Working With Images

Category: User Interface

Problem

How to store images in a table and retrieve and display them.

Ingredients

Image, ImageControl, OpenImageControl, AccessControl, ImageFormat, Query1, OpenFileControl

Recipe

The easiest way to handle images with Suneido is to use Image. Image uses the Windows OleLoadPicture, which handles bmp, gif, jpg, ico, emf, and wmf images (but not png). However, normally you won't want to use Image directly; you'll want to use the classes that are built on top of Image.

ImageControl

Displays an image on the screen.

OpenImageControl

Displays an image on the screen and allows the user to choose an image from a file.

ImageFormat

Prints an image on a report.

For example, to display an image file using ImageControl:

Window(#(Image 'c:/windows/clouds.bmp'))

Note: Depending on which version of Windows you are running, you may need to use different file names to make these examples work.

Or to allow choosing the image with OpenImageControl:

Window(#(OpenImage xmin: 200, ymin: 200))

You can use an Access Control to create and view images in a table. First, create a table. Enter and run this from QueryView:

create imagetable (image_name, image_field) key(image_name)

Then enter this in a library (e.g. mylib) as My_ImageAccess:

#(Access
    'imagetable'
    (Form
        (image_name)
        (image_field))
    )

You will also need Field_ definitions:

Field_image_name
Field_string
    {
    Prompt: 'Image Name'
    }

Field_image_field
Field_string
    {
    Prompt: ''
    Heading: 'Image'
    Control: (OpenImage xmin: 200 ymin: 200)
    }

Now you should be able to run it with:

Window(My_ImageAccess)

Add an image to the table with a name of "sample". You can then retrieve and display an image from the table using Query1 and ImageControl. For example:

imagename = "sample"
x = Query1("imagetable where image_name is " $ Display(imagename))
Window(Object("Image", x.image_field))

Discussion

Images can be stored in tables in two ways.

The first way is to store the actual image in the table. A string containing image information will be stored in the table. If you look at the "imagebook" table, for example, in Query View, you will see that it contains several images. The name of the image is stored in the name field. The actual image is in the text field.

The second way is to store the path to the image. If the image to be displayed was always going to be in the same place, the path can be stored instead of the actual image (e.g. "C:\WINDOWS\Clouds.bmp").

ImageControl can be used to display images that are stored as a path or as the actual image. OpenImageControl uses a combination of ImageControl and OpenFileControl. By double-clicking on the image, the user is allowed to browse to an image file that they would like to choose. They can also select whether the path to the image or the actual image should be stored.