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{
fpGUI - Free Pascal GUI Toolkit
Copyright (C) 2006 - 2014 See the file AUTHORS.txt, included in this
distribution, for details of the copyright.
See the file COPYING.modifiedLGPL, included in this distribution,
for details about redistributing fpGUI.
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.
Description:
Defines a scrollable frame widget.
This unit was originally written by David Emerson <dle3ab@angelbase.com>
}
unit fpg_scrollframe;
{$mode objfpc}{$H+}
interface
uses
Classes,
SysUtils,
fpg_base,
fpg_main,
fpg_widget,
fpg_panel,
fpg_scrollbar;
type
TfpgScrollFrame = class;
TfpgEmbeddingFrame = class (TfpgFrame)
// The purpose of the EmbeddingFrame is to pass scroll events to the ParentScrollFrame
private
FParentScrollFrame : TfpgScrollFrame;
protected
procedure HandleMouseScroll(x, y: integer; shiftstate: TShiftState;
delta: smallint); override;
procedure HandleMouseHorizScroll(x, y: integer; shiftstate: TShiftState;
delta: smallint); override;
public
property ParentScrollFrame : TfpgScrollFrame read FParentScrollFrame write FParentScrollFrame;
end;
TfpgAutoSizingFrame = class (TfpgEmbeddingFrame)
private
FMarginBR : integer;
procedure SetMarginBR (AValue: integer);
public
procedure AfterConstruction; override;
procedure AdjustDimsFor (w : TfpgWidget; updatewp: boolean = true);
procedure AdjustDimsWithout (w : TfpgWidget);
procedure RecalcFrameSize;
property MarginBR : integer read FMarginBR write SetMarginBR; // bottom-right margin
end;
TfpgASFrameClass = class of TfpgAutoSizingFrame;
TfpgScrollFrame = class(TfpgFrame)
private
FContentFrame: TfpgAutoSizingFrame;
FVisibleArea: TfpgEmbeddingFrame;
FHScrollBar: TfpgScrollBar;
FVScrollBar: TfpgScrollBar;
FScrollBarStyle: TfpgScrollStyle;
function GetXOffset: integer;
function GetYOffset: integer;
procedure SetXOffset(x: integer);
procedure SetYOffset(y: integer);
protected
procedure HandleMouseScroll(x, y: integer; shiftstate: TShiftState; delta: smallint); override;
procedure HandleMouseHorizScroll(x, y: integer; shiftstate: TShiftState; delta: smallint); override;
procedure HandleResize(awidth, aheight: TfpgCoord); override;
procedure HandleShow; override;
procedure HandlePaint; override;
procedure HScrollBarMove(Sender: TObject; position: integer);
procedure VScrollBarMove(Sender: TObject; position: integer);
procedure UpdateScrollbars; virtual;
property XOffset: integer read GetXOffset write SetXOffset; // these do not...
property YOffset: integer read GetYOffset write SetYOffset; // ...updatewindowposition
public
constructor Create (AOwner: TComponent); override;
constructor Create (AOwner: TComponent; ContentFrameType: TfpgASFrameClass); virtual;
procedure AfterCreate; override;
procedure SetContentFrameType(AContentFrameType: TfpgASFrameClass);
property ContentFrame: TfpgAutoSizingFrame read FContentFrame write FContentFrame;
end;
implementation
{ TfpgEmbeddingFrame }
procedure TfpgEmbeddingFrame.HandleMouseScroll(x, y: integer;
shiftstate: TShiftState; delta: smallint);
begin
ParentScrollFrame.HandleMouseScroll(x, y, shiftstate, delta);
end;
procedure TfpgEmbeddingFrame.HandleMouseHorizScroll(x, y: integer;
shiftstate: TShiftState; delta: smallint);
begin
ParentScrollFrame.HandleMouseHorizScroll(x, y, shiftstate, delta);
end;
{ TfpgAutoSizingFrame }
procedure TfpgAutoSizingFrame.SetMarginBR(AValue: integer);
begin
if FMarginBR=AValue then Exit;
FMarginBR:=AValue;
RecalcFrameSize;
end;
procedure TfpgAutoSizingFrame.AfterConstruction;
begin
inherited AfterConstruction;
RecalcFrameSize;
end;
procedure TfpgAutoSizingFrame.AdjustDimsFor (w: TfpgWidget; updatewp: boolean = true);
var
new_w, new_h: integer;
begin
if not w.Visible then
Exit;
new_w := w.Right+MarginBR+1;
new_h := w.Bottom+MarginBR+1;
if (Width < new_w) or (Height < new_h) then
begin
HandleResize(new_w, new_h);
if updatewp then
if ParentScrollFrame is TfpgScrollFrame then
ParentScrollFrame.UpdateScrollbars
else
UpdateWindowPosition;
end;
end;
procedure TfpgAutoSizingFrame.AdjustDimsWithout (w: TfpgWidget);
begin
if (Width = w.Right+MarginBR+1)
or (Height = w.Bottom+MarginBR+1) then
RecalcFrameSize;
end;
procedure TfpgAutoSizingFrame.RecalcFrameSize;
var
i : integer;
c : TComponent;
max_w, max_h : integer;
this_need : integer;
begin
if ComponentCount=0 then
Exit;
max_w := 1;
max_h := 1;
for i := 0 to ComponentCount-1 do begin
c := Components[i];
if c is TfpgWidget then
begin
if not TfpgWidget(c).Visible then
continue;
this_need := TfpgWidget(c).right+MarginBR+1;
if (this_need>max_w) then
max_w := this_need;
this_need := TfpgWidget(c).bottom+MarginBR+1;
if (this_need>max_h) then
max_h := this_need;
end;
end;
HandleResize(max_w, max_h);
if ParentScrollFrame is TfpgScrollFrame then
ParentScrollFrame.UpdateScrollbars
else
UpdateWindowPosition;
end;
{ TfpgScrollFrame }
function TfpgScrollFrame.GetXOffset: integer;
begin
result := -FContentFrame.Left;
end;
function TfpgScrollFrame.GetYOffset: integer;
begin
result := -FContentFrame.Top;
end;
procedure TfpgScrollFrame.SetXOffset (x: integer);
begin
if ContentFrame.Left = -x then
Exit;
FContentFrame.Left := -x;
end;
procedure TfpgScrollFrame.SetYOffset (y: integer);
begin
if ContentFrame.Top = -y then
Exit;
FContentFrame.Top := -y;
end;
procedure TfpgScrollFrame.HandleMouseScroll(x, y: integer;
shiftstate: TShiftState; delta: smallint);
begin
inherited HandleMouseScroll(x, y, shiftstate, delta);
with FVScrollBar do
begin
if not Visible then
Exit;
Position:=Position+delta*ScrollStep;
if YOffset=Position then
Exit;
YOffset:=Position;
end;
UpdateScrollbars;
end;
procedure TfpgScrollFrame.HandleMouseHorizScroll(x, y: integer;
shiftstate: TShiftState; delta: smallint);
begin
inherited HandleMouseHorizScroll(x, y, shiftstate, delta);
with FHScrollBar do
begin
if not Visible then
Exit;
Position:=Position+delta*ScrollStep;
if XOffset=Position then
Exit;
XOffset:=Position;
end;
UpdateScrollbars;
end;
procedure TfpgScrollFrame.HandleResize(awidth, aheight: TfpgCoord);
begin
inherited HandleResize(awidth, aheight);
if (csLoading in ComponentState) or (csUpdating in ComponentState) then
Exit; //==>
if HasHandle then
UpdateScrollBars;
end;
procedure TfpgScrollFrame.HandleShow;
begin
inherited HandleShow;
if (csLoading in ComponentState) then
Exit;
UpdateScrollBars;
end;
procedure TfpgScrollFrame.HandlePaint;
begin
if csDesigning in ComponentState then
begin
// clear background rectangle
Canvas.Clear(clDarkGray);
// When designing, don't draw colors
// but draw an outline
Canvas.SetLineStyle(1, lsDash);
Canvas.DrawRectangle(GetClientRect);
Canvas.SetLineStyle(1, lsSolid);
Canvas.Color := clUIDesignerGreen;
Canvas.DrawLine(0, 0, Width, Height);
Canvas.DrawLine(Width, 0, 0, Height);
Canvas.TextColor := clShadow1;
Canvas.DrawText(5, 5, Name + ': ' + ClassName);
Exit; //==>
end;
inherited HandlePaint;
end;
procedure TfpgScrollFrame.HScrollBarMove (Sender: TObject; position: integer);
begin
if position = XOffset then
Exit;
XOffset := position;
FContentFrame.UpdateWindowPosition;
end;
procedure TfpgScrollFrame.VScrollBarMove (Sender: TObject; position: integer);
begin
if position = YOffset then
Exit;
YOffset := position;
FContentFrame.UpdateWindowPosition;
end;
procedure TfpgScrollFrame.UpdateScrollbars;
var
contentWidth, contentHeight: integer;
visWidth, visHeight: integer;
Hfits, Vfits : boolean;
showHsb, showVsb : boolean;
prevHideHsb, prevHideVsb : boolean;
procedure hideScrollbar (sb : TfpgScrollBar);
begin
with sb do
if Visible then
begin
Visible := False;
UpdateWindowPosition;
end;
end;
procedure getVisWidth;
begin
if showVsb then
visWidth := Width - (FVScrollBar.Width-1)
else
visWidth := Width;
Hfits := visWidth >= contentWidth
end;
procedure getVisHeight;
begin
if showHsb then
visHeight := Height - (FHScrollBar.Height-1)
else
visHeight := Height;
Vfits := visHeight >= contentHeight;
end;
begin
if (csLoading in ComponentState) or (csUpdating in ComponentState) then
Exit; //==>
// if we don't want any scrollbars, hide them and exit
if FScrollBarStyle = ssNone then
begin
hideScrollbar (FHScrollBar);
hideScrollbar (FVScrollBar);
exit;
end;
// preliminary width/height calculations
prevHideHsb := not FHScrollBar.Visible;
prevHideVsb := not FVScrollBar.Visible;
showVsb := (FScrollBarStyle = ssBothVisible);
showHsb := showVsb;
contentWidth := ContentFrame.Width;
contentHeight := ContentFrame.Height;
getVisWidth;
getVisHeight;
// determine whether to show scrollbars for different configurations
case FScrollBarStyle of
ssHorizontal:
begin
hideScrollbar (FVScrollBar);
if not Hfits then
begin
showHsb := true;
getVisHeight;
end;
end;
ssVertical:
begin
hideScrollbar (FHScrollBar);
if not Vfits then
begin
showVsb := true;
getVisWidth;
end;
end;
ssAutoBoth:
if not Vfits then
begin
showVsb := true;
getVisWidth;
if not Hfits then
begin
showHsb := true;
getVisHeight;
getVisWidth;
end;
end
else if not Hfits then
begin
showHsb := true;
getVisHeight;
if not Vfits then
begin
showVsb := true;
getVisWidth;
getVisHeight;
end;
end;
end;
// show or hide the scrollbars
if showVsb then with FVScrollBar do
begin
if prevHideVsb then
Position := 0;
Visible := true;
Min := 0;
Max := contentHeight - visHeight; // may set position!
YOffset := Position;
if contentHeight > 0 then
SliderSize := visHeight / contentHeight
else
SliderSize := 0;
RepaintSlider;
Top := 0;
Left := visWidth;
Height := visHeight;
PageSize:= visHeight;
end
else
begin
FVScrollBar.Visible := false;
if Vfits then // if vertical doesn't fit and no scrollbar, do not change offset
YOffset := 0;
end;
if showHsb then with FHScrollBar do
begin
if prevHideHsb then
Position := 0;
Visible := true;
Min := 0;
Max := contentWidth - visWidth; // may set position!
XOffset := Position;
if contentWidth > 0 then
SliderSize := visWidth / contentWidth
else
SliderSize := 0;
RepaintSlider;
Top := visHeight;
Left := 0;
Width := visWidth;
PageSize:= visWidth;
end
else
begin
FHScrollBar.Visible := false;
if Hfits then // if horizontal doesn't fit and no scrollbar, do not change offset
XOffset := 0;
end;
FVScrollBar.UpdateWindowPosition;
FHScrollBar.UpdateWindowPosition;
FVisibleArea.SetPosition(0, 0, visWidth, visHeight);
FVisibleArea.UpdateWindowPosition;
FContentFrame.UpdateWindowPosition;
end;
constructor TfpgScrollFrame.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FVisibleArea := TfpgEmbeddingFrame.Create(self);
FVisibleArea.HandleMove(0, 0);
FVisibleArea.ParentScrollFrame := self;
FContentFrame := TfpgAutoSizingFrame.Create(FVisibleArea);
FContentFrame.HandleMove(0, 0);
FContentFrame.ParentScrollFrame := self;
end;
constructor TfpgScrollFrame.Create(AOwner: TComponent; ContentFrameType: TfpgASFrameClass);
begin
inherited Create(AOwner);
FVisibleArea := TfpgEmbeddingFrame.Create(self);
FVisibleArea.HandleMove(0, 0);
FVisibleArea.ParentScrollFrame := self;
FContentFrame := ContentFrameType.Create(FVisibleArea);
FContentFrame.HandleMove(0, 0);
FContentFrame.ParentScrollFrame := self;
end;
procedure TfpgScrollFrame.AfterCreate;
begin
inherited AfterCreate;
FVScrollBar := TfpgScrollBar.Create(self);
with FVScrollBar do begin
Orientation := orVertical;
OnScroll := @VScrollBarMove;
Position := 0;
ScrollStep := 10;
end;
FHScrollBar := TfpgScrollBar.Create(self);
with FHScrollBar do begin
Orientation := orHorizontal;
OnScroll := @HScrollBarMove;
Position := 0;
ScrollStep := 10;
end;
FScrollBarStyle := ssAutoBoth;
end;
procedure TfpgScrollFrame.SetContentFrameType(AContentFrameType: TfpgASFrameClass);
begin
if Assigned(FContentFrame) then
FContentFrame.Free;
FContentFrame := AContentFrameType.Create(FVisibleArea);
FContentFrame.HandleMove(0, 0);
FContentFrame.ParentScrollFrame := self;
end;
end.
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