/* 
 * tkWinRegion.c --
 *
 *	Tk Region emulation code.
 *
 * Copyright (c) 1995 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkWinRegion.c,v 1.4 2004/10/26 13:15:09 dkf Exp $
 */

#include "tkWinInt.h"


/*
 *----------------------------------------------------------------------
 *
 * TkCreateRegion --
 *
 *	Construct an empty region.
 *
 * Results:
 *	Returns a new region handle.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

TkRegion
TkCreateRegion()
{
    RECT rect;
    memset(&rect, 0, sizeof(RECT));
    return (TkRegion) CreateRectRgnIndirect(&rect);
}

/*
 *----------------------------------------------------------------------
 *
 * TkDestroyRegion --
 *
 *	Destroy the specified region.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Frees the storage associated with the specified region.
 *
 *----------------------------------------------------------------------
 */

void
TkDestroyRegion(r)
    TkRegion r;
{
    DeleteObject((HRGN) r);
}

/*
 *----------------------------------------------------------------------
 *
 * TkClipBox --
 *
 *	Computes the bounding box of a region.
 *
 * Results:
 *	Sets rect_return to the bounding box of the region.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TkClipBox(r, rect_return)
    TkRegion r;
    XRectangle* rect_return;
{
    RECT rect;
    GetRgnBox((HRGN)r, &rect);
    rect_return->x = (short) rect.left;
    rect_return->y = (short) rect.top;
    rect_return->width = (short) (rect.right - rect.left);
    rect_return->height = (short) (rect.bottom - rect.top);
}

/*
 *----------------------------------------------------------------------
 *
 * TkIntersectRegion --
 *
 *	Compute the intersection of two regions.
 *
 * Results:
 *	Returns the result in the dr_return region.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TkIntersectRegion(sra, srb, dr_return)
    TkRegion sra;
    TkRegion srb;
    TkRegion dr_return;
{
    CombineRgn((HRGN) dr_return, (HRGN) sra, (HRGN) srb, RGN_AND);
}

/*
 *----------------------------------------------------------------------
 *
 * TkUnionRectWithRegion --
 *
 *	Create the union of a source region and a rectangle.
 *
 * Results:
 *	Returns the result in the dr_return region.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TkUnionRectWithRegion(rectangle, src_region, dest_region_return)
    XRectangle* rectangle;
    TkRegion src_region;
    TkRegion dest_region_return;
{
    HRGN rectRgn = CreateRectRgn(rectangle->x, rectangle->y,
	    rectangle->x + rectangle->width, rectangle->y + rectangle->height);
    CombineRgn((HRGN) dest_region_return, (HRGN) src_region,
	    (HRGN) rectRgn, RGN_OR);
    DeleteObject(rectRgn);
}

/*
 *----------------------------------------------------------------------
 *
 * TkpBuildRegionFromAlphaData --
 *
 *	Set up a rectangle of the given region based on the supplied
 *	alpha data.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	The region is updated, with extra pixels added to it.
 *
 *----------------------------------------------------------------------
 */

void
TkpBuildRegionFromAlphaData(region, x, y, width, height, dataPtr,
	pixelStride, lineStride)
    TkRegion region;
    unsigned int x, y;			/* Where in region to update. */
    unsigned int width, height;		/* Size of rectangle to update. */
    unsigned char *dataPtr;		/* Data to read from. */
    unsigned int pixelStride;		/* num bytes from one piece of alpha
					 * data to the next in the line. */
    unsigned int lineStride;		/* num bytes from one line of alpha
					 * data to the next line. */
{
    unsigned char *lineDataPtr;
    unsigned int x1, y1, end;
    HRGN rectRgn = CreateRectRgn(0,0,1,1); /* Workspace region. */

    for (y1 = 0; y1 < height; y1++) {
	lineDataPtr = dataPtr;
	for {x1 = 0; x1 < width; x1 = end) {
	    /* search for first non-transparent pixel */
	    while ((x1 < width) && !*lineDataPtr) {
		x1++;
		lineDataPtr += pixelStride;
	    }
	    end = x1;
	    /* search for first transparent pixel */
	    while ((end < width) && *lineDataPtr) {
		end++;
		lineDataPtr += pixelStride;
	    }
	    if (end > x1) {
		/*
		 * Manipulate Win32 regions directly; it's more efficient.
		 */
		SetRectRgn(rectRgn, x+x1, y+y1, x+end, y+y1+1);
		CombineRgn((HRGN) region, (HRGN) region, rectRgn, RGN_OR);
	    }
	}
	dataPtr += lineStride;
    }

    DeleteObject(rectRgn);
}

/*
 *----------------------------------------------------------------------
 *
 * TkRectInRegion --
 *
 *	Test whether a given rectangle overlaps with a region.
 *
 * Results:
 *	Returns RectanglePart or RectangleOut.  Note that this is
 *	not a complete implementation since it doesn't test for
 *	RectangleIn.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TkRectInRegion(r, x, y, width, height)
    TkRegion r;
    int x;
    int y;
    unsigned int width;
    unsigned int height;
{
    RECT rect;
    rect.top = y;
    rect.left = x;
    rect.bottom = y+height;
    rect.right = x+width;
    return RectInRegion((HRGN)r, &rect) ? RectanglePart : RectangleOut;
}

/*
 *----------------------------------------------------------------------
 *
 * TkSubtractRegion --
 *
 *	Compute the set-difference of two regions.
 *
 * Results:
 *	Returns the result in the dr_return region.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TkSubtractRegion(sra, srb, dr_return)
    TkRegion sra;
    TkRegion srb;
    TkRegion dr_return;
{
    CombineRgn((HRGN) dr_return, (HRGN) sra, (HRGN) srb, RGN_DIFF);
}