An Introduction to Controls - PowerPoint PPT Presentation

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An Introduction to Controls

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Title: An Introduction to Controls

1
An Introduction to Controls

Rainer Becker
dFPUG / ISYS GmbH
Germany

2
About the Speaker

German FoxPro User Group
ISYS GmbH
MS Solution Provider
MS Consulting Services
Adress Rainer Becker, Messerschmittstr. 2a,
65760 Eschborn, Germany
Phone 01149-6173-68182, Fax -65997
CompuServe 100024,1364 / GO MSCESYS

3
Whats included

Short Introduction to principles of
Properties/Events/Methods
Guided Tour through all Controls
- walking all properties upstairs
Some words about
Containers, Naming, Builders

4
Whats excluded

Form Designer
Class Designer
Grid-Control
OLE-Controls
(but you might get a good base for all of that)

Classes
Inheritance
Non-Visual Objects
Event-Model

5
Form Designer
Toolbars

Properties
Data
Method
Layout
Other

Controls
Libs
Locks

Layout
Palette

Design

6
Vocabulary

What are Properties ?
What are Methods ?
What are Events ?
How to avoid confusion?
How to reference objects ?

7
What are PROPERTIES?

Think of them as bound variables
Public vars with a private path
Example COMMENT, HEIGHT
Add your own!
Later on you will need them - especially
for non-visual objects or even applications

8
What are METHODS?

Think of them as old-style snippets
Procedures bound to Controls/Forms
Example Refresh, SetFocus
Add your own!
You will sometimes need them
- but building your own is real fun!

9
What are EVENTS?

Think of them as old-style snippets
Procedures bound to Windows-Events
Example old-fashioned VALID, CLICK
You can not extend!
Events are methods bound to OS/VFP/USER
You normally need only some of them
- but it is great that there are so many!

10
Avoid Confusion

Events and Methods have a Procedure
Events could be seen as an Event Method
Some Properties are followed by actions
These Categories are not closed boxes
There are many - but most are easy to use!
Obey Graphical hints
Bold changed, Italic read-only
Use RESET TO DEFAULT (right mouse button)

11
Syntax

objectvariable.form.control.property Setting
THIS.
THISFORM.
THISFORMSET.
_SCREEN.
WITH.. ..ENDWITH, COUNT / PAGES

ACTIVEFORM.
ACTIVEPAGE.
ACTIVECONTROL.
PARENT.

12
Controls - A Guided Tour

Timers
Lines
Shapes
Images
Labels
Command Buttons
Option Buttons
Check Boxes
Text Boxes

Edit Boxes
Spinners
Combo Boxes
List Boxes
Option Groups
Command Groups
Page Frames
Grids
OLE-Controls

13
Not all of them are new! Renamed
Controls

Text gt Label control
GET-Field gt Text box
Edit Region gt Edit box
Popup gt Combo box
Radio button gt Optionb.
Push button gt Command
Screen(Set) gt Form (Set)
Picture gt Image

Really new are
Timers
Page
Grid
OCX
Nearly all are enhanced!

14
Lets start with a new but small one
Timers

Data
Methods
Layout
Other
Tips

Comment, Tag BASIC, TimerEvent,
Reset COORDINATES CLASS, Interval - Not executed
while Menu open - Not exact enough for RealTime
15
Timer Basic Data/Layout

Timer (one of each)
TimerEvent Procedure called at Event
ResetMethod Restart timer
IntervalProp. Timer in milliseconds
Data
Comment You should use it!
Tag Free property
Layout
Top, Left, Heigth, Width

16
Basic Other

Other
Name Naming conventions
Enabled logical Flag
Class Objects belong to classes
ClassLibrary optional VCX of the class
Baseclass Base class derived from
Parentclass optional derived from
Parent runtime container object

17
Basic Events/Methods

Events
Init Object initialised
Destroy Object removed
Error local error-handler
Methods
CloneObject runtime duplication
SaveAsClass objects from VCX to VCX
Read/WriteExpression/Method at design time

18
Lines

Data
Events
Methods
Layout
Other
Tips

--- CLICK, MOUSE, DRAG Drag, Move, UIEnable,
ZOrder DragIcon/Mode, BORDER,Draw- Mode,
MousePointer, LineSlant HelpContextID - No
3D-line-effects
19
Click Mouse EventsVisible Objects

Click
Click Mouse left click
DblClick Mouse double click
RightClick Mouse right click
Mouse
MouseMove Mouse over object
MouseDown Mouse pressed for click
MouseUp Mouse released
MousePointer 12 pointer versions

20
Drag Drop Visible Objects

Drag
DragDrop End of drag, target event
DragOver object over target, target event
Methods
Drag Method for manual dragging
Move Method for manual moving
Properties
DragIcon Cursor Icon for drag
DragMode automatic / manual

21
Properties Visible Objects

Bordercolor, -style, -width for border
Visible Temporary hide object
HelpContextID for HelpCompiler
ZOrder Meth. active Page, tlb order
UIEnable Evt. Page activate event
Drawmode 16 different modes
(Line/Shape/Form)
LineSlant special line property

22
Shapes
--- --- BackColor/Style, FillColor/Style, ColorSch
eme/Source, ToolTip SpecialEffect,
Curvature --- - Shapes in front block the click
event

Data
Methods
Layout
Other
Tips

23
Properties Plain Objects

Colors
BackStyle Transparent / Opaque (Default)
BackColor RGB-Color for Qpaque objects
FillColorStyle Transparent, Solid, Lines
FillColor RGB-Color if not transparent
ColorScheme Object/Form/Source/Default
ColorSource Scheme for AboveSource
ToolTipText ToolTip if Form.ShowTips.T.
SpecialEffect Plain or 3D
Curvature 0rectangle - 99circle

24
Images

Data
Methods
Layout
Other
Tips

--- --- Picture (Bitmap, Icon) Stretch
(Clip/Isometric/Stretch) --- - Stretch also used
for OLE
25
Labels

Data
Methods
Layout
Other
Tips

--- --- Caption, FONT, COLOR AutoSize, WordWrap,
Alignment --- - The Caption can be a function
26
Layout PropertiesObjects with Caption

FontName FontSize
FontFlags FontBold, FontItalic,
FontStrikeThru,
FontOutline,
FontUnderline, FontShadow
Color DisabledBackColor,
(Disabled)ForeColor
Caption Text to be shown (function)
Alignment Left/Right/Centered
AutoSize Resize horiz. for text
WordWrap Wrap words/resize vertical

27
Command Buttons

Data
Methods
Layout
Other
Tips

TerminateRead ErrorMessage, see
EVENTS DownPicture, DisabledPicture StatusBarText,
(StyleInv.) TabIndex, TabStop (Forms!)
Default, Cancel (not \! or \? ) - Use small
fonts with pictures - Use StatusBarText instead
28
Eventsfor accessible objects

When old-fashioned WHEN
Valid old-fashioned VALID
GotFocus Tabbed to it
LostFocus Tabbed somewhere else...
SetFocus Method (enabled visible)
KeyPress Key Preview Event !
Refresh SHOW GET (Requery,Page)
Message Return Message text (Old!)

29
Option Buttons

Data
Methods
Layout
Other
Tips

ControlSource Field or memvar Value same type as
the --- ControlSource Alignment (Left/Right)
for button SpecialEffect not for command
button --- - Only in Option Button Groups!
30
Avoid Confusion

Name object name
Caption title
ControlSource differs
memvar
field
function
Value object value

31
Check Boxes

Data
Methods
Layout
Other
Tips

--- InteractiveChangeEvent ProgrammaticChangeEvent
--- --- - ProgrammaticChange important!
32
Text Boxes

Data
Methods
Layout
Other
Tips

Format, InputMask, Margin, Read- Only,
Open/MemoWindow RangeHigh, RangeLow SELECT, Style
(SAY-compatible), PasswordChar HideSelection -
Play with selected areas!
33
Selected Text

SelStart Begin of selection
SelLength Number of chars
SelText Complete Selected text
HideSelection Show after LostFocus
SelectedForeColor Text color
SelectedBackColor Background color

34
Edit Boxes

Data
Methods
Layout
Other
Tips

MaxLength --- ScrollBars (vert.
horiz.) AllowTabs - Selected text applies here
35
Spinners

Data
Methods
Layout
Other
Tips

KeyboardHigh/LowValue, Spin- nerHigh/LowValue,
Increment UpEvent, DownEvent --- --- - Use
High/LowValues instead of RangeEvents
36
Combo Boxes

Data
Methods
Layout
Other
Tips

BoundColumn, DisplayValue AddItem,
AddListItem, ColumnCount, -Lines,
-Width Disabled/Select/Item/Back/ForeC TopIndex,
TopItemID, NEW IncrementalSearch,
Listcount, ListIndex, ListIdemID
37
LayoutCombo box