Retrieving documents coming from Twain devices

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Retrieving documents coming from Twain devices

Overview

Definition

Principle

Related examples

See also

Retrieving documents coming from Twain devices

Overview

Several WINDEV functions allow you to retrieve documents from a Twain device. Twain is a standard used by the devices for capturing images.

Examples of devices supporting the Twain standard:

scanner,
web camera,
digital camera.

When installing a Twain device, specific DLLs are installed: the DLLs for managing the Twain layer. These DLLs are required to use the TWAIN functions of WLanguage.

Definition

Which document is retrieved?

When using TWAIN functions, the retrieved document corresponds to:

the document found in a scanner.
the image broadcasted by a "web camera".
the first photo saved in a digital camera.
Remark: If the user interface is used, the document retrieved will correspond to the photo selected by the user. If several photos are selected, only the first selected photo will be retrieved.

User interface

The functions for retrieving a document are used to:

program how the document will be retrieved.
start the user interface of the Twain device used. The user interface corresponds to the main window of the software associated with the Twain device. This interface allows you to save the document, change the default settings of the device, etc, ... The available actions depend on the device used.

Principle

Retrieving a document coming from a Twain device

To retrieve a document coming from a Twain device:

Define (if necessary) the Twain device to use:


TwainCurrentSource	Allows you to find out and change the Twain device used by default.
TwainListSource	Returns the list of drivers for the Twain devices connected to the current computer.
TwainSelectSource	Displays a standard dialog box used to list the different Twain devices available on the current computer.

If the Twain device used corresponds to a scanner, the area to scan can be defined by TwainScanArea.
Retrieve the width and height of the document to capture (by a Twain device).
TwainSourceHeight Returns the height (in millimeters) of the document captured by a Twain device.
TwainSourceWidth Returns the width (in millimeters) of the document captured by a Twain device.

Retrieve the document coming from a Twain device.


TwainToBMP	Allows you to perform one of the following actions: save the document coming from the Twain device in a Bitmap file (".BMP" extension). view the document coming from the Twain device in the user interface of the device. save the document coming from the Twain device directly in memory in Bitmap format (in a buffer).
TwainToClipboard	Allows you to: copy the document coming from the Twain device into the clipboard. view the document coming from the Twain device in the user interface of device.
TwainToControl	Allows you to : view the document coming from the Twain device in an Image control. view the document coming from the Twain device in the user interface of device.
TwainToGIF	Allows you to: save the document coming from the Twain device in a GIF file. view the document coming from the Twain device in the user interface of device. save the document coming from the Twain device directly in memory in GIF format (in a buffer).
TwainToJPEG	Allows you to: save the document coming from the Twain device in a JPEG file. view the document coming from the Twain device in the user interface of device. save the document coming from the Twain device directly in memory in JPEG format (in a buffer).
TwainToPDF	Allows you to: save the document coming from the Twain device in a PDF file. view the document coming from the Twain device in the user interface of device. save the document coming from the Twain device directly in memory in PDF format (in a buffer).
TwainToTIFF	Allows you to: save the document coming from the Twain device in a TIFF file. view the document coming from the Twain device in the user interface of device. save the document coming from the Twain device directly in memory in TIFF format (in a buffer).

Remark: These functions can also be used to start the user interface of the Twain device used. You have the ability to specify whether the scanner must use the "duplex" mode.

Managing the duplex scanners

If the scanner supports the duplex mode, you have the ability to perform a double-sided scan. The generated document contains both sides of the scanned document.

Remark: Depending on the hardware used, the Twain driver may not be sufficient to support a double-sided scan. You may have to install additional drivers supplied by the manufacturer.

Operating mode in the 64-bit applications

In a 64-bit application, this function will automatically use the 64-bit Twain driver. The TWAIN cannot be used if this driver is not installed.

Related Examples:

Unit examples (WINDEV): TWAIN: digitizing

[ + ] Using a Twain device (scanner, digital camera, etc.):
- Select the device used
- Digitize a document in file format (BMP, GIF or JPEG)
- Digitize a document and display it in an Image control
- Digitize a document and store it in the clipboard

Sample components (WINDEV): WD Photocopier

[ + ] The Photocopier component enables you to photocopy documents via a scanner and a printer. The scanner must be Twain-compatible in order for the component to operate.
This component can be used in two modes:
- With an interface used to define some parameters such as the lightness or the number of copies.
- Without interface. The parameters of the computer will be used by default. You also have the ability to pass custom parameters