DynaPDF Manual - Page 617

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Function Reference

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TSetFillColor

// Optional

It is possible to extract images without a graphics state. The destination width and height, the

output resolution, and the parallelogram into which the image would be drawn are already pre-

computed and can be taken from the sructure TPDFImage.

1 bit images require a special processing if the image is drawn as an image mask. This is the case if

no color table is present and if the member Transparent of the TPDFImage structure is set to true.

Non-zero pixels are are rendered in the current fill color while zero pixel values produce no output.

To simply processing the current fill can be taken from the structure TPDFImage.

The provided fill color is already converted to the specified device color space if one of the color

conversion flags is set (pfConvImagesToGray, pfConvImagesToRGB, or pfConvImagesToCMYK),

or it was converted to the nearest device color space.

If a graphics state is used then it should contain at least these variables:

Parameter

Type

Initial Value

FillColor

double[32] or UI32

Black (0)

FillColorSpace

TExtColorSpace, IColorSpace*

esDeviceGray, NULL (optional)

Matrix

TCTM

{1, 0, 0, 1, 0, 0}

The fill color can be stored as array of double if the original values are of interest or as unsigned

integer if colors are converted to a device space with ConvColor().

The visible size of an image, measured in user space, can be calculated from the current

transformation matrix as follows:

double x1 = 0.0;

double y1 = 0.0;

double x2 = 1.0;

double y2 = 0.0;

double x3 = 0.0;

double y3 = 1.0;

// m_GState represents the current graphics state

Transform(m_GState.Matrix, x1, y1); // lower left corner

Transform(m_GState.Matrix, x2, y2); // lower right corner

Transform(m_GState.Matrix, x3, y3); // upper left corner

// CalcDistance() is described at Helper Functions.

double w = CalcDistance(x1, y1, x2, y2); // Width in user space

double h = CalcDistance(x1, y1, x3, y3); // Height in user space

The above values are already pre-computed and can be taken from the structure TPDFImage.

An image can be used several times in a document, e.g. if it represents a logo or other repeating

contents. To avoid the extraction of unnecessay duplicates a duplicate check should be performed

before extracting an image. If the image is not an inline image, the member ObjectPtr of the structure

TPDFImage represents a unique pointer to the image object.

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