The Undo Buffer

The Undo Buffer

The imaG control has four UNDO/REDO buffers, two for DRAW MODE and two for EDIT MODE.

The depth of the buffers depends of the size of the image (4 to 8).

In EDIT MODE the buffer is automatically set.

UNDO/REDO ACTIONS IN EDIT MODE	CONSTANTS
Pen	caUndoPen = 1
Brush	caUndoBrush = 2
Eraser	caUndoEraser = 3
Fill	caUndoFill = 4
Line	caUndoLine = 5
Rectangle	caUndoRectangle = 6
Filled Rectangle	caUndoRectangleFilled = 7
Round Rectangle	caUndoRoundRectangle
Filled Round Rectangle	caUndoRoundRectangleFilled = 9
Ellipse	caUndoEllipse = 10
Filled Ellipse	caUndoEllipseFilled = 11
Cut	caUndoCut = 12
Paste	caUndoPaste = 13
Delete	caUndoDelete = 14

In DRAW MODE the buffer is automatically set for some actions and is also programmable.

UNDO/REDO ACTIONS IN DRAW MODE	CONSTANTS
Cut	caUndoCut = 12
Paste	caUndoPaste = 13
Delete	caUndoDelete = 14
Draw Line	caUndoDrawLine = 15
Draw Text	caUndoDrawText = 16
Draw Point	caUndoDrawPoint = 17
Draw Circle	caUndoDrawCircle = 18
Mirror Horizontal	caUndoMirror = 19
Mirror Vertical	caUndoFlip = 20
Rotate 180º	caUndoRotateDown = 21
Edit	caUndoEdit = 22

When the imaG is turned to EDIT MODE the image (in DRAW MODE) is saved to the buffer.

The DRAW MODE Buffer will be cleared when changing the color depth.
The DRAW MODE Buffer will be cleared when changing the size of the image (Rotate +- 90º , ...)

The EDIT MODE Buffer will be cleared when turning from edit mode to draw mode.

With the Test property set to TRUE , all the UNDO/REDO actions will NOT effective to avoid large memory spaces.

PROGRAMMING THE UNDO BUFFER.

In DRAW MODE the UNDO/REDO buffer is programmable.

Before the image changes :

imaG.Undo_Add UndoName

After the image changes

PctureX.Undo_AddPalette (saves the redo palette)

UNDO-REDO ACTION.

imaG.Undo_Query (parameters ...) - presets the Undo/Redo buffer and returns the undo/redo values for recognizing the action

imaG.Undo_Undo or
imaG.Undo_Redo