Class CellBuffer

A detached copy of a rectangular block of cells, used by effects that need to remember what a region looked like before they started writing to it.

Inheritance
object
CellBuffer
Inherited Members
Namespace: Scylla.TextMode
Assembly: ScyllaTextMode.dll
Syntax
public sealed class CellBuffer
Remarks

Buffers are rented from and returned to a TextModeEffectPlayer rather than allocated per effect, because effects are started and restarted often and a full-screen region is a few thousand cells. A rented buffer keeps whatever capacity it grew to, so repeated use of the same region size stops allocating entirely.

Cells are copied whole, including the packed atlas and metrics fields that GlyphAtlasCache stamped into them. An effect that only moves or recolors existing content therefore needs no glyph cache at all: it can copy captured cells straight back into the grid.

Properties

Capacity

Gets the allocated capacity in cells, which may exceed CellCount after the buffer has been reused for a smaller region.

Declaration
public int Capacity { get; }
Property Value
Type Description
int

CellCount

Gets the number of cells currently held.

Declaration
public int CellCount { get; }
Property Value
Type Description
int

Columns

Gets the number of columns currently held.

Declaration
public int Columns { get; }
Property Value
Type Description
int

Rows

Gets the number of rows currently held.

Declaration
public int Rows { get; }
Property Value
Type Description
int

Methods

Blit(CellGrid, int, int)

Copies this buffer back into a grid at the given position, marking the affected rows dirty.

Declaration
public void Blit(CellGrid grid, int row, int column)
Parameters
Type Name Description
CellGrid grid

The grid to write into.
int row

Row index the buffer's top edge lands on.
int column

Column index the buffer's left edge lands on.
Remarks

Rows and columns that fall outside the grid are skipped, so a buffer may be written at a position that only partly overlaps the grid without further bounds checks.

Capture(CellGrid, in CellRect)

Copies a region of a grid into this buffer, resizing it to match.

Declaration
public CellRect Capture(CellGrid grid, in CellRect region)
Parameters
Type Name Description
CellGrid grid

The grid to read from.
CellRect region

The block of cells to copy.
Returns
Type Description
CellRect

The clamped region that was actually captured.
Remarks

The region is clamped to the grid first, so the buffer ends up holding only cells that actually exist. Check Rows and Columns afterwards to learn what was captured.

Clear()

Marks the buffer as holding nothing, without releasing its capacity.

Declaration
public void Clear()

GetCell(int, int)

Reads a single cell from the buffer by its position within the captured region.

Declaration
public Cell GetCell(int localRow, int localColumn)
Parameters
Type Name Description
int localRow

Row index relative to the buffer's top edge.
int localColumn

Column index relative to the buffer's left edge.
Returns
Type Description
Cell

The cell, or a default cell when the coordinate lies outside the buffer.

Resize(int, int)

Grows the buffer if needed so it can hold a region of the given size, and adopts that size.

Declaration
public void Resize(int rows, int columns)
Parameters
Type Name Description
int rows

Number of rows required.
int columns

Number of columns required.
Remarks

Existing contents are not preserved. Call Capture(CellGrid, in CellRect) after resizing.

SetCell(int, int, in Cell)

Writes a single cell into the buffer by its position within the captured region.

Declaration
public void SetCell(int localRow, int localColumn, in Cell cell)
Parameters
Type Name Description
int localRow

Row index relative to the buffer's top edge.
int localColumn

Column index relative to the buffer's left edge.
Cell cell

The cell to store.

TrimCapacity()

Releases the backing storage so a pathologically large buffer does not stay resident.

Declaration
public void TrimCapacity()