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wxWidgets/samples/scroll/scroll.cpp
Vadim Zeitlin 0a6b9955db fix typo in previous commit 
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60954 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
2009-06-07 16:01:34 +00:00

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/////////////////////////////////////////////////////////////////////////////
// Name: scroll.cpp
// Purpose: wxScrolledWindow sample
// Author: Robert Roebling
// RCS-ID: $Id$
// Copyright: (C) 1998 Robert Roebling, 2002 Ron Lee, 2003 Matt Gregory
// (C) 2008 Vadim Zeitlin
// Licence: wxWindows license
/////////////////////////////////////////////////////////////////////////////
#include "wx/wxprec.h"
#ifdef __BORLANDC__
#pragma hdrstop
#endif
#ifndef WX_PRECOMP
#include "wx/wx.h"
#endif
#include "wx/sizer.h"
#include "wx/log.h"
#include "wx/tglbtn.h"
#ifndef __WXMSW__
#include "../sample.xpm"
#endif
// ----------------------------------------------------------------------------
// a trivial example
// ----------------------------------------------------------------------------
// MySimpleCanvas: a scrolled window which draws a simple rectangle
class MySimpleCanvas : public wxScrolledWindow
{
public:
enum
{
// these numbers are not multiple of 10 (our scroll step) to test for
// the absence of rounding errors (e.g. we should have one more page
// than WIDTH/10 to show the right side of the rectangle)
WIDTH = 292,
HEIGHT = 297
};
MySimpleCanvas(wxWindow *parent)
: wxScrolledWindow(parent, wxID_ANY)
{
SetScrollRate( 10, 10 );
SetVirtualSize( WIDTH, HEIGHT );
SetBackgroundColour( *wxWHITE );
Connect(wxEVT_PAINT, wxPaintEventHandler(MySimpleCanvas::OnPaint));
}
private:
void OnPaint(wxPaintEvent& WXUNUSED(event))
{
wxPaintDC dc(this);
// this call is vital: it adjusts the dc to account for the current
// scroll offset
PrepareDC(dc);
dc.SetPen( *wxRED_PEN );
dc.SetBrush( *wxTRANSPARENT_BRUSH );
dc.DrawRectangle( 0, 0, WIDTH, HEIGHT );
}
};
// MySimpleFrame: a frame which contains a MySimpleCanvas
class MySimpleFrame : public wxFrame
{
public:
MySimpleFrame(wxWindow *parent)
: wxFrame(parent, wxID_ANY, "MySimpleCanvas")
{
new MySimpleCanvas(this);
// ensure that we have scrollbars initially
SetClientSize(MySimpleCanvas::WIDTH/2, MySimpleCanvas::HEIGHT/2);
Show();
}
};
// ----------------------------------------------------------------------
// a more complex example
// ----------------------------------------------------------------------
// MyCanvas
class MyCanvas : public wxScrolledWindow
{
public:
MyCanvas(wxWindow *parent);
private:
void OnPaint(wxPaintEvent& event);
void OnQueryPosition(wxCommandEvent& event);
void OnAddButton(wxCommandEvent& event);
void OnDeleteButton(wxCommandEvent& event);
void OnMoveButton(wxCommandEvent& event);
void OnScrollWin(wxCommandEvent& event);
void OnMouseRightDown(wxMouseEvent& event);
void OnMouseWheel(wxMouseEvent& event);
wxButton *m_button;
DECLARE_EVENT_TABLE()
};
class MyCanvasFrame : public wxFrame
{
public:
MyCanvasFrame(wxWindow *parent)
: wxFrame(parent, wxID_ANY, "MyCanvas")
{
m_canvas = new MyCanvas(this);
wxMenu *menuFile = new wxMenu();
menuFile->Append(wxID_DELETE, "&Delete all");
menuFile->Append(wxID_NEW, "Insert &new");
wxMenuBar *mbar = new wxMenuBar();
mbar->Append(menuFile, "&File");
SetMenuBar( mbar );
Connect(wxID_DELETE, wxEVT_COMMAND_MENU_SELECTED,
wxCommandEventHandler(MyCanvasFrame::OnDeleteAll));
Connect(wxID_NEW, wxEVT_COMMAND_MENU_SELECTED,
wxCommandEventHandler(MyCanvasFrame::OnInsertNew));
Show();
}
private:
void OnDeleteAll(wxCommandEvent& WXUNUSED(event))
{
m_canvas->DestroyChildren();
}
void OnInsertNew(wxCommandEvent& WXUNUSED(event))
{
(void)new wxButton(m_canvas, wxID_ANY, "Hello", wxPoint(100,100));
}
MyCanvas *m_canvas;
};
// ----------------------------------------------------------------------------
// example using sizers with wxScrolledWindow
// ----------------------------------------------------------------------------
const wxSize SMALL_BUTTON( 100, 50 );
const wxSize LARGE_BUTTON( 300, 200 );
class MySizerScrolledWindow : public wxScrolledWindow
{
public:
MySizerScrolledWindow(wxWindow *parent);
private:
// this button can be clicked to change its own size in the handler below,
// the window size will be automatically adjusted to fit the button
wxButton *m_button;
void OnResizeClick(wxCommandEvent& event);
};
class MySizerFrame : public wxFrame
{
public:
MySizerFrame(wxWindow *parent)
: wxFrame(parent, wxID_ANY, "MySizerScrolledWindow")
{
new MySizerScrolledWindow(this);
// ensure that the scrollbars appear when the button becomes large
SetClientSize(LARGE_BUTTON/2);
Show();
}
};
// ----------------------------------------------------------------------------
// example showing scrolling only part of the window
// ----------------------------------------------------------------------------
// this window consists of an empty space in its corner, column labels window
// along its top, row labels window along its left hand side and a canvas in
// the remaining space
class MySubColLabels : public wxWindow
{
public:
MySubColLabels(wxScrolledWindow *parent)
: wxWindow(parent, wxID_ANY)
{
m_owner = parent;
Connect(wxEVT_PAINT, wxPaintEventHandler(MySubColLabels::OnPaint));
}
private:
void OnPaint(wxPaintEvent& WXUNUSED(event))
{
wxPaintDC dc(this);
// This is wrong.. it will translate both x and y if the
// window is scrolled, the label windows are active in one
// direction only. Do the action below instead -- RL.
//m_owner->PrepareDC( dc );
int xScrollUnits, xOrigin;
m_owner->GetViewStart( &xOrigin, 0 );
m_owner->GetScrollPixelsPerUnit( &xScrollUnits, 0 );
dc.SetDeviceOrigin( -xOrigin * xScrollUnits, 0 );
dc.DrawText("Column 1", 5, 5);
dc.DrawText("Column 2", 105, 5);
dc.DrawText("Column 3", 205, 5);
}
wxScrolledWindow *m_owner;
};
class MySubRowLabels : public wxWindow
{
public:
MySubRowLabels(wxScrolledWindow *parent)
: wxWindow(parent, wxID_ANY)
{
m_owner = parent;
Connect(wxEVT_PAINT, wxPaintEventHandler(MySubRowLabels::OnPaint));
}
private:
void OnPaint(wxPaintEvent& WXUNUSED(event))
{
wxPaintDC dc(this);
// This is wrong.. it will translate both x and y if the
// window is scrolled, the label windows are active in one
// direction only. Do the action below instead -- RL.
//m_owner->PrepareDC( dc );
int yScrollUnits, yOrigin;
m_owner->GetViewStart( 0, &yOrigin );
m_owner->GetScrollPixelsPerUnit( 0, &yScrollUnits );
dc.SetDeviceOrigin( 0, -yOrigin * yScrollUnits );
dc.DrawText("Row 1", 5, 5);
dc.DrawText("Row 2", 5, 30);
dc.DrawText("Row 3", 5, 55);
dc.DrawText("Row 4", 5, 80);
dc.DrawText("Row 5", 5, 105);
dc.DrawText("Row 6", 5, 130);
}
wxScrolledWindow *m_owner;
};
class MySubCanvas : public wxPanel
{
public:
MySubCanvas(wxScrolledWindow *parent, wxWindow *cols, wxWindow *rows)
: wxPanel(parent, wxID_ANY)
{
m_owner = parent;
m_colLabels = cols;
m_rowLabels = rows;
(void)new wxButton(this, wxID_ANY, "Hallo I",
wxPoint(0,50), wxSize(100,25) );
(void)new wxButton(this, wxID_ANY, "Hallo II",
wxPoint(200,50), wxSize(100,25) );
(void)new wxTextCtrl(this, wxID_ANY, "Text I",
wxPoint(0,100), wxSize(100,25) );
(void)new wxTextCtrl(this, wxID_ANY, "Text II",
wxPoint(200,100), wxSize(100,25) );
(void)new wxComboBox(this, wxID_ANY, "ComboBox I",
wxPoint(0,150), wxSize(100,25));
(void)new wxComboBox(this, wxID_ANY, "ComboBox II",
wxPoint(200,150), wxSize(100,25));
SetBackgroundColour("WHEAT");
Connect(wxEVT_PAINT, wxPaintEventHandler(MySubCanvas::OnPaint));
}
// override the base class function so that when this window is scrolled,
// the labels are scrolled in sync
virtual void ScrollWindow(int dx, int dy, const wxRect *rect)
{
wxPanel::ScrollWindow( dx, dy, rect );
m_colLabels->ScrollWindow( dx, 0, rect );
m_rowLabels->ScrollWindow( 0, dy, rect );
}
private:
void OnPaint(wxPaintEvent& WXUNUSED(event))
{
wxPaintDC dc( this );
m_owner->PrepareDC( dc );
dc.SetPen( *wxBLACK_PEN );
// OK, let's assume we are a grid control and we have two
// grid cells. Here in OnPaint we want to know which cell
// to redraw so that we prevent redrawing cells that don't
// need to get redrawn. We have one cell at (0,0) and one
// more at (200,0), both having a size of (100,25).
// We can query how much the window has been scrolled
// by calling CalcUnscrolledPosition()
int scroll_x = 0;
int scroll_y = 0;
m_owner->CalcUnscrolledPosition( scroll_x, scroll_y, &scroll_x, &scroll_y );
// We also need to know the size of the window to see which
// cells are completely hidden and not get redrawn
int size_x = 0;
int size_y = 0;
GetClientSize( &size_x, &size_y );
// First cell: (0,0)(100,25)
// It it on screen?
if ((0+100-scroll_x > 0) && (0+25-scroll_y > 0) &&
(0-scroll_x < size_x) && (0-scroll_y < size_y))
{
// Has the region on screen been exposed?
if (IsExposed(0,0,100,25))
{
dc.DrawRectangle( 0, 0, 100, 25 );
dc.DrawText("First Cell", 5, 5);
}
}
// Second cell: (0,200)(100,25)
// It it on screen?
if ((200+100-scroll_x > 0) && (0+25-scroll_y > 0) &&
(200-scroll_x < size_x) && (0-scroll_y < size_y))
{
// Has the region on screen been exposed?
if (IsExposed(200,0,100,25))
{
dc.DrawRectangle( 200, 0, 100, 25 );
dc.DrawText("Second Cell", 205, 5);
}
}
}
wxScrolledWindow *m_owner;
wxWindow *m_colLabels,
*m_rowLabels;
};
class MySubScrolledWindow : public wxScrolledWindow
{
public:
enum
{
CORNER_WIDTH = 60,
CORNER_HEIGHT = 25
};
MySubScrolledWindow(wxWindow *parent)
: wxScrolledWindow(parent, wxID_ANY)
{
// create the children
MySubColLabels *cols = new MySubColLabels(this);
MySubRowLabels *rows = new MySubRowLabels(this);
m_canvas = new MySubCanvas(this, cols, rows);
// lay them out
wxFlexGridSizer *sizer = new wxFlexGridSizer(2, 2, 10, 10);
sizer->Add(CORNER_WIDTH, CORNER_HEIGHT); // just a spacer
sizer->Add(cols, wxSizerFlags().Expand());
sizer->Add(rows, wxSizerFlags().Expand());
sizer->Add(m_canvas, wxSizerFlags().Expand());
sizer->AddGrowableRow(1);
sizer->AddGrowableCol(1);
SetSizer(sizer);
// this is the key call: it means that only m_canvas will be scrolled
// and not this window itself
SetTargetWindow(m_canvas);
SetScrollbars(10, 10, 50, 50);
Connect(wxEVT_SIZE, wxSizeEventHandler(MySubScrolledWindow::OnSize));
}
protected:
// scrolled windows which use scroll target different from the window
// itself must override this virtual method
virtual wxSize GetSizeAvailableForScrollTarget(const wxSize& size)
{
// decrease the total size by the size of the non-scrollable parts
// above/to the left of the canvas
wxSize sizeCanvas(size);
sizeCanvas.x -= 60;
sizeCanvas.y -= 25;
return sizeCanvas;
}
private:
void OnSize(wxSizeEvent& WXUNUSED(event))
{
// We need to override OnSize so that our scrolled
// window a) does call Layout() to use sizers for
// positioning the controls but b) does not query
// the sizer for their size and use that for setting
// the scrollable area as set that ourselves by
// calling SetScrollbar() further down.
Layout();
AdjustScrollbars();
}
MySubCanvas *m_canvas;
};
class MySubFrame : public wxFrame
{
public:
MySubFrame(wxWindow *parent)
: wxFrame(parent, wxID_ANY, "MySubScrolledWindow")
{
new MySubScrolledWindow(this);
Show();
}
};
// ----------------------------------------------------------------------------
// more simple examples of wxScrolledWindow usage
// ----------------------------------------------------------------------------
// base class for both of them
class MyScrolledWindowBase : public wxScrolledWindow
{
public:
MyScrolledWindowBase(wxWindow *parent)
: wxScrolledWindow(parent, wxID_ANY,
wxDefaultPosition, wxDefaultSize,
wxBORDER_SUNKEN)
{
m_nLines = 50;
m_winSync = NULL;
m_inDoSync = false;
wxClientDC dc(this);
dc.GetTextExtent("Line 17", NULL, &m_hLine);
}
// this scrolled window can be synchronized with another one: if this
// function is called with a non-NULL pointer, the given window will be
// scrolled to the same position as this one
void SyncWith(MyScrolledWindowBase *win)
{
m_winSync = win;
DoSyncIfNecessary();
}
virtual void ScrollWindow(int dx, int dy, const wxRect *rect = NULL)
{
wxScrolledWindow::ScrollWindow(dx, dy, rect);
DoSyncIfNecessary();
}
protected:
// the height of one line on screen
int m_hLine;
// the number of lines we draw
size_t m_nLines;
private:
bool WasScrolledFirst() const { return m_inDoSync; }
void DoSyncIfNecessary()
{
if ( m_winSync && !m_winSync->WasScrolledFirst() )
{
m_inDoSync = true;
m_winSync->Scroll(GetViewStart());
m_inDoSync = false;
}
}
// the window to synchronize with this one or NULL
MyScrolledWindowBase *m_winSync;
// the flag preventing infinite recursion which would otherwise happen if
// one window synchronized the other one which in turn synchronized this
// one and so on
bool m_inDoSync;
};
// this class does "stupid" redrawing - it redraws everything each time
// and sets the scrollbar extent directly.
class MyScrolledWindowDumb : public MyScrolledWindowBase
{
public:
MyScrolledWindowDumb(wxWindow *parent) : MyScrolledWindowBase(parent)
{
// no horz scrolling
SetScrollbars(0, m_hLine, 0, m_nLines + 1, 0, 0, true /* no refresh */);
}
virtual void OnDraw(wxDC& dc);
};
// this class does "smart" redrawing - only redraws the lines which must be
// redrawn and sets the scroll rate and virtual size to affect the
// scrollbars.
//
// Note that this class should produce identical results to the one above.
class MyScrolledWindowSmart : public MyScrolledWindowBase
{
public:
MyScrolledWindowSmart(wxWindow *parent) : MyScrolledWindowBase(parent)
{
// no horz scrolling
SetScrollRate( 0, m_hLine );
SetVirtualSize( wxDefaultCoord, ( m_nLines + 1 ) * m_hLine );
}
virtual void OnDraw(wxDC& dc);
};
// ----------------------------------------------------------------------------
// implements a text viewer with simple block selection to test auto-scrolling
// functionality
// ----------------------------------------------------------------------------
class MyAutoScrollingWindow : public wxScrolledWindow
{
public:
MyAutoScrollingWindow( wxWindow* parent );
wxRect DeviceCoordsToGraphicalChars(wxRect updRect) const;
wxPoint DeviceCoordsToGraphicalChars(wxPoint pos) const;
wxPoint GraphicalCharToDeviceCoords(wxPoint pos) const;
wxRect LogicalCoordsToGraphicalChars(wxRect updRect) const;
wxPoint LogicalCoordsToGraphicalChars(wxPoint pos) const;
wxPoint GraphicalCharToLogicalCoords(wxPoint pos) const;
void MyRefresh();
bool IsSelected(int chX, int chY) const;
static bool IsInside(int k, int bound1, int bound2);
static wxRect DCNormalize(int x, int y, int w, int h);
private:
// event handlers
void OnDraw(wxDC& dc);
void OnMouseLeftDown(wxMouseEvent& event);
void OnMouseLeftUp(wxMouseEvent& event);
void OnMouseMove(wxMouseEvent& event);
void OnMouseCaptureLost(wxMouseCaptureLostEvent& event);
void OnScroll(wxScrollWinEvent& event);
// test data variables
static const char* sm_testData;
static const int sm_lineCnt; // line count
static const int sm_lineLen; // line length in characters
// sizes for graphical data
int m_fontH, m_fontW;
// selection tracking
wxPoint m_selStart; // beginning of blockwise selection
wxPoint m_cursor; // end of blockwise selection (mouse position)
// gui stuff
wxFont m_font;
DECLARE_EVENT_TABLE()
};
class MyAutoFrame : public wxFrame
{
public:
MyAutoFrame(wxWindow *parent)
: wxFrame(parent, wxID_ANY, "MyAutoScrollingWindow")
{
new MyAutoScrollingWindow(this);
Show();
}
};
// ----------------------------------------------------------------------------
// MyFrame: the main application frame showing all the classes above
// ----------------------------------------------------------------------------
class MyFrame: public wxFrame
{
public:
MyFrame();
private:
void OnAbout(wxCommandEvent& event);
void OnQuit(wxCommandEvent& event);
void OnTestSimple(wxCommandEvent& WXUNUSED(event)) { new MySimpleFrame(this); }
void OnTestCanvas(wxCommandEvent& WXUNUSED(event)) { new MyCanvasFrame(this); }
void OnTestSizer(wxCommandEvent& WXUNUSED(event)) { new MySizerFrame(this); }
void OnTestSub(wxCommandEvent& WXUNUSED(event)) { new MySubFrame(this); }
void OnTestAuto(wxCommandEvent& WXUNUSED(event)) { new MyAutoFrame(this); }
void OnToggleSync(wxCommandEvent& event);
void OnScrollbarVisibility(wxCommandEvent& event);
MyScrolledWindowBase *m_win1,
*m_win2;
DECLARE_EVENT_TABLE()
};
// ----------------------------------------------------------------------------
// MyApp
// ----------------------------------------------------------------------------
class MyApp : public wxApp
{
public:
virtual bool OnInit();
};
// ============================================================================
// implementation
// ============================================================================
// ----------------------------------------------------------------------------
// MyCanvas
// ----------------------------------------------------------------------------
const wxWindowID ID_ADDBUTTON = wxWindow::NewControlId();
const wxWindowID ID_DELBUTTON = wxWindow::NewControlId();
const wxWindowID ID_MOVEBUTTON = wxWindow::NewControlId();
const wxWindowID ID_SCROLLWIN = wxWindow::NewControlId();
const wxWindowID ID_QUERYPOS = wxWindow::NewControlId();
const wxWindowID ID_NEWBUTTON = wxWindow::NewControlId();
BEGIN_EVENT_TABLE(MyCanvas, wxScrolledWindow)
EVT_PAINT( MyCanvas::OnPaint)
EVT_RIGHT_DOWN( MyCanvas::OnMouseRightDown)
EVT_MOUSEWHEEL( MyCanvas::OnMouseWheel)
EVT_BUTTON( ID_QUERYPOS, MyCanvas::OnQueryPosition)
EVT_BUTTON( ID_ADDBUTTON, MyCanvas::OnAddButton)
EVT_BUTTON( ID_DELBUTTON, MyCanvas::OnDeleteButton)
EVT_BUTTON( ID_MOVEBUTTON, MyCanvas::OnMoveButton)
EVT_BUTTON( ID_SCROLLWIN, MyCanvas::OnScrollWin)
END_EVENT_TABLE()
MyCanvas::MyCanvas(wxWindow *parent)
: wxScrolledWindow(parent, wxID_ANY,
wxDefaultPosition, wxDefaultSize,
wxSUNKEN_BORDER | wxTAB_TRAVERSAL)
{
// you can use either a single SetScrollbars() call or these 2 functions,
// usually using them is better because you normally won't need to change
// the scroll rate in the future and the sizer can be used to update the
// virtual size automatically
SetScrollRate( 10, 10 );
SetVirtualSize( 500, 1000 );
(void) new wxButton( this, ID_ADDBUTTON, "add button", wxPoint(10,10) );
(void) new wxButton( this, ID_DELBUTTON, "del button", wxPoint(10,40) );
(void) new wxButton( this, ID_MOVEBUTTON, "move button", wxPoint(150,10) );
(void) new wxButton( this, ID_SCROLLWIN, "scroll win", wxPoint(250,10) );
wxPanel *test = new wxPanel( this, wxID_ANY,
wxPoint(10, 110), wxSize(130,50),
wxSIMPLE_BORDER | wxTAB_TRAVERSAL );
test->SetBackgroundColour( "WHEAT" );
SetBackgroundColour( "BLUE" );
}
void MyCanvas::OnMouseRightDown( wxMouseEvent &event )
{
wxPoint pt( event.GetPosition() );
int x,y;
CalcUnscrolledPosition( pt.x, pt.y, &x, &y );
wxLogMessage("Mouse down event at: %d %d, scrolled: %d %d",
pt.x, pt.y, x, y);
}
void MyCanvas::OnMouseWheel( wxMouseEvent &event )
{
wxPoint pt( event.GetPosition() );
int x,y;
CalcUnscrolledPosition( pt.x, pt.y, &x, &y );
wxLogMessage( "Mouse wheel event at: %d %d, scrolled: %d %d\n"
"Rotation: %d, delta = %d",
pt.x, pt.y, x, y,
event.GetWheelRotation(), event.GetWheelDelta() );
event.Skip();
}
void MyCanvas::OnPaint( wxPaintEvent &WXUNUSED(event) )
{
wxPaintDC dc( this );
PrepareDC( dc );
dc.DrawText( "Press right mouse button to test calculations!", 160, 50 );
dc.DrawText( "Some text", 140, 140 );
dc.DrawRectangle( 100, 160, 200, 200 );
}
void MyCanvas::OnQueryPosition( wxCommandEvent &WXUNUSED(event) )
{
wxPoint pt( m_button->GetPosition() );
wxLogMessage( "Position of \"Query position\" is %d %d", pt.x, pt.y );
pt = ClientToScreen( pt );
wxLogMessage("Position of \"Query position\" on screen is %d %d",
pt.x, pt.y);
}
void MyCanvas::OnAddButton( wxCommandEvent &WXUNUSED(event) )
{
wxLogMessage( "Inserting button at position 10,70..." );
wxButton *button = new wxButton( this, ID_NEWBUTTON, "new button",
wxPoint(10,70), wxSize(80,25) );
wxPoint pt( button->GetPosition() );
wxLogMessage( "-> Position after inserting %d %d", pt.x, pt.y );
}
void MyCanvas::OnDeleteButton( wxCommandEvent &WXUNUSED(event) )
{
wxLogMessage( "Deleting button inserted with \"Add button\"..." );
wxWindow *win = FindWindow( ID_NEWBUTTON );
if (win)
win->Destroy();
else
wxLogMessage( "-> No window with id = ID_NEWBUTTON found." );
}
void MyCanvas::OnMoveButton( wxCommandEvent &event )
{
wxLogMessage( "Moving button 10 pixels downward.." );
wxWindow *win = FindWindow( event.GetId() );
wxPoint pt( win->GetPosition() );
wxLogMessage( "-> Position before move is %d %d", pt.x, pt.y );
win->Move( wxDefaultCoord, pt.y + 10 );
pt = win->GetPosition();
wxLogMessage( "-> Position after move is %d %d", pt.x, pt.y );
}
void MyCanvas::OnScrollWin( wxCommandEvent &WXUNUSED(event) )
{
wxLogMessage("Scrolling 2 units up.\n"
"The white square and the controls should move equally!");
Scroll( wxDefaultCoord, GetViewStart().y+2 );
}
// ----------------------------------------------------------------------------
// MySizerScrolledWindow
// ----------------------------------------------------------------------------
MySizerScrolledWindow::MySizerScrolledWindow(wxWindow *parent)
: wxScrolledWindow(parent)
{
SetBackgroundColour( "GREEN" );
// Set the rate we'd like for scrolling.
SetScrollRate( 5, 5 );
// Populate a sizer with a 'resizing' button and some other static
// decoration
wxFlexGridSizer *sizer = new wxFlexGridSizer(2);
m_button = new wxButton( this, wxID_RESIZE_FRAME, "Press me",
wxDefaultPosition, SMALL_BUTTON );
sizer->Add(m_button, wxSizerFlags().Centre().Border(20));
sizer->Add(new wxStaticText(this, wxID_ANY, "This is just"),
wxSizerFlags().Centre());
sizer->Add(new wxStaticText(this, wxID_ANY, "some decoration"),
wxSizerFlags().Centre());
sizer->Add(new wxStaticText(this, wxID_ANY, "for you to scroll..."),
wxSizerFlags().Centre());
// Then use the sizer to set the scrolled region size.
SetSizer( sizer );
Connect(wxID_RESIZE_FRAME, wxEVT_COMMAND_BUTTON_CLICKED,
wxCommandEventHandler(MySizerScrolledWindow::OnResizeClick));
}
void MySizerScrolledWindow::OnResizeClick(wxCommandEvent &WXUNUSED(event))
{
// Arbitrarily resize the button to change the minimum size of
// the (scrolled) sizer.
if ( m_button->GetSize() == SMALL_BUTTON )
m_button->SetSizeHints(LARGE_BUTTON);
else
m_button->SetSizeHints(SMALL_BUTTON);
// Force update layout and scrollbars, since nothing we do here
// necessarily generates a size event which would do it for us.
FitInside();
}
// ----------------------------------------------------------------------------
// MyFrame
// ----------------------------------------------------------------------------
const wxWindowID Scroll_Test_Simple = wxWindow::NewControlId();
const wxWindowID Scroll_Test_Canvas = wxWindow::NewControlId();
const wxWindowID Scroll_Test_Sizers = wxWindow::NewControlId();
const wxWindowID Scroll_Test_Sub = wxWindow::NewControlId();
const wxWindowID Scroll_Test_Auto = wxWindow::NewControlId();
const wxWindowID Scroll_TglBtn_Sync = wxWindow::NewControlId();
const wxWindowID Scroll_Radio_ShowScrollbar = wxWindow::NewControlId();
BEGIN_EVENT_TABLE(MyFrame,wxFrame)
EVT_MENU(wxID_ABOUT, MyFrame::OnAbout)
EVT_MENU(wxID_EXIT, MyFrame::OnQuit)
EVT_MENU(Scroll_Test_Simple, MyFrame::OnTestSimple)
EVT_MENU(Scroll_Test_Canvas, MyFrame::OnTestCanvas)
EVT_MENU(Scroll_Test_Sizers, MyFrame::OnTestSizer)
EVT_MENU(Scroll_Test_Sub, MyFrame::OnTestSub)
EVT_MENU(Scroll_Test_Auto, MyFrame::OnTestAuto)
EVT_TOGGLEBUTTON(Scroll_TglBtn_Sync, MyFrame::OnToggleSync)
EVT_RADIOBOX(Scroll_Radio_ShowScrollbar, MyFrame::OnScrollbarVisibility)
END_EVENT_TABLE()
MyFrame::MyFrame()
: wxFrame(NULL, wxID_ANY, "wxWidgets scroll sample")
{
SetIcon(wxICON(sample));
wxMenu *menuFile = new wxMenu;
menuFile->Append(wxID_ABOUT, "&About..");
menuFile->AppendSeparator();
menuFile->Append(wxID_EXIT, "E&xit\tAlt-X");
wxMenu *menuTest = new wxMenu;
menuTest->Append(Scroll_Test_Simple, "&Simple scroll window\tF1",
"Simplest possible scrolled window test.");
menuTest->Append(Scroll_Test_Canvas, "Scrolled window with &children\tF2",
"Scrolled window with controls on it.");
menuTest->Append(Scroll_Test_Sizers, "Scrolled window with si&zer\tF3",
"Scrolled window with children managed by sizer.");
menuTest->Append(Scroll_Test_Sub, "Scrolled s&ub-window\tF4",
"Window only part of which is scrolled.");
menuTest->Append(Scroll_Test_Auto, "&Auto-scrolled window\tF5",
"Window which scrolls when the mouse is held pressed "
"outside of it.");
wxMenuBar *mbar = new wxMenuBar;
mbar->Append(menuFile, "&File");
mbar->Append(menuTest, "&Test");
SetMenuBar( mbar );
wxPanel *panel = new wxPanel(this);
const wxSizerFlags flagsExpand(wxSizerFlags(1).Expand());
wxSizer *topsizer = new wxBoxSizer(wxVERTICAL);
topsizer->Add(new wxStaticText(panel, wxID_ANY,
"The windows below should behave in the same way, even though\n"
"they're implemented quite differently, see the code for details.\n"
"\n"
"The lines redrawn during odd/even repaint iterations are drawn in\n"
"red/blue colour to allow seeing immediately how much is repainted,\n"
"don't be surprised by this."),
wxSizerFlags().Centre().Border());
m_win1 = new MyScrolledWindowDumb(panel);
m_win2 = new MyScrolledWindowSmart(panel);
wxSizer *sizerScrollWin = new wxBoxSizer(wxHORIZONTAL);
sizerScrollWin->Add(m_win1, flagsExpand);
sizerScrollWin->Add(m_win2, flagsExpand);
topsizer->Add(sizerScrollWin, flagsExpand);
const wxSizerFlags
flagsHBorder(wxSizerFlags().Centre().Border(wxLEFT | wxRIGHT));
wxSizer *sizerBtns = new wxBoxSizer(wxHORIZONTAL);
// the radio buttons are in the same order as wxSHOW_SB_XXX values but
// offset by 1
const wxString visibilities[] = { "&never", "&default", "&always" };
wxRadioBox *radio = new wxRadioBox(panel, Scroll_Radio_ShowScrollbar,
"Left &scrollbar visibility: ",
wxDefaultPosition, wxDefaultSize,
WXSIZEOF(visibilities), visibilities);
radio->SetSelection(wxSHOW_SB_DEFAULT + 1);
sizerBtns->Add(radio, flagsHBorder);
sizerBtns->Add(new wxToggleButton(panel, Scroll_TglBtn_Sync, "S&ynchronize"),
flagsHBorder);
topsizer->Add(sizerBtns, wxSizerFlags().Centre().Border());
panel->SetSizer(topsizer);
wxSize size = panel->GetBestSize();
SetSizeHints(size);
SetClientSize(2*size);
Show();
}
void MyFrame::OnToggleSync(wxCommandEvent& event)
{
if ( event.IsChecked() )
{
m_win1->SyncWith(m_win2);
m_win2->SyncWith(m_win1);
}
else
{
m_win1->SyncWith(NULL);
m_win2->SyncWith(NULL);
}
}
void MyFrame::OnScrollbarVisibility(wxCommandEvent& event)
{
m_win1->ShowScrollbars(wxSHOW_SB_NEVER,
wxScrollbarVisibility(event.GetSelection() - 1));
}
void MyFrame::OnQuit(wxCommandEvent &WXUNUSED(event))
{
Close(true);
}
void MyFrame::OnAbout( wxCommandEvent &WXUNUSED(event) )
{
(void)wxMessageBox( "wxScrolledWindow sample\n"
"\n"
"Robert Roebling (c) 1998\n"
"Vadim Zeitlin (c) 2008\n"
"Autoscrolling examples\n"
"Ron Lee (c) 2002\n"
"Auto-timed-scrolling example\n"
"Matt Gregory (c) 2003\n",
"About wxWidgets scroll sample",
wxICON_INFORMATION | wxOK );
}
// ----------------------------------------------------------------------------
// MyApp
// ----------------------------------------------------------------------------
IMPLEMENT_APP(MyApp)
bool MyApp::OnInit()
{
if ( !wxApp::OnInit() )
return false;
new MyFrame();
return true;
}
// ----------------------------------------------------------------------------
// MyScrolledWindowXXX
// ----------------------------------------------------------------------------
void MyScrolledWindowDumb::OnDraw(wxDC& dc)
{
// this is useful to see which lines are redrawn
static size_t s_redrawCount = 0;
dc.SetTextForeground(s_redrawCount++ % 2 ? *wxRED : *wxBLUE);
int y = 0;
for ( size_t line = 0; line < m_nLines; line++ )
{
int yPhys;
CalcScrolledPosition(0, y, NULL, &yPhys);
dc.DrawText(wxString::Format("Line %u (logical %d, physical %d)",
unsigned(line), y, yPhys), 0, y);
y += m_hLine;
}
}
void MyScrolledWindowSmart::OnDraw(wxDC& dc)
{
// this is useful to see which lines are redrawn
static size_t s_redrawCount = 0;
dc.SetTextForeground(s_redrawCount++ % 2 ? *wxRED : *wxBLUE);
// update region is always in device coords, translate to logical ones
wxRect rectUpdate = GetUpdateRegion().GetBox();
CalcUnscrolledPosition(rectUpdate.x, rectUpdate.y,
&rectUpdate.x, &rectUpdate.y);
size_t lineFrom = rectUpdate.y / m_hLine,
lineTo = rectUpdate.GetBottom() / m_hLine;
if ( lineTo > m_nLines - 1)
lineTo = m_nLines - 1;
int y = lineFrom*m_hLine;
for ( size_t line = lineFrom; line <= lineTo; line++ )
{
int yPhys;
CalcScrolledPosition(0, y, NULL, &yPhys);
dc.DrawText(wxString::Format("Line %u (logical %d, physical %d)",
unsigned(line), y, yPhys), 0, y);
y += m_hLine;
}
}
// ----------------------------------------------------------------------------
// MyAutoScrollingWindow
// ----------------------------------------------------------------------------
BEGIN_EVENT_TABLE(MyAutoScrollingWindow, wxScrolledWindow)
EVT_LEFT_DOWN(MyAutoScrollingWindow::OnMouseLeftDown)
EVT_LEFT_UP(MyAutoScrollingWindow::OnMouseLeftUp)
EVT_MOTION(MyAutoScrollingWindow::OnMouseMove)
EVT_MOUSE_CAPTURE_LOST(MyAutoScrollingWindow::OnMouseCaptureLost)
EVT_SCROLLWIN(MyAutoScrollingWindow::OnScroll)
END_EVENT_TABLE()
MyAutoScrollingWindow::MyAutoScrollingWindow(wxWindow* parent)
: wxScrolledWindow(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize,
wxVSCROLL | wxHSCROLL | wxSUNKEN_BORDER),
m_selStart(-1, -1),
m_cursor(-1, -1),
m_font(9, wxFONTFAMILY_TELETYPE, wxFONTSTYLE_NORMAL, wxFONTWEIGHT_NORMAL)
{
wxClientDC dc(this);
// query dc for text size
dc.SetFont(m_font);
dc.GetTextExtent(wxString("A"), &m_fontW, &m_fontH);
// set up the virtual window
SetScrollbars(m_fontW, m_fontH, sm_lineLen, sm_lineCnt);
}
wxRect
MyAutoScrollingWindow::DeviceCoordsToGraphicalChars(wxRect updRect) const
{
wxPoint pos(updRect.GetPosition());
pos = DeviceCoordsToGraphicalChars(pos);
updRect.x = pos.x;
updRect.y = pos.y;
updRect.width /= m_fontW;
updRect.height /= m_fontH;
// the *CoordsToGraphicalChars() funcs round down to upper-left corner,
// so an off-by-one correction is needed
++updRect.width; // kludge
++updRect.height; // kludge
return updRect;
}
wxPoint
MyAutoScrollingWindow::DeviceCoordsToGraphicalChars(wxPoint pos) const
{
pos.x /= m_fontW;
pos.y /= m_fontH;
pos += GetViewStart();
return pos;
}
wxPoint
MyAutoScrollingWindow::GraphicalCharToDeviceCoords(wxPoint pos) const
{
pos -= GetViewStart();
pos.x *= m_fontW;
pos.y *= m_fontH;
return pos;
}
wxRect
MyAutoScrollingWindow::LogicalCoordsToGraphicalChars(wxRect updRect) const
{
wxPoint pos(updRect.GetPosition());
pos = LogicalCoordsToGraphicalChars(pos);
updRect.x = pos.x;
updRect.y = pos.y;
updRect.width /= m_fontW;
updRect.height /= m_fontH;
// the *CoordsToGraphicalChars() funcs round down to upper-left corner,
// so an off-by-one correction is needed
++updRect.width; // kludge
++updRect.height; // kludge
return updRect;
}
wxPoint
MyAutoScrollingWindow::LogicalCoordsToGraphicalChars(wxPoint pos) const
{
pos.x /= m_fontW;
pos.y /= m_fontH;
return pos;
}
wxPoint
MyAutoScrollingWindow::GraphicalCharToLogicalCoords(wxPoint pos) const
{
pos.x *= m_fontW;
pos.y *= m_fontH;
return pos;
}
void MyAutoScrollingWindow::MyRefresh()
{
static wxPoint lastSelStart(-1, -1), lastCursor(-1, -1);
// refresh last selected area (to deselect previously selected text)
wxRect lastUpdRect(
GraphicalCharToDeviceCoords(lastSelStart),
GraphicalCharToDeviceCoords(lastCursor)
);
// off-by-one corrections, necessary because it's not possible to know
// when to round up until rect is normalized by lastUpdRect constructor
lastUpdRect.width += m_fontW; // kludge
lastUpdRect.height += m_fontH; // kludge
// refresh currently selected (to select previously unselected text)
wxRect updRect(
GraphicalCharToDeviceCoords(m_selStart),
GraphicalCharToDeviceCoords(m_cursor)
);
// off-by-one corrections
updRect.width += m_fontW; // kludge
updRect.height += m_fontH; // kludge
// find necessary refresh areas
int rx = lastUpdRect.x;
int ry = lastUpdRect.y;
int rw = updRect.x - lastUpdRect.x;
int rh = lastUpdRect.height;
if (rw && rh) {
RefreshRect(DCNormalize(rx, ry, rw, rh));
}
rx = updRect.x;
ry = updRect.y + updRect.height;
rw= updRect.width;
rh = (lastUpdRect.y + lastUpdRect.height) - (updRect.y + updRect.height);
if (rw && rh) {
RefreshRect(DCNormalize(rx, ry, rw, rh));
}
rx = updRect.x + updRect.width;
ry = lastUpdRect.y;
rw = (lastUpdRect.x + lastUpdRect.width) - (updRect.x + updRect.width);
rh = lastUpdRect.height;
if (rw && rh) {
RefreshRect(DCNormalize(rx, ry, rw, rh));
}
rx = updRect.x;
ry = lastUpdRect.y;
rw = updRect.width;
rh = updRect.y - lastUpdRect.y;
if (rw && rh) {
RefreshRect(DCNormalize(rx, ry, rw, rh));
}
// update last
lastSelStart = m_selStart;
lastCursor = m_cursor;
}
bool MyAutoScrollingWindow::IsSelected(int chX, int chY) const
{
if (IsInside(chX, m_selStart.x, m_cursor.x)
&& IsInside(chY, m_selStart.y, m_cursor.y)) {
return true;
}
return false;
}
bool MyAutoScrollingWindow::IsInside(int k, int bound1, int bound2)
{
if ((k >= bound1 && k <= bound2) || (k >= bound2 && k <= bound1)) {
return true;
}
return false;
}
wxRect
MyAutoScrollingWindow::DCNormalize(int x, int y, int w, int h)
{
// this is needed to get rid of the graphical remnants from the selection
// I think it's because DrawRectangle() excludes a pixel in either direction
const int kludge = 1;
// make (x, y) the top-left corner
if (w < 0) {
w = -w + kludge;
x -= w;
} else {
x -= kludge;
w += kludge;
}
if (h < 0) {
h = -h + kludge;
y -= h;
} else {
y -= kludge;
h += kludge;
}
return wxRect(x, y, w, h);
}
void MyAutoScrollingWindow::OnDraw(wxDC& dc)
{
dc.SetFont(m_font);
wxBrush normBrush(wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOW)
, wxSOLID);
wxBrush selBrush(wxSystemSettings::GetColour(wxSYS_COLOUR_HIGHLIGHT)
, wxSOLID);
dc.SetPen(*wxTRANSPARENT_PEN);
const wxString str = sm_testData;
size_t strLength = str.length();
wxString::const_iterator str_i = str.begin();
// draw the characters
// 1. for each update region
for (wxRegionIterator upd(GetUpdateRegion()); upd; ++upd) {
wxRect updRect = upd.GetRect();
wxRect updRectInGChars(DeviceCoordsToGraphicalChars(updRect));
// 2. for each row of chars in the update region
for (int chY = updRectInGChars.y
; chY <= updRectInGChars.y + updRectInGChars.height; ++chY) {
// 3. for each character in the row
bool isFirstX = true;
for (int chX = updRectInGChars.x
; chX <= updRectInGChars.x + updRectInGChars.width
; ++chX) {
// 4. set up dc
if (IsSelected(chX, chY)) {
dc.SetBrush(selBrush);
dc.SetTextForeground( wxSystemSettings::GetColour
(wxSYS_COLOUR_HIGHLIGHTTEXT));
} else {
dc.SetBrush(normBrush);
dc.SetTextForeground( wxSystemSettings::GetColour
(wxSYS_COLOUR_WINDOWTEXT));
}
// 5. find position info
wxPoint charPos = GraphicalCharToLogicalCoords(wxPoint
(chX, chY));
// 6. draw!
dc.DrawRectangle(charPos.x, charPos.y, m_fontW, m_fontH);
size_t charIndex = chY * sm_lineLen + chX;
if (chY < sm_lineCnt &&
chX < sm_lineLen &&
charIndex < strLength)
{
if (isFirstX)
{
str_i = str.begin() + charIndex;
isFirstX = false;
}
dc.DrawText(*str_i, charPos.x, charPos.y);
++str_i;
}
}
}
}
}
void MyAutoScrollingWindow::OnMouseLeftDown(wxMouseEvent& event)
{
// initial press of mouse button sets the beginning of the selection
m_selStart = DeviceCoordsToGraphicalChars(event.GetPosition());
// set the cursor to the same position
m_cursor = m_selStart;
// draw/erase selection
MyRefresh();
}
void MyAutoScrollingWindow::OnMouseLeftUp(wxMouseEvent& WXUNUSED(event))
{
// this test is necessary
if (HasCapture()) {
// uncapture mouse
ReleaseMouse();
}
}
void MyAutoScrollingWindow::OnMouseMove(wxMouseEvent& event)
{
// if user is dragging
if (event.Dragging() && event.LeftIsDown()) {
// set the new cursor position
m_cursor = DeviceCoordsToGraphicalChars(event.GetPosition());
// draw/erase selection
// MyRefresh();
// capture mouse to activate auto-scrolling
if (!HasCapture()) {
CaptureMouse();
}
}
}
void
MyAutoScrollingWindow::OnMouseCaptureLost(wxMouseCaptureLostEvent&
WXUNUSED(event))
{
// we only capture mouse for timed scrolling, so nothing is needed here
// other than making sure to not call event.Skip()
}
void MyAutoScrollingWindow::OnScroll(wxScrollWinEvent& event)
{
// need to move the cursor when autoscrolling
// FIXME: the cursor also moves when the scrollbar arrows are clicked
if (HasCapture()) {
if (event.GetOrientation() == wxHORIZONTAL) {
if (event.GetEventType() == wxEVT_SCROLLWIN_LINEUP) {
--m_cursor.x;
} else if (event.GetEventType() == wxEVT_SCROLLWIN_LINEDOWN) {
++m_cursor.x;
}
} else if (event.GetOrientation() == wxVERTICAL) {
if (event.GetEventType() == wxEVT_SCROLLWIN_LINEUP) {
--m_cursor.y;
} else if (event.GetEventType() == wxEVT_SCROLLWIN_LINEDOWN) {
++m_cursor.y;
}
}
}
MyRefresh();
event.Skip();
}
const int MyAutoScrollingWindow::sm_lineCnt = 125;
const int MyAutoScrollingWindow::sm_lineLen = 79;
const char *MyAutoScrollingWindow::sm_testData =
"162 Cult of the genius out of vanity. Because we think well of ourselves, but "
"nonetheless never suppose ourselves capable of producing a painting like one of "
"Raphael's or a dramatic scene like one of Shakespeare's, we convince ourselves "
"that the capacity to do so is quite extraordinarily marvelous, a wholly "
"uncommon accident, or, if we are still religiously inclined, a mercy from on "
"high. Thus our vanity, our self-love, promotes the cult of the genius: for only "
"if we think of him as being very remote from us, as a miraculum, does he not "
"aggrieve us (even Goethe, who was without envy, called Shakespeare his star of "
"the most distant heights [\"William! Stern der schonsten Ferne\": from Goethe's, "
"\"Between Two Worlds\"]; in regard to which one might recall the lines: \"the "
"stars, these we do not desire\" [from Goethe's, \"Comfort in Tears\"]). But, aside "
"from these suggestions of our vanity, the activity of the genius seems in no "
"way fundamentally different from the activity of the inventor of machines, the "
"scholar of astronomy or history, the master of tactics. All these activities "
"are explicable if one pictures to oneself people whose thinking is active in "
"one direction, who employ everything as material, who always zealously observe "
"their own inner life and that of others, who perceive everywhere models and "
"incentives, who never tire of combining together the means available to them. "
"Genius too does nothing except learn first how to lay bricks then how to build, "
"except continually seek for material and continually form itself around it. "
"Every activity of man is amazingly complicated, not only that of the genius: "
"but none is a \"miracle.\" Whence, then, the belief that genius exists only in "
"the artist, orator and philosopher? that only they have \"intuition\"? (Whereby "
"they are supposed to possess a kind of miraculous eyeglass with which they can "
"see directly into \"the essence of the thing\"!) It is clear that people speak of "
"genius only where the effects of the great intellect are most pleasant to them "
"and where they have no desire to feel envious. To call someone \"divine\" means: "
"\"here there is no need for us to compete.\" Then, everything finished and "
"complete is regarded with admiration, everything still becoming is undervalued. "
"But no one can see in the work of the artist how it has become; that is its "
"advantage, for wherever one can see the act of becoming one grows somewhat "
"cool. The finished and perfect art of representation repulses all thinking as "
"to how it has become; it tyrannizes as present completeness and perfection. "
"That is why the masters of the art of representation count above all as gifted "
"with genius and why men of science do not. In reality, this evaluation of the "
"former and undervaluation of the latter is only a piece of childishness in the "
"realm of reason. "
"\n\n"
"163 The serious workman. Do not talk about giftedness, inborn talents! One can "
"name great men of all kinds who were very little gifted. The acquired "
"greatness, became \"geniuses\" (as we put it), through qualities the lack of "
"which no one who knew what they were would boast of: they all possessed that "
"seriousness of the efficient workman which first learns to construct the parts "
"properly before it ventures to fashion a great whole; they allowed themselves "
"time for it, because they took more pleasure in making the little, secondary "
"things well than in the effect of a dazzling whole. the recipe for becoming a "
"good novelist, for example, is easy to give, but to carry it out presupposes "
"qualities one is accustomed to overlook when one says \"I do not have enough "
"talent.\" One has only to make a hundred or so sketches for novels, none longer "
"than two pages but of such distinctness that every word in them is necessary; "
"one should write down anecdotes each day until one has learned how to give them "
"the most pregnant and effective form; one should be tireless in collecting and "
"describing human types and characters; one should above all relate things to "
"others and listen to others relate, keeping one's eyes and ears open for the "
"effect produced on those present, one should travel like a landscape painter or "
"costume designer; one should excerpt for oneself out of the individual sciences "
"everything that will produce an artistic effect when it is well described, one "
"should, finally, reflect on the motives of human actions, disdain no signpost "
"to instruction about them and be a collector of these things by day and night. "
"One should continue in this many-sided exercise some ten years: what is then "
"created in the workshop, however, will be fit to go out into the world. What, "
"however, do most people do? They begin, not with the parts, but with the whole. "
"Perhaps they chance to strike a right note, excite attention and from then on "
"strike worse and worse notes, for good, natural reasons. Sometimes, when the "
"character and intellect needed to formulate such a life-plan are lacking, fate "
"and need take their place and lead the future master step by step through all "
"the stipulations of his trade. "
"\n\n"
"164 Peril and profit in the cult of the genius. The belief in great, superior, "
"fruitful spirits is not necessarily, yet nonetheless is very frequently "
"associated with that religious or semi-religious superstition that these "
"spirits are of supra-human origin and possess certain miraculous abilities by "
"virtue of which they acquire their knowledge by quite other means than the rest "
"of mankind. One ascribes to them, it seems, a direct view of the nature of the "
"world, as it were a hole in the cloak of appearance, and believes that, by "
"virtue of this miraculous seer's vision, they are able to communicate something "
"conclusive and decisive about man and the world without the toil and "
"rigorousness required by science. As long as there continue to be those who "
"believe in the miraculous in the domain of knowledge one can perhaps concede "
"that these people themselves derive some benefit from their belief, inasmuch as "
"through their unconditional subjection to the great spirits they create for "
"their own spirit during its time of development the finest form of discipline "
"and schooling. On the other hand, it is at least questionable whether the "
"superstitious belief in genius, in its privileges and special abilities, is of "
"benefit to the genius himself if it takes root in him. It is in any event a "
"dangerous sign when a man is assailed by awe of himself, whether it be the "
"celebrated Caesar's awe of Caesar or the awe of one's own genius now under "
"consideration; when the sacrificial incense which is properly rendered only to "
"a god penetrates the brain of the genius, so that his head begins to swim and "
"he comes to regard himself as something supra-human. The consequences that "
"slowly result are: the feeling of irresponsibility, of exceptional rights, the "
"belief that he confers a favor by his mere presence, insane rage when anyone "
"attempts even to compare him with others, let alone to rate him beneath them, "
"or to draw attention to lapses in his work. Because he ceases to practice "
"criticism of himself, at last one pinion after the other falls out of his "
"plumage: that superstitious eats at the roots of his powers and perhaps even "
"turns him into a hypocrite after his powers have fled from him. For the great "
"spirits themselves it is therefore probably more beneficial if they acquire an "
"insight into the nature and origin of their powers, if they grasp, that is to "
"say, what purely human qualities have come together in them and what fortunate "
"circumstances attended them: in the first place undiminished energy, resolute "
"application to individual goals, great personal courage, then the good fortune "
"to receive an upbringing which offered in the early years the finest teachers, "
"models and methods. To be sure, when their goal is the production of the "
"greatest possible effect, unclarity with regard to oneself and that "
"semi-insanity superadded to it has always achieved much; for what has been "
"admired and envied at all times has been that power in them by virtue of which "
"they render men will-less and sweep them away into the delusion that the "
"leaders they are following are supra-natural. Indeed, it elevates and inspires "
"men to believe that someone is in possession of supra-natural powers: to this "
"extent Plato was right to say [Plato: Phaedrus, 244a] that madness has brought "
"the greatest of blessings upon mankind. In rare individual cases this portion "
"of madness may, indeed, actually have been the means by which such a nature, "
"excessive in all directions, was held firmly together: in the life of "
"individuals, too, illusions that are in themselves poisons often play the role "
"of healers; yet, in the end, in the case of every \"genius\" who believes in his "
"own divinity the poison shows itself to the same degree as his \"genius\" grows "
"old: one may recall, for example, the case of Napoleon, whose nature certainly "
"grew into the mighty unity that sets him apart from all men of modern times "
"precisely through his belief in himself and his star and through the contempt "
"for men that flowed from it; until in the end, however, this same belief went "
"over into an almost insane fatalism, robbed him of his acuteness and swiftness "
"of perception, and became the cause of his destruction.";
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