Device-Transformation Matrix

To directly manipulate the device-transformation matrix it is necessary for applications to know the following values:

X1

the x-coordinate of the lower-left corner of the page viewport
Y1
the y-coordinate of the lower-left corner of the page viewport
X2
the x-coordinate of the upper-right corner of the page viewport
Y2
the y-coordinate of the upper-right corner of the page viewport
XPS
the presentation-space width -1
YPS
the presentation-space height -1.

The device-transformation matrix is defined as:

  ┌────────────────────────────────────┬──────────────────────────────┐  │  The device-transformation matrix: │  where:                      │
  │  ┌                 ┐               │                              │
  │  │ Msub11  0     0 │               │ a = (Xsub2-Xsub1)/(Xps+1)    │
  │  │  0     Msub22 0 │               │                              │
  │  │ Msub31 Msub32 1 │               │ b = (Ysub2-Ysub1)/(Yps+1)    │
  │  └                 ┘               │                              │
  │                                    │ c = Xsub1+(a-1)/2            │
  │                                    │                              │
  │                                    │ d = Ysub1+(b-1)/2            │
  │                                    │                              │
  └────────────────────────────────────┴──────────────────────────────┘

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