Copyright© Kambiz R. Khojasteh. All rights reserved.
Get future component updates from http://www.delphiarea.com.

DESCRIPTION

TPicShow is an image slider control with 127 transitional effects in pure Delphi code. The major characteristics of TPicShow are:

• Image transition can be controlled programmatically
• Image can be stretched or centered in the client area of the control
• Control can show a background image as centered, stretched, or tiled
• Transition process can use a separated thread
• New transitional effects can be easily implemented and added to the control

TDBPicShow is the data-aware version of TPicShow with ability to load bitmap or jpeg images (natively) from a blob field.

IMPORTANT NOTE FOR DELPHI 3.0 USERS: Two procedures in 'Graphics.pas' are missing a call to 'BitmapCanvasList.UnlockList'.
This bug will cause VCL graphics functions, which have not been called from the main thread, to hang. They cannot lock 'BitmapCanvasList' because the main thread never unlocks it. Because of this bug, running PicShow in threaded mode will lead your application to deadlock. For the bug details and fix please visit: http://www.dataweb.nl/~r.p.sterkenburg/generated/entry0016.htm.

ACKNOWLEDGMENT

Special thanks to:

• <k3nx@hotmail.com> for help on D5 support.
• Douglass Titjan <support@delphipages.com> for help on D5 support.
• Jerry McLain <jkmclain@srcaccess.net> for manual control idea.
• M. R. Zamani <M_R_Zamani@yahoo.com> for adding 8 effects (110..117).
• Elliott Shevin <ShevinE@aol.com> for adding 4 effects (123..126).
• Ken Otto <ken.otto@enviros.com> for adding native JPEG support to TDBPicShow and fixing a memory leak bug.
• Gary Bond <gary.bond@tesco.net> for name of the transitions.

KEY PROPERTIES

• AutoDisplay: Boolean (TDBPicShow only)
  Determines whether the control automatically displays the contents of a graphic BLOB in the database control.
  
  
• AutoSize: Boolean
  If set to true, Automatically sizes the control to the size of the loaded image if any is loaded.
  
  
• BgMode: TBackgroundMode
  TBackgroundMode = (bmNone, bmTiled, bmStretched, bmCentered)
  Determines how the control displays the background image on its client area.
  
  

  bmNone		Ignores the background image.
  bmTiled		Fills the client area of the control by the background image as tiled.
  bmStretched		Fills the client area of the control by stretching (or shrinking) the background image.
  bmCentered		Draws the background image on the center of the control's client area.

  
  
• BgPicture: TPicture
  Contains the background image of the control.
  
  
• Busy: Boolean (Read-only)
  Determines whether the control is performing an image transition.
  
  
• Center: Boolean
  If set to true and control's client area is larger than the loaded image, the image will be centered within the control's boundaries.
  
  
• Color: TColor
  Determines the background color of the control.
  
  
• DataField: String (TDBPicShow only)
  Specifies the field of dataset, which contains the image data.
  
  
• DataSource: TDataSource (TDBPicShow only)
  Links the control to a dataset.
  
  
• Delay: Word
  Determines the amount of delay in milliseconds before showing the next frame of the transition.
  
  
• Empty : Boolean (Read-only)
  Determines whether any image is loaded into the control.
  
  
• Picture: TPicture (Published in TPicShow only)
  Contains the image that the next call to Execute will show it.
  
  
• Progress: TPercent
  TPercent = 0..100
  Determines the current state of the running transition. When Busy property is false, changing this property has no effect.
  
  
• Reverse: Boolean
  If set to true, automatic transitions plays in reverse.
  
  
• Stretch: Boolean
  If set to true, when the control's client area is larger than the loaded image, the image it will be stretched (or shrinked) to fit within the control's boundaries.
  
  
• StretchFine: Boolean
  Determines the behavior of the Stretch property. If set to true, the image's aspect ratio remains unchanged.
  
  
• Step: Word
  Determines the amount of change in Progress in automatic transition.
  
  
• Style: TShowStyle
  TShowStyle = 0..127
  Specifies the index of the transition effect that will be used. By setting this property to zero, an OnCustomDraw event will be fired just before showing a new frame.
  
  
• StyleName: String
  Specifies the name of the transition effect that will be used.
  
  
• Threaded: Boolean
  If set to true, the control use a separated thread for the transition process.
  
  
• ThreadPriority: TThreadPriority
  TThreadPriority = (tpIdle, tpLowest, tpLower, tpNormal, tpHigher, tpHighest, tpTimeCritical)
  Determines the thread's scheduling priority relative to other threads in the process.

KEY METHODS

• procedure Execute
  Initials the transition and if Manual property is set false, starts it. If Manual property is set to true, after calling this method you can change the value of Progress property.
  
  
• procedure Clear
  Clears the client area of the control. Notice that calling this method does not clear the image loaded into Picture property.
  
  
• procedure Stop
  Stops the running transition.

KEY EVENTS

• OnAfterNewFrame: TCustomDrawEvent
  TCustomDrawEvent = procedure(Sender: TObject; Picture, Screen: TBitmap) of object
  This event is triggered just after creating a new frame of the transition and before drawing it on the control's client area.
  When PicShow is running in Threaded mode, this event occurs in control's thread.
  
  
• OnBeforeNewFrame: TCustomDrawEvent
  TCustomDrawEvent = procedure(Sender: TObject; Picture, Screen: TBitmap) of object
  This event is triggered just before creating a new frame of the transition.
  When PicShow is running in Threaded mode, this event occurs in control's thread.
  
  
• OnChange: TNotifyEvent (TPicShow only)
  Occurs when content of Picture property has changed.
  
  
• OnStart: TNotifyEvent
  Occurs before beginning of the transition. After calling Execute Method, the control copies the loaded image into a bitmap and use it for transition purpose. When this event is triggered, you can load another image into the component for the next transition.
  
  
• OnStop: TNotifyEvent
  Occurs when transition is completed or aborted.
  
  
• OnComplete: TNotifyEvent
  Occurs when the transition effect has compeleted normally. If transition stops by calling Stop method, this event does not occur.
  
  
• OnProgress: TNotifyEvent
  Occurs just after drawing a frame of the transition on the client area of the control.
  When PicShow is running in Threaded mode, this event occurs in control's thread.
  
  
• OnCustomDraw: TCustomDrawEvent
  TCustomDrawEvent = procedure(Sender: TObject; Picture, Screen: TBitmap) of object
  If Style property set to 0, this event is triggered when the control needs to create a new frame of the transition. The Picture parameter is the original image and the Screen parameter is a bitmap that you should update it.
  When PicShow is running in Threaded mode, this event occurs in control's thread.
  
  
• OnMouseEnter: TNotifyEvent
  Occurs when the mouse pointer moves over the control.
  
  
• OnMouseLeave: TNotifyEvent
  Occurs when the mouse pointer moves off from over the control.
  
  
• OnAfterLoadPicture: TNotifyEvent (TDBPicShow only)
  Occurs when a new picture is loaded into the control.
  
  
• OnBeforeLoadPicture: TNotifyEvent (TDBPicShow only)
  Occurs when a new picture is being load into the control.
  
  
• OnGetCraphicClass: TGetGraphicClassEvent(TDBPicShow only)
  TGetGraphicClassEvent = procedure(Sender: TObject; var GraphicClass: TGraphicClass) of object;
  Occurs when a new picture is about to load into the control. TDBPicShow can recognize JPEG images stored in blob fields, however it treats all other graphic formats as bitmap. This event gives this opportunity to the application to specify the graphic class type of the data in the blob field.

KNOWN ISSUES

• Transition on large images is slow.
  
• Control does not support transparency.

HISTORY

• 2.812 (October 25, 2002)
  - The components prevented Windows for being shutdown. This bug fixed.
  
  
• 2.811 (September 28, 2002)
  - Bug on proportional scaling of the image fixed.
  
  
• 2.81 (September 26, 2002)
  - There was a memory leak on loading large images (more than 1MB) into the control, which is fixed.
  - Race condition problem of the thread in TDBPicShow fixed.
  - New event OnGetGraphicClass added to TDBPicShow.
  - Algorithm of image rotation optimized.
  
  
• 2.8 (September 10, 2002)
  - Control's thread optimized. In threaded mode, control does not call Delphi Synchronize function anymore to synchronize itself with the main VCL thread. As the result, no more deadlock, faster thread termination, lower CPU usage, and smoother transitions. However, because of this change, the control cannot be compiled as non-windowed control anymore.
  - Now changing the value of Manual, Progress, and Reverse properties at the last step of transition takes effect.
  - New method OnStop added.
  
  
• 2.68 (Julay 9, 2002)
  - Minor bug fix.
  
  
• 2.67 (June 5, 2002)
  - Bug on releaseing the thread fixed.
  
  
• 2.66 (May 9, 2002)
  - Memory leak bug fixed.
  
  
• 2.65 (March 8, 2002)
  - A minor bug on effect number 118 (Fade) fixed.
  
  
• 2.64 (February 9, 2002)
  - A little improvement in performance.
  
  2.63 (January 14, 2002)
  - Bug raised on thread during the previous upgrade, fixed.
  - New event OnStart added.
  
  
• 2.62 (December 29, 2001)
  - Support for Delphi 6.0 Added.
  - Now both controls as default are windowed control. To change them from windowed control to non-windowed control, edit PicShow.pas and remove definition of WINCONTROL_PICSHOW compiler symbol.
  
  
• 2.61 (April 18, 2001)
  - New property StyleName added. This property is as same as Style property but uses name of the transition instead of its index (Thanks to Gary Bond).
  
  
• 2.60 (February 21, 2001)
  - Native JPEG support added to TDBPicShow (Thanks to Ken Otto)
  - OnAfterLoadPicture and OnBeforeLoadPicture added events added to TDBPicShow (Thanks to Ken Otto)
  - A memory leak bug fixed (Thanks to Ken Otto)
  
  
• 2.50 (September 7, 2000)
  - 5 new effects added; now 127 effects (Thanks to Elliott Shevin for 4 of these effects).
  - Component editor improved.
  
  
• 2.40 (June 16, 2000)
  - TDBPicShow is data-aware version of TPicShow that added to this version of the component set.
  
  
• 2.32 (June 14, 2000)
  - Since to this version, TPicShow only was a windowed control. Now, TPicShow can be a windowed or non-windowed control depending to definition of WINCONTROL_PICSHOW compiler directive.
  
  
• 2.31 (June 12, 2000)
  - OnBeforeNewFrame and OnAfterNewFrame events added.
  
  
• 2.30 (February 27, 2000)
  - Memory leak bug fixed.
  
  
• 2.20 (February 6, 2000)
  - Now, all styles can be played as reverse.
  - Reverse property added.
  - Now the value of Progress property can be manually decremented for all styles.
  - OnMouseEnter and OnMouseLeave events added
  - the parameters of OnCustomDraw event changed.
  - Some comments added to the source of demo application.
  
  

• 2.11 (February 1, 2000)
  - A minor bug fixed.
  
  

• 2.10 (January 31, 2000)
  - 5 new effects added; now 122 effects.
  - Property editors placed in a separate unit (Delphi 5 consideration).
  - Known bugs fixed.
  
  
• 2.00 (December 12, 1999)
  - Manual animation control added (Thanks to Jerry McLain for the idea).
  - Now all styles, play the image with an equal speed.
  - Stretch can keep the image aspect ratio.
  - Delay, Manual, Progress, StretchFine, and ThreadPriority properties added.
  - OnCustomDraw and OnProgress events added.
  
  
• 1.50 (November 17, 1999)
  - now Delphi 3.0 is supported.
  - Icon support added.
  
  
• 1.40 (November 16, 1999)
  - 8 new effects added; now 117 effects (Thanks to M. R. Zamani for these effects).
  - All reported bugs fixed.
  
  
• 1.30 (November 11, 1999)
  - BgMode and BgPicture properties added.
  - 32 new effects added; now 109 effects.
  - Thread management improved.
  
  
• 1.20 (November 9, 1999)
  - Empty property added.
  - OnChange event added.
  - Stop method added.
  - 30 new effects added; now 77 effects.
  - all known bugs fixed.
  
  

• 1.10 (November 6, 1999)
  - Busy property added.
  - Some bugs fixed.
  
  

• 1.00 (November 5, 1999)
  - Initial release with 47 effects.
  

LICENSE

PicShow family components are freeware. You may copy component's files AS LONG AS YOU COPY ALL OF THEM. If you want to change the source code in order to improve the components' features, performance, etc. please send me the new source code so that I can have a look at it. The changed source code should contain descriptions what you have changed, and of course your name. The only thing you MAY NOT CHANGE is the ORIGINAL COPYRIGHT INFORMATION.

DISCLAIMER

PicShow family components are provided "AS IS" without any warranty of any kind, either express or implied. The entire risk as to the quality and performance of the software is with you. The author is NOT liable for any DAMAGES resulting from the use and misuse of the components, especially he is NOT liable for DAMAGES that were caused BY ANY VERSION WHICH HAS NOT BEEN PROGRAMMED BY THE AUTHOR HIMSELF.