-- File: BitMap3dImpl.mesa
-- Last edited by Bier on December 18, 1982 1:41 am
-- Author: Eric Allan Bier on June 16, 1982 10:33 am
-- Contents: calls to GraphicsExtra.mesa to double buffer graphics

DIRECTORY
    BitMap3d,
    Graphics,
    GraphicsOps,
    ViewerClasses;
    
BitMap3dImpl: PROGRAM IMPORTS Graphics, GraphicsOps EXPORTS BitMap3d =
BEGIN

BitmapRef: TYPE = REF READONLY BitmapRep;
BitmapRep: TYPE = GraphicsOps.BitmapRep;

Viewer: TYPE = ViewerClasses.Viewer;

AlternateDisplayContext: TYPE = REF AlternateDisplayContextObj;
AlternateDisplayContextObj: TYPE = BitMap3d.AlternateDisplayContextObj;
-- RECORD [
    -- dc: Graphics.Context,
    -- bitMap: BitmapRef];
    
DrawAltDisplayContext: PUBLIC PROC [dc: Graphics.Context, altDC: AlternateDisplayContext] = {
    Graphics.SetCP[dc,0,0];
    GraphicsOps.DrawBitmap[dc, altDC.bitMap,
                                    altDC.bitMap.width, altDC.bitMap.height,
                                    0,0,
                                    0,altDC.bitMap.height];
    };
                                    
GetAltDisplayContext: PUBLIC PROC RETURNS [altDC: AlternateDisplayContext] = {
    bitMap: BitmapRef _ GraphicsOps.NewBitmap[10, 10];
    dc: Graphics.Context _ GraphicsOps.NewContextFromBitmap[bitMap];
    altDC _ NEW[AlternateDisplayContextObj _ [
        dc: dc,
        bitMap: bitMap]];
    };
    
ResizeBitMap: PUBLIC PROC [viewer: Viewer, altDC: AlternateDisplayContext] = {
    newBitMap: BitmapRef _ GraphicsOps.NewBitmap[viewer.cw, viewer.ch];
    GraphicsOps.SetTargetBitmap[altDC.dc, newBitMap];
    altDC.bitMap _ newBitMap;
    };
    
Erase: PUBLIC PROC [altDC: AlternateDisplayContext] = {
    mark: Graphics.Mark _ Graphics.Save[altDC.dc];
        Graphics.SetColor[altDC.dc, Graphics.white];
        Graphics.DrawBox[altDC.dc,Graphics.GetBounds[altDC.dc]];
        Graphics.SetColor[altDC.dc, Graphics.white];
        Graphics.Restore[altDC.dc,mark];
    };    -- end of Erase
    
END.