Displaying an Image

The LEADTOOLS methods for painting an image use four rectangles. Two of them, the source rectangle and the destination rectangle, determine how much an image is scaled (zoomed) when it is displayed. The other two, the source clipping rectangle and the destination clipping rectangle, determine which part of an image is painted. For a complete description of the rectangles, with illustrations, refer to the RasterImagePainter.Paint method. Other painting methods, which implement features such as transitional effects and region processing, use the same rectangles.

By default, LEADTOOLS will load images assuming that the horizontal and vertical resolution (DPI) of the image are the same. In the case of most fax images however, the horizontal resolution is typically twice its vertical resolution (for example 200 by 100). When these images are loaded, they will appear elongated if the image resolution is ignored. Set the Leadtools.Controls.ImageViewer.UseDpi property to true to take image resolution into account when displaying images with the ImageViewer. For printing, set the Leadtools.Controls.RasterImagePrinter.UseDpi property to true to account for image resolution. Use the Leadtools.WinForms.RasterImageList.UseDpi property to account for image resolution in a RasterImageList.

When painting an image with a display mode of 256 colors or less, you must specify the palette to use. To do so, refer to Handling Palette Changes.

You can zoom in on an image either by making the display rectangle larger or by making source rectangle smaller (so that it gets only a portion of the image). If you zoom in by making the source rectangle smaller, you must consider the view perspective of the image. For general information about the view perspective, refer to Accounting for View Perspective. LEADTOOLS offers additional options while displaying an image including transparency, dithering options, favor black, halftone, contrast, gamma, intensity, window-leveling and paint and transition effects.