IMAGUNDO.C

/****************************************************************************/ 
/*                                                                          */ 
/*                 Copyright (C) 1987-1996 Microsoft Corp.                */ 
/*                           All Rights Reserved                            */ 
/*                                                                          */ 
/****************************************************************************/ 
/****************************** Module Header ******************************* 
* Module Name: imagundo.c 
* 
* Contains routines for handling the Undo buffers. 
* 
* History: 
* 
****************************************************************************/ 
 
#include "imagedit.h" 
 
 
STATICFN VOID NEAR ImageAllocUndo(VOID); 
 
 
 
/************************************************************************ 
* ImageUndo 
* 
* Undoes the last editing operation by restoring the image to the 
* saved undo buffer. 
* 
* History: 
* 
************************************************************************/ 
 
VOID ImageUndo(VOID) 
{ 
    HDC hdcTemp; 
    HBITMAP hbmOld; 
 
    /* 
     * Is there anything to undo? 
     */ 
    if (!ghbmUndo) 
        return; 
 
    hdcTemp = CreateCompatibleDC(ghdcImage); 
    hbmOld = SelectObject(hdcTemp, ghbmUndo); 
    BitBlt(ghdcImage, 0, 0, gcxImage, gcyImage, hdcTemp, 0, 0, SRCCOPY); 
 
    /* 
     * For icons and cursors, restore the AND mask also. 
     */ 
    if (giType != FT_BITMAP) { 
        SelectObject(hdcTemp, ghbmUndoMask); 
        BitBlt(ghdcANDMask, 0, 0, gcxImage, gcyImage, hdcTemp, 0, 0, SRCCOPY); 
    } 
 
    SelectObject(hdcTemp, hbmOld); 
    DeleteDC(hdcTemp); 
 
    fImageDirty = TRUE; 
 
    /* 
     * Delete the undo buffer, now that it has been used. 
     */ 
    ImageFreeUndo(); 
 
    ViewUpdate(); 
} 
 
 
 
/************************************************************************ 
* ImageUpdateUndo 
* 
* Makes a snapshot of the current image and places it in the undo 
* buffer. 
* 
* Arguments: 
* 
* History: 
* 
************************************************************************/ 
 
VOID ImageUpdateUndo(VOID) 
{ 
    HDC hdcTemp; 
    HBITMAP hbmOld; 
 
    /* 
     * If there are currently no undo buffers, allocate them now. 
     */ 
    if (!ghbmUndo) 
        ImageAllocUndo(); 
 
    hdcTemp = CreateCompatibleDC(ghdcImage); 
    hbmOld = SelectObject(hdcTemp, ghbmUndo); 
    BitBlt(hdcTemp, 0, 0, gcxImage, gcyImage, ghdcImage, 0, 0, SRCCOPY); 
 
    /* 
     * For icons and cursors, update the undo AND mask also. 
     */ 
    if (giType != FT_BITMAP) { 
        SelectObject(hdcTemp, ghbmUndoMask); 
        BitBlt(hdcTemp, 0, 0, gcxImage, gcyImage, ghdcANDMask, 0, 0, SRCCOPY); 
    } 
 
    SelectObject(hdcTemp, hbmOld); 
    DeleteDC(hdcTemp); 
} 
 
 
 
/************************************************************************ 
* ImageAllocUndo 
* 
* Allocates buffers for an undo operation.  For icons and cursors, 
* this includes an AND mask undo buffer.  This function does not 
* initialize the bits.  The function ImageFreeUndo frees the buffers 
* allocated by this function. 
* 
* History: 
* 
************************************************************************/ 
 
STATICFN VOID NEAR ImageAllocUndo(VOID) 
{ 
    ImageFreeUndo(); 
 
    /* 
     * Allocate an undo bitmap of the specified size. 
     */ 
    if (!(ghbmUndo = MyCreateBitmap(ghdcImage, gcxImage, gcyImage, 16))) { 
        Message(MSG_OUTOFMEMORY); 
        return; 
    } 
 
    /* 
     * For icons and cursors, allocate an undo AND mask also. 
     */ 
    if (giType != FT_BITMAP) { 
        if (!(ghbmUndoMask = CreateBitmap(gcxImage, gcyImage, 
                (BYTE)1, (BYTE)1, NULL))) { 
            ImageFreeUndo(); 
            Message(MSG_OUTOFMEMORY); 
            return; 
        } 
    } 
} 
 
 
 
/************************************************************************ 
* ImageFreeUndo 
* 
* Free's the undo buffers. 
* 
* History: 
* 
************************************************************************/ 
 
VOID ImageFreeUndo(VOID) 
{ 
    if (ghbmUndo) { 
        DeleteObject(ghbmUndo); 
        ghbmUndo = NULL; 
    } 
 
    if (ghbmUndoMask) { 
        DeleteObject(ghbmUndoMask); 
        ghbmUndoMask = NULL; 
    } 
}