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{
fpGUI - Free Pascal Graphical User Interface
Copyright (C) 2000 - 2001 by
Areca Systems GmbH / Sebastian Guenther
Copyright (C) 2006 by Graeme Geldenhuys
member of the fpGUI development team.
Scrollbox class declarations
See the file COPYING.fpGUI, included in this distribution,
for details about the copyright.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
**********************************************************************}
{%mainunit fpgui.pp}
{ Scrolling support implementation }
{$IFDEF read_interface}
TScrollingSupport = class
private
Parent: TWidget;
FBorders: TRect;
FClientRect: TRect;
FVirtualSize: TSize;
FHorzScrollBar, FVertScrollBar: TScrollBar;
FOnClientRectChange: TNotifyEvent;
function EvMouseWheel(Event: TMouseWheelEventObj): Boolean;
public
constructor Create(AParent: TWidget);
destructor Destroy; override;
function ProcessEvent(Event: TEventObj): Boolean;
function DistributeEvent(Event: TEventObj): Boolean;
function SendToChild(AChild: TWidget; Event: TEventObj): Boolean;
procedure CalcSizes;
procedure Resized;
function CalcClientSize(AHorzBarVisible, AVertBarVisible: Boolean): TSize;
procedure SetVirtualSize(const ASize: TSize);
function ScrollPos: TPoint;
procedure DefHorzScrollHandler(Sender: TObject; var APosition: Integer);
procedure DefVertScrollHandler(Sender: TObject; var APosition: Integer);
property Borders: TRect read FBorders;
property ClientRect: TRect read FClientRect;
property HorzScrollBar: TScrollBar read FHorzScrollBar;
property VertScrollBar: TScrollBar read FVertScrollBar;
property OnClientRectChange: TNotifyEvent read FOnClientRectChange write FOnClientRectChange;
end;
TCustomScrollBox = class(TWidget)
protected
ScrollingSupport: TScrollingSupport;
procedure Paint(Canvas: TFCanvas); override;
function ProcessEvent(Event: TEventObj): Boolean; override;
function DistributeEvent(Event: TEventObj): Boolean; override;
// procedure EvKeyPressed(Key: Word; Shift: TShiftState); override;
procedure CalcSizes; override;
procedure Resized; override;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
end;
TScrollBox = class(TCustomScrollBox)
end;
{$ENDIF read_interface}
{$IFDEF read_implementation}
// ===================================================================
// TScrollingSupport
// ===================================================================
constructor TScrollingSupport.Create(AParent: TWidget);
begin
Parent := AParent;
FHorzScrollBar := TScrollBar.Create(Parent);
HorzScrollBar.Name := '#Scrolling_HorzBar';
HorzScrollBar.Embedded := True;
HorzScrollBar.SetEmbeddedParent(Parent);
FVertScrollBar := TScrollBar.Create(Parent);
VertScrollBar.Name := '#Scrolling_VertBar';
VertScrollBar.Orientation := Vertical;
VertScrollBar.Embedded := True;
VertScrollBar.SetEmbeddedParent(Parent);
end;
destructor TScrollingSupport.Destroy;
begin
inherited Destroy;
end;
function TScrollingSupport.ProcessEvent(Event: TEventObj): Boolean;
var
HorzScrollBarHeight, VertScrollBarWidth: Integer;
Canvas: TFCanvas;
begin
if Event.InheritsFrom(TPaintEventObj) then
begin
if HorzScrollBar.Visible then
HorzScrollBarHeight := HorzScrollBar.MinSize.cy
else
HorzScrollBarHeight := 0;
if VertScrollBar.Visible then
VertScrollBarWidth := VertScrollBar.MinSize.cx
else
VertScrollBarWidth := 0;
Canvas := TPaintEventObj(Event).Canvas;
Parent.Style.DrawScrollBoxBorder(Canvas,
Rect(0, 0, Parent.Width, Parent.Height));
Parent.Style.DrawWindowBackground(Canvas, Rect(VertScrollBar.Left,
HorzScrollBar.Top, VertScrollBar.Left + VertScrollBarWidth,
HorzScrollBar.Top + HorzScrollBarHeight));
Result := False;
end else if Event.InheritsFrom(TMouseWheelEventObj) then
Result := EvMouseWheel(TMouseWheelEventObj(Event))
else
Result := False;
end;
function TScrollingSupport.DistributeEvent(Event: TEventObj): Boolean;
begin
Result := Event.SendToChild(HorzScrollBar) or
Event.SendToChild(VertScrollBar);
end;
function TScrollingSupport.SendToChild(AChild: TWidget;
Event: TEventObj): Boolean;
var
Canvas: TFCanvas;
OldMatrix: TGfxMatrix;
begin
if Event.InheritsFrom(TPreparePaintEventObj) then
begin
Canvas := TPaintEventObj(Event).Canvas;
OldMatrix := Canvas.Matrix;
Canvas.AppendTranslation(Point(ClientRect.Left - HorzScrollBar.Position,
ClientRect.Top - VertScrollBar.Position));
Result := Event.SendToChild(AChild);
Canvas.Matrix := OldMatrix;
end else if Event.InheritsFrom(TPaintEventObj) then
begin
Canvas := TPaintEventObj(Event).Canvas;
Canvas.SaveState;
try
Canvas.AppendTranslation(Point(-HorzScrollBar.Position,
-VertScrollBar.Position));
if Canvas.IntersectClipRect(ClientRect) {and Canvas.IntersectClipRect(
Rect(AChild.Left + ClientRect.Left, AChild.Top + ClientRect.Top,
AChild.Left + AChild.Width + ClientRect.Left,
AChild.Top + AChild.Height + ClientRect.Top))} then
begin
{Canvas.AppendTranslation(AChild.Left + ClientRect.Left,
AChild.Top + ClientRect.Top);
Inc(Event.RefCount);
Result := AChild.SendEvent(Event);}
Canvas.AppendTranslation(ClientRect.TopLeft);
Result := Event.SendToChild(AChild);
end else
Result := False;
finally
Canvas.RestoreState;
end;
end else
Result := Event.SendToChild(AChild);
end;
procedure TScrollingSupport.CalcSizes;
begin
FBorders := Parent.Style.GetScrollBoxBorders;
with Parent, Borders do
begin
FMinSize := HorzScrollBar.MinSize + VertScrollBar.MinSize +
TopLeft + BottomRight;
FDefSize := HorzScrollBar.DefSize + VertScrollBar.DefSize +
TopLeft + BottomRight;
end;
end;
procedure TScrollingSupport.Resized;
var
HorzScrollBarHeight, VertScrollBarWidth: Integer;
procedure CalcScrollBarSizes;
begin
if HorzScrollBar.Visible then
HorzScrollBarHeight := HorzScrollBar.MinSize.cy
else
HorzScrollBarHeight := 0;
if VertScrollBar.Visible then
VertScrollBarWidth := VertScrollBar.MinSize.cx
else
VertScrollBarWidth := 0;
end;
var
Canvas: TFCanvas;
HorzBarVisible, VertBarVisible,
LastHorzBarVisible, LastVertBarVisible: Boolean;
begin
HorzBarVisible := HorzScrollBar.Visible;
VertBarVisible := VertScrollBar.Visible;
LastHorzBarVisible := not HorzBarVisible;
if FVirtualSize <> gfxbase.Size(0, 0) then
with gfxbase.Size(ClientRect) do
begin
HorzScrollBar.PageSize := cx;
VertScrollBar.PageSize := cy;
end;
FBorders := Parent.Style.GetScrollBoxBorders;
with FBorders do
begin
while (HorzBarVisible <> LastHorzBarVisible) or
(VertBarVisible <> LastVertBarVisible) do
begin
LastHorzBarVisible := HorzBarVisible;
LastVertBarVisible := VertBarVisible;
CalcScrollBarSizes;
HorzScrollBar.SetBounds(
Point(Left, Parent.Height - HorzScrollBar.MinSize.cy - Bottom),
gfxbase.Size(Parent.Width - VertScrollBarWidth - Left - Right,
HorzScrollBar.MinSize.cy));
VertScrollBar.SetBounds(
Point(Parent.Width - VertScrollBar.MinSize.cx - Right, Top),
gfxbase.Size(VertScrollBar.MinSize.cx,
Parent.Height - HorzScrollBarHeight - Top - Bottom));
ClientRect.Left := Left;
ClientRect.Top := Top;
ClientRect.Right := Parent.Width - Right - VertScrollBarWidth;
ClientRect.Bottom := Parent.Height - Bottom - HorzScrollBarHeight;
if Assigned(OnClientRectChange) then
OnClientRectChange(Self);
HorzBarVisible := HorzScrollBar.Visible;
VertBarVisible := VertScrollBar.Visible;
end;
end;
end;
function TScrollingSupport.CalcClientSize(AHorzBarVisible,
AVertBarVisible: Boolean): TSize;
begin
FBorders := Parent.Style.GetScrollBoxBorders;
Result := Parent.BoundsSize - Borders.TopLeft - Borders.BottomRight;
if AVertBarVisible then
Dec(Result.cx, VertScrollBar.MinSize.cx);
if AHorzBarVisible then
Dec(Result.cy, HorzScrollBar.MinSize.cy);
end;
procedure TScrollingSupport.SetVirtualSize(const ASize: TSize);
begin
FVirtualSize := ASize;
HorzScrollBar.Max := FVirtualSize.cx;
VertScrollBar.Max := FVirtualSize.cy;
end;
function TScrollingSupport.ScrollPos: TPoint;
begin
Result.x := HorzScrollBar.Position;
Result.y := VertScrollBar.Position;
end;
procedure TScrollingSupport.DefHorzScrollHandler(Sender: TObject;
var APosition: Integer);
var
Delta: Integer;
r: TRect;
begin
Delta := HorzScrollBar.Position - APosition;
r := ClientRect;
if Delta < 0 then // Scrolling to the right side
Dec(r.Left, Delta)
else // Scrolling to the left side
Dec(r.Right, Delta);
Parent.Scroll(r, Delta, 0);
end;
procedure TScrollingSupport.DefVertScrollHandler(Sender: TObject;
var APosition: Integer);
var
Delta: Integer;
r: TRect;
begin
Delta := VertScrollBar.Position - APosition;
r := ClientRect;
if Delta < 0 then // Scrolling downwards
Dec(r.Top, Delta)
else // Scrolling upwards
Dec(r.Bottom, Delta);
Parent.Scroll(r, 0, Delta);
end;
function TScrollingSupport.EvMouseWheel(Event: TMouseWheelEventObj): Boolean;
var
mshift: TShiftState;
begin
if Parent.DistributeEvent(Event) then
exit;
mshift := Event.Shift * [ssShift, ssAlt, ssCtrl, ssMeta,
ssSuper, ssHyper, ssAltGr];
if not VertScrollBar.Visible then
Include(mshift, ssShift);
if mshift = [] then
VertScrollBar.Position := VertScrollBar.Position +
Round(Event.WheelDelta * VertScrollBar.SmallChange)
else if mshift = [ssShift] then
HorzScrollBar.Position := HorzScrollBar.Position +
Round(Event.WheelDelta * VertScrollBar.SmallChange);
Result := True;
end;
// ===================================================================
// TCustomScrollBox
// ===================================================================
constructor TCustomScrollBox.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
WidgetStyle := WidgetStyle + [wsClickable, wsOpaque];
FCanExpandWidth := True;
FCanExpandHeight := True;
ScrollingSupport := TScrollingSupport.Create(Self);
end;
destructor TCustomScrollBox.Destroy;
begin
ScrollingSupport.Free;
inherited Destroy;
end;
// Protected methods
procedure TCustomScrollBox.Paint(Canvas: TFCanvas);
begin
{
Style.DrawWindowBackground(Canvas, Rect(HorzScrollBar.Left,
VertScrollBar.Top, HorzScrollBar.Left + HorzScrollBar.Width,
VertScrollBar.Top + VertScrollBar.Height));}
end;
function TCustomScrollBox.ProcessEvent(Event: TEventObj): Boolean;
begin
Result := ScrollingSupport.ProcessEvent(Event) or
inherited ProcessEvent(Event);
end;
function TCustomScrollBox.DistributeEvent(Event: TEventObj): Boolean;
begin
Result := ScrollingSupport.DistributeEvent(Event) or
inherited DistributeEvent(Event);
end;
procedure TCustomScrollBox.CalcSizes;
begin
ScrollingSupport.CalcSizes;
end;
procedure TCustomScrollBox.Resized;
begin
ScrollingSupport.Resized;
end;
{ !!!: Move to TScrollingSupport as soon as this is a real event
procedure TCustomScrollBox.EvKeyPressed(Key: Word; Shift: TShiftState);
var
mshift: TShiftState;
begin
mshift := Shift * [ssShift, ssAlt, ssCtrl, ssMeta, ssSuper, ssHyper, ssAltGr];
if mshift = [] then
case Key of
keyLeft:
HorzScrollBar.ButtonUpClick(nil);
keyRight:
HorzScrollBar.ButtonDownClick(nil);
keyUp:
VertScrollBar.ButtonUpClick(nil);
keyDown:
VertScrollBar.ButtonDownClick(nil);
keyPageUp:
VertScrollBar.PageUp;
keyPageDown:
VertScrollBar.PageDown;
keyHome:
VertScrollBar.Position := 0;
keyEnd:
VertScrollBar.Position := VertScrollBar.Max - VertScrollBar.PageSize;
end
else if mshift = [ssShift] then
case Key of
keyPageUp:
HorzScrollBar.PageUp;
keyPageDown:
HorzScrollBar.PageDown;
keyHome:
HorzScrollBar.Position := 0;
keyEnd:
HorzScrollBar.Position := HorzScrollBar.Max - HorzScrollBar.PageSize;
end
else
inherited EvKeyPressed(Key, Shift);
end;}
{$ENDIF read_implementation}
|