INPUT_METHOD_AWARE = 0x00400000UL; /* 23 */
const uint32 _B_RESERVED7_ = 0x00200000UL; /* 22 */
/*
#define _RESIZE_MASK_ ~(B_FULL_UPDATE_ON_RESIZE|_B_RESERVED1_|B_WILL_DRAW|\
B_PULSE_NEEDED|B_NAVIGABLE_JUMP|B_FRAME_EVENTS|B_NAVIGABLE|\
B_SUBPIXEL_PRECISE|B_DRAW_ON_CHILDREN|B_INPUT_METHOD_AWARE|_B_RESERVED7_)
*/
#define _RESIZE_MASK_ ~(B_FULL_UPDATE_ON_RESIZE|_B_RESERVED1_|B_WILL_DRAW|B_PULSE_NEEDED|B_NAVIGABLE_JUMP|B_FRAME_EVENTS|B_NAVIGABLE|B_SUBPIXEL_PRECISE|B_DRAW_ON_CHILDREN|B_INPUT_METHOD_AWARE|_B_RESERVED7_)
const uint32 _VIEW_TOP_ = 1UL;
const uint32 _VIEW_LEFT_ = 2UL;
const uint32 _VIEW_BOTTOM_ = 3UL;
const uint32 _VIEW_RIGHT_ = 4UL;
const uint32 _VIEW_CENTER_ = 5UL;
inline uint32 _rule_(uint32 r1, uint32 r2, uint32 r3, uint32 r4)
{ return ((r1 << 12) | (r2 << 8) | (r3 << 4) | r4); }
#define B_FOLLOW_NONE 0
#define B_FOLLOW_ALL_SIDES _rule_(_VIEW_TOP_, _VIEW_LEFT_, _VIEW_BOTTOM_, _VIEW_RIGHT_)
#define B_FOLLOW_ALL B_FOLLOW_ALL_SIDES
#define B_FOLLOW_LEFT _rule_(0, _VIEW_LEFT_, 0, _VIEW_LEFT_)
#define B_FOLLOW_RIGHT _rule_(0, _VIEW_RIGHT_, 0, _VIEW_RIGHT_)
#define B_FOLLOW_LEFT_RIGHT _rule_(0, _VIEW_LEFT_, 0, _VIEW_RIGHT_)
#define B_FOLLOW_H_CENTER _rule_(0, _VIEW_CENTER_, 0, _VIEW_CENTER_)
#define B_FOLLOW_TOP _rule_(_VIEW_TOP_, 0, _VIEW_TOP_, 0)
#define B_FOLLOW_BOTTOM _rule_(_VIEW_BOTTOM_, 0, _VIEW_BOTTOM_, 0)
#define B_FOLLOW_TOP_BOTTOM _rule_(_VIEW_TOP_, 0, _VIEW_BOTTOM_, 0)
#define B_FOLLOW_V_CENTER _rule_(_VIEW_CENTER_, 0, _VIEW_CENTER_, 0)
class BBitmap;
class BCursor;
class BMessage;
class BPicture;
class BPolygon;
class BRegion;
class BScrollBar;
class BScrollView;
class BShape;
class BShelf;
class BString;
class BWindow;
class ViewAttr;
struct _view_attr_;
struct _array_data_;
struct _array_hdr_;
struct overlay_restrictions;
// BView class -----------------------------------------------------------------
class BView : public BHandler {
public:
BView(BRect frame, const char* name,
uint32 resizeMask, uint32 flags);
virtual ~BView();
BView(BMessage* data);
static BArchivable* Instantiate(BMessage* data);
virtual status_t Archive(BMessage* data, bool deep = true) const;
virtual void AttachedToWindow();
virtual void AllAttached();
virtual void DetachedFromWindow();
virtual void AllDetached();
virtual void MessageReceived(BMessage* msg);
void AddChild(BView* child, BView* before = NULL);
bool RemoveChild(BView* child);
int32 CountChildren() const;
BView* ChildAt(int32 index) const;
BView* NextSibling() const;
BView* PreviousSibling() const;
bool RemoveSelf();
BWindow *Window() const;
virtual void Draw(BRect updateRect);
virtual void MouseDown(BPoint where);
virtual void MouseUp(BPoint where);
virtual void MouseMoved(BPoint where,
uint32 code,
const BMessage* a_message);
virtual void WindowActivated(bool state);
virtual void KeyDown(const char* bytes, int32 numBytes);
virtual void KeyUp(const char* bytes, int32 numBytes);
virtual void Pulse();
virtual void FrameMoved(BPoint new_position);
virtual void FrameResized(float new_width, float new_height);
virtual void TargetedByScrollView(BScrollView* scroll_view);
void BeginRectTracking(BRect startRect,
uint32 style = B_TRACK_WHOLE_RECT);
void EndRectTracking();
void GetMouse(BPoint* location,
uint32* buttons,
bool checkMessageQueue = true);
void DragMessage(BMessage* aMessage,
BRect dragRect,
BHandler* reply_to = NULL);
void DragMessage(BMessage* aMessage,
BBitmap* anImage,
BPoint offset,
BHandler* reply_to = NULL);
void DragMessage(BMessage* aMessage,
BBitmap* anImage,
drawing_mode dragMode,
BPoint offset,
BHandler* reply_to = NULL);
BView* FindView(const char* name) const;
BView* Parent() const;
BRect Bounds() const;
BRect Frame() const;
void ConvertToScreen(BPoint* pt) const;
BPoint ConvertToScreen(BPoint pt) const;
void ConvertFromScreen(BPoint* pt) const;
BPoint ConvertFromScreen(BPoint pt) const;
void ConvertToScreen(BRect* r) const;
BRect ConvertToScreen(BRect r) const;
void ConvertFromScreen(BRect* r) const;
BRect ConvertFromScreen(BRect r) const;
void ConvertToParent(BPoint* pt) const;
BPoint ConvertToParent(BPoint pt) const;
void ConvertFromParent(BPoint* pt) const;
BPoint ConvertFromParent(BPoint pt) const;
void ConvertToParent(BRect* r) const;
BRect ConvertToParent(BRect r) const;
void ConvertFromParent(BRect* r) const;
BRect ConvertFromParent(BRect r) const;
BPoint LeftTop() const;
void GetClippingRegion(BRegion* region) const;
virtual void ConstrainClippingRegion(BRegion* region);
void ClipToPicture(BPicture* picture,
BPoint where = B_ORIGIN,
bool sync = true);
void ClipToInversePicture(BPicture* picture,
BPoint where = B_ORIGIN,
bool sync = true);
virtual void SetDrawingMode(drawing_mode mode);
drawing_mode DrawingMode() const;
void SetBlendingMode(source_alpha srcAlpha,
alpha_function alphaFunc);
void GetBlendingMode(source_alpha* srcAlpha,
alpha_function* alphaFunc) const;
virtual void SetPenSize(float size);
float PenSize() const;
void SetViewCursor(const BCursor* cursor, bool sync=true);
virtual void SetViewColor(rgb_color c);
void SetViewColor(uchar r, uchar g, uchar b, uchar a = 255);
rgb_color ViewColor() const;
void SetViewBitmap(const BBitmap* bitmap,
BRect srcRect, BRect dstRect,
uint32 followFlags = B_FOLLOW_TOP|B_FOLLOW_LEFT,
uint32 options = B_TILE_BITMAP);
void SetViewBitmap(const BBitmap* bitmap,
uint32 followFlags = B_FOLLOW_TOP|B_FOLLOW_LEFT,
uint32 options = B_TILE_BITMAP);
void ClearViewBitmap();
status_t SetViewOverlay(const BBitmap* overlay,
BRect srcRect, BRect dstRect,
rgb_color* colorKey,
uint32 followFlags = B_FOLLOW_TOP|B_FOLLOW_LEFT,
uint32 options = 0);
status_t SetViewOverlay(const BBitmap* overlay, rgb_color* colorKey,
uint32 followFlags = B_FOLLOW_TOP|B_FOLLOW_LEFT,
uint32 options = 0);
void ClearViewOverlay();
virtual void SetHighColor(rgb_color a_color);
void SetHighColor(uchar r, uchar g, uchar b, uchar a = 255);
rgb_color HighColor() const;
virtual void SetLowColor(rgb_color a_color);
void SetLowColor(uchar r, uchar g, uchar b, uchar a = 255);
rgb_color LowColor() const;
void SetLineMode(cap_mode lineCap,
join_mode lineJoin,
float miterLimit = B_DEFAULT_MITER_LIMIT);
join_mode LineJoinMode() const;
cap_mode LineCapMode() const;
float LineMiterLimit() const;
void SetOrigin(BPoint pt);
void SetOrigin(float x, float y);
BPoint Origin() const;
void PushState();
void PopState();
void MovePenTo(BPoint pt);
void MovePenTo(float x, float y);
void MovePenBy(float x, float y);
BPoint PenLocation() const;
void StrokeLine(BPoint toPt,
pattern p = B_SOLID_HIGH);
void StrokeLine(BPoint pt0,
BPoint pt1,
pattern p = B_SOLID_HIGH);
void BeginLineArray(int32 count);
void AddLine(BPoint pt0, BPoint pt1, rgb_color col);
void EndLineArray();
void StrokePolygon(const BPolygon* aPolygon,
bool closed = true,
pattern p = B_SOLID_HIGH);
void StrokePolygon(const BPoint* ptArray,
int32 numPts,
bool closed = true,
pattern p = B_SOLID_HIGH);
void StrokePolygon(const BPoint* ptArray,
int32 numPts,
BRect bounds,
bool closed = true,
pattern p = B_SOLID_HIGH);
void FillPolygon(const BPolygon* aPolygon,
pattern p = B_SOLID_HIGH);
void FillPolygon(const BPoint* ptArray,
int32 numPts,
pattern p = B_SOLID_HIGH);
void FillPolygon(const BPoint* ptArray,
int32 numPts,
BRect bounds,
pattern p = B_SOLID_HIGH);
void StrokeTriangle(BPoint pt1,
BPoint pt2,
BPoint pt3,
BRect bounds,
pattern p = B_SOLID_HIGH);
void StrokeTriangle(BPoint pt1,
BPoint pt2,
BPoint pt3,
pattern p = B_SOLID_HIGH);
void FillTriangle(BPoint pt1,
BPoint pt2,
BPoint pt3,
pattern p = B_SOLID_HIGH);
void FillTriangle(BPoint pt1,
BPoint pt2,
BPoint pt3,
BRect bounds,
pattern p = B_SOLID_HIGH);
void StrokeRect(BRect r, pattern p = B_SOLID_HIGH);
void FillRect(BRect r, pattern p = B_SOLID_HIGH);
void FillRegion(BRegion* a_region, pattern p= B_SOLID_HIGH);
void InvertRect(BRect r);
void StrokeRoundRect(BRect r,
float xRadius,
float yRadius,
pattern p = B_SOLID_HIGH);
void FillRoundRect(BRect r,
float xRadius,
float yRadius,
pattern p = B_SOLID_HIGH);
void StrokeEllipse(BPoint center,
float xRadius,
float yRadius,
pattern p = B_SOLID_HIGH);
void StrokeEllipse(BRect r, pattern p = B_SOLID_HIGH);
void FillEllipse(BPoint center,
float xRadius,
float yRadius,
pattern p = B_SOLID_HIGH);
void FillEllipse(BRect r, pattern p = B_SOLID_HIGH);
void StrokeArc(BPoint center,
float xRadius,
float yRadius,
float start_angle,
float arc_angle,
pattern p = B_SOLID_HIGH);
void StrokeArc(BRect r,
float start_angle,
float arc_angle,
pattern p = B_SOLID_HIGH);
void FillArc(BPoint center,
float xRadius,
float yRadius,
float start_angle,
float arc_angle,
pattern p = B_SOLID_HIGH);
void FillArc(BRect r,
float start_angle,
float arc_angle,
pattern p = B_SOLID_HIGH);
void StrokeBezier(BPoint* controlPoints,
pattern p = B_SOLID_HIGH);
void FillBezier(BPoint* controlPoints,
pattern p = B_SOLID_HIGH);
void StrokeShape(BShape* shape,
pattern p = B_SOLID_HIGH);
void FillShape(BShape* shape,
pattern p = B_SOLID_HIGH);
void CopyBits(BRect src, BRect dst);
void DrawBitmapAsync(const BBitmap* aBitmap,
BRect srcRect,
BRect dstRect);
void DrawBitmapAsync(const BBitmap* aBitmap);
void DrawBitmapAsync(const BBitmap* aBitmap, BPoint where);
void DrawBitmapAsync(const BBitmap* aBitmap, BRect dstRect);
void DrawBitmap(const BBitmap* aBitmap,
BRect srcRect,
BRect dstRect);
void DrawBitmap(const BBitmap* aBitmap);
void DrawBitmap(const BBitmap* aBitmap, BPoint where);
void DrawBitmap(const BBitmap* aBitmap, BRect dstRect);
void DrawChar(char aChar);
void DrawChar(char aChar, BPoint location);
void DrawString(const char* aString,
escapement_delta* delta = NULL);
void DrawString(const char* aString, BPoint location,
escapement_delta* delta = NULL);
void DrawString(const char* aString, int32 length,
escapement_delta* delta = NULL);
void DrawString(const char* aString,
int32 length,
BPoint location,
escapement_delta* delta = 0L);
virtual void SetFont(const BFont* font, uint32 mask = B_FONT_ALL);
#if !_PR3_COMPATIBLE_
void GetFont(BFont* font) const;
#else
void GetFont(BFont* font);
#endif
void TruncateString(BString* in_out,
uint32 mode,
float width) const;
float StringWidth(const char* string) const;
float StringWidth(const char* string, int32 length) const;
void GetStringWidths(char* stringArray[],
int32 lengthArray[],
int32 numStrings,
float widthArray[]) const;
void SetFontSize(float size);
void ForceFontAliasing(bool enable);
void GetFontHeight(font_height* height) const;
void Invalidate(BRect invalRect);
void Invalidate(const BRegion* invalRegion);
void Invalidate();
void SetDiskMode(char* filename, long offset);
void BeginPicture(BPicture* a_picture);
void AppendToPicture(BPicture* a_picture);
BPicture* EndPicture();
void DrawPicture(const BPicture* a_picture);
void DrawPicture(const BPicture* a_picture, BPoint where);
void DrawPicture(const char* filename, long offset, BPoint where);
void DrawPictureAsync(const BPicture* a_picture);
void DrawPictureAsync(const BPicture* a_picture, BPoint where);
void DrawPictureAsync(const char* filename, long offset,
BPoint where);
status_t SetEventMask(uint32 mask, uint32 options=0);
uint32 EventMask();
status_t SetMouseEventMask(uint32 mask, uint32 options=0);
virtual void SetFlags(uint32 flags);
uint32 Flags() const;
virtual void SetResizingMode(uint32 mode);
uint32 ResizingMode() const;
void MoveBy(float dh, float dv);
void MoveTo(BPoint where);
void MoveTo(float x, float y);
void ResizeBy(float dh, float dv);
void ResizeTo(float width, float height);
void ScrollBy(float dh, float dv);
void ScrollTo(float x, float y);
virtual void ScrollTo(BPoint where);
virtual void MakeFocus(bool focusState = true);
bool IsFocus() const;
virtual void Show();
virtual void Hide();
bool IsHidden() const;
bool IsHidden(const BView* looking_from) const;
void Flush() const;
void Sync() const;
virtual void GetPreferredSize(float* width, float* height);
virtual void ResizeToPreferred();
BScrollBar* ScrollBar(orientation posture) const;
virtual BHandler* ResolveSpecifier(BMessage* msg,
int32 index,
BMessage* specifier,
int32 form,
const char* property);
virtual status_t GetSupportedSuites(BMessage* data);
bool IsPrinting() const;
void SetScale(float scale) const;
// Private or reserved ---------------------------------------------------------
virtual status_t Perform(perform_code d, void* arg);
virtual void DrawAfterChildren(BRect r);
// added by OBOS - DO NOT use this when programming BeOS R5!!!
float Scale() const;
private:
friend class BScrollBar;
friend class BWindow;
friend class BBitmap;
friend class BPrintJob;
friend class BShelf;
friend class BTabView;
virtual void _ReservedView2();
virtual void _ReservedView3();
virtual void _ReservedView4();
virtual void _ReservedView5();
virtual void _ReservedView6();
virtual void _ReservedView7();
virtual void _ReservedView8();
#if !_PR3_COMPATIBLE_
virtual void _ReservedView9();
virtual void _ReservedView10();
virtual void _ReservedView11();
virtual void _ReservedView12();
virtual void _ReservedView13();
virtual void _ReservedView14();
virtual void _ReservedView15();
virtual void _ReservedView16();
#endif
BView(const BView&);
BView& operator=(const BView&);
void InitData(BRect f, const char* name, uint32 rs, uint32 fl);
status_t ArchiveChildren(BMessage* data, bool deep) const;
status_t UnarchiveChildren(BMessage* data, BWindow* w = NULL);
status_t setViewImage(const BBitmap* bitmap,BRect srcRect, BRect dstRect,
uint32 followFlags, uint32 options);
void BeginPicture_pr(BPicture* a_picture, BRect r);
void SetPattern(pattern pat);
void DoBezier(int32 gr, BPoint* controlPoints, pattern p);
void DoShape(int32 gr, BShape* shape, pattern p);
void DoPictureClip(BPicture* picture, BPoint where, bool invert,
bool sync);
bool removeFromList(BView* a_view);
bool removeSelf();
bool do_owner_check() const;
void setOwner(BWindow* the_owner);
void do_activate(int32 state);
void check_lock() const;
void check_lock_no_pick() const;
void movesize(uint32 code, int32 h, int32 v);
void handle_tick();
char *test_area(int32 length);
void removeCommArray();
_array_hdr_ *new_comm_array(int32 cnt);
BView *RealParent() const;
void SetScroller(BScrollBar* sb);
void UnsetScroller(BScrollBar* sb);
void RealScrollTo(BPoint);
void initCachedState();
void setCachedState();
void updateCachedState();
void setFontState(const BFont* font, uint16 mask);
void fetch_font();
uchar font_encoding() const;
BShelf* shelf() const;
void set_shelf(BShelf* );
void deleteView( BView* aView);
bool do_owner_check_no_pick() const;
BView* findView( const BView* aView, const char* viewName ) const;
bool attachView( BView *aView );
bool addToList( BView *aView, BView *before = NULL);
bool removeFromList();
bool callDetachHooks( BView *aView );
// Debugging methods
void PrintToStream();
void PrintTree();
int32 server_token;
uint32 fFlags; // used // was: f_type
float originX; // used // was: origin_h
float originY; // used // was: origin_v
BWindow* owner; // used
BView* parent; // used
BView* next_sibling; // used
BView* prev_sibling; // used
BView* first_child; // used
int16 fShowLevel; // used
bool top_level_view; // used
bool fNoISInteraction;
BPicture* cpicture; // used
_array_data_* comm; // used
BScrollBar* fVerScroller; // used
BScrollBar* fHorScroller; // used
bool f_is_printing;
bool _unused_bool0; // was: attached;
bool _unused_bool1;
bool _unused_bool2;
ViewAttr* fPermanentState;// used
ViewAttr* fState; // used
BRect fBounds; // used
BShelf* fShelf; // used
void* pr_state;
uint32 fEventMask; // used
uint32 fEventOptions; // used
uint32 _reserved[4];
#if !_PR3_COMPATIBLE_
uint32 _more_reserved[3];
#endif
};
//------------------------------------------------------------------------------
// inline definitions ----------------------------------------------------------
inline void BView::ScrollTo(float x, float y)
{
ScrollTo(BPoint(x, y));
}
//------------------------------------------------------------------------------
inline void BView::SetViewColor(uchar r, uchar g, uchar b, uchar a)
{
rgb_color a_color;
a_color.red = r; a_color.green = g;
a_color.blue = b; a_color.alpha = a;
SetViewColor(a_color);
}
//------------------------------------------------------------------------------
inline void BView::SetHighColor(uchar r, uchar g, uchar b, uchar a)
{
rgb_color a_color;
a_color.red = r; a_color.green = g;
a_color.blue = b; a_color.alpha = a;
SetHighColor(a_color);
}
//------------------------------------------------------------------------------
inline void BView::SetLowColor(uchar r, uchar g, uchar b, uchar a)
{
rgb_color a_color;
a_color.red = r; a_color.green = g;
a_color.blue = b; a_color.alpha = a;
SetLowColor(a_color);
}
//------------------------------------------------------------------------------
#endif // _VIEW_H
/*
@log
* added PrintToStream() method for debugging BView.
*/