The ProgressBar component is used to indicate the process of performing a task.
To use the component, in Min and the Max properties define indicator scale minimum and maximum values. In the Position property, set the current value displayed in the indicator. Various additional properties enable users to customize component appearance.
If you work in operating system using Aero theme, smooth progress bar is used. If values change quite rapidly (for several seconds), progress bar lag occurs. Such lag is not an error in the ProgressBar operation; it is an operating result of the system component behind the ProgressBar. If process initiated by the ProgressBar component is in progress for a short time period and timely progress bar display is required, the following bypass can be used: prior to setting in the Position property the value displayed by the indicator, a slightly increased value should be set for such property. It causes an instant drawing of the process indicator. To improve progress bar display in the end point (when the Max value is reached), slightly increase maximum permissible component range, set indicator value and reset initial maximum permissible value.
If indicator value is changed according to timer control, to enable correct display using the above algorithm the following code in Fore language can be used:
Class TESTForm: Form
Button1: Button;
Timer1: Timer;
ProgressBar1: ProgressBar;
Pos: Integer;
Sub Button1OnClick(Sender: Object; Args: IMouseEventArgs);
Begin
Pos := 0;
Timer1.Enabled := True;
End Sub Button1OnClick;
Sub Timer1OnTimer(Sender: Object; Args: IEventArgs);
Begin
Pos := Pos + 1;
If (Pos < ProgressBar1.Max) Then
ProgressBar1.Position := Pos + 1;
ProgressBar1.Position := Pos;
Else
ProgressBar1.Max := ProgressBar1.Max + 1;
ProgressBar1.Position := ProgressBar1.Max;
ProgressBar1.Max := ProgressBar1.Max - 1;
Timer1.Enabled := False;
End If;
End Sub Timer1OnTimer;
End Class TESTForm;
It is also recommended to consider using the PPProgressBar component instead of the ProgressBar component. PPProgressBar does not depend on system components, thus display lag does not occur.
| Property name | Brief description | |
| Align | The Align property determines the behavior of the component, when the size of its parent component is changed. | |
| AllowDrag | The AllowDrag property determines whether an object can be dragged from the component. | |
| AllowDrop | The AllowDrop property determines whether the component can accept a dragged object. | |
| Anchors | The Anchors property returns settings that determine the percentage of the size change for the current component when the parent component is resized. | |
| BorderStyle | The BorderStyle property determines the style of a component border. | |
| Brush | The Brush property specifies the brush used to fill the component area. | |
| ClientHeight | The ClientHeight property is used to receive or specify the height of the component’s client space. | |
| ClientWidth | The ClientWidth property is used to receive or specify the width of the component’s client space. | |
| Color | The Color property determines the background color of a component. | |
| ComponentCount | The ComponentCount property returns the number of child components. | |
| Components | The Components property returns the child component. | |
| Cursor | The Cursor property determines the look of the cursor over the component. | |
| Data | The Data property is used to store any custom data. | |
| Enabled | The Enabled property determines whether the component is available for the user. | |
| Focused | The Focused property returns True, if the focus is set on the component. | |
| Font | The Font property determines the set of characteristics, describing the font, used to display text. | |
| Height | The Height property determines the component height. | |
| HelpContext | The HelpContext property determines a unique index for the context help section for this component. | |
| Hint | The Hint property determines the hint text for the component. | |
| Left | The Left property determines the coordinate of the left border of the component. | |
| Max | The Max property determines the maximum value for the progress bar. | |
| Min | The Min property determines the minimum value for the progress bar. | |
| Name | The Name property determines the component name. | |
| Orientation | The Orientation property determines the indicator orientation. | |
| Parent | The Parent property determines the parent component. | |
| ParentColor | The ParentColor property determines whether the component inherits the color of the parent component. | |
| ParentFont | The ParentFont property determines whether the component should use the font of the parent component. | |
| ParentShowHint | The ParentShowHint property determines when a tooltip is displayed. | |
| PopupMenu | The PopupMenu property determines the context menu to be displayed on right-click. | |
| Position | The Position property determines the current position of the indicator. | |
| Scrolls | The Scrolls property returns parameters of component's scrollbars. | |
| ShowHint | The ShowHint property enables and disables showing a hint for the component. | |
| Smooth | The Smooth property determines the indicator appearance. | |
| StepSize | The StepSize property determines the value to move the indicator on calling of the method StepIt . | |
| TabOrder | The TabOrder property determines the component position in the tab order. | |
| TabStop | The TabStop property determines whether the focus is set to a component when the TAB button is pressed. | |
| Tag | The Tag property is not used by the compiler. The user can change the value of the Tag property and use it as required. | |
| Text | The Text property determines the row identifying a component for user. | |
| Top | The Top property determines the coordinate of the top border of the component. | |
| Visible | The Visible property determines the visibility of the component during execution. | |
| Width | The Width property determines the component width. |
| Method name | Brief description | |
| BringToFront | The BringToFront method brings a component to front. | |
| ClientToScreen | The ClientToScreen method converts point coordinates relative to component coordinates into display coordinates. | |
| DoDragDrop | The DoDragDrop method allows to start drag-and-drop operation. | |
| GetImage | The GetImage method returns the image of the component with all the child components. | |
| ScreenToClient | The ScreenToClient method converts screen coordinates of a point to coordinates specified relative to the component coordinate system. | |
| SendToBack | The SendToBack method sends a component to back. | |
| SetFocus | The SetFocus method sets focus to this component. | |
| StepBy | The StepBy method changes the indicator position by the value, set in the input parameter. | |
| StepIt | The StepIt method changes the indicator position by the value, set in the StepSize property. |
| Event name | Brief description | |
| OnBeginDrag | The OnBeginDrag event occurs for a component, when a user starts to drag an object from the component. | |
| OnClick | The OnClick event occurs if a user clicks a component area using the main mouse button. | |
| OnDblClick | The OnDblClick event occurs if a user double-clicks a component area using the mouse button. | |
| OnDragDrop | The OnDragDrop event occurs for a component if a user drops a dragged object over it. | |
| OnDragEnter | The OnDragEnter event occurs when a dragged object crosses the borders of this component. | |
| OnDragLeave | The OnDragLeave event occurs when a dragged object leaves the borders of this component. | |
| OnDragOver | The OnDragOver event occurs for this component when a user drags a dragged object over it. | |
| OnEnter | The OnEnter event occurs when a component receives focus. | |
| OnExit | The OnExit event occurs when a component loses focus. | |
| OnHScroll | The OnHScroll event occurs when the horizontal scrollbar slider changes its position. | |
| OnKeyDown | The OnKeyDown event occurs if a component is focused and a keyboard key is pressed. | |
| OnKeyPress | The OnKeyPress event occurs if a component is focused when a user presses a character key. | |
| OnKeyPreview | The OnKeyPreview event occurs prior to each event requiring clicking. | |
| OnKeyUp | The OnKeyUp event occurs if a component is focused and a user releases any button previously pressed. | |
| OnMouseDown | The OnMouseDown event occurs when the pointer is in component area and a mouse button is pressed. | |
| OnMouseEnter | The OnMouseEnter event occurs when mouse cursor enters the component area. | |
| OnMouseHover | The OnMouseHover event occurs when mouse cursor is held in the component area. | |
| OnMouseLeave | The OnMouseLeave event occurs when mouse cursor leaves the component area. | |
| OnMouseMove | The OnMouseMove event occurs on moving the cursor over component. | |
| OnMouseUp | The OnMouseUp event occurs on releasing mouse button when the cursor is in component area. | |
| OnMouseWheel | The OnMouseWheel event occurs if the component has focus when the mouse wheel is rotated. | |
| OnVScroll | The OnVScroll event occurs when the vertical scrollbar slider changes its position. |
See also: