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FreeRDP/libfreerdp/codec/region.c
zihao.jiang 2a91988975 resolve comments from hardening
2015-03-21 00:04:30 +08:00

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/**
* FreeRDP: A Remote Desktop Protocol Implementation
*
* Copyright 2014 Thincast Technologies GmbH
* Copyright 2014 Hardening <contact@hardening-consulting.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <assert.h>
#include <winpr/memory.h>
#include <freerdp/log.h>
#include <freerdp/codec/region.h>
#define TAG FREERDP_TAG("codec")
/*
* The functions in this file implement the Region abstraction largely inspired from
* pixman library. The following comment is taken from the pixman code.
*
* A Region is simply a set of disjoint(non-overlapping) rectangles, plus an
* "extent" rectangle which is the smallest single rectangle that contains all
* the non-overlapping rectangles.
*
* A Region is implemented as a "y-x-banded" array of rectangles. This array
* imposes two degrees of order. First, all rectangles are sorted by top side
* y coordinate first (y1), and then by left side x coordinate (x1).
*
* Furthermore, the rectangles are grouped into "bands". Each rectangle in a
* band has the same top y coordinate (y1), and each has the same bottom y
* coordinate (y2). Thus all rectangles in a band differ only in their left
* and right side (x1 and x2). Bands are implicit in the array of rectangles:
* there is no separate list of band start pointers.
*
* The y-x band representation does not minimize rectangles. In particular,
* if a rectangle vertically crosses a band (the rectangle has scanlines in
* the y1 to y2 area spanned by the band), then the rectangle may be broken
* down into two or more smaller rectangles stacked one atop the other.
*
* ----------- -----------
* | | | | band 0
* | | -------- ----------- --------
* | | | | in y-x banded | | | | band 1
* | | | | form is | | | |
* ----------- | | ----------- --------
* | | | | band 2
* -------- --------
*
* An added constraint on the rectangles is that they must cover as much
* horizontal area as possible: no two rectangles within a band are allowed
* to touch.
*
* Whenever possible, bands will be merged together to cover a greater vertical
* distance (and thus reduce the number of rectangles). Two bands can be merged
* only if the bottom of one touches the top of the other and they have
* rectangles in the same places (of the same width, of course).
*/
struct _REGION16_DATA {
long size;
long nbRects;
};
static REGION16_DATA empty_region = { 0, 0 };
void region16_init(REGION16 *region)
{
assert(region);
ZeroMemory(region, sizeof(REGION16));
region->data = &empty_region;
}
int region16_n_rects(const REGION16 *region)
{
assert(region);
assert(region->data);
return region->data->nbRects;
}
const RECTANGLE_16 *region16_rects(const REGION16 *region, int *nbRects)
{
REGION16_DATA *data;
assert(region);
assert(region->data);
data = region->data;
if (!data)
{
if (nbRects)
*nbRects = 0;
return 0;
}
*nbRects = data->nbRects;
return (RECTANGLE_16 *)(data + 1);
}
static INLINE RECTANGLE_16 *region16_rects_noconst(REGION16 *region)
{
REGION16_DATA* data;
data = region->data;
if (!data)
return NULL;
return (RECTANGLE_16*)(&data[1]);
}
const RECTANGLE_16 *region16_extents(const REGION16 *region)
{
return &region->extents;
}
static RECTANGLE_16 *region16_extents_noconst(REGION16 *region)
{
return &region->extents;
}
BOOL rectangle_is_empty(const RECTANGLE_16 *rect)
{
/* A rectangle with width = 0 or height = 0 should be regarded
* as empty.
*/
return ((rect->left == rect->right) || (rect->top == rect->bottom)) ? TRUE : FALSE;
}
BOOL region16_is_empty(const REGION16 *region)
{
assert(region);
assert(region->data);
return (region->data->nbRects == 0);
}
BOOL rectangles_equal(const RECTANGLE_16 *r1, const RECTANGLE_16 *r2)
{
return ((r1->left == r2->left) && (r1->top == r2->top) &&
(r1->right == r2->right) && (r1->bottom == r2->bottom)) ? TRUE : FALSE;
}
BOOL rectangles_intersects(const RECTANGLE_16 *r1, const RECTANGLE_16 *r2)
{
RECTANGLE_16 tmp;
return rectangles_intersection(r1, r2, &tmp);
}
BOOL rectangles_intersection(const RECTANGLE_16 *r1, const RECTANGLE_16 *r2,
RECTANGLE_16 *dst)
{
dst->left = MAX(r1->left, r2->left);
dst->right = MIN(r1->right, r2->right);
dst->top = MAX(r1->top, r2->top);
dst->bottom = MIN(r1->bottom, r2->bottom);
return (dst->left < dst->right) && (dst->top < dst->bottom);
}
void region16_clear(REGION16 *region)
{
assert(region);
assert(region->data);
if (region->data->size)
free(region->data);
region->data = &empty_region;
ZeroMemory(&region->extents, sizeof(region->extents));
}
static INLINE REGION16_DATA* allocateRegion(long nbItems)
{
long allocSize = sizeof(REGION16_DATA) + (nbItems * sizeof(RECTANGLE_16));
REGION16_DATA* ret = (REGION16_DATA*) malloc(allocSize);
if (!ret)
return ret;
ret->size = allocSize;
ret->nbRects = nbItems;
return ret;
}
BOOL region16_copy(REGION16 *dst, const REGION16 *src)
{
assert(dst);
assert(dst->data);
assert(src);
assert(src->data);
if (dst == src)
return TRUE;
dst->extents = src->extents;
if (dst->data->size)
free(dst->data);
if (!src->data->size)
{
dst->data = &empty_region;
}
else
{
dst->data = allocateRegion(src->data->nbRects);
if (!dst->data)
return FALSE;
CopyMemory(dst->data, src->data, src->data->size);
}
return TRUE;
}
void region16_print(const REGION16 *region)
{
const RECTANGLE_16 *rects;
int nbRects, i;
int currentBandY = -1;
rects = region16_rects(region, &nbRects);
WLog_DBG(TAG, "nrects=%d", nbRects);
for (i = 0; i < nbRects; i++, rects++)
{
if (rects->top != currentBandY)
{
currentBandY = rects->top;
WLog_DBG(TAG, "band %d: ", currentBandY);
}
WLog_DBG(TAG, "(%d,%d-%d,%d)", rects->left, rects->top, rects->right, rects->bottom);
}
}
void region16_copy_band_with_union(RECTANGLE_16 *dst,
const RECTANGLE_16 *src, const RECTANGLE_16 *end,
UINT16 newTop, UINT16 newBottom,
const RECTANGLE_16 *unionRect,
int *dstCounter,
const RECTANGLE_16 **srcPtr, RECTANGLE_16 **dstPtr)
{
UINT16 refY = src->top;
const RECTANGLE_16 *startOverlap, *endOverlap;
/* merges a band with the given rect
* Input:
* unionRect
* | |
* | |
* ==============+===============+================================
* |Item1| |Item2| |Item3| |Item4| |Item5| Band
* ==============+===============+================================
* before | overlap | after
*
* Resulting band:
* +-----+ +----------------------+ +-----+
* |Item1| | Item2 | |Item3|
* +-----+ +----------------------+ +-----+
*
* We first copy as-is items that are before Item2, the first overlapping
* item.
* Then we find the last one that overlap unionRect to agregate Item2, Item3
* and Item4 to create Item2.
* Finally Item5 is copied as Item3.
*
* When no unionRect is provided, we skip the two first steps to just copy items
*/
if (unionRect)
{
/* items before unionRect */
while ((src < end) && (src->top == refY) && (src->right < unionRect->left))
{
dst->top = newTop;
dst->bottom = newBottom;
dst->right = src->right;
dst->left = src->left;
src++; dst++; *dstCounter += 1;
}
/* treat items overlapping with unionRect */
startOverlap = unionRect;
endOverlap = unionRect;
if ((src < end) && (src->top == refY) && (src->left < unionRect->left))
startOverlap = src;
while ((src < end) && (src->top == refY) && (src->right < unionRect->right))
{
src++;
}
if ((src < end) && (src->top == refY) && (src->left < unionRect->right))
{
endOverlap = src;
src++;
}
dst->bottom = newBottom;
dst->top = newTop;
dst->left = startOverlap->left;
dst->right = endOverlap->right;
dst++; *dstCounter += 1;
}
/* treat remaining items on the same band */
while ((src < end) && (src->top == refY))
{
dst->top = newTop;
dst->bottom = newBottom;
dst->right = src->right;
dst->left = src->left;
src++; dst++; *dstCounter += 1;
}
if (srcPtr)
*srcPtr = src;
*dstPtr = dst;
}
static RECTANGLE_16* next_band(RECTANGLE_16* band1, RECTANGLE_16* endPtr, int* nbItems)
{
UINT16 refY = band1->top;
*nbItems = 0;
while((band1 < endPtr) && (band1->top == refY))
{
band1++;
*nbItems += 1;
}
return band1;
}
static BOOL band_match(const RECTANGLE_16* band1, const RECTANGLE_16* band2, RECTANGLE_16* endPtr)
{
int refBand2 = band2->top;
const RECTANGLE_16* band2Start = band2;
while ((band1 < band2Start) && (band2 < endPtr) && (band2->top == refBand2))
{
if ((band1->left != band2->left) || (band1->right != band2->right))
return FALSE;
band1++;
band2++;
}
if (band1 != band2Start)
return FALSE;
return (band2 == endPtr) || (band2->top != refBand2);
}
/** compute if the rectangle is fully included in the band
* @param band a pointer on the beginning of the band
* @param endPtr end of the region
* @param rect the rectangle to test
* @return if rect is fully included in an item of the band
*/
static BOOL rectangle_contained_in_band(const RECTANGLE_16 *band, const RECTANGLE_16 *endPtr,
const RECTANGLE_16 *rect)
{
UINT16 refY = band->top;
if ((band->top > rect->top) || (rect->bottom > band->bottom))
return FALSE;
/* note: as the band is sorted from left to right, once we've seen an item
* that is after rect->left we're sure that the result is False.
*/
while( (band < endPtr) && (band->top == refY) && (band->left <= rect->left))
{
if (rect->right <= band->right)
return TRUE;
band++;
}
return FALSE;
}
BOOL region16_simplify_bands(REGION16 *region)
{
/** Simplify consecutive bands that touch and have the same items
*
* ==================== ====================
* | 1 | | 2 | | | | |
* ==================== | | | |
* | 1 | | 2 | ====> | 1 | | 2 |
* ==================== | | | |
* | 1 | | 2 | | | | |
* ==================== ====================
*
*/
RECTANGLE_16 *band1, *band2, *endPtr, *endBand, *tmp;
int nbRects, finalNbRects;
int bandItems, toMove;
finalNbRects = nbRects = region16_n_rects(region);
if (nbRects < 2)
return TRUE;
band1 = region16_rects_noconst(region);
endPtr = band1 + nbRects;
do
{
band2 = next_band(band1, endPtr, &bandItems);
if (band2 == endPtr)
break;
if ((band1->bottom == band2->top) && band_match(band1, band2, endPtr))
{
/* adjust the bottom of band1 items */
tmp = band1;
while (tmp < band2)
{
tmp->bottom = band2->bottom;
tmp++;
}
/* override band2, we don't move band1 pointer as the band after band2
* may be merged too */
endBand = band2 + bandItems;
toMove = (endPtr - endBand) * sizeof(RECTANGLE_16);
if (toMove)
MoveMemory(band2, endBand, toMove);
finalNbRects -= bandItems;
endPtr -= bandItems;
}
else
{
band1 = band2;
}
}
while(TRUE);
if (finalNbRects != nbRects)
{
int allocSize = sizeof(REGION16_DATA) + (finalNbRects * sizeof(RECTANGLE_16));
region->data = realloc(region->data, allocSize);
if (!region->data)
{
region->data = &empty_region;
return FALSE;
}
region->data->nbRects = finalNbRects;
region->data->size = allocSize;
}
return TRUE;
}
BOOL region16_union_rect(REGION16 *dst, const REGION16 *src, const RECTANGLE_16 *rect)
{
const RECTANGLE_16* srcExtents;
RECTANGLE_16* dstExtents;
const RECTANGLE_16 *currentBand, *endSrcRect, *nextBand;
REGION16_DATA* newItems = NULL;
RECTANGLE_16* dstRect = NULL;
int usedRects, srcNbRects;
UINT16 topInterBand;
assert(src);
assert(src->data);
assert(dst);
srcExtents = region16_extents(src);
dstExtents = region16_extents_noconst(dst);
if (!region16_n_rects(src))
{
/* source is empty, so the union is rect */
dst->extents = *rect;
dst->data = allocateRegion(1);
if (!dst->data)
return FALSE;
dstRect = region16_rects_noconst(dst);
dstRect->top = rect->top;
dstRect->left = rect->left;
dstRect->right = rect->right;
dstRect->bottom = rect->bottom;
return TRUE;
}
newItems = allocateRegion((1 + region16_n_rects(src)) * 4);
if (!newItems)
return FALSE;
dstRect = (RECTANGLE_16*) (&newItems[1]);
usedRects = 0;
/* adds the piece of rect that is on the top of src */
if (rect->top < srcExtents->top)
{
dstRect->top = rect->top;
dstRect->left = rect->left;
dstRect->right = rect->right;
dstRect->bottom = srcExtents->top;
usedRects++;
dstRect++;
}
/* treat possibly overlapping region */
currentBand = region16_rects(src, &srcNbRects);
endSrcRect = currentBand + srcNbRects;
while (currentBand < endSrcRect)
{
if ((currentBand->bottom <= rect->top) || (rect->bottom <= currentBand->top) ||
rectangle_contained_in_band(currentBand, endSrcRect, rect))
{
/* no overlap between rect and the band, rect is totally below or totally above
* the current band, or rect is already covered by an item of the band.
* let's copy all the rectangles from this band
+----+
| | rect (case 1)
+----+
=================
band of srcRect
=================
+----+
| | rect (case 2)
+----+
*/
region16_copy_band_with_union(dstRect,
currentBand, endSrcRect,
currentBand->top, currentBand->bottom,
NULL, &usedRects,
&nextBand, &dstRect);
topInterBand = rect->top;
}
else
{
/* rect overlaps the band:
| | | |
====^=================| |==| |=========================== band
| top split | | | |
v | 1 | | 2 |
^ | | | | +----+ +----+
| merge zone | | | | | | | 4 |
v +----+ | | | | +----+
^ | | | 3 |
| bottom split | | | |
====v=========================| |==| |===================
| | | |
possible cases:
1) no top split, merge zone then a bottom split. The band will be splitted
in two
2) not band split, only the merge zone, band merged with rect but not splitted
3) a top split, the merge zone and no bottom split. The band will be split
in two
4) a top split, the merge zone and also a bottom split. The band will be
splitted in 3, but the coalesce algorithm may merge the created bands
*/
UINT16 mergeTop = currentBand->top;
UINT16 mergeBottom = currentBand->bottom;
/* test if we need a top split, case 3 and 4 */
if (rect->top > currentBand->top)
{
region16_copy_band_with_union(dstRect,
currentBand, endSrcRect,
currentBand->top, rect->top,
NULL, &usedRects,
&nextBand, &dstRect);
mergeTop = rect->top;
}
/* do the merge zone (all cases) */
if (rect->bottom < currentBand->bottom)
mergeBottom = rect->bottom;
region16_copy_band_with_union(dstRect,
currentBand, endSrcRect,
mergeTop, mergeBottom,
rect, &usedRects,
&nextBand, &dstRect);
/* test if we need a bottom split, case 1 and 4 */
if (rect->bottom < currentBand->bottom)
{
region16_copy_band_with_union(dstRect,
currentBand, endSrcRect,
mergeBottom, currentBand->bottom,
NULL, &usedRects,
&nextBand, &dstRect);
}
topInterBand = currentBand->bottom;
}
/* test if a piece of rect should be inserted as a new band between
* the current band and the next one. band n and n+1 shouldn't touch.
*
* ==============================================================
* band n
* +------+ +------+
* ===========| rect |====================| |===============
* | | +------+ | |
* +------+ | rect | | rect |
* +------+ | |
* =======================================| |================
* +------+ band n+1
* ===============================================================
*
*/
if ((nextBand < endSrcRect) && (nextBand->top != currentBand->bottom) &&
(rect->bottom > currentBand->bottom) && (rect->top < nextBand->top))
{
dstRect->right = rect->right;
dstRect->left = rect->left;
dstRect->top = topInterBand;
dstRect->bottom = MIN(nextBand->top, rect->bottom);
dstRect++; usedRects++;
}
currentBand = nextBand;
}
/* adds the piece of rect that is below src */
if (srcExtents->bottom < rect->bottom)
{
dstRect->top = MAX(srcExtents->bottom, rect->top);
dstRect->left = rect->left;
dstRect->right = rect->right;
dstRect->bottom = rect->bottom;
usedRects++;
dstRect++;
}
if ((src == dst) && (src->data->size))
free(src->data);
dstExtents->top = MIN(rect->top, srcExtents->top);
dstExtents->left = MIN(rect->left, srcExtents->left);
dstExtents->bottom = MAX(rect->bottom, srcExtents->bottom);
dstExtents->right = MAX(rect->right, srcExtents->right);
newItems->size = sizeof(REGION16_DATA) + (usedRects * sizeof(RECTANGLE_16));
dst->data = realloc(newItems, newItems->size);
if (!dst->data)
{
free(newItems);
return FALSE;
}
dst->data->nbRects = usedRects;
return region16_simplify_bands(dst);
}
BOOL region16_intersects_rect(const REGION16 *src, const RECTANGLE_16 *arg2)
{
const RECTANGLE_16 *rect, *endPtr, *srcExtents;
int nbRects;
assert(src);
assert(src->data);
rect = region16_rects(src, &nbRects);
if (!nbRects)
return FALSE;
srcExtents = region16_extents(src);
if (nbRects == 1)
return rectangles_intersects(srcExtents, arg2);
if (!rectangles_intersects(srcExtents, arg2))
return FALSE;
endPtr = rect + nbRects;
for (endPtr = rect + nbRects; (rect < endPtr) && (arg2->bottom > rect->top); rect++)
{
if (rectangles_intersects(rect, arg2))
return TRUE;
}
return FALSE;
}
BOOL region16_intersect_rect(REGION16 *dst, const REGION16 *src, const RECTANGLE_16 *rect)
{
REGION16_DATA *newItems;
const RECTANGLE_16 *srcPtr, *endPtr, *srcExtents;
RECTANGLE_16 *dstPtr;
int nbRects, usedRects;
RECTANGLE_16 common, newExtents;
assert(src);
assert(src->data);
srcPtr = region16_rects(src, &nbRects);
if (!nbRects)
{
region16_clear(dst);
return TRUE;
}
srcExtents = region16_extents(src);
if (nbRects == 1)
{
BOOL intersects = rectangles_intersection(srcExtents, rect, &common);
region16_clear(dst);
if (intersects)
return region16_union_rect(dst, dst, &common);
return TRUE;
}
newItems = allocateRegion(nbRects);
if (!newItems)
return FALSE;
dstPtr = (RECTANGLE_16*) (&newItems[1]);
usedRects = 0;
ZeroMemory(&newExtents, sizeof(newExtents));
/* accumulate intersecting rectangles, the final region16_simplify_bands() will
* do all the bad job to recreate correct rectangles
*/
for (endPtr = srcPtr + nbRects; (srcPtr < endPtr) && (rect->bottom > srcPtr->top); srcPtr++)
{
if (rectangles_intersection(srcPtr, rect, &common))
{
*dstPtr = common;
usedRects++;
dstPtr++;
if (rectangle_is_empty(&newExtents))
{
/* Check if the existing newExtents is empty. If it is empty, use
* new common directly. We do not need to check common rectangle
* because the rectangles_intersection() ensures that it is not empty.
*/
newExtents = common;
}
else
{
newExtents.top = MIN(common.top, newExtents.top);
newExtents.left = MIN(common.left, newExtents.left);
newExtents.bottom = MAX(common.bottom, newExtents.bottom);
newExtents.right = MAX(common.right, newExtents.right);
}
}
}
newItems->nbRects = usedRects;
newItems->size = sizeof(REGION16_DATA) + (usedRects * sizeof(RECTANGLE_16));
if (dst->data->size)
free(dst->data);
dst->data = realloc(newItems, newItems->size);
if (!dst->data)
{
free(newItems);
return FALSE;
}
dst->extents = newExtents;
return region16_simplify_bands(dst);
}
void region16_uninit(REGION16 *region)
{
assert(region);
if (region->data)
{
if (region->data->size)
free(region->data);
region->data = NULL;
}
}
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