Handling pictures

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4D v18

4D Write Pro Reference

Handling pictures

Adding pictures

Adding pictures to a 4D Write Pro document can be accomplished in multiple ways and depend on your needs:

to add a background picture, use the wk background image or wk background image url attribute with the WP SET ATTRIBUTES command
to add an inline picture, i.e. inserted in the text flow just like a character, use the WP INSERT PICTURE or the ST INSERT EXPRESSION command
to add an anchored picture in the page (behind or in front of the text), use the WP Add picture command.

The way you add a picture determines the layer it is positioned in, as illustrated in the diagram below:

Background pictures

Pictures can be set as the background of 4D Write Pro documents and document elements (tables, paragraphs, sections, headers/footers, etc.).

Here is an example showing two different ways a picture can be used as a document's background:

Background pictures can be set either programmatically or via the context menu. For more information, see the Background section in the Using a 4D Write Pro area article.

Positioning and displaying of anchored pictures

Anchored pictures are added with an absolute position, in front of/behind text, as well as anchored to the page or specific parts of a document (i.e., header, footer, sections). Setting an absolute position for a picture is accomplished with the WP Add picture and WP SET ATTRIBUTES commands.

Anchored picture positions can be modified with the following specific attributes and/or standard actions:

Property (constant)	Standard action
wk anchor layout	anchorLayout
wk anchor horizontal offset
wk anchor horizontal align	anchorHorizontalAlign
wk anchor vertical offset
wk anchor vertical align	anchorVerticalAlign
wk anchor origin	anchorOrigin
wk anchor page	anchorPage
wk anchor section	anchorSection
	moveToBack
	moveToFront

All anchored pictures are displayed in the Page view mode only. They're not displayed if:

they are anchored to a header or footer which is not visible;
the view mode is Draft;
they are centered or anchored to sections and the Show HTML WYSIWYG option is checked;
the "Show background" option is not selected.

Picture expressions

You can insert 4D expressions that return pictures in your 4D Write Pro areas. Expressions can be variables, fields, project methods(*), object attributes or collection elements.

(*)Keep in mind that calling a 4D project method as an expression requires that the method has been explicitly allowed beforehand (see Managing expressions).

You can see an expression's reference in the picture tip(*):

(*)As there is no text associated with an anchored image, its expression reference cannot be displayed.

All image attributes can be applied to picture expressions (wk image and wk image url attributes can only be read). Note however, that since pictures have specific attributes, 4D Write Pro must evaluate the expression at least once to detect that its result is a picture and handle it as a picture expression. It means that when a picture expression is inserted with ST INSERT EXPRESSION, ST COMPUTE EXPRESSIONS must be called before setting any picture attributes.

If the image resulting from the expression could not be computed or loaded, 4D Write Pro displays the default black frame image:

Note: As with other expressions, picture expressions are also impacted by the ST COMPUTE EXPRESSIONS and ST FREEZE EXPRESSIONS commands.

Anchored pictures

Anchored picture expressions are added with the WP Add picture command (without the second parameter), followed by a call to the WP SET ATTRIBUTES command with the wk image expression selector.

Example:

 obImage:=WP Add picture(myDoc)

 WP SET ATTRIBUTES(obImage;wk image expression;"vpicture")

You can also insert picture expressions using WP SET ATTRIBUTES and wk image expression on existing anchored pictures.

Calling the WP RESET ATTRIBUTES command with wk image expression is similar to calling ST FREEZE EXPRESSIONS (on the entire document) in that the expression is cleared from the image attribute. However ST FREEZE EXPRESSIONS computes the expression before clearing, whereas WP RESET ATTRIBUTES does not. If an expression has never been computed, the default black frame image will be displayed.

Inline pictures

Inline picture expressions are added with the ST INSERT EXPRESSION command.

Examples:

  //Insert a picture variable

 ST INSERT EXPRESSION(*;"WParea";"vPicture";ST Start highlight;ST End highlight)

 

  //Insert a field

 ST INSERT EXPRESSION(*;"WParea";"[DOC]SamplePict";ST Start highlight;ST End highlight)

 

  //Insert a 4D method

 ST INSERT EXPRESSION(*;"WParea";"M_ComputeChart";ST Start highlight;ST End highlight)

Picture properties

All pictures have properties (attributes) such as height, width, borders, etc., that can be get or set via the 4D Write Pro language (WP GET ATTRIBUTES and WP SET ATTRIBUTES) or standard actions.

The full list of properties available for pictures is provided on the 4D Write Pro Attributes page.
The Image section contains attributes that are specific to pictures only.
The Using 4D Write Pro standard actions page also lists available image properties.

Picture reference or picture URL

You can work with picture references (picture variables, fields, expressions) or picture URLs (text representing a local or network address of the picture).

Two sets of attributes allow you to define if you want to set or get picture reference or a picture URL:

wk image, wk background image, wk list style image: to set or to get picture references.
When you get a picture using one of these attributes, you receive a 4D picture, no matter how the picture was defined.
wk image url, wk background image url, wk list style image url: to set or get picture URLs.
When you get a picture using one of these attributes, you receive a text. If the picture was defined through a reference (e.g. a picture variable), you get a local URI followed by the image in Base64.

Example:

 $range:=WP Get selection(WPArea) //get the picture selected by user

 $range:=WP Picture range($range) //create a range

 $url:="http://doc.4d.com/image/logo/poweredby4D_web.png"

 

 WP SET ATTRIBUTES($range;wk image;$url) //set an image reference from a URL

 

  //get the image

 C_PICTURE(vPictureGet)

 WP GET ATTRIBUTES($range;wk image;vPictureGet) //vPictureGet contains an image

 C_TEXT(vPictureURLGet)

 WP GET ATTRIBUTES($range;wk image url;vPictureURLGet) //vPictureURLGet=$url

Retrieving pictures

The following commands can be used to return pictures:

WP Picture range - applies only for inline images
WP Selection range - applies only for user-selected images

Mouse/keyboard actions

Pictures can be manipulated via the mouse or the keyboard. Available actions include:

SELECT
- Pictures in the Front layer can be selected by clicking on them;
- Background pictures can be selected by CTRL+ clicking on it (Windows) or COMMAND+clicking on it (Mac);
- Only a single picture with an absolute position can be selected: multiple selection is not possible.

MOVE
- Pictures can be moved and resized using the mouse; (inline images cannot be dragged outside the document).

INSERT
- If pictures with an absolute position are pasted in Draft mode, they are displayed inline at the beginning of the current keyboard selection.

CUT/PASTE/COPY
- Pictures can be copied to the clipboard, or cut/pasted while selected.
- Pasting a picture with an absolute position in Page mode will paste the picture in the first selected page and anchor it to that page, no matter the original page anchoring settings; pasted pictures will retain their offsets, unless it is pasted into a different mode than the original (for instance if the picture is copied in Page mode and pasted in Embedded mode, the offsets are reset to 0).

DELETE -Pictures can be deleted while selected with the:
- DELETE key, or
- keyboard shortcut for the action Clear