ImagerBasic.mesa
This interface provides the public data structures shared by clients and the Imager.
Last Edited by:
Crow, Plass, Wyatt, July 6, 1983 2:38 pm
DIRECTORY Scaled USING [Value];
ImagerBasic:
CEDAR
DEFINITIONS
= BEGIN
Basic Definitions (Numbers and Shapes)
Pair: TYPE = RECORD [x, y: REAL];
IntPair: TYPE = RECORD [x, y: INTEGER];
Edge: TYPE = RECORD [a, b: Pair];
IntEdge: TYPE = RECORD [a, b: IntPair];
Rectangle: TYPE = RECORD [x, y, w, h: REAL];
IntRectangle: TYPE = RECORD [x, y, w, h: INTEGER];
Bezier: TYPE = RECORD [b0, b1, b2, b3: Pair]; -- Bezier control points for a cubic curve
Transformations
TransformType: TYPE = { none, identity, rot90, rot180, rot270, mirrorX, mirrorY, mirror45Deg, mirror135Deg, hard };
Transformation:
TYPE =
RECORD [
-- a transformation matrix
a, b, c, d, e, f: REAL, -- matrix elements
type: TransformType -- identifies special matrix forms
];
The form of the complete transformation matrix is:
a d 0
b e 0
c f 1
Clipping
Visibility: TYPE = {visible, partlyVisible, invisible};
Paths
A client of the Imager may keep a path representation in a form appropriate for its own use; it only needs to unravel it into a series of MoveTo, LineTo and CurveTo operations when it is asked.
Path: TYPE = REF PathRep;
PathRep:
TYPE =
RECORD [
generateProc:
PROC [
path: Path,
move: PROC [Pair],
line: PROC [Pair],
curve: PROC [Pair, Pair, Pair]
],
data: REF ANY
];
Masks
StrokeEnds: TYPE = {butt, square, round};
Colors
Color: TYPE = REF;
CIEColor: TYPE = REF CIEColorRep;
CIEColorRep:
TYPE =
RECORD [x, y, Y:
CARDINAL];
CIE Chromaticity coordinates
SampledColor: TYPE = REF SampledColorRep;
SampledColorRep:
TYPE =
RECORD [
transparent: BOOLEAN, -- are 0 samples white (false) or transparent (true)?
pa: PixelArray, -- the array of samples
m: Transformation, -- transforms from pa to device coordinates
colorMap: ATOM -- maps samples into colors
];
PixelArrays
PixelArray: TYPE = REF PixelArrayRep;
PixelArrayRep:
TYPE =
RECORD [
xPixels, yPixels: INT, -- dimensions of the array, in pixels, in standard coordinates ((0, 0) at lower left, y increasing upwards, x increasing to the right).
maxSampleValue: INT, -- the range of sample values is [0..maxSampleValue]
samplesPerPixel: INT, -- number of samples for each pixel
get:
PROC [
self: PixelArray,
buffer: PixelBuffer,
object implementation fills this with the requested number of samples.
nSamples:
NAT,
number of samples to put in buffer.
layer:
INT,
in the range [0..samplesPerPixel)
xStart, yStart: Scaled.Value,
position of first sample.
xDelta, yDelta: Scaled.Value
increment to get to successive samples.
],
data:
REF
ANY
for use by the get proc; some devices may discriminate on this REF to get at the representation directly, if they are able to recognize it.
];
PixelBuffer: TYPE = REF PixelBufferRep;
PixelBufferRep:
TYPE =
RECORD [
SEQUENCE maxLength: NAT OF CARDINAL
];
END.