Adds a rectangle to this region.

Notes:

1. If this region's error flag is already set, this function has no effect.

2. If the operation causes the capacity of this region to be exceeded, or if memory allocation fails, the region is cleared, freeing up any memory which has been allocated; its error flag is also set.

Gets the minimal rectangle that bounds the entire region.

Tests whether the region's error flag is set.

The error flag may be set:

1. when an attempt to allocate more memory for the region fails

2. if an attempt is made to expand a fixed size region beyond its allocated size

3. if ForceError() has been called.

Use Clear() to unset the error flag, clear the region and free all allocated memory.

TRegion::ForceError TRegion::Clear

Clears this region.

This frees up any memory which has been allocated and unsets the error flag.

Clips the region to the specified rectangle.

The resulting region is the area of overlap between the region and the rectangle. If there is no overlap, all rectangles within this region are deleted and the resulting region is empty.

Tests whether a point is located within the region.

If the point is located on the top or left hand side of any rectangle in the region, it is considered to be within that rectangle and within the region.

If the point is located on the right hand side or bottom of a rectangle, it is considered to be outside that rectangle, and may be outside the region.

Copies another region to this region.

The state of the specified region's error flag is also copied.

Gets the number of rectangles in this region.

Ensure that the region is big enough to hold aCount rectangles. Any allocation increase is for at least the granularity count of rectangles. Similar to SetListSize, but always preserves existing iCount rectangles.

Sets the error flag, and clears the region.

This frees up memory allocated to the region.

Replaces this region with the area of intersection between it and the specified region.

Note that if the error flag of either this region or the specified region is set, then this region is cleared and its error flag is set. This frees up allocated memory.

Replaces this region with the area of intersection between two specified regions.

Notes:

1. If the error flag of either of the two specified regions is set, then this region is cleared and its error flag is set. This frees up allocated memory.

2. If this region's error flag is already set, then the function has no effect.

Tests whether where there is any intersection between this region and the specified rectangle.

Tests whether the region is fully enclosed within the specified rectangle.

Tests whether the region is empty.

Merges a rectangle with this region.

If requested it looks for a rectangle in the region that covers the new rectangle, if found method returns immediately. Otherwise, or if an enclosing rectangle is not found, the new aRect is subtracted from all intersecting rectangles, and then aRect is appended to the region.

Moves the region by adding X and Y offsets to the co-ordinates of its corners.

The size of the region is not changed.

Moves the region by adding a TPoint offset to the co-ordinates of its corners.

The size of the region is not changed.

Gets a pointer to the array of rectangles defining this region.

TRegion::Count

Ensure that the region is big enough to hold aCount rectangles.

After an RRegion's iCount has reduced try to release some memory. Hysteresis rule: reduce allocated memory to iCount, but only if the released memory will also be at least the granularity.

Sorts the region's array of rectangles according to their vertical position on the screen.

The sort uses the bottom right hand corner co-ordinates of the rectangles. The co-ordinates of the top and left hand sides are irrelevant to the sort operation.

Higher rectangles take precedence over lower ones. For rectangles at the same vertical position, the leftmost takes priority.

Note that the sort order may need to be different from the default if, for example, a region is moved downwards so that lower non-overlapping rectangles need to be redrawn (and sorted) before higher ones. In this case, use the second overload of this function.

Sorts the region's array of rectangles according to a specified sort order.

The sort uses the bottom right hand co-ordinates of the rectangles. The co-ordinates of the top and left hand sides are irrelevant to the sort operation

The order of the sort is determined by whether the iX and iY members of aOffset are positive, or zero or less. If aOffset.iY is greater than zero, lower rectangles take precedence over higher rectangles in the list order. Otherwise, higher rectangles take precedence. For rectangles of equal height, aOffset.iX becomes relevant to the sort. If is greater than zero, rightmost rectangles take precedence. Otherwise, leftmost rectangles take precedence.

Note that the sort order may need to be different from the default if, for example, a region is moved downwards so that lower non-overlapping rectangles need to be redrawn (and sorted) before higher ones.

Removes a rectangle from this region.

If there is no intersection between the rectangle and this region, then this region is unaffected.

Removes a region.

If there is no area of intersection between the two regions, this region is unaffected.

Removes a region.

If there is no area of intersection between the two regions, this region is unaffected.

Merges all rectangles within this region which share an adjacent edge of the same length.

The function subsequently checks for allocated but unused memory, if this memory is at least as large as the granularity it is released to the system.

Replaces this region with the union of it and the specified region.

Note that if the error flag of either this region or the specified region is set, then this region is cleared and its error flag is set. This frees up allocated memory.

Gets a rectangle from the region.